Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
318 FXUS65 KGGW 211010 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 410 AM MDT Fri Jun 21 2024 .DISCUSSION... KEY MESSAGES: - Shower and thunderstorm chances increase today, with stronger storms and more widespread wetting rain expected. - A few isolated severe cells late this afternoon and evening are possible, with large hail the primary threats. - Warmer and drier weather expected for next week. WEATHER PATTERN OVERVIEW: An active jet/zonal flow will remain across the northern States/Canadian border region for the next week. A shortwave pushing through the northern Rockies today will help trigger thunderstorm development this afternoon. With southeast low level flow will aid in developing favorable conditions for supercells with deep-layer shear, strong buoyancy, and relatively low cloud bases. High pressure over the northern plains will keep an instability axis over central Montana with storms propagating southeast through the early evening. This will put the best threat for severe weather over the southwest zones (southern Phillips, western Garfield and Petroleum counties) for the late afternoon and evening. As the shortwave moves east, the storms will also lift east, but conditions will be not quite as favorable for severe storms. Rain totals through Saturday morning vary from a tenth to a half inch over the CWA, with locally higher amounts where storms train. Afterward, a ridging pattern will favor seasonably warm and drier conditions from Sunday into the middle of next week. FORECAST CONFIDENCE and DEVIATIONS: There is high confidence (60-80%) in general thunder with minimal chances (10%) for severe weather at a particular point Friday afternoon and evening. Confidence is medium to high for the general conditions remaining slightly warmer and drier than normal through much of next week. && .AVIATION... VFR - MVFR. Low clouds will linger over the Yellowstone Valley, with MVFR conditions at KGDV, possibly spreading to the other TAF sites through the morning hours. Ceilings will lift as thunderstorms develop over the region this afternoon and evening, although brief MVFR conditions are possible with some of the stronger storms. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow