Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
140 FXUS65 KMSO 040927 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 327 AM MDT Sat May 4 2024 .DISCUSSION...Today should be the warmest day of the week even though high to mid level clouds will be steadily increasing. Temperatures are still anticipated to be 5 to 10 degrees above seasonal averages. A significant low pressure system will move on shore near the California/Oregon border and track across southern Idaho Saturday night into Sunday night. Cooler temperatures and widespread shower activity is expected over the Northern Rockies during this time frame. Then the low starts to track to the northeast across southwest Montana into eastern Montana on Monday. This path appears to enhance the precipitation across Lemhi county into southwest Montana. Snow levels will be lowering to around 5000 feet by Monday morning, causing accumulating snow on Lost Trail, Homestake and MacDonald Passes along with Gilmore Summit and Georgetown Lake. These locations have a 50 to 80% chance of receiving over 2 inches of snow by Monday morning. The low appears to settle along the Montana and North Dakota border and intensify Tuesday into Wednesday. This amplification of the low will create north to northeasterly flow over the Northern Rockies. This flow pattern is conducive to upslope flow along the Continental Divide, especially around Glacier National Park. Marias pass has a 90% chance of receiving over 2 inches of new snow Tuesday into Wednesday and even a 60% chance for greater than 4 inches. The bulk of the low pressure system will move off to the east while a portion of energy drifts back to the Great Basin region during the latter part of the work week. This pattern shift will leave the Northern Rockies in a weak northerly to easterly upper level flow Wednesday through Friday. Temperatures will gradually warm, but still remain below seasonal averages. Shower activity is expected to decrease in coverage and intensity each day. A ridge of high pressure is still expected to build over the region during the weekend causing a warming and drying trend. && .AVIATION...A ridge of high pressure will be the dominant feature over the region today, but high level clouds will be steadily increase as the next system approaches the region. Precipitation is expected to start moving into north central Idaho and Lemhi county this evening with rain showers potentially impacting KSMN after 05/03z. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$