Long Range Weather Forecast Discussion December 29-January 12
James Munley
Long Range Weather Forecast Discussion December 29-January 12
227 PM EST Fri. Dec. 26, 2025
Dec. 29-Jan. 2: A ridge is forecast in the West. Most of the country will be dry with the Pacific moisture blocked. The exception will be the Great Lakes.
Most of the nation will experience dry conditions except for the Great Lakes. The western ridge will break down, allowing a trough to push into the West. This will bring rain and mountain snow to much of the West by the end of next week.
Jan. 3-7: The GFS pushes a trough that will go into the West, pushing the ridge eastward. The ECMWF has a broad trough across the nation, but it is not as strong as in previous runs.
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 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. 8-12: The GFS brings a trough into the northern states. The ECMWF has a broad trough across much of the country. The ensembles have a weak trough across the East.
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.
Little change is expected in the precipitation anomaly forecast from the previous period.
Jim Munley
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