Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
352 FXUS65 KMSO 132009 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 209 PM MDT Thu Jun 13 2024 .DISCUSSION...Our streak of gorgeous late spring days continues, expect 80s to low 90s (Hells Canyon, Idaho) for temperatures today. Add in bountiful sunshine with light breezes and hopefully you can enjoy some time outside. Friday will be quite similar with an uptick in westerly winds as an open wave slides onshore the Pacific Northwest. Friday afternoon an isolated shower or thunderstorm will be possible in southwest Montana and Lemhi County Idaho. Saturday will be very breezy with gusts in the valleys up to 40 mph and in the mountains 40 mph or greater. Temperatures will also cool, in some cases 15 to 20 degrees compared to Friday. For those recreating on area lakes please exercise caution as choppy conditions will be possible. Chances for showers increase region wide but north of I-90 will have the best chance for measurable precipitation, with a greater than 40% of at least 0.10 of an inch. Sunday remains cooler and breezy with shower activity confined along the Canadian border and Glacier National Park. Snow levels which will become very important by Monday, will have already lowered to around 6000 feet. Dress accordingly for outdoor activities that take you into the mountains, hypothermia can happen even in June. Monday the models are in high agreement for a closed low, winter- like system to begin to affect the Northern Rockies. Although there remains differences in timing and exact placement of the low pressure. Expect widespread wet conditions with very cool conditions, winds will turn northeasterly. Heavy, wet accumulating snow is expected above 5000 feet, throughout southern Idaho County and most of western Montana. In western Montana, above 6000 feet a trace to 14 inches is possible, while in the Bitterroot, Anaconda, and Pintler Mountains, Bob Marshal Wilderness, and Glacier National Park Region the highest terrain has a 25% chance of receiving 14 to 20 inches of snow. This amount snow accumulating on trees with foliage could cause branches to go down on back country roads, be prepared. Due to the high impact potential above 6000 feet and moderate confidence of the event actually happening, winter storm watches have been issued along Continental Divide from the Canadian border through MacDonald Pass on I-90, including Georgetown Lake and the Anaconda and Pintler Mountains. The main snow event will be overnight Monday through Tuesday. Similar events to this one, in June 2008 and 2001, produced a small area of valley snow down to 2800 feet. There is insufficient confidence in either low pressure track or intensity currently, but you are encouraged to follow future forecasts as 1 to 2 inches of heavy, wet snow on trees with leaves could easily cause broken branches leading to localized power outages with winter driving conditions in area mountain passes. && .AVIATION...High pressure currently over the region is bringing generally sunny skies and light, terrain driven winds. By Friday, winds aloft will increase significantly from the southwest ahead of an approaching weather system. These winds will be able to mix down into the valleys by Friday afternoon, with gusts to 25kts common across all of western Montana and north central Idaho. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Watch from Monday afternoon through Tuesday evening for West Glacier Region. Winter Storm Watch from Monday evening through Tuesday evening for Butte/Blackfoot Region...Potomac/Seeley Lake Region. ID...None. && $$