606 FXUS65 KGGW 311639 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 1039 AM MDT Thu Jul 31 2025 .DISCUSSION... KEY MESSAGES: 1) Patchy fog will be brurning off this morning. 2) Scattered thunderstorms are possible south of the Missouri River mainly this evening. 3) The region will be on the west side of a weak ridge, showers and thunderstorm opportunities will continue into early next week. WEATHER PATTERN OVERVIEW: A weak upper ridge with a relaxed jet stream will keep mesoscale winds from the east, with some drying northeast winds remaining over the northeast portion of the CWA. A few showers will pass through near the Yellowstone River early this morning, and then by noon a few isolated thunderstorms will slowly develop in this same area. By late afternoon, a weak shortwave will allow some strong thunderstorms to develop along the southern fringes of the area. There is low (30 percent) confidence an isolated severe wind and hail storm will move through Petroleum county this evening. Popcorn thunderstorms are expected to develop across most of the area from south to north tonight and continue into Friday. WPC has the area outlined for marginal excessive rainfall for Friday and Saturday since there will be very little wind shear to push storms around, and precipitable water values are very high for this time of year. This monsoonal pattern will linger through early next week while the area maintains near seasonable temperatures. FORECAST CONFIDENCE & DEVIATIONS: There is generally low confidence of severe thunderstorms occurring today, and high confidence on monsoonal moisture reaching northeast Montana tonight. Increased winds through midnight tonight with two parts NBM 90 and one part NBM. && .AVIATION... Expected Flight Category: VFR. Discussion: There is low confidence (10% chance) of visibilities dipping into MVFR through 18Z due to some isolated pockets of smoke. A few weak showers and thunderstorms will move in from the south by early afternoon for KSDY and KGDV. There is moderate to high confidence all TAF sites will experience scattered storms this evening into the overnight. There is low confidence (10% chance) of visibilities dipping into MVFR through 18Z due to some isolated pockets of smoke. Wind: East 7 to 18 knots. Gusty and shifting winds near any thunderstorms. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow