Freezing Rain Risk Threatens to Disrupt the Tuesday Morning Commute Across Southern Ontario

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The weather story across Southern Ontario throughout the weekend has been dominated by what most would consider as ‘perfect’ winter weather. While the temperature was colder than we’ve been used to this winter, it was accompanied by a rare sight - the sun! As we start the week, our attention will turn to the potential for freezing rain starting early Tuesday morning and lingering throughout the afternoon.

The overall severity of this freezing rain event is expected to be fairly minor with 2-4mm of ice accretion at most. However, the main concern will be because of the timing as it collides with the busy morning commute throughout the GTA. This is certainly enough ice to create slick driving conditions out on the roads, especially on untreated surfaces. As a result, expect travel delays on Tuesday and potentially even some school bus cancellations.

We will start to see patchy freezing rain move into our region just after midnight starting with Southwestern Ontario as it slowly progresses to the northeast. Locations such as London and parts of Grey-Bruce counties could see a few hours of freezing rain before switching over to rain. Those closest to the Lake Huron shoreline and the Windsor/Chatham region should remain above the freezing mark throughout this event.

By the mid-morning hour just before dawn, an expansive band of freezing rain is expected to stretch through Kitchener-Waterloo and across the GTA. Several hours of freezing rain lingering into the late morning hours is likely, especially in higher elevations like Guelph and Orangeville. Freezing rain will transition to rain by the noon hour with those closest to the shoreline such as Downtown Toronto seeing a quicker switchover. Total accretion of a few millimetres is possible away from the lakeshore.

The heaviest freezing rain is expected across southern parts of Central and Eastern Ontario including Barrie, Muskoka, Peterborough and Kingston. Freezing rain will start by the late morning with the worst conditions during the early afternoon. This is where we believe that some regions will pick up more than just a glazing of ice with up to 5mm of accretion possible. Those in the Ottawa Valley will see the freezing rain start later in the afternoon and lingering into the evening and will be overall lighter so accretion will remain under 2mm.

Precipitation will come to an end by the evening across Southern Ontario although scattered flurries may continue overnight into Wednesday as temperatures hover around the freezing mark. More messy weather is possible to end off the week on Thursday and Friday with another system bringing the risk of freezing rain and accumulating snow. More details on that in the coming days as we get closer.

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Update: Heavy Freezing Rain Risk Extended Southeast, Eastern Newfoundland Impacts Increased

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After reviewing the latest model data, we've updated our freezing rain forecast to reflect a southeast shift in the heaviest precipitation and to include additional freezing rain expected for Monday morning.

Corner Brook and Deer Lake will still get significant ice accretion, but it is a bit less than originally expected. From Gander, through Terra Nova, to Clarenville can now expect to impacted more by the storm.

Typically, 10mm of ice accretion from freezing rain is enough to damage trees and power lines. Beyond that, with 25+mm, we could be looking at extensive damage. Wind gusts appear to remain light through the day tomorrow and into Sunday morning, but will pick up by Sunday afternoon. Gusts will be in the 40-50km/h range and this could trigger additional damage to trees and power lines.

We've already begun to see some light freezing rain around Port aux Basques with the transition from snow to rain and in the early morning hours, there will be a pocket hitting the Corner Brook and Deer Lake area. It will spread south and east through the morning and by mid-afternoon, the heaviest freezing rain will start and it will last into overnight. The freezing rain will continue throughout the day Sunday and into Monday morning, but it will be focused over Central and Eastern Newfoundland, giving Western Newfoundland a reprieve.

Messy Winter Storm Takes Aim at Atlantic Canada This Weekend; Bringing Heavy Rain, Snow and Freezing Rain to Nova Scotia

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The next several days will be quite messy across Atlantic Canada with a major winter storm bringing rain, freezing rain, and snow to the region beginning tomorrow morning. For Nova Scotia, the big story from this storm will be widespread heavy rain with 30-50mm expected to fall over the next two days.

The storm will start off as snow, beginning in the early hours of Friday in Western Nova Scotia and spreading eastward throughout the morning. The snow will only last for a couple of hours before transitioning to heavy rain. Yarmouth and Shelburne will likely avoid having snow and will rather have rain right from the start of the storm. Overall snow accumulation will be minor across most of the province with up to 10cm expected to fall in Cumberland County the Cape Breton Highlands. Any snow will quickly melt with the following rain and double digit temperatures.

The steady rain will continue into the afternoon and we’re expecting a brief period of clearing before picking back up again in the evening lasting through to Saturday afternoon. Saturday morning is when we’re going to see the heaviest rain to start in the west and it will reach Cape Breton Island by early afternoon. After several hours of this heavy rain, things will begin to clear up in the late afternoon and early evening. Up to 50mm of rain will fall across Nova Scotia by Saturday evening and there could be higher amounts locally.

On Saturday afternoon, the temperatures will be hovering around 0° in Northern Nova Scotia and there is the threat of freezing rain. Untreated surfaces may become icy quite quickly so be cautious when travelling in the area.

The strongest winds from this storm will be felt with the heavy rain tomorrow afternoon. Along coastal areas, wind gusts will be in the 70-80 km/h range while further inland, expect 60-70 km/h. The exception will be Les Suêtes winds which may be up to 100 km/h and possibly higher.

A second round of precipitation will move in from the south overnight Saturday and may bring widespread freezing rain across the province on Sunday. We will provide further updates on that possibility on Saturday.

Winter Storm to Dump Up to 15-25cm of Snow on Eastern Ontario Between Thursday and Friday

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UPDATED FORECAST

ISSUED: Thursday, Jan. 12, 2023 (3:00 PM)

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Eastern Ontario continues to be in the bullseye with the highest snowfall totals of this event. However, the latest model data indicates that this system will be weaker than expected and that the overall totals will be lower and more localized to eastern parts of the province.

Based on this change in the data, we have adjusted our forecast by reducing the highest totals from this event down to 15-25cm which encompasses much of the Ottawa Valley. The heaviest snow is still expected to fall during the overnight hours into Friday morning. Snowfall accumulation above 10cm will be mainly found in Eastern Ontario as we have significantly decreased the expected totals around Georgian Bay and Lake Simcoe.

Around 5-10cm of snow is possible from York Region through Peterborough and into Kingston. The Hamilton and Niagara region may also pick up locally near 10cm with lake enhancement off Lake Ontario. Less than 5cm is expected for the rest of Southern Ontario.

ORIGINAL FORECAST

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The start of 2023 has been fairly unnoteworthy when it comes to the weather across Southern Ontario thanks to a mild stretch of temperatures. However, that has come to an end with the arrival of much cooler air this week and a potential winter storm on the horizon over the next few days. We are watching a system expected to affect Southern Ontario starting early Thursday with the risk of freezing rain across Central and Eastern Ontario throughout the day. Later on Thursday, the temperature will drop allowing for the precipitation to transition over to heavy snow. This heavy snow will linger overnight and into Friday which could result in significant accumulation, particularly in parts of Eastern Ontario with up to 25-40cm of snow possible.

The precipitation associated with this system will come in two separate waves starting with the first round of light to moderate precipitation just after midnight tonight. For Southwestern Ontario and the GTA, the main precipitation type will be rain while we see some freezing rain mixing in further north around the Dundalk Highlands and Lake Simcoe. A few hours of icing is possible throughout the morning hours for Orangeville, Barrie, Orillia, Muskoka, Kawartha Lakes and Haliburton. By the late morning, the freezing rain will taper off and either switch over to some wet snow or drizzle as the first round of precipitation moves out. Those in the Ottawa Valley will remain on the cold side of this system and see mainly snow during the early part of Thursday.

Later on Thursday during the afternoon, we will see the second wave of precipitation move into the region starting with the Niagara region and GTA. Moderate to heavy rainfall will be ongoing extending into the evening in this area as the system tracks to the northeast. By the evening, the upper edge of the precipitation will reach Eastern Ontario and clash with the colder air. As a result, there is the potential for some freezing rain during the evening throughout the Ottawa Valley.

Overnight the colder air will become more entrenched throughout Central and Eastern Ontario allowing for precipitation to transition over to heavy snow after the midnight hour. The most intense snowfall rates will be found just west of Ottawa over the Pembroke and Renfrew region. All areas of Southern Ontario will see some snow during the morning on Friday once the switchover occurs but we expect less snow further to the west where less moisture is present. Lake enhancement off Georgian Bay and Lake Ontario could result in locally higher totals in the Collingwood and Hamilton regions.

All precipitation will come to an end by Friday evening as the system moves out of the region.

