FXUS65 KGGW 200702 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 102 AM MDT Wed May 20 2026 .KEY MESSAGES... - A frontal passage will bring scattered showers and thunderstorms this afternoon and evening. An isolated storm or two may be on the stronger side with wind gusts to 60 mph. - A second round of showers and isolated thunderstorms will be possible near the ND border Thursday afternoon. - Warmer temperatures are expected beginning Friday with 80s for highs beginning Sunday onward. && .DISCUSSION... WEATHER PATTERN OVERVIEW: Forecast begins with northwest flow running from British COlumbia through eastern Montana and to the central US Plains. A series of ridge trough couplets are embedded within this flow pattern. Today into Tonight: the first upper trough in NW flow moves into the area this morning. This system will bring a cold front across eastern montana this afternoon and evening with rain showers and isolated to scattered thunderstorms. SPC's HREF shows some isolated cells within this frontal passage producing wind gusts up to 60 mph which will need to be monitored. The passage itself looks like it will be a 6 hour trek across the area starting around noon and exiting around 6 to 7 PM. Precip will be very hit- and-miss with most areas receiving nothing but a few location getting 1 to 2 tenths of an inch max. Thursday: The surface trough that moves into the region during the previous afternoons kind of stalls out at the ND border and will become a focal point from the morning to afternoon hours for additional showers and isolated thunderstorms. These do not look severe yet at this time. Thursday night into Sunday: Conditions will clear and warm through these time periods with maybe a weak shower possible Saturday night. Sunday night onward: Synoptic ensembles are starting to firm up on a ridge moving into the region and then closing up into a high pressure system for a short time Monday and Tuesday with very warm temperatures. Butting up against this will be a deeply amplified trough across the Pacific Northwest. These two features will play chicken for awhile with a chance at the high/ridge over eastern Montana to break down and southern flow with strong thunderstorms to take over Tuesday to Thursday afternoon. If the ridge stays put, we'll be dry and hot. If it moves forward then we become wet quickly with possible severe Wx depending on timing. FORECAST CONFIDENCE & DEVIATIONS: Changes to NBM were focused to hourly PoPs in the late afternoon and evening along with during the day on Wednesday. Hourly NBM data had a definitive 6 hour bias that was throwing natural hourly trends off. Used and NPoP blend of available CAMs and shrink stretched up PoPs a few percent afterward to try to quick blend in a slightly better trend. Also did this for Wind and Wind Gust to better capture the timing of the frontal passage that was washed out by NBM. Confidence in timing any showers and thunderstorms today is HIGH. Confidence in severe winds gusts from cells embedded in the system Wednesday is LOW. && .AVIATION... LAST UPDATED: 0345Z FLIGHT CAT RANGE: VFR. DISCUSSION: Expect VFR and mid to high clouds across the region through the night and early morning Wednesday. Showers and thunderstorms will move through the area late morning to early afternoon and take about a 6 hour trek across the region. There is a outside chance (5-20%) for one or two cells to become severe with wind gusts up to 50kts, but the chance at any given terminal is too low to place in the TAFs directly till they are clear on radar this coming afternoon. Storms should exit all terminals by about 02Z before clearing out for most of the night with only and isolated showers possible from then on. LLWS: There is a small chance(10-30%) for some low level wind shear at KGDV and KSDY between 06Z and 12Z this morning. WIND: S to SW at 10 to 15 kts through mid morning. Veering W in the late morning. Briefly increasing to 15-25 kts with the frontal passage this afternoon. Becoming light and variable Wednesday evening. GAH && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow