395
FXUS65 KGGW 130622
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1222 AM MDT MON JUL 13 2026
KEY MESSAGES
- DANGEROUS HEAT IS AGAIN EXPECTED ACROSS NORTHEAST MONTANA TODAY.
NEAR 100 HIGHS WILL BE POSSIBLE IN THE YELLOWSTONE VALLEY
AGAIN. FOR THESE LOCATIONS AN EXTREME HEAT WARNING IS STILL OUT
THOURGH MONDAY EVENING. FOR ALL OTHER LOCATIONS A HEAT ADVISORY
IS IN EFFECT.
- TEMPERATURES WILL REDUCE TO 80S AND 90S FOR HIGHS THROUGH THE
WORK WEEK.
- THERE IS AN ISOLATED CHANCE FOR SHOWERS ALONG PHILLIPS AND
NORTHERN VALLEY TONIGHT WHICH COULD BRING A SUDDEN WIND BURST
GUST. NEXT SIGNIFICANT CHANCE FOR RAIN WILL BE TUESDAY NIGHT
AND WEDNESDAY IN THE WEST.
DISCUSSION
WEATHER PATTERN OVERVIEW:
AN UPPER RIDGE BREAKS DOWN TODAY AND TOPPLES OVER SLOWLY TO THE
EAST. THERE IS AN EXTREME HEAT WARNING IN PLACE TODAY ACROSS THE
SE AND THE YELLOWSTONE VALLEY WHERE TEMPS WILL STILL CLOSE IN ON
100 DEGREES. ALL OTHER LOCATIONS THAT RUN 90 TO 95 FOR MAX TEMPS
OF HEAT INDEX HAVE BEEN DOWNGRADED TO A HEAT ADVISORY FOR THE
SAME AMOUNT OF TIME.
REPEATED CAM RUNS HAVE SUGGESTED THAT THUNDERSTORMS OVER CENTRAL
MONTANA WILL DRIFT INTO OUR NORTHWEST DURING THE EVENING HOURS.
MOST DOWNDRAFT CAPE SEEMS CONFINED TO THE WEST BEFORE IT PASSES
THE PHILLIPS BORDER WITH ONLY ABOUT 500 TO 1000 J/KG LEFT OVER AS
IT MOVES THROUGH PHILLIPS AND NORTHERN VALLEY COUNTY.
WITH THE RIDGE TOPPLED OVER A FEW SHORTWAVE TROUGHS MOVE THROUGH
THE FLOW ACROSS THE REGION. THE FIRST SHORTWAVE IS SUPPOSED TO
MOVE THROUGH IN LATE TUESDAY AFTERNOON AND GENERATE SHOWERS AND
THUNDERSTORMS ACROSS THE NORTHWEST THROUGH THE NIGHT AND SPREAD
THEM A BIT FARTHER SW INTO WEDNESDAY MORNING. HIGHEST TOTALS WILL
BE CONFINED TO THE WEST WITH 1 TO 2 TENTHS OF AN INCH IN PHILLIPS
COUNTY WITH AREAS ALONG THE YELLOWSTONE VALLEY RECEIVING NOTHING
IN THE SE.
THE NEXT COUPLE WIGGLES IN THE UPPER LEVEL FLOW ARE MORE SUBTLE
AND MAY NOT CARRY ENOUGH LIFT OR MOISTURE TO BRING A WETTING
RAIN THURSDAY OR FRIDAY. IN ADDITION WARM TEMPERATURES AND LOW RH
MAY INHIBIT ACCUMULATING RAIN FOR MOST LOCATIONS AS THEY PASS.
BUT, ANY PRECIPITATION REMAINS WELCOME.
FORECAST CONFIDENCE & DEVIATIONS:
DEVIATIONS FROM NBM INCLUDE... AN EARLY CAMS BLEND FOR HOURLY
POPS, WINDGUSTS, AND WIND FIELDS THROUGH 12Z THIS MORNING. AND A
SECOND CAMS POP BLEND FOR THUNDERSTORMS MOVING THROUGH VALLEY AND
PHILLIPS COUNTY FOR TUESDAY NIGHT WHICH WERE UN-RESOLVED IN NBM.
THERE IS MODERATE TO LOW CONFIDENCE OF A FEW LOCATIONS REACHING
100 TODAY ALONG THE YELLOWSTONE VALLEY.
THERE IS MODERATE CONFIDENCE OF SHOWERS AND THUNDERSTORMS TONIGHT
IN THE NORTHWEST DURING THE EVENING.
THERE IS MODERATE CONFIDENCE OF PRECIPITATION ACROSS THE WEST
TUESDAY NIGHT TO WEDNESDAY. AND HIGH CONFIDENCE OF NONE IN THE
YELLOWSTONE.
GAH
AVIATION
UPDATED: 0530Z
FLIGHT CATEGORY: VFR
LLWS: ANY CURRENT LOW LEVEL WIND SHEAR SHOULD GIVE OUT AROUND 14Z
WITH THE PASSAGE OF THE MORNING FRONT OVER ALL TERMINALS.
DENSITY ALTITUDE: HOT TEMPERATURES FROM 95-100 DEGREES WILL LEAD
TO NEEDS FOR INCREASED LENGTH OF RUNWAY AND INCREASED POWER FOR
TAKE OFF. WORST TIMES WILL BE IN THE AFTERNOON AND EVENING FROM
19Z TO 02Z TODAY AND POSSIBLY TUESDAY AND WEDNESDAY AS WELL.
DISCUSSION: MAINLY DRY WEATHER AND MOSTLY CLEAR SKIES ARE EXPECTED
OVER THE TAF CYCLE. A FEW CONVECTIVE MODELS SUGGEST ISOLATED DRY
THUNDERSTORMS JUST NORTHWEST OF KGGW IN THE EVENING HOURS.
ROUGHLY 01 TO 05Z.
SFC WIND: S WIND OF 10 TO 15 KTS WILL FLIP NORTH BEHIND A FRONT
THIS MORNING. VEERING FURTHER N TO NE AND INCREASING TO 10 TO 20
KTS IN THE AFTERNOON. VEERING FURTHERN NE TO E IN THE EVENING
THORUGH TUESDAY MORNING.
GGW WATCHES/WARNINGS/ADVISORIES
LAKE WIND ADVISORY UNTIL 6 AM MDT EARLY THIS MORNING FOR CENTRAL
AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-GARFIELD-
MCCONE-PETROLEUM.
HEAT ADVISORY UNTIL 2 AM MDT TUESDAY FOR CENTRAL AND SOUTHEAST
PHILLIPS-CENTRAL AND SOUTHERN VALLEY-DANIELS-GARFIELD-MCCONE-
NORTHERN PHILLIPS-NORTHERN VALLEY-PETROLEUM-SHERIDAN-SOUTHWEST
PHILLIPS-WESTERN ROOSEVELT.
HIGH WIND WARNING UNTIL 4 AM MDT EARLY THIS MORNING FOR DAWSON-
EASTERN ROOSEVELT-MCCONE-PRAIRIE-RICHLAND-SHERIDAN-WIBAUX.
EXTREME HEAT WARNING UNTIL 2 AM MDT TUESDAY FOR DAWSON-EASTERN
ROOSEVELT-PRAIRIE-RICHLAND-WIBAUX.
WEATHER.GOV/GLASGOW
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