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The overall impacts of the freezing rain are expected to be fairly minor due to the limited timeframe and precipitation intensity. We are looking at total ice accretion up to 2mm extending from the Dundalk Highlands and through Central and Eastern Ontario (away from the Lake Ontario shoreline).

Our main focus with this winter storm will be on the potential significant snowfall totals that parts of the Ottawa Valley could pick up by the end of Friday. Current indications suggest the total accumulation will range from 25-40cm for the Renfrew and Pembroke regions. Slightly lower totals are expected throughout the rest of the Ottawa Valley including the city itself picking up around 15-25cm of snow.

For other parts of Eastern Ontario and much of Central Ontario, snowfall totals will approach somewhere between 10 to 20cm although there is some uncertainty due to the extent of the moisture further west. It’s possible some areas around Georgian Bay and Northeastern Ontario could struggle to reach 10cm in total accumulation.

Regions around the Golden Horseshoe will see a general 5-10cm of accumulation, but we could see locally higher totals along the southern Lake Ontario shoreline around Hamilton due to lake enhancement pushing totals close to 15cm. Less than 5cm is expected in Southwestern Ontario where rain will be the main story.

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Midweek System to Bring a Wintery Mix to Parts of Southern Ontario With Prolonged Freezing Rain and Heavy Snowfall

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updated fORECAST

Issued: Wednesday, January 4, 2023 - 1:30 PM

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Based on the latest model data, there has been a shift in the location of the heaviest freezing rain due to the cold air not making it as far south as initially expected. We have updated our forecast to reflect these latest trends in the models.

This now puts the Ottawa Valley and northern parts of Central Ontario in the bullseye for the heaviest freezing rain accretion. The expected impact for the Kawartha Lakes and Kingston region will be lower as they will see more rain instead of prolonged freezing rain.

In addition to the shift in freezing rain risk, we have bumped up the expected ice accretion from 6-12mm to 8-16mm in the hardest-hit regions. This amount of ice is approaching the threshold that we would consider to be significant. However, the limited timeframe of 12-16 hours with freezing rain should limit the worst impacts compared to a more prolonged event. Power outages and icy road conditions will still be a big concern throughout the day and especially into the overnight hours when the freezing rain will be the most intense.

For those further north including Sudbury and North Bay, the story will be a mix of snow and ice pellets. And the rest of Southern Ontario will see between 15-30mm of rain by the end of Thursday.

PREVIOUS fORECAST

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The rollercoaster of a season that has been this winter across Southern Ontario continues after the brief taste of weather we normally see in late fall or early spring rather than in January. This will come in the form of a messy winter system moving across our region over the next few days. Depending on the location, we could be looking at a fairly prolonged period of freezing rain late Wednesday into early Thursday morning for Central and Eastern Ontario. Further north, the story will be a mix of ice pellets and heavy snow with up to 10-25cm of total accumulation.

The impacts from this system will be less of a concern for Southwestern Ontario and the GTA where temperatures will stay above the freezing mark and keep the predominant precipitation type as rain. With rainfall totals ranging from 10 to 25mm, it could pose an issue in areas prone to flooding with the ground being partially frozen and unable to absorb a lot of moisture. This is especially true with all the rainfall that these areas have already received in the past week. There could even be the risk of an isolated non-severe thunderstorm towards the Lake Huron shoreline this evening.

Precipitation in the form of rain is already ongoing throughout the region as of Tuesday afternoon. As temperatures slowly drop late in the evening and overnight, we will see some areas transition over to freezing rain starting with the higher elevations of the Dundalk Highlands and over Algonquin Park. For the overnight and into Wednesday morning, the wintery precipitation will be primarily contained to those regions.

By the afternoon on Wednesday, the below-freezing temperatures will clash with the system over Eastern Ontario leading to the development of an expansive and heavy band of freezing rain. This will start with the Bancroft and Ottawa Valley area during the afternoon and expand southward towards the Kawartha Lakes and Kingston region by late Wednesday. Those on the northern edge of the freezing rain including Algonquin Park, Bancroft and Ottawa will see some ice pellets and wet snow mixing in with the freezing rain by the evening.

The heaviest freezing rain is expected to occur during the overnight hours on Wednesday and early Thursday morning through Peterborough and Kingston along with the Orangeville region. Precipitation will slowly come to an end by the late morning hours on Thursday as the system moves out of the province.

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In terms of the overall impact of this system, it will likely be from the prolonged freezing rain in locations such as Shelburne, Orangeville, Peterborough, Tweed, Kingston and Brockville. Total ice accretion here will range from 6-12mm in the hardest hit regions although some ice pellets mixing in along the northern edge could reduce the actual accumulation. This amount of ice could lead to icy road conditions along with localized power outages and tree damage. Kingston and Brockville in particular could see the worst impact from the freezing rain with some models pointing to upwards of 15mm of ice accretion.

As you go further north, the focus will shift to ice pellets and heavy snow throughout Muskoka, Algonquin Park and the Ottawa Valley. Total accumulation will be hard to measure in this area due to the mix of precipitation but it certainly could cause some poor road conditions. Accumulating snow is possible for Northeastern Ontario with between 10-25cm of snow.

Those regions just to the north of the GTA around Lake Simcoe and into the northern shoreline of Lake Ontario could see some brief freezing rain with 2-6mm of ice accretion. The rest of Southern Ontario will stay on the warm side of this system seeing rainfall totals between 10-25mm.

Blizzard Continues in Parts of Southern Ontario Through Christmas Eve With Up to an Additional 50cm of Snow

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'Twas the night before Christmas, when all through the house
Not a creature was stirring, not even a mouse;
because they have been buried in the snow…

It certainly has been an eventful start to the holidays across Southern Ontario after a major winter storm brought much of the region to a standstill over the past 48 hours. From flash freeze and heavy snow to damaging wind gusts, we’ve seen everything from this storm that continues to hammer parts of the traditional snowbelt with crippling blizzard conditions. These conditions have resulted in many road closures in the hardest-hit areas and emergency officials are asking people to stay off the road.

We are now approaching the night before the big day and the snow squalls that have buried regions east of Lake Huron and Georgian Bay along with the Niagara and Kingston regions refuse to let up. The relentless snow squall activity will continue to lead to rapid snowfall accumulation for the areas that have already been hardest hit. Parts of Grey, Bruce, Huron and Perth counties east of Lake Huron in addition to Muskoka east of Georgian Bay have seen snow drifts approach 100cm. And as the snow squalls continue overnight into Christmas morning, we expect to see an additional 25-50cm of snow on top of what has already been received. Meaning that the final snowfall totals for this weekend could be well over 100cm in some areas!

Overnight we do expect to see somewhat of a break for regions to the northeast and east of the lakes with the snow squalls drifting southward by morning. This will bring the snow squall threat down into regions southeast of Lake Huron and Georgian Bay including northern Simcoe County and Kawartha Lakes. The lake effect snow off Lake Erie and Lake Ontario should shift south of the border after pummeling the Fort Erie and Prince Edward County regions. Squalls will continue throughout Sunday with this primarily northwesterly flow although they may drift back north towards the end of the day. It looks like the snow squalls will remain ongoing into Monday although the exact locations impacted is unclear.

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As we have seen so far with this storm, the snowfall accumulation will be intense but very localized so not everyone will experience the ‘crippling’ conditions. And some locations that have yet to see these conditions are expected to have conditions worsen later tonight so don’t let your guard down just yet!

The highest totals still to come will extend from the Bruce Peninsula through Southern Muskoka and Northern Simcoe County where we are looking at an additional 30-50cm of snow by the end of Monday. Some localized pockets may even exceed 50cm and come close to 75cm depending on where the squall sets up and how long it locks in place.

A more widespread region will pick up around an additional 20-40cm of snow which includes the rest of Muskoka, Kawartha Lakes and regions east of Lake Huron. The K/W region along with Barrie and Peterborough is right on the bubble and could go either way so we’ve gone with a 10-25cm range here due to the low confidence in how far inland these squalls will make it. The accumulation gradient will be quite tight so surrounding regions will see little in terms of snowfall ranging from 5-15cm.

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The snow squall activity to the east through the Niagara and Kingston regions will be primarily a story for just this evening with bands shifting southward overnight. Regardless, we are expecting quite a heavy dumping of snow still ahead for Fort Erie and Prince Edward County seeing an additional 20-40cm (likely towards the lower end of this range). Port Colborne and Kingston will see around 10-25cm of more snowfall by the end of the weekend. And the surrounding locations including Welland, Belleville and Brockville will get 5-15cm of additional accumulation.

