The Difference Between CFS V2 and CIC-CA Upper Air Forecast for Winter 2022-23

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Highlight: North America/Europe Upper Air Projections for Winter 2022-23

Fig. 1: NCEP CFS V2 500 MB anomaly forecast for DEC/JAN/FEB 2022-23.

Fig. 2: CIC-CA 500 MB anomaly forecast for DEC/JAN/FEB 2022-23.

Executive summary: Winter outlooks for the U.S. and Europe gain increased importance due to undesirable market conditions propelled by the Ukraine War. La Nina will hold for northern hemisphere winter and many climate forecasts for the upcoming winter season strongly indicate La Nina influence which warmer-than-normal for the South and East U.S. plus Europe. Climate Impact Company does not dismiss the La Nina influence. However, significant weight is given to the influence on climate of warm SSTA across the mid-latitude oceans. The difference in forecast methodology renders a polar vortex pattern for upcoming winter in Central Canada with a weaker upper trough likely in Europe. Both (U.S. and Europe) scenarios offer a much colder risk compared to a standard La Nina climate forecast for U.S. and Europe for upcoming winter.

Discussion: The NCEP CFS V2 projected upper air forecast across North America and Europe indicates a polar vortex regime over Western Canada and a La Nina upper-level ridge pattern stretching from the Southeast Pacific through the Southeast Coast (Fig. 1). The downstream influence of the North America pattern on Europe indicates the presence of a persistent upper-level ridge. Sensible weather produced by these projections is cold across Western Canada to the North-central U.S. with above normal snowfall, warm and dry across the4 Southern U.S. to the Mid-Atlantic States while the Midwest is wet.

The Climate Impact Company constructed analog (CIC-CA) forecast is based on reginal SSTA influence including equal weight to ENSO of persistent warmer-than-normal SSTA across the mid-latitude North Pacific and North Atlantic. The CIC-CA forecast has similar features but slight shift in position which has implications especially for the U.S. The polar vortex pattern is farther east and over central Canada. The amplification of the trough splits the Southern La Nina ridge with one center off the U.S. West Coast and a second off Newfoundland (Fig. 2). The downstream implications on Europe caused by the North America pattern are a eastward shift of an upper-level high-pressure ridge to Northwest Russia. In this scenario, sensible weather is colder for the Central U.S. and possibly the Southern States. A mild winter is limited to the Southwest U.S. and possibly the immediate East Coast. In Europe a warm pattern indicated by NCEP CFS V2 is replaced by a more temperate regime.

Implications of the CIC-CA Forecast is a legitimate cold concern for the U.S. for upcoming winter centered on Chicago in the U.S. HDD count (issued shortly) for Central U.S. cities including Texas is above the 10-year and 30-year normal. Additionally, the CIC-CA forecast is drier for the East-central U.S. compared to NCEP CFS V2 which suggests the river level of the Mississippi Rover is not likely to recover during winter. The CIC-CA forecast also supports West U.S. drought continuing while NCEP CFS V2 suggests increased wet risk for the Northwest States.

In Eurasia, the high-latitude upper-level high-pressure ridge across Northwest Russia suggests an upper-level low-pressure trough forms over Central Eurasia which is just off the chart presented. Beneath that trough, gathering arctic air is likely and a cold air source region for Europe evolves by mid-winter and could possibly shift westward across Europe the second half of winter.

Conclusions: The prevailing view of most winter 2022-23 forecasts for the U.S. is a very La Nina-like South/East U.S. warmer-than-normal regime associated with dryness. A wet risk is enhanced in the Midwest States and possibly the Northwest U.S. In Europe, a milder-than-normal winter climate is indicated. Climate Impact Company disagrees. The CIC-CA forecast indicates a pattern much more conducive of cold weather risk to the U.S. for winter 2022-23. A polar vortex pattern is persistent across Central Canada enabling above normal Northern U.S. snow, an attendant cold air source region and the ability to propel cold air masses at times south and eastward. There is no “ridge bridge” to create a cross-polar arctic express from Siberia to North America. Due to this difference in opinion in the North America winter outlook, a downstream residual influence on climate across Europe favors a temperate winter with cold air risk from the east during the second half of winter.