Issued: Monday, September 7th, 2020 at 4 AM PT

Valid: Monday, September 7th, 2020

Forecaster: James Follett

After many British Colombians have been enjoying prevailing sunshine and basking heat that was a real treat which is more typical for July and Early August. A big change in the weather will come for Today Monday, September 7th.

For folks in the Interior, Okanagan, and Kootenays. where it’s been almost a week of 30C+ temperatures and lot’s of sunshine, you will wake up to fairly Gusty winds to 70 km/h, except up to 90 km/h for extreme southern sections of the Okanagan desert and Interior from Whistler to Hope and up to Penticton. and a fairly much cooler day with temperatures 5 to 15 degrees cooler than have been experiencing. Highs are only expected to be in the 20-25 degree range, which is right around average for this time of year between 20 and 22 degrees. The good news is that with the Gusty winds and cooler Temperatures is that there will be sunshine!!

For folks in Vancouver, Vancouver Metro, Vancouver Island, Victoria and all along the BC Coast, you have also been spoiled with warm basking sunshine! and here is the good news! The heat will continue for you! in fact it might be even hotter than yesterday, many areas flirting with 30*C, winds will also be Gusty up to 70 km/h.

For folks in parts of Central spreading far North from North of Kamloops to Williams Lake, Quesnel, and past Prince George, you can Cooler temperatures of around 15 to 20*C, but also will see the least Gusty winds, winds Gusting up to 60 km/h, however there are many locations that may not even get winds Gusting past 40 km/h.

For folks in the Columbia Mountains & Coast Mountains, you will be dealing with a very chilly day! Cold air, typical of Late October and early November will flow down from the mountains & Rockies, Highs only around 5 to 10*C and there might be quite a few locations that may not even get above 5*C, as for winds the Coast Mountains will see Gusts up to 80 km/h, and there could be a few isolated locations getting near 90 km/h. The Columbia Mountains will see small Gusts of up to 60 km/h.

Discussion:

A very large and intense trough of Low pressure located over Northern Ontario is digging far south to a point where it is going to do a buckle in the jet stream. A jet stream is the driver of all weather! and tracker of all weather, it divides cold air from the North to the Warm air down South. When you get a backwards “U” you get what is called a ridge! and that brings Fair weather and warmth, meanwhile when you get a “U” shape, you have what is called a trough and those bring unsettled weather and often cooler temperatures.

Most of the time you may see a roller coaster of a jet stream on a Weather map. the Front and backward “U’s” Think of a steering wheel of a car! you have 1 hand at 3 and 9 O’clock so side by side. you turn the wheel to the right, your hand goes up, while the right hand goes down. That left hand that went up is a ridge, and if the winds are strongest to the right, it is just going to “dig” the right hand falls, and so that is a trough.

In our weather situation for this system, we have a very large ridge of High pressure ( the backwards U shape) just off our coast, meanwhile at the same time we have a Large low ( trough) the “U” shape over Western Alaska, the winds right now are strongest on the right side of the Alaskan trough which will be the Left side on our ridge! this means that the trough is lifting our ridge up north further, this will actually send more sunshine and further warmth for much of the BC coast! However, for everyone else in the province, the strong winds in the jet stream on the right side of our ridge which is the left on our very large trough over Ontario. this will send the dive and the Cooler and windy side to much of BC, however the precipitation should generally skip the province with exception to parts of Eastern BC near the Rockies and Mountains.

So areas under the ridge tomorrow which will be everyone up and down the entire BC Coast. will see a very lovely Labour Day Monday! and for Northern and Central BC, can expect clouds and much cooler air. parts of the mountains will see temperatures near freezing. for the Southern portions, look for some warmth, about seasonal temperatures, Gusty winds and sunshine!

Now because of the large convergence of the large ridge and large trough, this will bring in some very Gusty winds for much of the province, everyone will see Gusts above 40 km/h, but the strongest winds will be found towards the South, Interior, Okanagan and surrounding areas where Gusts of 70 to as high as 90 km/h is likely.

Trough will be close enough to bring rain to the Rocky Mountains, Columbia Mountains Tonight through tomorrow afternoon. Generally this will be a light rain event, not looking at much rainfall roughly around 5 to 10 mm. there are isolated pockets that can see amounts up to 15 mm on the extreme SE sections of BC, we couldn’t be able to move the legend that is covering that area, but I am forecasting 15 mm in some isolated areas.

Now even though we are going to see a large change in temperatures, and Gusty winds and little rainfall.. that is nowhere near as bad as what the Prairies and much of the Mid-Western states! the Prairies are looking at snow, and cold temperatures near or below freezing.

Think that is bad? How about this, Denver Colorado… still having a heatwave with temperatures nearing 40*C, breaking records they will have one more day of this gorgeous weather, because tomorrow… They can see up to a half foot of snow! Rain, Sleet and strong winds along also with temperatures about 70 degrees colder in a 24 hour period! There are Excessive Heat warning, red flag warnings AND a winter storm warning issued for that state all at the same time! so Be grateful for our small change, compared to a complete flip from blistering heat to a blizzard in a 24 hour period.

Now that change of only a 24 hour period… that will also be the case for us, Tonight into Tuesday, the giant ridge of High pressure off our coast is going to push north and east further inland, this will bring in back that gorgeous sunshine and warmer temperatures for the province, and this will develop a Cut off low for California, they could see some beneficial rain and wind for several days!

and the models are suggesting that the jet stream will be over our province for the next 10 days, well into Mid September with several many more days of 30+ degree heat coming to the south and coast. There are signs that we could see some cooler air and rainfall from a low off the coast after the 10 day period.

Closer to the future though, plan on a change in weather today, followed by another long stretch heatwave for the Interior beginning Wednesday into the weekend.