The character of the -AO regime is about to change. The high-latitude high-pressure ridge shifts from Greenland to Alaska and gradually an Alaska “ridge bridge” toward Siberia develops. The result is increasing risk of a cross-polar arctic air surge from Siberia into North America in 7-10 days. The pattern described is often referred to as the “Siberian Express” and the Alaska “ridge bridge” phrase became popular after the North America “polar vortex” winter of 2013-14.

The November 2022 northern hemisphere snow cover was tied for 3rd most in the 1966-2022 record. In North America, November 2022 ranked 3rd most snowy on record while Eurasia was 12th most snowy of the past 57 years.

The NCEP FCS V2 Nino34 SSTA forecast continues an aggressive trend that indicates ending of La Nina early in 2023 followed by a shift into El Nino middle of 2023. ECM is indicating a much stronger El Nino developing middle of 2023. Climate Impact Company will issue a new ENSO forecast for 2023 late this week!

Medium-range forecasts are trending warmer across North America and especially the U.S. The catalyst to this warmer trend is a cold stratosphere over the polar region stretching south across Canada as indicated by the GFS in 5 days. As a review, the cooling and constricting stratosphere is compensated for by the warming troposphere below. Consequently, the upper-level pattern in the troposphere creating our weather is less able to produce cold air and arctic air generation is cutoff. Arctic air already present will retreat to deep snow cover.