If you haven’t heard yet, it’s going to get cold next week as a pattern change takes place. Throughout my past posts, I’ve discussed how the MJO and the change in phase of the PNA will both play a role in the impending pattern flip-flop. We have now reached that time when the cold air is imminent.
Starting Monday, an area of cold air originating from northwestern Canada (basically the Arctic) will dive down south into the northern Rockies and Plains. That cold air will gradually intrude and dominate areas to the south and west. By midweek, the cold air will take over the entire Central U.S., all the way down to the Gulf Coast. The cold front will finally sweep through the East Coast by next weekend, so the Northeast and Southeast (including Florida) will also get in on the chilly air.
Once the cold air moves in, the pattern will lock in. The models have been fairly consistent the past several days, forecasting the cold air to dominate the weather through at least mid-December, but I have reason to believe it will last even longer than that.
The images above show the European model’s forecast temperature departures from average at day 7 and then at day 15. Notice how there isn’t really much change in the overall pattern and placement of the cold air. The cold air will likely continue to dominate the Eas,t while the West will enjoy drier, warmer weather due to a ridge of high pressure.
The axis of the coldest air next week will be across the Mississippi and Ohio Valleys. That’s where the highest negative temperature anomalies are forecast. I’m predicting temperatures will be up to 30 degrees below normal. I also want to note that on the outer fringes of where the cold air will be, like the East Coast and Plains, there may be periods where it is actually warmer than average.
The cold is coming. Get out the winter appeal if you haven’t yet, because you sure are going to need it!