Mega-cluster Ensemble “Most Likely” Forecast Indicates Cold Spike East March 18th

Climate Impact Company Daily Feature

Issued: Friday, March 6, 2026

Highlight: Mega-cluster ensemble “most likely” forecast indicates a cold spike in the East centered on March 18^th.

Fig. 1-2: The mega-cluster “most likely” (56% risk) U.S. temperature anomaly forecast for March 17^th and “caveat” forecast for March 18^th.

Discussion: At midday, 7 of 14 forecasts (combining dynamic and AI models) are cold in the East during the 11-15-day period. ECM OP and Weather Next V2 appear coldest while GFS OP is warmest. Support from climate signals to substantiate the cold forecast is poor. Cold East U.S. solutions given moderate strength arctic oscillation and North Atlantic oscillation are difficult to generate. The mega-cluster ensemble “most likely” March 17^th scenario is heavily biased by ECM which supports vigorous chill in the East and equally impressive warmth over Nevada (Fig. 1). ECM, GFS, and CMC are near equally shared to generate a “caveat” forecast for March 18 which is very cold across the eastern half of the U.S. (Fig. 2). The only explanation is release of energy in the troposphere as the stratosphere flips from warmer than normal toward normal in the 8-14/11-15-day period. Although unsubstantiated, 50% of the operational models showing a colder scenario require (weekend) monitoring. Climate Impact Company prefers the ECM ENS/AIFS ENS which is moderately cold throughout the East U.S. in the 11-15-day period.