U.S. Sunday Report: An “atmospheric river” into Northern California this week, potential very cold 11-15-day outlook, and a big snowstorm beginning next weekend.
02/02/2025, 3:01 pm EST
Fig. 1-2: ECM ENS 15-day U.S. temperature anomaly forecast and the 12Z GFS+ECM 11-15-day temperature anomaly forecast.
Fig. 3-4: The NBM 5-day rainfall forecast across Texas and vicinity plus the GFS+ECM 8-14-day percent of normal precipitation outlook.
Discussion: The 12Z ECM ENS 15-day temperature anomaly forecast for the U.S. reveals eroding cold in the Northeast, expansive warmth in the Gulf region extending to the Midwest States, and new cold developing in Western Canada (Fig. 1). The 12Z GFS +ECM U.S. 11-15-day temperature anomaly forecast reveals very cold weather across Montana and vicinity with now cold extending southward toward Texas (Fig. 2). The East sifts cooler to near normal in the 11-15-day period.
Heavy precipitation events are in the forecast. In Texas to Louisiana and Arkansas this week, a rainfall event producing 2-4 inches of rain is projected (Fig. 3). Unlike last week, the entire event is all rain. In the 8-14-day period as new cold returns to the U.S., a stormy pattern featuring plenty of snow extends from the Northwest U.S. to the northern Appalachian Mountains (Fig. 4).
The U.S. population weight HDD forecast reveals a significant warmer change since Friday primarily due to the warm-up in the East (Fig. 5). The CFS V2 and ECM combined for a much warmer forecast compared to yesterday (Fig. 6). The extended-range models are doubting cold into the East.
Fig. 5-6: U.S. gas population weight HDD forecast utilizing all models, their consensus, and comparison with 24 hours ago and the 10-year/30-year normal plus the week 3-5 HDD forecast consensus between CFS V2 and ECM.