Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
805 FXUS65 KMSO 221839 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 1239 PM MDT Sat Jun 22 2024 .DISCUSSION...A brief weak ridge of high pressure will be the dominate weather feature over the Northern Rockies this weekend, allowing for afternoon highs to run 10-15 degrees above normal. Most valleys in western Montana will top out in the mid to upper 80s and low 90s for the valleys of north-central Idaho. Currently, there is a 40-50% probability Sunday afternoon temperatures will reach 90F in the Missoula and Bitterroot Valleys for the first time this season. The ridge will breakdown late Sunday afternoon and evening, as a weak cold front pushes through the region. Isolated showers will be possible along the front, but the most notable change will be an increase in westerly wind gusts. Those with plans to recreate on area lakes, in particular Flathead Lake, can expect a slight increase in chop, with around a 50% probability for gusts reaching 25 MPH after 3PM. The ridge quickly rebuilds early next week and very warm conditions return. High temperatures could be 10 to 15 degrees above normal by the middle of the week. The normal first 90F degree day for Missoula is June 18th, if we reach 90F on Wednesday (26 June) it would be similar to 2022 when our 1st 90F was 27 June. The question is do we have sufficient soil moisture to slow afternoon warming and delay till July the 1st 90F in Missoula. A southwesterly flow will develop by the end of the week, that is expected to open the door for scattered showers and thunderstorms across western Montana and north-central Idaho Thursday and Friday. A shortwave trough of low pressure traversing the Rockies in British Columbia will allow for more coverage of precipitation over northwestern Montana. && .AVIATION...High pressure over the Northern Rockies will bring pleasant weather to the region, with primarily terrain driven winds this afternoon. The ridge will breakdown late in the day Sunday, that will allow for an increase in westerly winds, up to 25kts for most aviation sites. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$