816
FXUS65 KGGW 181854
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1254 PM MDT MON MAY 18 2026
KEY MESSAGES
- TUESDAY MORNING WILL BE COLD ACROSS NORTHEAST MONTANA, WITH
CHANCES FOR NEAR RECORD LOWS IF CLOUDS CLEAR OUT OVERNIGHT.
- WARM WEATHER RETURNS MID WEEK. THE NEXT CHANCE FOR SHOWERS
RETURNS WEDNESDAY.
DISCUSSION
WEATHER PATTERN OVERVIEW:
A STRONG UPPER TROUGH WILL KEEP COOL CONDITIONS THROUGH TONIGHT
BEFORE WEAKENING AND ALLOWING TEMPERATURES CLIMB CLOSER TO NORMAL
BY WEDNESDAY. TONIGHT LOW TEMPERATURES LOOK TO DROP BELOW
FREEZING WITH CLEARING SKIES AND LIGHT WIND. WITH THESE COOLER
TEMPERATURES, MAKE SURE TO PROTECT SENSITIVE VEGETATION.
BY MID WEEK UPPER LEVEL RIDGING OVER THE WEST COAST WILL ALLOW
QUICK MOVING SHORTWAVE TROUGHS TO SNEAK THROUGH THE OVERALL QUASI-
ZONAL FLOW, BRINGING SOME ISOLATED THUNDERSTORM CHANCES THROUGH
THE END OF THE WEEK. THE BEST CHANCE FOR THUNDERSTORMS WILL BE
WEDNESDAY. MODEL PLUMES CONTINUE TO SUGGEST WEAK INSTABILITY IN
THE ~300 J/KG MLCAPE RANGE DURING WEDNESDAY EVENING. GEFS FORECAST
RH AND DEWPOINT FOR WEDNESDAY EVENING CONTINUE TO RISE.
FORECAST CONFIDENCE & DEVIATIONS:
NO CHANGES TO NBM.
AVIATION
LAST UPDATED: 1900Z
FLIGHT CAT RANGE: MVFR-IFR THROUGH DAYTIME. MVFR-VFR BY TUESDAY.
DISCUSSION: OVERCAST CONDITIONS WITH ISOLATED RAIN SHOWERS WILL
PERSIST OVER THE REGION THROUGH THE AFTERNOON AND EVENING. CLOUDS
BEGIN TO CLEAR OUT SOMETIME OVERNIGHT FROM WEST TO EAST, AND ANY
CLOUDS THAT DO REMAIN SHOULD BE RIGHT AROUND THE MVFR THRESHOLD.
TEMPERATURES COULD BE BELOW FREEZING FOR MANY LOCATIONS TUESDAY
MORNING.
WINDS: WINDS WILL BE NORTH TO NORTHWEST THROUGH THIS EVENING AT
10-15KTS. BY CLOSE TO MIDNIGHT, EXPECT A TRANSITION TO LIGHT AND
VARIABLE WINDS WHICH SHOULD REMAIN THROUGH MIDDAY TUESDAY.
CLIFF
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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