Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
672 FXUS65 KMSO 211818 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 1218 PM MDT Fri Jun 21 2024 .DISCUSSION...Unstable conditions aloft over northwest Montana has allowed for some convection today. With a trough exiting the region, mid and upper level stability has increased through the day, while the sunshine has warmed and destabilized the lower levels. The balance of the two will result in some thunderstorm development this afternoon over the Flathead Valley and along the Continental Divide, but it will be limited in strength due to the increasing stability aloft. Once the storms move east of the Continental Divide and catch up with the upper level trough, they will blossom into much stronger storms. The NWS Forecast Office in Great Falls will be watching those storms east of the Divide for some potentially severe weather today. Sunday, a trough moves along the Canadian border. Most of the rain with it will stay north of the border as well. An associated cold front to the south will cause increased winds across western Montana, especially southwest Montana. Ensembles are wavering on how strong the winds will be and after trending stronger last night, have trended a little weaker again today. We`ll continue to watch it closely to see if it warrants a Lake Wind Advisory for Flathead Lake, but at this time it appears there is only a 20 percent chance that winds will gust over 30 mph on Flathead Lake Sunday. Current timing of the front in the models suggests the peak winds would only occur with the frontal passage around 5 PM Sunday evening on the lake. Next week, a ridge builds in and temperatures will peak on Wednesday near 90 degrees in western Montana and reach near 100 degrees in Riggins, ID. Along with the warming trend comes a drying trend with relative humidity dropping into the mid teens. Late next week on Thursday and Friday, ensembles have come into better agreement on a trough digging into the region with another cold front. Most of the remaining uncertainty is related to how deep the trough will dig, and whether it will become a cutoff low or not. The cut off low pattern typically brings more rain, but recent model trends are towards an open wave, or trough type pattern. This would bring some rain in the form of thunderstorms and also more wind. && .AVIATION...A trough leaving the region today has allowed for some lingering convection this afternoon. Thunderstorms will mainly affect the vicinity of terminal KGPI, while the building ridge behind the trough keeps other area terminals clear. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$