Long Range Weather Forecast Discussion December 28-January 11
James Munley
Long Range Weather Forecast Discussion December 28-January 11
204 PM EST Thu. Dec. 25, 2025
Dec. 28-Jan. 1: The idea of the flow remains the same at the start of the period, a trough is forecast in the West, and a zonal flow with above normal heights is expected across the eastern and central states. A piece of the western trough slides across the northern states, setting up a trough over the Northeast.
An upper ridge will shift through the east-central states this week as a deep troughing off the West Coast shifts inland by the weekend. This will bring an end to the atmospheric river event in the western United States. Unseasonable warmth with record temperatures is expected before a frontal system passage. The colder northern tier will have several plowable snow chances from the Great Lakes to the northern Mid-Atlantic and Northeast, associated with a northern stream trough and frontal systems. Expect enhanced Lake Effect snow on Sunday and Monday.
Jan. 2-6: A trough is forecast in the West with a zonal flow and above normal heights across the remainder of the nation.
Above normal temperatures are forecast from the Mississippi Valley to the Pacific Coast. Anomalies could be greater than 8°F. Below normal temperatures are forecast for most of the Southeast, the Mid-Atlantic, and the Northeast. Anomalies could be near 6°F.
Above normal precipitation is forecast for the West. The probability of occurrence is 35-40 percent. Below-normal precipitation is forecast for most of the Southeast and northern New England. The probability of occurrence is nearly 40 percent.
Jan. 7-11: The GFS sinks a trough into the center of the nation. The ECMWF and its ensembles have a ridge in the West and a trough in the East.
Below-normal temperatures are forecast from Washington eastward across the upper Mississippi Valley and the upper Great Lakes region. Anomalies are expected to be 2-4°F. Above-normal temperatures are forecast for California eastward into the Midwest and the Southeast. Anomalies could be up to 6°F.
Above-normal precipitation is forecast for northern California, the Northwest, and the northern and central Rockies. The probability of occurrence is nearly 40 percent. Below-normal precipitation is forecast for most of southern and eastern Texas, the Southeast, and northern New England. The probability of occurrence is nearly 40 percent.
Jim Munley
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