451
FXUS65 KTFX 290542
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1142 PM MDT FRI AUG 28 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS WITH HIGHER
RAINFALL AMOUNTS THROUGH THE WEEKEND, WITH THE POTENTIAL FOR
SOME MINOR MOUNTAIN SNOW AT RIDGE TOPS ON SUNDAY.
- BREEZY AND GUSTY WINDS ON SUNDAY, ESPECIALLY ALONG THE ROCKY
MOUNTAIN FRONT AND CRAZY MOUNTAINS.
- BELOW NORMAL TEMPERATURES FOR SUNDAY AND MONDAY.
UPDATE
/ISSUED 823 PM MDT FRI AUG 28 2026/
UPDATED FORECAST IS OUT FOR THIS EVENING. MAIN ADJUSTMENT WAS TO
ADD SHOWERS/THUNDERSTORMS OVER NIGHT TO CENTRAL/SOUTHWEST MT. THE
MAIN IMPACT FROM THE STORMS OVERNIGHT WILL BE LIGHTNING/STRONG
WIND GUSTS. OVERNIGHT LOWS LOOK ON TRACK. BRUSDA
DISCUSSION
/ISSUED 823 PM MDT FRI AUG 28 2026/
- METEOROLOGICAL OVERVIEW:
CLOSED UPPER LEVEL LOW OFF THE COAST OF BRITISH COLUMBIA AND
ASSOCIATED UPPER LEVEL TROUGH WILL DIG SOUTH OVER THE PACIFIC
NORTHWEST BY SATURDAY MORNING BEFORE TRACKING EAST ALONG THE
CANADIAN BORDER THROUGH THE DAY ON SUNDAY. SOUTHWESTERLY FLOW
ALOFT AHEAD OF THE APPROACHING UPPER LEVEL TROUGH WILL CONTINUE TO
TRANSPORT PACIFIC MOISTURE NORTH AND EAST OVER THE NORTHERN
ROCKIES THROUGH THE TIMEFRAME. STRATIFORM RAIN AND SHOWERS ARE THE
PREDOMINANT PRECIPITATION DRIVERS CURRENTLY HOWEVER ISOLATED
EMBEDDED AND AIR MASS THUNDERSTORMS COULD DEVELOP THIS AFTERNOON
AS MID LEVEL STRATIFORM DRIES OUT AND DAYTIME HEATING REACHES ITS
MAX. HIGH TEMPERATURES IN THE UPPER 70S TO UPPER 80S TODAY WILL
FALL TO THE 60S TO LOW 70S BY SUNDAY AS THE TROUGH PROPAGATES
THROUGH THE CWA AND EXITS MONDAY MORNING. MID LEVEL WINDS WILL
SHIFT WESTERLY BY SUNDAY AFTERNOON AND CREATE STRONG AND GUSTY
SURFACE WINDS FOR MOST OF THE CWA AS THE LOW TRACKS EASTWARD.
AREAS ALONG THE NORTHERN ROCKY MOUNTAIN FRONT WILL SEE THE HIGHEST
WINDS DUE TO PRESSURE GRADIENT FORCING AND CROSS-BARRIER
DOWNSLOPING.
