Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
602 FXUS65 KMSO 180841 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 241 AM MDT Tue Jun 18 2024 .DISCUSSION...An upper level trough remains over the region through this evening leading to periodic showers. A disturbance within the trough will slide southeast across northwest Montana this morning resulting in an uptick of showers for northwest and west-central Montana. Snow levels will start the day around 5000 feet rising over 6000 feet this afternoon. Additional snowfall of 1-3 inches is anticipated where showers persist but overall impacts are diminishing with winter weather highlights scheduled to end this morning. Thinning cloud cover and light winds tonight into Wednesday morning will allow for areas of frost, mainly from the Mission Valley southward to Lemhi County. Gardeners should plan to protect any sensitive vegetation. There is great consensus (near 100%) of a warming and drying trend Wednesday through Friday under southwest flow. There is a 20-30% chance of showers or thunderstorms each day, focused mainly along the Divide. This is followed by a brief ridge over the weekend. Under the ridge, daytime temperatures peak about 15 degrees above normal (upper 80s western Montana valleys, low/mid 90s for north- central Idaho). Early next week, most ensembles (80%) support a weak trough or zonal flow leading to an increase in daily breezes with high temperatures dropping back to seasonable levels. Precipitation amounts look minimal at this point. && .AVIATION...An upper level trough remains over the region through this evening leading to periodic showers. A shortwave within the trough will slide SE across NW Montana this morning resulting in an uptick of showers for NW and WC Montana, including airfields KGPI, KMSO, KBTM, and KHRF. Patchy morning fog may occur where partial clearing occurs. By this afternoon, CAPE values reach near 500 J/kg thus isolated thunderstorms are expected. Occasional lowered ceilings and visibility reductions will occur with precipitation episodes. Showers greatly diminish after sunset as instability and widespread forcing subsides. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Warning until 6 AM MDT Tuesday for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region... Potomac/Seeley Lake Region. Winter Weather Advisory until 9 AM MDT Tuesday for West Glacier Region. ID...Winter Storm Warning until 5 AM PDT Tuesday for Southern Clearwater Mountains. && $$