On behalf of the entire Instant Weather team, we would like to wish everyone a safe and happy holiday weekend!

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‘Crippling’ Blizzard to Put a Damper on the Holiday Weekend in Parts of Southern Ontario With Up to 100cm of Snow Possible

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As we approach the final days before Christmas, Mother Nature is set to deliver what has the potential to be a crippling blizzard for parts of Southern Ontario over the next few days. In addition to the blizzard risk in the traditional snowbelt, there is also the threat of strong wind gusts, a flash freeze and significantly colder temperatures. All these threats will combine to amplify this winter storm into a very serious situation across Southern Ontario. This has prompted Environment Canada to issue a blizzard warning mentioning the risk of a ‘Crippling’ blizzard and that ‘Travel will become dangerous and is not advised’.

The effects of this system have already started to be felt with a mix of rain, freezing rain and snow depending on your location. Precipitation will continue to build overnight and into Friday morning with temperatures hovering around the freezing mark. With rain ongoing throughout the morning, temperatures will start to plunge starting with Deep Southwestern Ontario just after midnight and reaching the GTA by late morning. Those in Eastern Ontario will see a switch over to regular rain as temperatures temporarily rise during the morning, but the temperature plunge will happen by the early afternoon.

While this normally wouldn’t be a big issue, the previous rainfall combined with the rapidly dropping temperature will cause the rain to turn to ice. Especially with how quickly the temperature will drop leaving little time for road crews to deal with the icy conditions. For example, Toronto will be around 4°C at 8 am, 2°C at 10 am, -5 at 12 pm and -8 by 2 pm. Over 12 degrees in temperature drop within 6 hours! Please exercise extreme caution out on the roads as black ice can be hard to spot. Stay home if possible or until several hours after the freeze to give time for road crews to clean up the roads.

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The other component of this complex storm will be the strong wind gusts developing as the system rapidly intensifies over the region. Based on the latest data there has been a slight decrease in the expected wind gusts, but we are still expecting a damaging wind storm. Winds will begin to pick up through the early afternoon hours and continue for the rest of the day and into the evening.

We expect the strongest wind gusts will be found in the Niagara region just off the northeastern shoreline of Lake Erie where gusts could approach or even exceed 110km/h. This is especially the case directly along the shoreline in locations like Port Colborne and Fort Erie. Outside of this area, strong wind gusts ranging from 80-100km/h will be a threat throughout Southwestern Ontario, the GTA and into Eastern Ontario. The strongest gusts will be found directly along the shorelines of Lake Huron, Lake Ontario and along the Dundalk Highlands where the 100km/h gusts are more likely while further inland will be closer to 80-90km/h.

With wind gusts this intense, we will likely see widespread power outages which may last for a prolonged period. The heavy snowfall accumulation and icy conditions will make it difficult for hydro crews to effectively restore power to everyone so it may take some time. Another danger would be the frigid temperatures expected over the weekend with the wind chill making it feel into the -20s by Saturday morning. Anyone without power could struggle to stay warm so be sure to have a plan in place should that occur.

These strong wind gusts will also pose a problem with the lake effect snow expected to develop on Friday resulting in widespread blizzard conditions in areas east of Lake Huron and Georgian Bay along with the Niagara region. Travel in those regions will likely become near impossible with highways closures almost certain due to reduced visibility and plows being unable to keep up with the intense snowfall rates. All travel should be avoided here until conditions improve as you don’t want to be stranded out in your vehicle with bitterly cold temperatures.

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Back to the snowfall story which could be quite serious for those that are impacted by snow squall activity over the weekend. With cold air firmly in place, the system stalled out and rotating over the region will be enhanced by some locally heavy lake effect bands of snow starting Friday afternoon. It appears that it will be primarily a westerly flow which means the lake effect snow will really focus on the Grey-Bruce region along with those in Muskoka and Parry Sound.

The system-related snowfall will begin to taper off overnight Friday, but the lake effect snow will continue and could even further intensify. Current model guidance suggests that a very prolific snow squall will set up across the Bruce Peninsula, going over Georgian Bay and coming back inland through around Port Carling and Bracebridge. The snow squall may remain locked in through that general region all the way through Saturday and into Sunday. While this will limit the impact to a smaller region, it will mean those who do see it is going to be pummeled by intense snowfall amounts.

Lake effect snow and localized snow squalls will also be ongoing east of Lake Huron. It currently appears that the lake effect snow here will come in the form of multiple weaker bands instead of one main intense squall. This doesn’t mean the impact will be less, in fact, it could be just as bad with stronger wind gusts expected in this area. And the overall impact will be more widespread rather than contained in one small zone as is the case east of Georgian Bay.

Snow squall activity will continue into Sunday with similar locations being impacted. In terms of accumulation, the ‘winner’ (if you can call it that) by the end of the weekend appears to be somewhere in the Muskoka region where data continue to point towards upwards of 100cm over the next 3 days. Now, this will be very focused and not the entire region will see crazy totals like this. But we believe somewhere within that area will pick up that much.

Those east of Lake Huron can expect around 50-75cm (maybe up to 100cm in some spots) of snow with lower amounts further inland. Important to note that the snowfall is spread throughout several days so accumulation over any given 24 hour period will max out at around 20-40cm.

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The other location set to receive a blast of snow is the southeastern tip of the Niagara region. This is thanks to a strong snow squall setting up Friday afternoon and continuing throughout the weekend. There is still some uncertainty on the extent of how much impact it will have on our side of the border. As this band will also bury Buffalo (for the second time this year) and the most intense parts could remain south of the border. Regardless those in Port Colborne and Fort Erie will likely see anywhere from 40-75cm with maybe as much as 100cm, particularly for the Fort Erie area.

Outside of the snowbelts, we are looking at 25-50cm of snow throughout Central and Eastern Ontario which will remain on the cold side of this system for the most part. Slightly lower totals are expected for Deep Southwestern Ontario and Northern GTA ranging from 15-30cm. And finally, the GTA including Hamilton, Toronto and right along the Lake Ontario shoreline should escape the worst when it comes to snowfall. We are currently looking at around 5-15cm by the end of the weekend for them.

For Christmas Day, the weather shouldn’t be that bad unless you are in the aforementioned areas receiving snow squall activity. However, roads could still be quite messy with ice and snow so be sure to drive according to the conditions if you must travel. Looking into next week, we see the risk of more lake-effect snow which we will be closely watching.

Please stay safe and stay home if you can!

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Potentially Historic ‘Nightmare Before Christmas’ Storm Threatens to Ruin Holiday Plans Across Southern Ontario

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We are watching what could be a life-threatening winter storm for Southern Ontario in the days before Christmas. You might be rolling your eyes reading this and thinking 'Oh yeah, another storm where we'll barely get anything'. And your skepticism is warranted as it has been quite a long time since we've experienced a storm of this scale.

However, it's important to emphasize that the particular dynamics of this upcoming storm are very concerning with the combined threat of a flash freeze, rapid drop in temperatures, destructive wind gusts and blizzard conditions. While there is still time for models to change, the confidence in this storm is quite high and you should be getting prepared now. We don't take a forecast like this lightly as it can cause a lot of stress, but it's a lot better to be prepared for the worst rather than being caught off guard.

The uniqueness of this storm has made us rethink our usual approach to forecasting a winter storm as the danger from this event isn't focused on one particular threat type (like heavy snow, wind or freezing rain). The concern is how the different threats will combine and help to maximize their impact on our region over the next few days. So we've decided to start our preliminary forecast with a regional look at the impact of this winter storm including the expected conditions on each day. We know many are trying to plan their holiday travel and that the timing of this event is what matters the most.

We have put together maps and forecast discussions for each region throughout Southern Ontario. We will still have our regular forecast maps including snowfall totals and maximum wind gusts, but the purpose of this is to provide a more holistic view of the impacts over the several days. Our full forecast will be released sometime late Wednesday or early Thursday.

IMPORTANT: There has been some confusion regarding the regional map. To clarify, the graphic on the right of each regional forecast is unrelated to the map. We have chosen to break down the impact and threat type by each day and went into detail about timing. The map shows the overall impact of this storm. We understand that using the same colour on the graphic and the map resulted in this confusion and we will be fixing it for future forecasts.

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For Southwestern Ontario, Thursday will start as the calm before the storm with temperatures near the freezing mark as you wake up in the morning. By the afternoon, temperatures will slowly rise into the low single digits along with some light rain moving into the region later in the afternoon. This rain will set the stage for our first hazard associated with this multi-day event when combined with an expected rapid temperature drop just after midnight and into Friday morning.

