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Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
309 FXUS65 KGGW 162054 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 254 PM MDT Fri Aug 16 2024 .DISCUSSION... KEY MESSAGES: - With an approaching short-wave disturbance from the west, multiple rounds of showers and thunderstorms are possible for differing portions of northeast Montana, now through Saturday. Some lightning, gusty winds, and brief heavy rain are possible. - A slight warming trend through this weekend will bring the return of widespread high temperatures back up to the mid 90s, especially on Sunday. WEATHER PATTERN OVERVIEW: A 500 hPa trough from the Gulf of Alaska will move south today, parking itself off the Washington sate coastline, cutting off from the jet stream, while a shortwave trough traverses the Great Plains and parking itself in the ECONUS, setting up a large-scale Omega Block pattern. A shortwave trough downstream of the west coast low pressure system, will move along the MT/Canada border today and tonight flattening the ridge over eastern Montana and the Dakotas. This will bring chances for showers and thunderstorms to NE Montana mainly tonight when the wave passes through the area. Chances for measurable rain tonight will be as high as 60-70 percent over portions of Valley, Phillips, and Garfield Counties, but only 30-40 percent over the remainder of the region. The upper ridge rebounds over Montana over the weekend with warmer high temperatures mainly in the mid 90s from Sunday through Wednesday. Weak disturbances moving through the ridge could bring shower and thunderstorms at times for Monday and Tuesday. FORECAST CONFIDENCE & DEVIATIONS: Average to good confidence on the shower and thunderstorm chances tonight. Low to average confidence on thunderstorm chances beyond Saturday. With respect to high temperatures from Sunday onward, the probability of reaching 100F for max temperatures is highest for locations in lower elevations of adjacent river valleys, though these probabilities of exceedance do not go above a 25% chance. We will have to carefully monitor the trends for the 500 hPa high pressure and how much heights increase in subsequent model runs and to see if we creep back up to the 100s. && .AVIATION... UPDATED: 2055Z, Friday afternoon, August 16th FLIGHT CAT: Mainly VFR with occasional MVFR. DISCUSSION: Tonight, as thunderstorms move through NE MT, a few TAF sites may be directly impacted. Some lingering haze from wildfires is possible over the next several days, but for now the impact to visibility is expected to be minimal. WINDS: Generally from the east at 10 to 15 mph this evening, then variable and gusty near the stronger storms tonight. Tomorrow, winds will be more from the SE around 10 to 12 mph. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow