480
FXUS65 KGGW 142121
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
321 PM MDT MON SEP 14 2026
KEY MESSAGES
- ADDITIONAL RAIN TOTALS FOR THE REMAINDER OF TODAY AND TONIGHT ARE
EXPECTED TO BE LESS THAN 0.20".
- SUSTAINED WINDS WILL BE 20 TO 30 MPH THIS AFTERNOON AND EVENING,
WHILE GUSTS HAVE THE POTENTIAL TO REACH 60 MPH.
- PRECIPITATION IS CURRENTLY ANTICIPATED TO BEGIN EARLY FRIDAY
MORNING AND LAST THROUGH SUNDAY NIGHT.
DISCUSSION
SYNOPTIC SETUP:
THE LOW PRESSURE SYSTEM THAT BROUGHT RAIN SHOWERS THIS MORNING HAS
BEGUN TO EXIT NORTHEASTWARD. LOW-LEVEL MOISTURE ASSOCIATED WITH
THE BACKSIDE OF THE LOW WILL CONTINUE MOVING THROUGHOUT THE
REGION, PRODUCING CONTINUED SHOWERS NORTH OF THE MISSOURI RIVER
THROUGH THIS EVENING. ADDITIONAL RAIN TOTALS FOR THE REMAINDER OF
TODAY AND TONIGHT ARE EXPECTED TO BE LESS THAN 0.20".
A TIGHT PRESSURE GRADIENT ON THE BACKSIDE OF THE LOW WILL RESULT
IN STRONG W-NW SURFACE WINDS THIS AFTERNOON AND EVENING. SUSTAINED
WINDS WILL BE 20 TO 30 MPH, WHILE GUSTS HAVE THE POTENTIAL TO
REACH 60 MPH. IT SHOULD BE NOTED THAT SIGNIFICANT CLOUD CEILINGS
MAY BE WORKING TO INHIBIT MIXING, POTENTIALLY DIMINISHING CHANCES
FOR WINDS AS STRONG AS THE FORECASTED MAXIMUM. A HIGH WIND
WARNING HAS BEEN ISSUED FOR EASTERN PORTIONS OF THE CWA. A LAKE
WIND ADVISORY HAS BEEN ISSUED FOR FORT PECK LAKE. WAVE HEIGHTS
HAVE THE POTENTIAL TO REACH UP TO 6 FEET.
THIS SYSTEM WILL MOVE NE AND OUT OF THE REGION BY TOMORROW
MORNING AS A WEAK UPPER-LEVEL RIDGE BEGINS TO BUILD OVER MONTANA.
HOWEVER, A SWATH OF MOISTURE MOVING THROUGHOUT THE 700MB FLOW WILL
CONTRIBUTE TO CHANCES OF RAIN SHOWERS ACROSS NW PORTIONS OF THE
CWA EARLY MORNING WEDNESDAY. THERE IS LITTLE INDICATION THAT ANY
RAIN AMOUNTS WILL EXCEED THAT OF A WETTING RAIN (0.10" OF
ACCUMULATION), ASIDE FROM LIMITED AREAS STRADDLING THE CANADIAN
BORDER.
COME THURSDAY NIGHT, A CUT OFF LOW OVER THE CALIFORNIA-OREGON
BORDER WILL BEGIN TO REJOIN MAINSTREAM FLOW AND MOVE OVER IDAHO
AND WESTERN MONTANA BY FRIDAY MORNING. THE LOW WILL THEN
GRADUALLY MEANDER ACROSS THE STATE THROUGH THE WEEKEND. LOW-LEVEL
MOISTURE AND VORTICITY-INDUCED INSTABILITY ASSOCIATED WITH THE
SYSTEM WILL LIKELY CAUSE RAIN SHOWERS AND POTENTIAL THUNDERSTORMS
ACROSS THE ENTIRETY OF THE CWA. PRECIPITATION IS CURRENTLY
ANTICIPATED TO BEGIN EARLY FRIDAY MORNING AND LAST THROUGH
SATURDAY NIGHT. AS OF THE LATEST RUN, THE NBM INDICATED RAIN
TOTALS FOR THE EVENT OF ROUGHLY .50" WITH LOCALIZED AREAS OF 1"
OR GREATER ACROSS THE CWA. NO PARTICULARLY STRONG WINDS ARE
ANTICIPATED FOR THIS EVENT.
FORECAST CONFIDENCE & DEVIATIONS:
- CONFIDENCE IN ADDITIONAL RAIN AMOUNTS FOR THE REMAINDER OF TODAY
AND TONIGHT ARE MODERATE TO HIGH.
- CONFIDENCE IN RAIN CHANCES AND TOTALS WEDNESDAY MORNING IS LOW.
- CONFIDENCE IN RAIN CHANCES THIS WEEKEND IS MODERATE. CONFIDENCE
IN RAIN TOTALS THIS WEEKEND IS LOW.
DON
AVIATION
LAST UPDATED: 2041Z
FLIGHT CAT RANGE: IFR THROUGH 00Z, THEN A TRANSITION TO MVFR
CONDITIONS BY 06Z.
DISCUSSION: A LOW PRESSURE SYSTEM THAT BROUGHT SHOWERS AND IFR
CEILINGS ACROSS THE REGION THIS MORNING IS MOVING TOWARDS THE
NORTHEAST AND BEGINNING TO EXIT THE AREA. MVFR CONDITIONS REMAIN
THROUGH MIDNIGHT TONIGHT, BUT LOW CLOUDS REMAIN THROUGH 12Z
TUESDAY.
SFC WIND: NORTHWEST AT 25-30 KNOTS BETWEEN 21Z AND 02Z TUESDAY,
WITH GUSTS UP TO 40 KNOTS THROUGH 03Z. NORTHWEST AT 10 KNOTS
THROUGH 09Z BEFORE VEERING EAST AT 18Z.
MPT
GGW WATCHES/WARNINGS/ADVISORIES
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR CENTRAL AND
SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-GARFIELD-MCCONE-
PETROLEUM.
HIGH WIND WARNING UNTIL MIDNIGHT MDT TONIGHT FOR DANIELS-DAWSON-
EASTERN ROOSEVELT-PRAIRIE-RICHLAND-SHERIDAN-WESTERN ROOSEVELT-
WIBAUX.
WEATHER.GOV/GLASGOW
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