Prohibitive U.S. Warmth Ahead of January Pattern Change

Charts of the day: ECM upper air forecasts for January.

Discussion: ECM “weeklies” indicate development of a stormy and cold upper trough in the Central/East U.S. as the middle third of January arrives.

Medium-range 6-10 Day Forecast Valid December 17-21, 2023 (24-hour change left)

Discussion: The East/Southeast U.S. Coast is stormy keeping the Gulf States temperate and causing a slightly cooler change. Everywhere else remains very warm.

Medium-range 11-15 Day Forecast Valid December 22-26, 2023 (24-hour change left)

Discussion: MJO-inspired push of mild Pacific air across North America leads to a potentially record warm Christmas Week.

U.S. Medium-range Precipitation Forecast

Discussion: Sings of a transient MJO across the equatorial Pacific appear with a storm track heading for California in the 6-10-day period and across the entire southwest quadrant of the U.S. in the 11-15-day period. This precipitation will be heavy snow in mountain areas. The East Coast grapples with heavy rain in the 6-10-day period.

Days 16-20 Extended range Temperature Forecast valid December 27-31, 2023 (previous below)

Discussion: Cautiously preferring the “less hot” CFS V2 projection for late December. The ECM forecast stays very warm. The Southern U.S. storm track stays intact.