Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
261 FXUS65 KGGW 211051 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 451 AM MDT Tue May 21 2024 .DISCUSSION... KEY MESSAGES: - A more widespread chance for showers and thunderstorms will begin late Wednesday through Friday. Unsettled weather will remain likely at times into the upcoming weekend. WEATHER PATTERN OVERVIEW: An upper trough will prevail across the western CONUS this week with occasional shortwaves helping produce enough lift and instability for daily shower and thunderstorm chances. A more organized low pressure system will track through the northern Rockies for the second half of this week with a more widespread opportunity for wetting rains from showers and thunderstorms. This unsettled weather pattern looks to linger into the upcoming weekend. CONFIDENCE LEVEL and POTENTIAL DEVIATIONS FROM BASE FORECAST: Confidence is high that a wetter weather pattern is set to unfold for the second half of this week with ensembles showing strong consensus for a broad trough pattern and low pressure system pushing through the region. Confidence is lower on exact precipitation amounts and precise location given the convective nature of expected precipitation, but in general, expecting greater QPF to the southwest and lesser to the northeast. For now, have decided to remain close to the base forecast given that the NBM lines up with consensus view of a cool but wet pattern unfolding and the above average confidence. As the event works its way into the short term and human detail gains greater input value, some deviations become increasingly likely to better capture mesoscale details and placement of precipitation. && .AVIATION... VFR conditions. Mid level clouds are expected across the north with a few shower along the Canadian border this morning. DISCUSSION: Mainly clear skies are expected tonight while isolated showers over north-central Montana mainly move into southern Sask tonight. Isolated to scattered showers will develop SW of the terminals this afternoon and evening. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow