Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
963 FXUS65 KGGW 181505 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 905 AM MDT Tue Jun 18 2024 .DISCUSSION... Going forecast in good shape but latest models are consistently showing some drying moving in this afternoon compared to going forecast. Therefore, blended current forecast grids with latest models. Didn`t go wholesale with latest models as upper trough over the area will make things unstable this afternoon. TFJ Previous Discussion... KEY MESSAGES: - Cool temperatures today with rain continuing in most areas. and Tuesday. - Gusty Winds across Fort Peck Lake will continue into this afternoon. - Warmer temperatures starting on Wednesday with frequent chances for showers and thunderstorm chances between Wednesday and Saturday, especially Friday afternoon and night. WEATHER PATTERN OVERVIEW: Upper trough over central Montana this morning will move across eastern Montana today. The system will continue to bring rain with isolated thunderstorms to most of NE Montana today. The heaviest rain will through Jordan, Circle, Sidney and Culbertson today where best upper level dynamics of expected to track. This area has a 40-60% chance of a half inch or more rain and a 60-80% chance of a quarter inch or more rain today. This is in addition to any rain that has occurred with this system so far. The upper low moves through central Montana tonight and eastern Montana on Tuesday which will keep the rain going most of the time until the low moves to the northeast Tuesday night. At this point, there is a 60-80 percent chance of a half inch of rain and a 20-40 percent chance of an inch of rain today and Tuesday from this event. The trough moves to east this evening which will allow the rain to diminish. On Wednesday, Montana transitions to an unstable WSW to SW flow aloft with an upper trough on the Pacific coast and a ridge to the east. This will bring warmer temperatures and frequent chances for showers and thunderstorms. The trough splits on Thursday and the northern branch trough moves inland along the Canadian Border starting Thursday night and reaching eastern Montana on Saturday. This will gradually increase the chances for showers and thunderstorms between Thursday night and Saturday. With warmer temperatures, some of these thunderstorms could be severe. Upper ridge on Sunday brings hot and dry weather with highs near 90. FORECAST CONFIDENCE and DEVIATIONS: Confidence is high on the rain in most areas this morning but the confidence is low over northern Phillips, northern Valley and Daniels Counties where several models have dry slotting. Confidence is also lower this afternoon and evening as the upper trough moves east. The base forecast has several hours of dry weather in various locations today but with a somewhat unstable atmosphere and short term models varying on when to have rain today, filled in the dry parts of the base forecast today with a chance of showers and this evening with a slight chance of showers. From Wednesday onward, confidence is high on a gradual warming trend. Confidence is low on precipitation chances Wednesday and Thursday. Confidence increases to moderate of precipitation chances between Thursday night and Saturday. && .AVIATION... LAST UPDATE: 1500Z, Tuesday morning, June 18th FLIGHT CAT RANGE: A mix of VFR, MVFR and IFR today, becoming VFR tonight. DISCUSSION: Low clouds with rain at times today will bring cloud bases will vary from VFR to IFR levels across the region. KGGW will be VFR most of the time while KSDY and KGDV will IFR most of the time today. The low clouds move to the east in the late afternoon and early evening and CIGS will rise to VFR by 00Z. Skies will gradually clear tonight. Will need to watch for areas of fog late tonight with wet ground. WIND: Becoming north 10 to 20 knots this morning and north to northwest at 10 to 20 knots this afternoon. Winds will become light and variable this evening. * We will continue at add "AMD NOT SKED" to the KSDY TAF till it is available online. TFJ && .GGW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory until 4 PM MDT this afternoon for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum. && $$ weather.gov/glasgow