861
FXUS65 KGGW 181824
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1224 PM MDT SAT JUL 18 2026
KEY MESSAGES
- UPPER RIDGING WILL KEEP HIGHS IN THE 90S IN PLACE THROUGH
SUNDAY. HEAT RELATED EFFECTS ARE POSSIBLE ESPECIALLY SATURDAY
WHEN THE HUMIDITY IS A FACTOR.
- THERE IS A LOW CHANCE OF THUNDERSTORMS (10-20%) TODAY AND
TOMORROW. HOWEVER SOMES CELLS COULD BECOME SEVERE IN THE EVENING
ACROSS PHILLIPS COUNTY TODAY AND THE YELLOWSTONE VALLEY
TOMORROW AFTERNOON.
- A BRIEF COOLDOWN IS EXPECTED MONDAY.
DISCUSSION
WEATHER PATTERN OVERVIEW:
FORECAST BEGINS WITH A LARGE RIDGE RUNNING FROM WYOMING UP
THROUGH EASTERN MONTANA AND THROUGH THE WESTERN CANADIAN PRAIRIE
PROVINCES. TO THE WEST A LOW PRESSURE SYSTEM IS MOVING ONSHORE
OVER SOUTHERN BC AND THE PCNW. SW FLOW RESIDES BETWEEN THESE TWO
AIRMASSES WHICH IS THROWING SHORTWAVES THROUGH WESTERN AND CENTRAL
MONTANA WHICH PERIODICALLY MOVES ACROSS EASTERN MT WHEN THEY CAN
BLUNT THE RIDGE A BIT.
TODAY AND SUNDAY: FIRST SHORTWAVE BUMPING UP AGAINST THE RIDGE
OVER THE AREA IS DRAGGING RAINS SHOWERS TO THE NORTHWEST ACROSS
THE CWA THIS MORNING. THESE SHOULD CLEAR OUT ABOUT MID AFTERNOON
ALLOWING HEATING TO SET OFF A SECOND WAVE OF SHOWERS AND
THUNDERSTORMS OVER CENTRAL MONTANA. THE THUNDERSTORMS THAT MOVE
NORTHWEST THROUGH THE AREA ARE EXPECTED TO CLIP PHILLIPS COUNTY
IN OUR NW CWA SOMETIME AFTER 6PM. HREF SHOWCASES A FEW MAX WIND
GUSTS UP TO 60 MPH COMING FROM CELLS AS THEY DIE OUT IN THE
EVENING MOVING ACROSS THE BLAINE/PHILLIPS COUNTY BORDER. BUT
DOESN'T LET THEM MOVE MUCH DEEPER BEFORE DYING OFF COMPLETELY. SPC
HAS PLACED A MARGINAL RISK OVER THIS AREA FOR THE EVENING HOURS.
PRECIPITABLE WATER IS ALSO AROUND 1.6 INCHES TO 1.2 INCHES AND
SUGGESTS THAT THESE STORMS COULD BE PROLIFIC RAIN PRODUCERS AS
THEY MOVE THROUGH AND DIE OUT. AS THE STORMS EXIT THE AREA
OVERNIGHT THE STALLED BOUNDARY TO THE EAST IS EXPECTED TO
TRANSITION TO SURFACE TROUGH AND MOVE ALONG BEHIND THEM. AS IT
DOES SO IT WILL SET SOME SHOWERS AND THUNDERSTORMS OFF ACROSS THE
AREA SUNDAY AFTERNOON. THE MOST SEVERE CELLS LOOK TO BE FOCUSED
ACROSS THE YELLOWSTONE VALLEY BEFORE JUMPING THE MT/ND BORDER.
THERE IS UNCERTAINTY HERE WITH SOME CAMS MOVING THE BOUNDARY
ACROSS THE BORDER ENTIRELY BEFORE GENERATING ANYTHING LEAVING THE
LOCATION MOSTLY DRY.
MONDAY THROUGH TUESDAY WITH THE RIDGE BLUNTED TO THE SOUTH FLOW
BECOMES ZONAL, DRY, AND COOLER WITH HIGHS IN THE 80S.
WEDNESDAY THROUGH THE WEEKEND. THE PATTERN BEGINS TO WARM UP WITH
A RETURN FROM ZONAL FLOW ACROSS THE REGION TO FULL ON HOT RIDGE
FRIDAY AND SATURDAY. THERE IS SOME SUGGESTION THAT WE MAY BE
LOOKING AT 100S FOR HIGHS WITH EXCESSIVE HEAT WARNINGS AGAIN IF
THIS COMES TO PASS FROM THE ENSEMBLE DATA.
FORECAST CONFIDENCE & DEVIATIONS:
DEVIATION FROM NBM INCLUDE ATTEMPTING TO GET THE RAIN SHOWERS ON
RADAR BASHED BACK IN PLACE FOR THE NEXT SEVERAL HOURS. WHILE
DEFAULT HOURLY NBM PPI01 HAS DRY CONDITIONS ACROSS THE AREA THIS
MORNING, CAMS MODELS ARE ONLY A LITTLE BETTER WITH THE RAIN
EXISTING BUT OVER THE SE CWA RATHER THAN THE NW AND CENTRAL WHERE
IT WAS OCCURING ON MRMS. WITH NO MODEL DATA AVAILABLE THAT LOOKED
CLOSE ENOUGH, ENDED UP BLENDING A FEW CAMS AND THEN DRAGGING THOSE
HIGHER POPS OVER THE LOCATIONS EXPECTED TO BE AFFECTED THROUGH
ROUGHLY 6PM BY HAND. FOR THIS REASON CONFIDENCE IN POPS FOR THE
NEXT SEVERAL HOURS IS LOW.
AVIATION
LAST UPDATE: 1730Z
FLIGHT CAT RANGE: VFR.
DISCUSSION: SCATTERED RAINSHOWERS THIS MORNING THROUGH THE EARLY
AFTERNOON MAY BRIEFLY LOWER CEILINGS BUT SHOULD GENERALLY NOT GO
BELOW VFR. A SECOND WAVE OF ISOLATED RAIN SHOWERS AND
THUNDERSTORMS IS EXPECTED TO REACH KGGW FROM THE WEST AROUND 08 TO
10Z BUT AGAIN IMPACTS LOOK MINIMAL.
SFC WIND: S TO SE AT 10 TO 15 KTS GUST 20 THROUGH THE AFTERNOON
HOURS. BACKING TO THE E TO SE AND REDUCING TO 10 KTS OR LESS THIS
EVENING THROUGH TONIGHT. TURNING W TO NW BEHIND A FRONT MID
MORNING AND INCREASING TO 10 TO 20 GUST 25 KTS THROUGH THE DAY.
GAH
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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