Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
896 FXUS65 KGGW 171531 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 931 AM MDT Tue Sep 17 2024 .DISCUSSION... No changes were made to going forecast. Severe thunderstorm potential this evening still looks possible, and heavy rain tonight through Wednesday Night mainly for Phillips and Petroleum. TFJ Previous Discussion... KEY MESSAGES: 1) Warm temperatures today will give way to near average temperatures afterward. 2) Scattered thunderstorms this morning, and then strong to severe storms starting late this afternoon and continuing through early Wednesday morning. 3) Western zones could see a significant rain event tonight through Thursday morning. Lower amounts for eastern zones. WEATHER PATTERN OVERVIEW: A warm front slowly moving across the area is creating enough forcing to produce scattered thunderstorms south of the Missouri River and over the Little Rocky Mountains early this morning, producing light rain and virga. The low level jet and warm front will work together to produce scattered thunderstorms at times through mid morning. One more warm day with dewpoints in the 50s and low 60s today in tandem with the upper low and surface low will aid in strong to severe thunderstorms developing from north to south. While a few storms could develop as early as late afternoon, the best chances for severe storms starts around 6 pm and continues until 3 am Wednesday. The storms will be aided with 0 to 6 km shear being around 30 to 40 knots and surface CAPE around 1000 to 2000 J/kg. The initial thunderstorms will move through tonight and early Wednesday morning. The surface low and upper low will become stacked over the area late tonight and remain over the area through Wednesday night. Moisture will continue to get dragged into the area from the Pacific and Gulf of Mexico. This will lead to precipitation amounts being rather high for central Montana and as far east as Glasgow and Jordan. The probability of 1 inch or more rain west of Glasgow and Jordan tonight through Thursday morning is 70 to 90 percent and drops rapidly east of there. The probability of 2 inches or more rain is 50 to 70 percent between Malta, Zortman and Winnett and drop rapidly east of there. Dry slotting at times will limit overall rainfall amounts in the east. However, convective showers will have the potential to bring locally heavy rain. The SW zones could see strong winds on Wednesday afternoon and evening with a tight surface gradient on the SW side of the surface low. At this point, winds speeds will likely stay below High Wind Warning criteria but a Lake Wind Advisory is likely for Fort Peck Lake. Temperatures closer to seasonal average will settle across the region behind the front starting on Wednesday. The upper level low will depart to the northeast on Thursday taking the rain with it. Temperatures will remain close to average through the end of the weekend. FORECAST CONFIDENCE & DEVIATIONS: High confidence exists on above average temperatures occurring today as well as the upcoming cooldown starting Wednesday. There is moderate confidence of strong to severe storms occurring late this afternoon through early Wednesday morning. High confidence of rainfall greater than 1" occurring in Phillips and Petroleum counties, with low to medium confidence of 1" of rain further east. && .AVIATION... Last Updated: 0800Z Category: VFR most of the time today and tonight, MVFR at times in thunderstorms with most areas in MVFR after 09Z Wednesday. Discussion: Isolated to scattered showers and thunderstorms could impact a TAF site this morning prior to 16z. Thunderstorms become possible after 21z this afternoon and continues overnight. There is a possibility of wind gusts exceeding 50 knots and hail occurring in any thunderstorms. Low clouds late tonight will bring MVFR ceilings in most areas. KSDY will likely remain VFR. Winds: East to southeast at 6 to 16 knots today. KGGW and KOLF will have NE winds around 10 knots this evening and veer to the SE late tonight while KSDY and KGDV has SE to south winds around 10 knots tonight. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow