Long Range Weather Forecast Discussion May 9-23
James Munley
Long Range Weather Forecast Discussion May 9-23
157 PM EDT Wed. May 6, 2026
May 9-13: 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 through Monday. A lingering frontal boundary across the lower Mississippi Valley into the Southeast will cause rain across the area. Below-normal temperatures will continue across the Great Lakes into the Northeast through the weekend. A warming trend will occur across much of the western and central states.
May 14-18: The GFS moves the eastern ridge while the ECMWF keeps a ridge in the West and a trough in the East. The ECMWF AI also lifts the eastern trough, but it is slower. The GFS AI has the trough over the Great Lakes.
A front will sink south across the Northeast and the Midwest with rain on Monday. Rain is also expected for the Front Range of the Rockies and the central and southern Plains on Friday.
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 northern California, the Northwest, the northern and parts of the central Rockies, the Plains, and the Mississippi Valley, parts of the Gulf Coast, and the Midwest. The probability of occurrence is 35 percent. Above-normal precipitation is forecast for parts of the northern Plains to the Northeast. The probability of occurrence is nearly 43 percent.
May 19-23: The GFS has a trough in the West with a zonal flow and above normal heights across the central and eastern states. The ECMWF has a ridge in the West and a trough in the East. The AI version has some slight troughing across the Northeast.
A frontal boundary moves across the Mississippi Valley and the Great Lakes on Thursday and into the Northeast late Thursday and Friday. A system develops across the Rockies, bringing rain and high-elevation snow from Tuesday into Thursday.
Above normal temperatures are forecast from the Mississippi Valley to the Pacific Coast. Anomalies are expected to be near or greater than 8°F.
Below-normal precipitation is forecast for northern California, the Northwest, the northern and parts of the central Rockies, the Plains, and the Mississippi Valley, parts of the Gulf Coast, and the Midwest. The probability of occurrence is 35 percent. Above-normal precipitation is forecast for parts of the northern Plains to the Northeast. The probability of occurrence is nearly 43 percent.
Jim Munley
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