Temperatures will drop by 10-15 degrees in the span of a few hours resulting in a flash freeze throughout the region. Roads will likely become quite icy during the predawn hours on Friday. In addition to this, the rain will transition over to snow with more intense bands east of Lake Huron due to some lake enhancement of the system snowfall.

As the heavy snow continues with a particular focus on areas east of Lake Huron, the system will stall out over our region and rapidly intensify. This intensification will result in the development of some strong to damaging wind gusts ranging from 90-110km/h inland and even stronger directly along the shoreline.

Friday afternoon and evening are when we expect the worst conditions with gusty winds combined with heavy snow leading to blizzard conditions. Highway closures are almost certain and any non-essential travel should be avoided late Friday. The strong wind gusts will likely result in widespread power outages and make for a very dangerous situation with one of the coldest nights of the season so far on Friday. It will feel like into the -20s once you factor in the brisk wind chill. It's VERY important that you don't venture out in these conditions as when (not if) you get stranded in your vehicle, it will probably be a long time until emergency officials can get to you.

Snow squall activity will continue east of Lake Huron throughout Saturday and into early Sunday. This will likely lead to snowfall accumulation of over 50cm between Friday and Sunday for the Grey-Bruce region. The rest of Southwestern Ontario can expect around 15-30cm of snow by the end of the weekend. We hope that the power outages can be limited because Saturday and Sunday night appears to be just as cold making for one of the coldest Christmas in recent memory.

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Temperatures will start on a mild note throughout the GTA on Thursday as warm air flows in advance of the approaching system. Daytime highs are expected to approach the mid-single digits as the rain starts to move in by late Thursday afternoon. The mild air will hold on throughout the evening and overnight with heavy rainfall. Total rainfall accumulation of up to 10-20mm is possible by Friday morning. Temperatures are expected to take a plunge by the late morning and early afternoon dropping over 5-10 degrees in a few hours. With the ground still wet from the previous rainfall, there is a strong flash freeze risk as roads will become quite icy.

Rain will turn over to snow by Friday afternoon across the Golden Horseshoe as we see the increase in wind gusts later in the day. Damaging wind gusts approaching 90-110km/h (higher in the Niagara region off Lake Erie) are expected during the evening and overnight hours. Power outages are possible in the hardest hit regions along with poor driving conditions due to blowing snow and even localized blizzard conditions in the Niagara region.

Snow squalls will also develop off Lake Erie and further enhance the system snowfall for the Niagara region. The heaviest snowfall rates will be found right along the Lake Erie shoreline including Port Colborne and Fort Erie. Lake effect snow activity will continue throughout the day on Saturday and into Sunday while the system-related snowfall will taper off for the rest of the GTA by early Saturday.

Current data suggests that much of the GTA could end up in a dry pocket when it comes to snowfall accumulation. At this point, most of the GTA will see around 5-15cm of snow over the weekend. The only exception is the Niagara region which will see snow squalls pushing totals into the 20-40cm range over the weekend. Localized spots right along the Lake Erie shoreline may even pick up more than that!

The main danger from this storm in the Golden Horseshoe will be the flash freeze risk on Friday late morning along with damaging wind gusts. Those who lose power from the wind damage could stay in the dark for an extended period due to the widespread impact expected. This isn't a good situation with the wind chill making it feel into the -20s over the weekend so be sure to have a plan in place to stay warm! And of course, the Niagara region will be heavily impacted by the snow squalls burying them in lots of snow along with blizzard conditions. Travel should be avoided in this region until conditions improve.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

The forecast for Central and Eastern Ontario is quite complex as it will start on Thursday with temperatures slightly below the freezing mark. Temperatures will only rise to near the freezing mark during the afternoon as light snowfall approaches the region later in the day. Those along the Lake Ontario shoreline are expected to be slightly warmer which will allow them to see light rain instead of snow. Snow (rain near the Lake Ontario shoreline) will continue to intensify throughout the evening and overnight on Thursday.

By Friday morning, there could be a brief warm-up throughout Central and Eastern Ontario allowing for the snow to switch over to rain for a few hours. Temperatures are expected to plunge well below the freezing mark later in the day as colder air floods into the region. As a result, there is the risk of a flash freeze especially around the Lake Ontario shoreline with a lot more rain on surfaces to freeze up. Expect icy road conditions during the afternoon as the temperature quickly drops which will also transition the precipitation back over to snow.

The worst conditions are expected late Friday into Saturday as the low-pressure system rapidly intensifies as it stalls out over the region. Lake-enhanced snowfall east of Georgian Bay and northeast of Lake Ontario will be the main focus with intense snowfall rates and blizzard conditions as wind gusts strengthen early Saturday. Regions including Muskoka, Parry Sound, Kingston and Prince Edward County will bear the brunt of this system with a focused snow squall developing off both Georgian Bay and Lake Ontario. Expect dangerous travel conditions throughout the hardest hit region during the morning and afternoon on Saturday. Avoid all non-essential if you can.

Wind gusts will also be an issue in this part of Southern Ontario but to a lesser extent. The only area expected to see near damaging wind gusts is along the Lake Ontario shoreline with gusts approaching 90-100km/h. Otherwise, wind gusts will range from 60-80km/h for the rest of Central and Eastern Ontario.

Snow squalls and very dangerous conditions will continue east of Georgian Bay throughout Saturday and into Christmas Day on Sunday. If you are in the affected regions, you should make plans to not travel on Christmas Day as roads in this area will likely be impassible due to the extensive amount of snowfall over the last few days.

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Disruptive Winter Storm Targets Southern Ontario Starting Thursday With Heavy Snow and Significant Freezing Rain Risk

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The next few days are going to be quite messy across Southern Ontario as our first winter storm of the season takes aim at the region. The exact impacts of this storm will be very location dependant ranging from up to 15-30cm of snowfall accumulation to a prolonged freezing rain risk. In addition to the wintery weather, strong to damaging wind gusts are expected to accompany the system on Thursday which could pose additional risks when combined with the heavy snow and freezing rain.

Precipitation in advance of the approaching low-pressure system will reach Deep Southwestern Ontario by the early hours of Thursday. This system will tap into some warm air from the Gulf of Mexico which is expected to clash with the colder air currently over the province. The warm air will win out for regions further south including Windsor, Leamington, Chatham and along the Lake Erie shoreline. As a result, precipitation here will predominantly fall as regular rain with minimal impact.

With the precipitation spreading further to the northeast throughout the pre-dawn hours on Thursday, the cold air will become trapped at the surface as the warmer air overtakes it at higher levels of the atmosphere. This will allow for the development of a band of freezing rain stretching from Sarnia through London and into the Hamilton/Niagara regions by the mid-morning hours. Several hours of freezing rain is possible especially for higher elevations away from the shoreline of Lake Huron and Erie which could experience heavy prolonged freezing rain throughout the morning.

The battle between the cold and warm air will continue as the precipitation approaches the GTA and Central Ontario by the late morning and early afternoon. This time, it appears the cold air will retain control at all levels of the atmosphere resulting in the predominant precipitation type coming in the form of heavy snow or ice pellets. Meanwhile to the southwest, the freezing rain risk will come to an end as it switches over to a rain/snow mix by the afternoon.

Persistent heavy snow will continue through the afternoon and evening around the Golden Horseshoe and into parts of Central and Eastern Ontario. Expect a very slow and messy evening commute on Thursday with road conditions likely to be very poor when combined with the wet snow and strong wind gusts.

We should see the precipitation slowly taper off overnight and into Friday morning from west to east. However, Eastern Ontario will continue to experience light to moderate snowfall throughout the day on Friday as the system stalls out over New England with precipitation wrapping back around into Eastern Ontario.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

The first effects of this storm will begin to be felt just after midnight as the wind starts to pick up in the southwest, especially around the Lake Huron shoreline. Strong to damaging wind gusts are expected to dominate the story throughout the early morning hours on Thursday with the strongest gusts being found around Lake Huron ranging from 90-100km/h.

Further inland, gusts will range from 70-90km/h for much of Southwestern and Central Ontario along with the Golden Horseshoe. Less of an impact when it comes to the wind is expected for Eastern Ontario with gusts maxing out at around 50-70km/h. We expect that the damaging wind gusts will diminish by the late morning or early afternoon on Thursday, but they could remain quite strong throughout the day.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

As mentioned earlier in the forecast, the impacts of this winter storm will vary across Southern Ontario with freezing rain in the southwest, a messy mix in between and heavy snow throughout Central and Eastern Ontario. The easiest part of this forecast will be the Windsor and Chatham region which is expected to remain on the warm side of this storm with rainfall totals ranging from 10-25mm over the next 48 hours.

