663 FXUS65 KGGW 100703 AFDGGWArea Forecast Discussion National Weather Service Glasgow MT 103 AM MDT Wed Sep 10 2025
.DISCUSSION...
KEY MESSAGES:
- Mild haze of wildfire smoke will continue through midnight tonight before exiting.
- A surface trough over central Montana will aid in a few showers this morning.
- A storm system from the Pacific will pave the way for multiple rounds of accumulating rain showers and thunderstorms late this week into the weekend.
WEATHER PATTERN OVERVIEW: A few rain showers are expected across the western half of the GGW CWA through the early afternoon in response to a surface trough moving through central Montana. No accumulation is expected east of HWY 191. A deep trough over the western U.S. will help bring some showers and storms overnight tonight in the wake of a shortwave trough that is expected to match up with peak heating on Thursday afternoon. There is moderate confidence of a few severe thunderstorms occurring somewhere in the area on Thursday, with isolated severe wind and hail the main threats.
Then cooler temperatures and accumulating rainfall are expected to occur this weekend as the trough moves further eastward. There is moderate to high confidence of a few locations receiving a wetting rain, but placement of the highest rainfall is still quite uncertain.
FORECAST CONFIDENCE & DEVIATIONS: Deviated from the NBM to increase winds on Day 1 with a mix of NBM 90. Also adjusted PoPs for Day 1 to at least include precipitation chances for a broader portion of the area.
There is moderate confidence on a few rain showers occurring this morning across locations in the western half of the area. There is moderate to high confidence of thunderstorms occurring on Thursday afternoon for the entire area. There is high confidence on cooler temperatures occurring this weekend, with low confidence on precipitation amounts and placement on Thursday through Sunday.
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.AVIATION...
UPDATE: 0900Z, September 10th
FLIGHT CONDITIONS: VFR
PATTERN: A weak surface trough will aid in isolated showers through 18Z. There is high confidence of MVFR conditions occurring through 06Z Thursday before isolated showers and thunderstorms attempt to reach KGDV and KSDY.
WINDS: For KGGW, southeast at 10 to 15 knots, increasing to 14 to 20 knots after 18Z. For all other sites, east at 5 to 10 knots, becoming southeast at 10 to 20 knots after 16Z.
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.GGW WATCHES/WARNINGS/ADVISORIES... None. &&
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weather.gov/glasgow
NWS GGW Office Area Forecast Discussion