Major Severe Weather Outbreak South-central and East U.S. Next 2 Days
03/04/2025, 5:21 am EST
Charts of the day: Comparing calendar winter 2024-25 stratospheric warming events.
Discussion: The U.S. arctic outbreaks in January and February were triggered by unconventional stratospheric warming events in that the warming was confined to Canada and the attendant polar vortex was locally generated, over North-central U.S. to cause the cold. Note that the stratosphere was cold on the Europe side of the North Pole. The March stratospheric warming event is stronger and across wider aerial coverage. However, the core of the warming is on the Siberia side of the North Pole therefore less reliably effective at generating North America cold.
Medium-range 6-10 Day Forecast Valid March 10-14, 2025 (AI Graph Cast right)
Discussion: The GFS and ECM, the most common operational models, are combined to generate the 6-10-day forecast. The forecast is trending colder in Canada and the California while in the U.S. to the east of the Divide, a mild pattern continues. The reliable AI Graph Cast projection is similar although the Canada and California chill is sharper.
Medium-range 11-15 Day Forecast Valid March 15-19, 2025 (AI Graph Cast right)
Discussion: Once again, the GFS and ECM are combined to generate the 11-15-day forecast. Only the Coastal Northeast is mild with colder temperatures elsewhere although not arctic cold in character. The AII Graph Cast is colder in Canada and California/Nevada while east of the Divide the mild regime is gone in favor of near normal.
U.S. Medium-range Precipitation Forecast
Discussion: GFS and ECM are equally weighted to produce the medium-range percent of normal precipitation forecast. The outlook is consistent focusing storminess on California in the 6-10-day period followed a storm track stretching across the northern half of the U.S. in the 11-15-day forecast.
Days 16-20 Extended range Temperature Forecast valid March 20-24, 2025
Discussion: The extended range forecast is seasonably chilly across much of the U.S. with storm tracks evident in the East and Western Canada.