As we move further to the northeast, a few hours of freezing rain is possible during the mid-morning hours for the Lake Huron shoreline, Sarnia, St. Thomas and the Niagara region before transitioning over to rain. Expect around 2-6mm of ice accretion along with 5-10mm of rain after the switchover occurs later in the morning.

The threat of more prolonged freezing rain will exist for areas inland east of Lake Huron (such as Listowel and Stratford), through London and into Brantford. Freezing rain here could linger throughout the morning and into the early afternoon with total accretion ranging from 6-12mm. This amount of ice accumulation combined with the strong wind gusts could result in localized power outages along with very icy conditions on untreated surfaces.

Closer to the GTA, the exact precipitation type becomes less clear with a mix of freezing rain, ice pellets and snow possible for locations including Owen Sound, Fergus, Guelph, Hamilton and Oakville. This area we’re less confident about this as a slight shift in the temperature gradient could result in more snow if it’s colder than expected or more freezing rain/ice pellets if it’s warmer than expected. So don’t focus too much on the exact accumulation because it will likely get tricky to quantify with the multiple precipitation types. Either way, this wintery mix will make for quite the mess out on the roads.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

The focus for those on the colder side of this storm which includes all of Central and Eastern Ontario along with parts of the GTA will be on heavy snowfall and ice pellets. Locations along the Lake Ontario shoreline through the City of Toronto and into the Dundalk Highlands (Orangeville, Shelburne, Collingwood etc.) will mainly see snowfall with totals ranging from 10-20cm by the end of Friday. Ice pellets may also mix in at times, but limited accumulation from ice pellets is expected.

For snow lovers, you’ll want to be north of the GTA in a zone encompassing Newmarket and east throughout Eastern Ontario including Peterborough, Bancroft and Ottawa. This area is on track to see the highest snowfall totals from this event with between 15-30cm of snow expected by Saturday. Regions east of Georgian Bay will mainly see snow as well, but the snow is expected to be less intense so total accumulation here will top out at around 10-20cm.

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Multi-Day Snowfall Event Across Southeastern Saskatchewan Late Tuesday Could Dump 25cm+ of Snow by the End of the Week

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While the winter has started off on a slow note across Saskatchewan, that is about to change this week with a Colorado Low tracking through the province starting Tuesday evening. This will set the stage for a multi-day snowfall event as multiple rounds of precipitation affect mainly southeastern Saskatchewan between Wednesday and Friday. By the time the system moves out on Friday, we expect that total snowfall accumulation could range from 5 to 25cm+ in the hardest-hit locations.

The first effects of the Colorado Low are being felt Tuesday evening as the initial band of precipitation crosses across the North Dakota border and into Southwestern Manitoba. As a result, the worst conditions will be found in locations such as Oxbow, Estevan, Carlyle and Moosomin with the heaviest snowfall rates. By midnight, the moderate to heavy snowfall will have spread to much of southeastern Saskatchewan with the heaviest snow along the international border. Snow will continue overnight and into Wednesday morning although it will become more scattered later in the morning. Flurries and light snow will linger throughout the day on Wednesday and pick up in intensity towards the late afternoon and evening.

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Overnight Wednesday, steady snow is expected to affect regions along the Manitoba border into early Thursday morning before tapering off by sunrise. Another round of snow will move in during the afternoon on Thursday, slowly tracking to the west. The overnight hours on Thursday will be dominated by steady light snowfall continuing into the early part of Friday before the system responsible for this snowy weather finally moves out by the end of Friday.

Moving to the western part of the province, it’s possible that snowfall could be quite isolated so not everyone highlight will see snowfall and areas in the 5-10cm may end up being missed, depending on where exactly the snowfall falls. For more detailed timing on when the snowfall will start and stop through these next few days, download our free app Instant Weather and tap the “Hours” button to see the estimated timing for your exact location. More details ASAP and please take care if you have to travel during these conditions.

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Multi-Day Snowfall Event Across Manitoba Starting Late Tuesday Could Dump Up to 30cm of Snow by the End of the Week

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While the winter has started off on a slow note across Manitoba, that is about to change this week with a Colorado Low tracking through the province starting Tuesday evening. This will set the stage for a multi-day snowfall event as multiple rounds of precipitation affect southern parts of Manitoba between Wednesday and Friday. By the time the system moves out on Friday, we expect that total snowfall accumulation could range from 20 to 30cm in the hardest-hit locations.

The first effects of the Colorado Low will begin being felt early Tuesday evening as the initial band of precipitation crosses across the North Dakota border and into Southwestern Manitoba. As a result, the worst conditions will be found in locations such as Killarney, Boissevain, Brandon and Virden with the heaviest snowfall rates. By midnight, the moderate to heavy snowfall will have spread all across Southern Manitoba with the heaviest snow along the international border. Snow will continue overnight and into Wednesday morning although it will become more scattered later in the morning. Flurries and light snow will linger throughout the day on Wednesday and pick up in intensity towards the late afternoon and evening.

Overnight Wednesday, the focus will turn to Southwestern Manitoba with those further east getting a break from the snow. Steady snow is expected to affect regions along the Saskatchewan border into early Thursday morning before tapering off by sunrise. Another round of snow will move in during the afternoon on Thursday starting with the eastern sections of the province and slowly tracking to the west. The overnight hours on Thursday will be dominated by steady light snowfall continuing into the early part of Friday before the system responsible for this snowy weather finally moves out by the end of Friday.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

As we will be dealing with multiple rounds of snow over the next few days, forecasting the exact accumulation is a little tricky. This isn’t a short event that lasts for 6-12 hours which is generally easier to forecast compared to a multi-day event. This also means that the impacts will be substantially less significant as the snow will fall over a long period and allow road crews to keep up with the accumulation on roads

With that being said, it appears the highest snowfall totals will be found in the southwestern corner of Manitoba with up to 20-30cm of snow expected over the next 48 hours. This includes Virden, Brandon, Milita and Killarney. 10-20cm of this snow will be on the ground by the end of Wednesday with an additional 5-10cm expected throughout the day on Thursday. The rest of Western Manitoba can expect total snowfall accumulation ranging from 10-25cm by the end of Thursday.

Moving to the eastern part of the province, the heavier snowfall totals will be contained to regions along the international border including Morden, Winkler, Emerson and Piney which could pick up around 15-25cm of snow over the next few days. South-central Manitoba including the Interlakes region along with Winnipeg and Portage La Prarie is forecasted to see 10-15cm of accumulation with the bulk of that snow coming on Wednesday.

However, there is some uncertainty on exactly how far north this system will track which would affect where the precipitation cutoff occurs. If the bands of snow make it further north than expected, these locations could certainly overachieve the forecast and approach the 15-20cm mark. Especially when it comes to elevated areas around Morden and Miami.

Current indications suggest that we could see another 5-15cm of snow on Friday in addition to what we’ve forecasted over the next two days. We have decided to leave Friday out of this forecast as it is still a few days away and it’s important to see how these first two days play out before we talk about Friday. Be sure to check for an updated forecast late Wednesday or early Thursday.

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Winter Sets In Across Southern Ontario With Up to 6-12cm of Snow on the Way for Sunday

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

It’s hard to believe that we’re already well into December considering we have yet to experience the traditional winter weather for this time of the year. The temperature has been relatively mild with the heavy snowfall accumulation being contained to the snowbelt region that has seen a few rounds of lake effect snow over the past few weeks. That will change to an extent over the next 24 hours as a fast-moving system is set to bring snow on Sunday. We could see appreciable accumulation of up to 6-12cm in the hardest hit region by the end of the day.

The snow will start late Saturday starting with Southwestern Ontario, and spreading to the northeast throughout the predawn hours on Sunday. We expect to see the worst condition during the mid to late morning hours across Central Ontario and around the Golden Horseshoe. Those in Eastern Ontario around the Kingston region will see the snow starting later in the morning and lingering into the afternoon. Precipitation will clear from west to east and should fully move out of the province by the late afternoon.

By the time the precipitation tapers off, we expected the heaviest accumulation to encompass higher elevations north of the GTA, much of Central Ontario around Lake Simcoe, and eastward through Peterborough and Kingston. These areas are forecasted to receive between 6-12cm of accumulation although it should be noted that some localized areas could overachieve the forecast and may approach the 15cm mark. The precipitation associated with this system will be quite focused so as a result, accumulation will drop off quite fast outside of the main zone.

