Long Range Weather Forecast Discussion May 11-25
James Munley
Long Range Weather Forecast Discussion May 11-25
250 PM EDT Fri. May 8, 2026
May 11-15: An upper-level low over eastern Canada will continue to send multiple shortwaves across the East. This will keep conditions cool and wet. A ridge is forecast in the West with a trough in the East.
An upper-level low over eastern Canada will continue to send multiple shortwaves across the East. This will bring cool, unsettled weather across the central and eastern states. Frontal passages will cause showers and storms across the eastern and central states. Below-normal temperatures will spread into eastern states through Tuesday. A strengthening ridge across the West will cause above-normal temperatures. The warm air will gradually move into the central states by midweek.
May 16-20: The period starts with an almost zonal flow. A trough will settle over the East by the end of the period.
A couple of systems will move across the central and eastern states during this period. The first system will move from the central Plains by Saturday and to the Northeast by Sunday. The next system moves from the Plains on Sunday and tracks northeast through the Great Lakes, sending a cold front through the East. Rain and storms will be possible from the southern Plains to the Northeast late on Monday and Tuesday.
Above normal temperatures are forecast from the Mississippi Valley to the Pacific Coast, the Gulf Coast, and the Southeast. Anomalies are expected to be near or greater than 8°F in parts of the Rockies.
Below-normal precipitation is forecast for parts of northern California, the northern Rockies, the central and northern Plains, the upper Mississippi Valley, eastern Texas, the lower Mississippi Valley, most of the Southeast, parts of the Mid-Atlantic, and southern New England. The probability reaches 40 percent in the East. Above-normal precipitation is forecast for the southern Four Corners. The probability of occurrence is 35 percent.
May 21-25: The ECMWF and the GFS have a trough over the Northwest and the Northeast. The ECMWF is more amplified, with an upper-level low over Baja.
A front in the Plains will cause rain and storms. High pressure will cover the East. A system will move into the Northwest, causing rain and high-elevation snow.
Below-normal temperatures are forecast for most of the Northwest, the Mid-Atlantic, and the Northeast. Anomalies of 4°F are possible. Above-normal temperatures are forecast for parts of the northern Rockies, most of the middle and upper Mississippi Valley, and most of the Southeast. Anomalies may be 6°F or more in some locations of the northern Plains.
Above-normal precipitation is forecast for parts of the northern Rockies, most of the Plains, the lower Mississippi Valley, and most of the Southeast. The probability of occurrence is up to 40 percent across Texas. Below-normal precipitation is forecast for the upper Mississippi Valley eastward across the northern Mid-Atlantic and the Northeast. The probability of occurrence is 35 percent.
Jim Munley
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