Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
198 FXUS65 KGGW 120838 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 238 AM MDT Mon May 12 2025 .DISCUSSION... KEY MESSAGES: - Scattered showers and thunderstorms possible from the late afternoon and evening with a weak chance(2-10%) for a severe wind burst with any dying cells. - Red Flag is expected this afternoon with unusually hot temps in the 90s. Gusty winds will allow for a chance at fire runs. - Cold Front arrives Tuesday with a slow-moving weather system bringing the best chance for accumulating rainfall to NE MT Tuesday night into Wednesday. WEATHER PATTERN OVERVIEW: Southwesterly flow aloft along a surface trough oriented from Jordan to WOlf Point to Plentywood has set up an environment favorable for the development gusty winds and isolated to scattered thunderstorms across most of NE MT this afternoon and evening. With an inverted "V" in the soundings there will be enough Downdraft CAPE to generate a severe burst of wind with dying cells. The surface trough will convert to a cold front overnight and exit the area Tuesday. This will lead to gradually cooling temperatures and a very strong chance for significant rain Tuesday night and Wednesday. Rain chances 0.01"= (40%-90%) 0.10"= (30%-80%) 0.25"= (10%-60%) 0.50"= (1%-30%) Afterward temperatures will remain cool through the Weekend with scattered rain chance on and off through Thursday. FORECAST CONFIDENCE & DEVIATIONS: Deviations included a 50/50 blend of NBM/NBM90 for wind gusts during peak diurnal hours for today. A slight tweak upward with temps by a few degrees and down on RH along the eastern border to match up with the Bismark office. This allowed areas affected by the critical Red Flag conditions to expand as well. For confidence in the red flag focus is really given to the best placement for the surface trough this afternoon, as it phases well with normal high gusts across the north and low RH across the southeast. However, the surface front analyzed across the area by WPC may be what turns into this surface trough and analysis currently places this front a bit farther southeast than anticipated. There could be decreased confidence if the trough moves conditions farther southeast today and pulls the main features for the Red Flag out of phase with each other. GAH && .AVIATION... LAST UPDATE: 0730Z FLIGHT CAT RANGE: VFR DISCUSSION: Unusually hot weather will hold today with all terminals hitting near or above 90 this afternoon which may lead to increased DENSITY ALTITUDE. A surface trough running from KJDN to KOLF to KPWD will become the focal point of any showers(20-50% chance) and thunderstorms(10-30% chance) late this afternoon through the evening from 22-06Z. Any storms that develop have the chance for gusty erratic winds as they collapse. After 06Z remaining showers should confine themselves to west of KGGW through the morning hours. WIND: Light if not calm and S to variable this morning. Veering to the SW to W after sunrise and increasing to 10 to 20 kts gusting 25 kts in the afternoon. Veering farther to the NW to N and reducing to 5 to 15 kts this evening through tonight. GAH && .GGW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM this morning to 9 PM MDT this evening for Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck Reservation and Daniels/Roosevelt/Sheridan Counties- Southern Petroleum and Southern Garfield Counties-The Lower Missouri River Breaks including the Charles M Russell National Wildlife Refuge. && $$ weather.gov/glasgow