Long Range Weather Forecast Discussion December 27-January 10
James Munley
Long Range Weather Forecast Discussion December 27-January 10
217 PM EST Wed. Dec. 24, 2025
Dec. 27-31: The idea on 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 the Northeast as a northern stream trough and frontal systems. Expect enhanced Lake Effect snow on Sunday and Monday.
Jan. 1-5: The ECMWF depicts a ridge in the West and a trough in the East. The GFS has a trough in the Northeast.
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.
Below normal precipitation is forecast for central and northern California, the Northwest, and western Montana, the southern Plains, the lower Mississippi Valley, the Southeast, the Tennessee Valley, the Mid-Atlantic, and the Northeast. The probability of occurrence is up to 45 percent.
Jan. 6-10: The GFS builds a ridge into the West, pushing a trough in the East after a ridge builds in. The ECMWF has a trough across the country.
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 the Southeast and northern New England. The probability of occurrence is nearly 40 percent.
Jim Munley
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