Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
397 FXUS65 KGGW 070845 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 245 AM MDT Fri Jun 7 2024 .DISCUSSION... KEY MESSAGES: - A cold front passage this morning will increase PoPs(40%) immediately along the International Border, with a wetting rain possibility (at least a tenth of an inch) remaining low (<15%). - Below normal temperatures are expected this weekend with Sunday expected to the coolest day. - A general warming trend to above-normal temperatures through the remainder of the forecast period. WEATHER PATTERN OVERVIEW: A shortwave trough rotating around an upper low over the Canadian Prairies will bring a cold front through the forecast area this morning. Chances for showers will be limited to along the Canadian Border this morning with this system. While models still have their differences with what to do with the upper low over the weekend, they are trending towards drifting the low to the south in a way that will bring a dry cold front through the forecast area Saturday afternoon or evening with a cool day on Sunday. There are also model differences in how quickly to moves the cold pool east early next week and low chances for rain showers <30% exist Sunday night and Monday as several EC ensemble members but very few GFS ensemble members want to bring some light rain through the area as the cold pool exits the area. Tuesday onward: Northeast Montana will be on the northern fringes of upper-level ridge influence as models come back into alignment for the region. This results in a general warming trend to above normal high temperatures by mid week. Waves on the periphery of the ridge could bring low chances for showers at times. FORECAST CONFIDENCE and DEVIATIONS: NBM ensembles continue to have difficulty resolving a cold pool that sets over the Canadian Prairies. A ridge ahead of it over southern Hudson Bay is forcing the cold pool to backslide south and west into Montana Saturday where it bumps up against the newly developing ridge over the western half of the CONUS. However, the difference in the position of that pool`s backslide among ensemble members ranges from the Dakotas to central Saskatchewan this weekend. This in turn is having a large knock on affect on temperature ranges from Saturday night into Sunday night along with any frontal features associated with it. The range for highs on Sunday between the NBM 10 and NBM 90 is nearly a 20 degree spread, leading to very low confidence in the forecast. The GFS ensembles have clustered closer to the NBM 10 which is the cold end of the temperatures possibilities on Sunday while the EC ensembles still have a 20+ degree spread. There is also little model precip confidence Sunday night and Monday with the differences in movement of the upper low and its associated cold pool. && .AVIATION... LAST UPDATE: 0845Z FLIGHT CAT RANGE: VFR DISCUSSION: There will be a mid level deck of clouds this morning with a cold front mainly north of the Missouri River that could reach as far south as KSDY. A few isolated to scattered showers are expected this morning mainly along the Canadian Border. Skies will clear in the late morning. Daytime cumulus is expected this afternoon. WIND: Light and variable winds early will become NE 5 to 15 knots this morning and to the north and NW at 10 to 20 knots this afternoon. NW winds will diminish to 5 to 10 knots tonight. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow