I keep hearing people... even professionals saying there is no pattern change and this cold shot will be transient because there isnt NAO blocking. these people have become used to the last two winters and seem to think this one should behave EXACTLY to a tee like the last two. Well guess what it wont happen that way.
The pattern is fixing to change and the warm intrusions that once stopped by on occasion through the fall will be gone after this weekend. Sure there will be pre frontal warmups due to southerly flow from a LPS crossing the conus but for the most part winter wx has become established and longstaying after this weekend.
As you can see the NAO looks to be headed into negative territory with the ensemble forecasts
This is the GFS ensemble 8-10 day mean
That is called an EPO/PNA block in the pacific and that is called a NAO block in the Atlantic.... even though it is an east based block once you get the EPO..PNA and NAO in our favor this is a very cold signal....this will tend to carve out a deep trough over most of the conus and eastern united states.
This will create a cold and stormy pattern here in TN. With the PNA forecast to stay mostly positive and the NAO headed toward negative it is fixing to get really cold and I think there could be a massive arctic intrusion around December the 10th
