Long Range Weather Forecast Discussion January 1-15
James Munley
Long Range Weather Forecast Discussion January 1-15
214 PM EST Mon. Dec. 29, 2025
Jan. 1-5: A trough is forecast over the eastern Pacific and the West Coast, with another trough over the East. A ridge is forecast in between. The eastern trough gradually lifts out by the end of the period.
A broad cyclonic flow aloft in the East will keep a cold airmass in place. A ridge in the West will flatten as it gets pushed to the east across the Plains by the weekend. Unsettled conditions are expected to affect the West Coast by Thursday, with a potentially well-organized storm system reaching central and northern California late in the week. A low along a frontal boundary across the southern states is expected to bring rain to the Southeast on Friday.
Jan. 6-10: The eastern trough re-establishes itself in the East due to an upper low in eastern Canada, but it too lifts out as a ridge builds east. The ECMWF ensembles have a little more troughing in 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.
Below normal precipitation is forecast for most of California and the coastal areas of Oregon, Washington, and the southern Plains. The probability of occurrence is 35 percent. Above normal precipitation is forecast for a portion of the Great Lakes, Oregon, and most of the Southeast. The probability of occurrence is 25 percent.
Jan. 11-15: The GFS has a trough in the West and a ridge in the East, while the ECMWF has a broad trough across the eastern and central states. The Ensembles agree with the ECMWF. A trough is forecast over eastern Asia, but it will be lifting out.
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.
Below normal Precipitation is forecast west of the Divide, the southern and central Plains into the middle Mississippi Valley. The probability of occurrence is 35 percent. Above normal precipitation is forecast for most of the Southeast, the Mid-Atlantic, and the Northeast. The probability of occurrence is 35 percent.
Jim Munley
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