Northern Hemisphere Pattern Change Catalyst for Late January is an Evolving -PNA and +SCAND Pattern

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Beginning midweek the northern hemisphere jet stream will trough on the U.S. West Coast and re-strengthen in western Europe. In-between the two vigorous trough patterns a third trough resides south of Greenland. By late January the pattern still remains although with slightly less amplitude. These features shape the last third of January 2021 climate for the northern hemisphere.

Fig. 1: An emerging negative phase Pacific North America (PNA) pattern coupled with an evolving positive phase of the Scandinavia Index will cause significant pattern change for the northern hemisphere for the last third of January.

Discussion: Beginning midweek the northern hemisphere jet stream will trough on the U.S. West Coast and re-strengthen in western Europe. In-between the two vigorous trough patterns a third trough resides south of Greenland. By late January the pattern still remains although with slightly less amplitude. These features shape the last third of January 2021 climate for the northern hemisphere. Included will be a vigorous West Coast and Mid-south U.S. storm track. The increased Pacific influence lowers the risk of important U.S. cold weather (except in the snow-covered Northwest). Across the North Atlantic a ferocious storm track emerges U.K. to France and into Southeast Europe stretching to the Black Sea region. Once again, a lot of marine air (from the North Atlantic) involved with this pattern which defeats cold risk. Western Europe is temperate while the recent Eastern Europe to Black Sea chill reverses milder. Well to the east the -PNA/+SCAND pattern causes a warming influence on China the next 10 days.