We expect between 4-8cm of snow is possible for northern parts of the GTA and just north of the Lake Ontario shoreline. Those near the shoreline including the City of Toronto, Hamilton and Southwestern Ontario will be hovering right near the freezing mark so some of the snow will likely melt on contact or come down in the form of rain. So we are forecasting total accumulation for them ranging from 2 to 6cm. Less than 2cm of snow is expected for the rest of Southern Ontario.

Significant Snow Squalls Continue Into Sunday Around Lake Huron and Georgian Bay With Up to 25-50cm of Additional Accumulation

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

It has been quite the eventful past 48 hours across parts of Southern Ontario as we have experienced the first major lake effect snow event of the season. Strong southwesterly winds have resulted in the formation of persistent and intense squalls off Lake Huron, Georgian Bay, Lake Ontario and Lake Erie over the last few days. This has meant that some locations not traditionally used to facing the brunt of these squalls including the Niagara region and the Kingston/Brockville area have seen the worst impacts. Although we certainly have gotten off easy compared to our neighbours south of the border with some locations in upstate New York including Buffalo and Watertown being buried in up to 100-200cm since Thursday!

Snow squalls continue to affect those regions this afternoon with rapid snowfall accumulation and near-zero visibility out on the roads. The lake effect activity is expected to continue into Sunday, but the focus will turn towards the southeastern shoreline around Georgian Bay and the Grey-Bruce region. These squalls will become more disorganized throughout the evening as we see a change in the wind direction from southwesterly to more of a northwesterly flow. This will allow for the squalls to reorganize overnight and early Sunday morning with the main squalls stretching across Grey-Bruce and over Georgian Bay before coming inland again throughout the Simcoe County region. Strong wind gusts ranging from 40-70km/h on Sunday will likely cause blowing snow and reduced visibility.

The localized intense band of snow could stretch inland quite far and affect areas as east as Kawartha Lakes and Peterborough. There is even a chance that it could stretch from Georgian Bay to the Lake Ontario shoreline around the Cobourg region. We expect the worst conditions will be primarily during the morning and early afternoon on Sunday. A secondary band might develop off Lake Huron from Goderich and into the K/W region, but it won’t be as intense as the squall further to the north. Regardless, both squalls could bring very poor driving conditions throughout the affected regions so consider avoiding any non-essential travel on Sunday. Organized lake effect snow will come to an end around the dinner hour, but scattered flurries may linger throughout the evening and into the overnight.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

Those in the Owen Sound region won’t be catching a break as they’re yet again expecting to see some of the highest snowfall totals on Sunday along with Chatsworth, Wiarton and Meaford. They can expect an additional 25-50cm on top of what they’ve already seen over the past few days. The rest of the southern shoreline of Georgian Bay including Collingwood, Midland and Wasaga Beach is looking at an additional 15-30cm of snow.

Those further inland including Barrie, Orillia, Northern York Region and the Kawartha Lakes will see around 10-20cm although that depends on the exact placement of the squalls and some may see barely anything. To the south, the secondary band affecting the Wingham, Listowel and K/W area will put down around 10-20cm of snow. Less than 10cm is expected outside of the traditional snowbelts as shown on the map.

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Snow Squall Outbreak to Dump Up to 75cm of Snow on Parts of Southern Ontario This Weekend

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

A multi-day snow squall outbreak is currently underway and is expected to linger into the weekend bringing with it very dangerous conditions through parts of the snowbelts. The focus will be on areas to the northeastern shorelines of Georgian Bay, Lake Ontario and Lake Erie where a persistent southwesterly will allow for intense snow squalls to set up over the next 48 hours. Some of the hardest hit regions including Wiarton, Owen Sound, Muskoka, Parry Sound, Fort Erie and Prince Edward County could be looking at locally up to 40-75cm between Friday and Saturday. Combined with strong wind gusts, this will present a dangerous situation out on the roads making travel nearly impossible in the affected regions. Consider postponing any non-essential travel between Friday and Saturday within the hardest-hit area. Blizzard-like conditions can’t be ruled out along with thundersnow as we saw in some areas throughout the overnight hours.

Lake effect snow will continue to linger throughout the morning and into this afternoon, however, it will be fairly disorganized and shouldn’t lead to significant accumulation. The main activity is south of the border through the Buffalo and Watertown regions which are expecting a heavy dumping of snow with up to 100-150cm by the end of the weekend! More organized snow squalls will develop off Georgian Bay late Friday as the wind direction shifts to a predominantly southwesterly flow. These squalls will stretch across the Bruce Peninsula and over Georgian Bay before coming inland somewhere around Parry Sound and Port Carling. Expect very hazardous conditions along Hwy 400 and 11 east of Georgian Bay starting early Saturday morning and continuing throughout the day.

The intense squalls affecting regions northeast of Lake Erie and Lake Ontario will slowly shift to the north overnight and into Saturday morning. As a result, we expect to see rapid snowfall accumulation through parts of the Niagara and Kingston/Prince Edward County regions along with reduced visibility making for poor driving conditions. Current indications suggest that the bands will break apart by the late afternoon or early evening hours, but this will only be temporary as the wind direction shifts around. A few more hours of heavy snow is possible overnight as a system moves through the region and is enhanced by the lakes.

Snow squalls could redevelop on Sunday, but it looks like a more southwesterly flow which would affect areas east of Lake Huron and southeast of Georgian Bay. More details on the potential Sunday squalls will be included in a separate forecast to be posted on Saturday.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

The hardest hit regions in terms of accumulation will encompass the Bruce Peninsula including Wiarton and Owen Sound along with Parry Sound, Port Carling and Rosseau. Accumulation here is expected to top at around 40-75cm over the next two days, however, it’s important to note that the totals will be highly variant and not everyone will see extreme totals up to 75cm. It all depends on where the band sets up and if it locks into any particular region which if it does, could result in even locally more than 75cm of accumulation.

The rest of the northeasterly shoreline of Georgian Bay in addition to regions further inland including Midland, Bracebridge, Huntsville and North Bay will see around 25-50cm which again will be extremely dependent on your location. Accumulation will drop off quite fast further south and east you go with Simcoe County picking up between 10-25cm depending on the location.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

For the snow squalls of Lake Erie and Lake Ontario, the biggest impact will be felt south of the border as mentioned above, but that doesn’t mean we are entirely off the hook. A very localized pocket that includes the southeastern tip of the Niagara region such as Port Colborne and Fort Erie will face the brunt of the Lake Erie snow squall on our side of the border. They could see as much as 40-75cm of snow by the end of the weekend. This is also the case for Prince Edward County which will see lake effect snow off Lake Huron.

The accumulation gradient with these bands will be quite tight so totals will quickly diminish to the northwest. We are looking at around 25-50cm for locations such as Welland, Brighton, Napanee and Kingston. Slightly lower totals are expected for St. Catharines, Niagara Falls and Belleville with accumulation ranging from 15-30cm. For the GTA, impacts will be fairly minimal, but the Hamilton region could see up to 5-10cm thanks to that Lake Erie band briefly pushing through during the afternoon on Saturday.

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First Widespread System Snowfall of the Season for Southern Ontario With Up to 5-15cm Possible Between Tuesday & Wednesday

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

It sure feels like someone just flipped the switch between fall and winter! We have gone from near-record-breaking temperatures at the start of November to now looking at a very snowy forecast for the next week. We got a taste of this over the weekend with snow squalls dumping locally significant snowfall accumulation to parts of the snowbelts around Lake Huron and Georgian Bay.

Now it’s the rest of Southern Ontario’s turn to face the wintery wrath of Mother Nature as we are tracking a potential system to bring accumulating snow starting late Tuesday. When the precipitation finally tapers off throughout the day on Wednesday, we will be looking at widespread accumulation ranging from 6-12cm with locally higher amounts up to 16cm through parts of the GTA and into the Dundalk Highlands. In the wake of this system, our focus will turn back to the lakes as we watch the risk of more snow squalls east of Georgian Bay and even northeast of Lake Erie for the end of the week.

The complexity of the next 48 hours when it comes to the weather will begin Tuesday late morning or early afternoon. There is a brief window of opportunity where we may see a localized band of lake effect snow develop off the western shoreline of Lake Ontario. The target of this band would be the Burlington, Oakville and Mississauga region with a quick few centimetres of snow along with reduced visibility possible. Normally, this wouldn’t be even noteworthy, however, it’s early in the season and even weak events tend to have implications on traffic throughout the GTA. So be aware of some possible travel delays in the western GTA during the afternoon on Tuesday.

