Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
974 FXUS65 KMSO 270739 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 139 AM MDT Mon May 27 2024 .DISCUSSION...A ridge of high pressure will continue to build over the Northern Rockies today, rounding out the holiday weekend with dry weather and daytime high temperatures just slightly above normal. Expect 70s today for the valleys of western Montana, and 80s for the lower Salmon River valley as the ridge axis sits over western Montana this afternoon. On Tuesday, the ridge continues to amplify and shift eastward as a trough of low pressure deepens over the West Coast, putting the Northern Rockies under moist southwesterly flow. While Tuesday will be the warmest day of the work week, a lot of factors are pointing towards good likelihood of afternoon thunderstorms. North-central Idaho will have the best chances for thunder at 40-50 percent. The Missoula and Bitterroot Valleys and northwest Montana across Lincoln and western Flathead County will have about a 30-40 percent chance for thunder. Pacific moisture, along with good instability and shear, and a dry lower atmosphere, will fuel storms capable of producing strong, gusty outflow winds, brief heavy rain, lightning, and small hail in the late afternoon and evening hours. The chances for storms to become severe (wind over 58 mph) is about 5 percent. The low over the west coast arrives in the Northern Rockies on Wednesday, bringing more widespread stratiform rain to the region. Impacts under this pattern will be characterized by temperatures 5-10 degrees below normal, gusty westerly winds (20-35 mph in valleys), and widespread shower activity. Model ensemble solutions are leaning towards a return to high pressure by next weekend, with about 85 percent showing a broad ridge over the western U.S. && .AVIATION...High pressure today will keep visibility and ceilings at VFR across the Northern Rockies with light to moderate winds. The next chance for impactful weather will be on Tuesday as clouds increase and there will be chances for afternoon thunderstorms across the Northern Rockies. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$