IW StormRisk storm track arrows and colour key
/The StormRisk storm track arrows have been added so that you can see the predicted direction of travel of the storm(s).
With the radar turned on:
Here are some examples of the colours of the outlines with the Total Severe Risk percentages. Note that the thickness of the outline also increases when the risk increases as well. You can see that in some of the examples where there is another outline present in the screenshots (24-48).
Note that the black colour for greater than 85% is a bug. You will not be able to see against the black map but it will show up well when radar is on.