Fast forward to later in the day, we expect to see the first effects of the system starting with Extreme Southwestern Ontario along with those along the Lake Erie shoreline by Tuesday evening. As is typical with the first ‘major’ system-related snowfall event in Southern Ontario, there will be a divide between the cold and warm air. This will make determining the exact precipitation type difficult, but at this point, it appears that the Windsor and Chatham region will remain warm enough to see just rain and those directly along the shorelines where temperatures are kept a few degrees warmer thanks to the warm waters of Lake Erie. Further north, it will be primarily snow extending from Sarnia, through London and into the GTA. Again, those along the shoreline in the GTA will see less snow and more rain due to Lake Ontario keeping the temperature slightly above the freezing mark.

Moderate to heavy snowfall will continue overnight with the worst conditions found during the predawn hours of Wednesday. There is also some indication that we may see lake enhancement off the western shoreline of Lake Ontario and into the Dundalk Highlands which will lead to boosted snowfall rates in this area. For Eastern Ontario, the snow won’t start until early Wednesday morning with the heaviest accumulation occurring later in the morning and early afternoon. We will begin to see the snow clearing from west to east late on Wednesday morning in Southwestern Ontario and by the mid-afternoon in Eastern Ontario. It should be fully moved out of Southern Ontario by the late afternoon.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

When it comes to the expected snowfall totals from this system, it will be quite uneven due to the presence of lake enhancement from Lake Ontario. Based on the latest data, we believe a small pocket to the northwest of Lake Ontario (excluding those directly along the shoreline) that includes Halton Hills, Brampton, Orangeville and Shelburne will see the most snow from this event ranging from 8-16cm. Otherwise, totals will generally range from 6-12cm for a big chunk of Southern Ontario that extends from K/W, through the GTA, into Peterborough and Eastern Ontario.

We are expecting slightly less with 4-8cm being forecasted for Southwestern Ontario including Sarnia, and London due to the lower snowfall ratio and potential for rain mixing in and reducing the total accumulation. This is also the case through Central Ontario further to the northwest as the bulk of the moisture will be focused on regions south and east of Lake Simcoe. Limited accumulation is expected in Deep Southwestern Ontario and the Niagara region as they will be staying on the warm side of this system and see mostly rain.

As mentioned at the start of the forecast, we are watching what could be our first multi-day snow squall event of the season for regions east of Georgian Bay starting Friday and lingering into the weekend. By the end of the weekend, some localized regions around Parry Sound and Muskoka could be measuring snow in feet (1ft = 30cm) instead of centimetres! Although, there is still some uncertainty in the exact strength of the lake-effect snow and the wind direction. We may also see some fairly prolific squall activity off the northeastern shoreline of Lake Ontario and Erie which would bring significant accumulation and major travel issues to the Niagara and Kingston regions on Friday into Saturday. More details on that in the coming days.

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Weekend Snow Squalls Could Bring Up to 15-30cm of Snow to Parts of Southern Ontario by Monday Morning

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While we have been treated to a rather mild start to November, it was only inevitable that the word many in the traditional snowbelts of Southern Ontario dread will make its way into the weather conversation. The arrival of cold temperatures this weekend combined with the relatively warm waters of Lake Huron and Georgian Bay is expected to kick off the lake effect snow season.

Scattered precipitation is currently ongoing across parts of Southern Ontario coming down in the form of light rain along the shorelines and even wet flurries in areas that have already approached the freezing mark. As this disturbance exits the region in the coming hours, we expect to see the development of localized, but intense snow squalls off Lake Huron and Georgian Bay as early as the midnight hour.

Based on the northwesterly flow expected to dominate overnight and into Sunday, it appears the focus of the lake effect bands will be on the southeasterly shorelines of Lake Huron and Georgian Bay. The worst conditions will be found during the early morning hours of Sunday when the temperature will be the coldest resulting in optimized accumulation. Our focus will be on two main squalls with the Lake Huron one stretching from between Goderich to Grand Bend and inland to just north of London. The Georgian Bay squall is expected to stay closer to the shoreline affecting the Meaford, Collingwood, Wasaga Beach and perhaps the City of Barrie at times. Strong wind gusts ranging from 30-60km/h combined with the heavy snow will result in very poor road conditions and maybe even some road/highway closures in the hardest-hit regions. Consider postponing any non-essential travel on Sunday.

As we head into the late afternoon and early evening on Sunday, we expect to see a temporary shift in the wind direction to a more WNW flow which would push the squalls to the north. Regions like Kincardine, Listowel, Midland and Orillia will see some brief bursts of heavy snow as the squalls stall over the area for a few hours late Sunday. The squalls will retreat south overnight as they slowly weaken by Monday morning with flurries lingering throughout the early part of Monday, but should be mostly finished by the afternoon.

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

By Monday morning, we could be talking about some localized significant snowfall totals in parts of the snowbelts. It looks like the ‘winner’ (or loser, depending on your perspective) of this snow squall event will be a small zone to the northwest of London off the Lake Huron shoreline. Locations including Goderich, Clinton, Grand Bend, Exeter and Lucan could pick up between 15-30cm of snowfall accumulation over the next 36 hours. Keep in mind that lake effect snow is traditionally very localized and while one location can get dumped on, a location down the road may see just a dusting of snow so this isn’t guaranteed. Furthermore, temperatures are very close to the freezing mark and could even rise briefly above freezing during the day which could compress some of the accumulation and make it look like less has fallen.

Surrounding the hardest-hit region, we are looking at snowfall accumulation generally ranging from 10-20cm for locations east of Lake Huron and southeast of Georgian Bay including London, Wingham, Kincardine, Collingwood, Wasaga Beach, Angus and Barrie. A few locations, particularly around Georgian Bay could overachieve these amounts and pick up closer to 25-30cm, however, the confidence isn’t high enough to merit the addition of a 15-30cm zone on the forecast map. Even further away, we are expecting around 5-10cm of snow for regions including the rest of Simcoe County, into Northern York Region and much of Southwestern Ontario. Everyone else in Southern Ontario could see a few rounds of scattered flurries throughout the day on Sunday, but we aren’t expecting any accumulation, especially with temperatures right near the freezing mark

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Remnants of Hurricane Nicole to Bring Heavy Rainfall to Southern Ontario Starting Friday

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The weather across Southern Ontario has been fairly inconsequential so far in November when we normally get the first taste of winter. While the month has been dominated by unseasonably warm temperatures with multiple days of temperatures into the 20s, that is about to change as we go into the upcoming weekend. The remnants of what was Hurricane Nicole which made landfall in Florida is currently tracking up the east coast of America and is expected to spread heavy rain across Southern Ontario starting Friday afternoon.

In the wake of this system, we will see a sharp cooldown plunging temperatures to near or below the freezing mark by Sunday morning. This will serve as a kickstart to the lake effect snow machine off Lake Huron and Georgian Bay with the potential for accumulating snow in parts of the traditional snowbelts late Saturday into Sunday. Even parts of Southern Ontario including the GTA that have yet to see the first flakes of the season thus far could see that change this weekend with lake effect flurries quite widespread.

Before we get to the winter wonderland in store for us over the weekend, we must get through the rain on Friday. The first bands of precipitation are expected to reach the Lake Erie shoreline sometime during the early afternoon on Friday. As such, the Niagara and Hamilton regions will be the first to see the rain as it spreads further to the north and west later in the afternoon. By the dinner hour, most of Southern Ontario will be in the middle of the moderate to heavy rainfall so expect poor driving conditions for the evening commute and plan some extra time to get to your destination. Rain will continue throughout the evening as it slowly clears from the southwest late in the evening. Most of Southern Ontario will be finished with the rain by midnight although it will linger around overnight for Eastern Ontario.

There has been a slight eastern shift in the track of this system over the past 24 hours and as a result, we are now looking at lower overall rainfall totals for Southern Ontario. The heaviest totals appear to be contained to the Niagara region and into Eastern Ontario from Kingston through Brockville and Cornwall which will see around 30-50mm of rain. There will be a sharp gradient between the heaviest and lower totals with locations like Hamilton and Ottawa being right on the bubble between moderate and heavier rainfall picking up between 20-30mm of rain. It’s important to note that any shift in the track of this system could push totals into the ‘locally’ range if it tracks further to the west.

The vast majority of Southern Ontario including London, K/W, GTA and Barrie are on track to see between 10-20mm of rain. The lowest impact will be found further to the northwest where we’re expecting less than 10mm of rain for Southwestern Ontario, into the Muskoka region and Northeastern Ontario. Earlier it looks like Nicole could’ve brought some stronger wind gusts to our region, but currently, the more eastern track has greatly diminished the wind threat to Southern Ontario. Wind gusts across the region will generally range from 40-60km/h throughout the day on Friday with localized gusts up to 70km/h.