SYNOPTIC PATTERN NEXT WEEK WILL BE PRIMARILY UNDER THE INFLUENCE
OF LONGWAVE TROUGHING OVER THE PACIFIC COAST KEEPING SOUTHWESTERLY
FLOW OVER THE CWA BRINGING ABOVE NORMAL PWAT'S AND WARMER
TEMPERATURES UNTIL FRIDAY WHEN THE LONG WAVE TROUGH PROPAGATES
EASTWARD. - AKINS
- FORECAST CONFIDENCE & SCENARIOS:
EFI'S INDICATE ELEVATED WINDS ABOVE CLIMATE NORMS FOR THE NORTHERN
ROCKY MOUNTAIN FRONT AS WELL AS HIGHER THAN NORMAL QPF'S FOR THE
SOUTHWEST OF MONTANA FOR SATURDAY AND SUNDAY. NBM SIGNALS OF 80%+
PROBABILITIES FOR WIND GUSTS OVER 35 KT FOR NORTHERN RMF AND
LEESIDE OF CRAZY MTNS ALONG HWY 191. CONFIDENCE IS LOWER BUT STILL
WORTH MENTIONING FOR GUSTS OVER 50 KT WITH NBM SIGNALING 30%
PROBABILITY IN THE SAME AREAS. PROBABILITIES COULD INCREASE OR
DECREASE DEPENDING ON LATITUDINAL POSITION OF THE UPPER LOW'S
TRACK AS WELL AS TIMING OF THE JET STREAK POSITION DURING MAXIMUM
MIXED LAYER TIMES ON SUNDAY. FOR QPF'S ON SATURDAY, NBM IS
INDICATING A 40% PROBABILITY FOR RAINFALL OVER 1" FOR THE WEST
YELLOWSTONE AREA FROM NOON SATURDAY UNTIL 6PM SUNDAY AS WELL AS
30% PROBABILITIES OF OVER 1" IN THE LITTLE BELTS AND BRIDGER MTNS.
- AKINS
AVIATION
29/06Z TAF PERIOD
RAIN SHOWERS WILL BEGIN IN SOUTHWEST MT AROUND 08Z, MOVING
NORTHEAST THROUGH KWYS, KEKS, KBZN AND KLWT. THUNDERSTORMS WILL
BEGIN TO DEVELOP IN SOUTHWEST MT AROUND 16Z, ALSO MOVING IN A
NORTHEAST FASHION IN THE HOURS TO FOLLOW. THE MAIN THREAT WITH
THESE THUNDERSTORMS IS GUSTY, ERRATIC WINDS AND FREQUENT
LIGHTNING, ALTHOUGH ANY THUNDERSTORM THAT DEVELOPS WILL BE CAPABLE
OF PRODUCING SMALL HAIL AND BRIEF, HEAVY DOWNPOURS.
AS THE THUNDERSTORMS DISSIPATE IN CENTRAL MT, RAIN SHOWERS WILL
DEVELOP OVER KHLN AND KGTF AROUND 03Z. VFR CONDITIONS WILL
GENERALLY PREVAIL THROUGHOUT THIS TAF PERIOD EXCEPT FOR DURING
THUNDERSTORMS, IN WHICH MVFR CONDITIONS ARE POSSIBLE. DUE TO
PASSING RAIN SHOWERS AND THUNDERSTORMS THERE WILL BE MOUNTAIN
OBSCURATION AT TIMES.
FOR KGTF: RAIN SHOWERS WILL BEGIN TO DEVELOP AROUND KGTF STARTING
NEAR 15Z, IN WHICH VISIBILITY MAY LOWER TO MVFR CONDITIONS.
THUNDERSTORMS WILL BEGIN TO DEVELOP AROUND 21Z, BEFORE DISSIPATING
AROUND 02Z. RAIN SHOWERS WILL FOLLOW THIS THUNDERSTORM ACTIVITY.
WITH THE WIND DIRECTION BEING PREDOMINATELY SOUTHWEST, THERE IS A
LESS THAN 10% CHANCE OF A CROSS-WIND EXCEEDING 15 KTS OUTSIDE OF
A THUNDERSTORM. -DZOMBA
PRELIMINARY POINT TEMPS/POPS
GTF 58 80 50 64 / 20 70 80 70
CTB 50 75 47 61 / 10 60 60 40
HLN 54 78 48 66 / 30 80 90 50
BZN 52 76 46 67 / 40 60 80 80
WYS 40 63 36 61 / 70 90 90 90
DLN 51 74 45 68 / 50 70 70 50
HVR 56 83 52 67 / 10 20 80 60
LWT 55 76 49 63 / 30 60 70 80
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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