Ever since the major storm of October 29th, the upper air pattern has been in an a massive upheaval. The first big change comes later tonight and into the weekend as we see a very cold Canadian air mass plunging into the East with widespread freezes and record lows. This air mass will be pulling out on Sunday which is no surprise. However in another week or so we may be seeing the strongest blocking signature in the upper air that we have seen in quite some time. The North Atlantic Oscillation has been somewhat absent for the last several years with only brief appearances. Now we may be seeing a blocking pattern that sets up and plans a lengthy stay.
When the North Atlantic oscillation is negative as it is forecast to be beginning November 17th it means that pressures across the polar regions are higher than normal. This displaces the jet stream well to the south and creates conditions which favor colder average temperatures in the Eastern US. It also could influence the storm track so that any storm system tracks further south which opens the possibility for some early snows for some areas. The confidence level on this happening is rather high since all of the models are going in this direction though of course each one has some variation in how strong the blocking will be...READ MORE AT http://www.meteorologistjoecioffi.com/index.php/2017/11/09/blocking-pattern-develops-thanksgiving-week/