As mentioned, the departure of this system on Saturday will be marked with a very substantial cooldown during the day and continuing overnight. By Sunday morning, much of Southern Ontario will wake up to temperatures in the low negative single digits. The only exception will be those closest to the shorelines of Lake Ontario and Erie which will hold at just above the freezing mark.

This arrival of cold air combined with the still relatively warm waters of the Great Lakes will allow for the development of lake effect snow off Lake Huron and Georgian Bay. Current indications suggest that we should see a band develop off Lake Huron and Georgian Bay with a primarily northwesterly flow starting Saturday evening. This would put the target zone around the Goderich and Stratford regions off Lake Huron along with the Barrie and Wasaga Beach regions off Georgian Bay. These areas could see locally significant snowfall totals ranging from up to 10-20cm by the end of the weekend.

There is still some uncertainty and the exact locations affected could change so we don’t have a forecast map for this event yet. We will provide a more detailed forecast by Saturday afternoon which will include expected accumulation. Lake effect snow is expected to linger throughout the day on Sunday before finally tapering off by late evening. While the accumulation will be contained to the aforementioned regions, the potential for scattered lake effect flurries will be quite expansive including the Golden Horseshoe and parts of Southwestern Ontario.

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Weekend Winter Storm To Bring Heavy Snow, Prolonged Freezing Rain or Significant Rainfall to Northern Ontario

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

We are monitoring a system set to affect Northern Ontario this weekend which will bring a mixed bag of precipitation to the region depending on your location. Impacts will vary from heavy snow to the northwest of Thunder Bay, prolonged freezing rain through the Geraldton area and heavy rainfall for Northeastern Ontario. This will all begin tonight as an approaching system starts to spread rain across southern parts of Northeastern Ontario along the Lake Superior shoreline

Moisture will continue to be pumped into Northern Ontario throughout the overnight hours as precipitation slowly spreads to the northwest. By Saturday afternoon, the outer bands of the precipitation will encounter colder air resulting in an area of mixed precipitation developing somewhere from Marathon through Moosonee. It will start out as some ice pellets or light snow before a more potent band of freezing rain will set up around the Geraldton area by late Saturday. Further west, the predominant precipitation type will be sleet and heavy snow affecting locations such as Thunder Bay and Armstrong. Precipitation will linger overnight although it will slowly taper off by Sunday morning as the system moves out of the region.

In terms of impact, those in Northeastern Ontario including Sault Ste. Marie, Elliot Lake, Sudbury and Timmins will stay on the warm side of this winter storm and see all rain with total accumulation ranging from 30-60mm by Sunday morning. For the Marathon and Moosonee areas, you will start off with some mixed precipitation for a few hours during the late afternoon and early evening on Saturday before switching over to regular rain. The biggest impact will be around Geraldton with the potential for up to 4-8mm of ice accretion from freezing rain along with some mixed precipitation. Icy road conditions and power outages are possible in this region.

Accumulating snow is possible for parts of Northwestern Ontario with Thunder Bay picking up between a trace to 5cm of snow plus ice pellets. The heaviest snow will be found to the north for the Armstrong and Fort Hope region which could see up to 10-20cm of snow from this storm by Sunday. In addition to this, there will be strong wind gusts late Saturday with gusts approaching 70-90km/h mainly for regions to the north of Georgian Bay.

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Possible Fall Wind Storm on Saturday Across Southern Ontario With Gusts Up to 95km/h and the Risk of Thunderstorms

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

It has been a strange start to November across Southern Ontario which is about to continue into the first weekend of this month. The weather story of the month so far has been the spooky fog that has set in since Halloween night. Most areas have seen the fog burn off throughout the day on Friday and current data indicates that it should stay that way. It’s possible we see some isolated fog patches overnight into Saturday morning especially near the shorelines as the fog blows in off the lakes, but it won’t be as thick or widespread as we have seen the last few nights.

The retreat of the fog will allow many areas to finally take full advantage of daylight heating from the sun bringing temperatures well into the double digits and potentially even low 20s for some locations. As we are already into November, these temperatures could come close to breaking records this weekend. These unseasonably warm temperatures are expected to continue on Sunday and Monday with daytime highs hitting double digits, but won’t be as warm as Saturday.

However, there is a catch with this warm weather as we are expecting some rain to slide into Southern Ontario by late Saturday and continue into early Sunday. It won’t be particularly heavy with total accumulation ranging from 5-10mm for Southern Ontario. Heavier rain will be found throughout Northeastern Ontario where totals could range from 30-60mm and as a result, Environment Canada has issued a rainfall warning for the affected regions.

The bigger threat this weekend will be the potential wind storm across Southern Ontario bringing gusts of up to 80-95km/h starting Saturday afternoon and lasting into early Sunday. Current data suggest that the strongest wind gusts will be found along the Lake Huron and Georgian Bay shoreline with maximum gusts of 85-95km/h. This could lead to some minor wind damage and even some sporadic power outages. The rest of Southern Ontario will see wind gusts ranging from 70-90km/h.

Something also quite rare for November may occur this weekend which is the risk of an isolated thunderstorm as a line of heavy rain sweeps across the region late Saturday and into the overnight hours. As a result, some locations may experience slightly higher wind gusts within the thunderstorms compared to what we’re forecasting. We can’t rule out an isolated 100+km/h wind gust somewhere in Southwestern Ontario.

The good news is that the active weather is expected to clear out quite fast. We should see the rain and wind come to an end early Sunday morning with another nice day ahead. Looking towards the next week, we expect to see a cool down by the middle of the week with overnight lows dipping to near the freezing mark, but there isn’t much precipitation in the near future.

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The Battle of the Seasons With Accumulating Snow and Temperatures Near 20°C in the Coming Days for Southern Ontario

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NOTE: You can click on the map to open a zoomable image which will be easier to read.

After we had a relatively mild start to fall, the past week or so has been dominated by a taste of wintery weather. Over the last few days, we’ve seen near-freezing temperatures and the first snowfall of the season in some parts of Southern Ontario. If you weren’t quite ready for this blast of wintery weather, you won’t like what is ahead for the next 24 hours with more snow and chilly temperatures. The good news is that there is light at the end of the tunnel as we see the return of milder air in time for the weekend.

Precipitation aided by lake enhancement off Lake Huron and Georgian Bay continues to linger across Southern Ontario on Wednesday. With temperatures expected to slide close to the freezing mark overnight, the precipitation will transition over to some light to moderate snow. This will be especially the case in the higher elevations of the Dundalk Highlands and into northern parts of Muskoka where even some accumulation is possible. Wet snow will continue into Thursday morning with the heaviest snow located east of Georgian Bay as a somewhat intense band of lake effect snow sets up over the Huntsville area. Reduced visibility and slushy roads will result in poor driving conditions throughout the affected region so be sure to take your time if you have to travel in the morning.

In terms of accumulation, this is very tricky to forecast as temperatures will be right near the freezing mark. Some of the models we review to create our forecast are showing significant totals of up to 15-20cm for parts of Muskoka by the end of Thursday. However, this isn’t realistic as it doesn’t account for most of the snow melting on contact as it falls onto the ground. We are going with a maximum of 4-8cm for total accumulation, but it’s important to note that this could be an underestimate if temperatures are slightly colder than expected.

Outside of that localized region, those who see snow over the next day will experience very little accumulation if anything at all. There could be a few centimetres of accumulation in parts of the Dundalk Highlands including Hanover, Shelburne and the Blue Mountains. The snow will come to an end by the afternoon on Thursday as temperatures slowly warm up and the snow transitions over to rain. Another night of near-freezing temperatures is expected as we go into Friday morning, but the lake-effect precipitation will have tapered off so we shouldn’t see any snow.

NOTE: You can click on the map to open a zoomable image which will be easier to read.

As our focus turns towards the weekend, we are watching what will be a radical change in our weather with the arrival of milder air which will push the temperatures into the double digits on Friday with even more of a warm-up on the weekend. If you have any activities you wanted to get done before winter comes then this weekend would be the perfect time to get them done.

Both Saturday and Sunday will feature well above seasonal temperatures pushing into the 20s which is quite uncommon this late in the season along with sunny skies. Even if you can’t get out and enjoy the weather this weekend, it will be sticking around for at least a few more days into early next week. It looks like more seasonal temperatures will return by the end of next week.

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