Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
059 FXUS65 KGGW 120925 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 325 AM MDT Sun May 12 2024 .DISCUSSION... KEY MESSAGES: - Canadian wildfire smoke is causing reductions in visibility and air quality this morning, likely to mostly mix out in the afternoon. - Warmer than normal temperatures continue, particularly on Monday. - There will be frequent chances for showers and thunderstorms beginning Monday afternoon and continuing for the next several days. WEATHER PATTERN OVERVIEW: A shortwave trough with a weak cold front is bringing slightly cooler temperatures today along with a few rain showers and wildfire smoke out of Canada. Temperatures rebound on Monday ahead of a stronger shortwave trough, with a cold front that will move through the forecast area Monday afternoon and night. Models and ensembles are pointing towards enough instability for a few thunderstorms with this system. The NBM generally has a 20-30 percent probability of a thunderstorm Monday afternoon and night at this point and less than a 40 percent chance of a tenth of an inch of rainfall due to the more localized nature of convection. The pattern favors near normal temperatures Tuesday and beyond, though ensemble models differ on the extent of troughing and moisture available for continued shower/thunderstorm chances. CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST: The main deviation was to use HRRR smoke concentrations with slight adjustment when comparing to current observations to add in mention of smoke and visibility as low as 3 miles today. High confidence exists on above average temperatures through Monday. The current NBM highs continue to be at the lower end of the NBM possibilities (5-25%), so raised highs about a few degrees so that most locations are closer to the NBM 25% that matched up well yesterday. There is low confidence on the timing of showers and thunderstorms Tuesday and beyond, as well as the total amount of rain for any particular location. -Zanker && .AVIATION... LAST UPDATED: 0900Z FLIGHT CONDITIONS: MVFR - VFR DISCUSSION: Smoke is reducing visibility into the MVFR category this morning, particularly for KGGW and KOLF. Based on forecast smoke concentrations, there is medium confidence for gradual improvement by the afternoon. Otherwise, look for isolated rain showers this morning, scattered mid level clouds and winds around 10 knots or less. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow