Area Forecast Discussion
Issued by NWS Glasgow, MT
Issued by NWS Glasgow, MT
147 FXUS65 KGGW 030821 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 221 AM MDT Fri May 3 2024 .DISCUSSION... KEY MESSAGES: - Night-time temperatures will drop below freezing in many areas tonight. - Unusually warm conditions are expected on Sunday. - Another round of rain is expected starting Sunday night through at least Thursday. Ranges are looking on track to be around a inch and a half to 2 inches for many locations with moderate confidence(50-70%). WEATHER PATTERN OVERVIEW: Synoptic Setup: Forecast begins with a trough running down from Saskatchewan through eastern Montana and Wyoming. A closed low sits off the coast of the Pacific Northwest with a ridge formed up between these two features from Nevada through the Pacific Northwest and into British Columbia. Today through Tonight: Local trough will exit for the Dakotas taking the surface low along with it. This will pull the showers remaining across the area this morning towards the east and northeast with the final showers clearing or dissipating around Noon. Clearing should begin to filter in behind the showers during the late afternoon and early evening. By around Midnight enough clouds will exit to drop off temps to near freezing or lower as cold air continues to filter in. Saturday through Sunday: Expect a warming trend of 10 to 15 degrees each day as the ridge to the west moves into the region. The ridge looks like it is going to tap into Desert Southwest air which will make it unusually warm for the region by Sunday with 70s and perhaps brief 80s for highs. Meanwhile, the closed low from the PCNW will ram itself onshore and push into the Intermountain west while stretching into a very amplified trough in response to the ridge. Sunday night through Monday night: A southern flow interface will setup between the extremely warm temps of the exiting ridge and the incoming trough over the Intermountain West. This will start pulling gulf moisture into the Great Plains potentially all the way up toward eastern Montana. The intense cool down will generate a closed low over south central Montana with enough lift energy to not only generate rain showers but also thunderstorms across the region through these periods. There is a small chance (5-20%) that some of these thunderstorms could become severe, but with overnight convection being the main periods of interest there will be no insolation and severe weather will likely not occur. Will need to monitor SKEW-Ts in these periods as they get within CAM model ranges for further scrutiny. Tuesday through Thursday night: Closed low will migrate northeastward and start to cut off from the warm air. However, this just means that most of the convective elements will become mainly stratiform. Main problem here onward is that positioning of the low is in question with a range for its center position from South Dakota all the way up to southern Saskatchewan. The low looks to generate a trowal in most models which will bring a heavy amount of rain to areas directly under or behind it. The majority of the ensembles place this over eastern Montana which could easily generate 1 to 2 inches to the area it hits. This feature has remained consistent over the last 48 hours raising confidence to moderate(50-70%). Friday onward: A new ridge looks to move into the area which will raise temps and dry conditions out. GAH && .AVIATION... LAST UPDATED: 0730Z FLIGHT CAT RANGE: VFR - LIFR DISCUSSION: Low clouds, rain, and snow showers will linger through the morning at KGGW, KOLF and KSDY with some clearing of precip around 18Z. With temperatures hovering around freezing and wintry mixed showers across the area, ICING aircraft surfaces may become a problem that could hold on till about 18Z when the showers clear. Ceilings will be the main controlling factor through the cycle at the Terminals with MVFR ceilings being pretty universal till about 00-02Z this evening. IFR or worse will have an impact at KSDY and briefly KOLF around 10-19Z this morning. VFR should return to all the terminals this evening around 00-02Z. WIND: NW at 10 to 20 kts from this morning through today. Calming to 5 to 10 kts this evening through tonight. GAH && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow