Of course, the explanation is complex. But, in my view, a large contribution to the unexpected cold pattern occurring mid-to-late meteorological winter across the U.S. was caused by the poleward latent heat release (caused by seasonality) across the record warm northern hemisphere oceans last mid-to-late autumn.

During recent weeks and particularly in February, the Nino3 SSTA region located in the eastern equatorial Pacific Ocean has warmed significantly while near the Dateline, La Nina cool waters persist. The difference between the two regions implies the 2024-25 La Nina episode has shifted west toward the Dateline implying formation of La Nina Modoki.

Stratospheric warming is indicated in the polar region in the 11-15-day period. The warming is immense and should cause arctic air to form at ground level. Forecast models are slow to identify the arctic air risk. What may happen is "chunks" of arctic air form and bring brief but potent cold as indicated by AIFS into the Northeast U.S. centered on March 11.

Titanic subtropical high pressure leads to the hottest weather of calendar summer in East Brazil and much of Australia into early March. Nearby heavy rains are in Argentina while a major tropical cyclone is close to the Australia East Coast.