October looks to finish off warm like the last 5 months. I had predicted normal to only slightly above, but looks like Ottawa will be close to 2 degrees above normal, despite the cool down the last week. Normal for October is 12.7c, we are currently averaging 14.2c.
Here is the average temperature departures from normal to date for North America:
This week will warm up above normal by Tuesday – Thursday (around 13 – 14c), then back near normal or slightly below for the weekend (normal for the area is around 9 – 10c). Some models are predicting above normal for the next 15 days;
However the reliable Euro model and long range guidance is predicting a significant pattern change near the middle of the month, as the jet stream will shift much further south in the east allowing cold air to drop from the Arctic and flipping the pattern to a warm West, cold East look. This could kick off the Lake Effect snow season around the Great Lakes for places downwind like Bracebridge, Collingwood, Barrie, London, Buffalo NY etc. It could also switch gears for our area and set us into a winter pattern. Normals really start to drop towards the end of the month to near 4 – 5c. A couple degrees below normal could start bringing accumulating storms to the East. The Weather Network has a write up about the change as well here
Speaking of winter, Thursday into Friday’s snow brought around 5 cms to parts of Ottawa, west and northwest of the region. October snow is fairly common in the area, however 5 cms is a bit extreme. I’ve done the stats before on snow and cold in October and the correlation between the rest of the winter, in particular December’s temperatures. It’s about a 50/50 split on the impact for winter, but the impact on Decembers temperatures is close to a 60/40 split, meaning 60% of the time the coming December is warmer, 40% it is not. So we will see what happens this year. I certainly find it frustrating getting snow in October but not at Christmas, which happened last year. This year is certainly different in terms of the winter pattern…my winter forecast will explain more soon…