779
FXUS65 KTFX 180553
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1153 PM MDT WED SEP 17 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- MAINLY DRY CONDITIONS WITH INCREASINGLY WARMER TEMPERATURES
ARE EXPECTED THROUGH SATURDAY.
- WINDY CONDITIONS DEVELOP SATURDAY NIGHT THROUGH SUNDAY WITH
STRONG WINDS POSSIBLE ALONG THE ROCKY MOUNTAIN FRONT.
- SCATTERED PRECIPITATION AND MORE SEASONAL TEMPERATURES DEVELOP
LATE SUNDAY THROUGH MONDAY BEFORE WARMING AGAIN EARLY NEXT
WEEK.
DISCUSSION
/ISSUED 508 PM MDT WED SEP 17 2025/
- METEOROLOGICAL OVERVIEW:
A NARROW, POSITIVELY TILTED UPPER-LEVEL RIDGE CURRENTLY STRETCHING
FROM THE INTERIOR NORTHWESTERN U.S. INTO ALBERTA WILL WEAKEN OVER
THE REST OF THE WORK WEEK. A SHORTWAVE MOVING ACROSS SOUTHERN
BRITISH COLUMBIA AND ALBERTA LATE FRIDAY WILL CAUSE A BROADER
UPPER-LEVEL RIDGE TO SHIFT EAST OF THE NORTHERN ROCKIES THIS
WEEKEND. THIS WILL LEAD TO RELATIVELY MILD WEATHER THROUGH THE
FIRST PART OF THE WEEKEND, WITH TEMPERATURES RISING ABOVE SEASONAL
AVERAGES AND PEAKING ON SATURDAY. SURFACE HIGH PRESSURE EAST OF
THE ROCKIES WILL KEEP WINDS LIGHT THROUGH FRIDAY. BREEZY WINDS
WILL DEVELOP ON SATURDAY AS A LEE-SIDE TROUGH FORMS EAST OF THE
ROCKIES AND THE UPPER RIDGE AXIS SHIFTS EASTWARD. A LARGER-SCALE
PACIFIC UPPER TROUGH WILL MOVE INTO WESTERN CANADA LATE THIS
WEEKEND, WITH SURFACE LOW PRESSURE TRACKING EAST ACROSS CENTRAL
ALBERTA ON SUNDAY. THIS SYSTEM WILL DRAG A PACIFIC COLD FRONT EAST
ACROSS THE NORTHERN ROCKIES LATE SUNDAY, LIKELY BRINGING THE
FIRST "FALL-LIKE" WIND EVENT OF THE SEASON. A MODERATE TO STRONG
PRESSURE GRADIENT ACROSS THE ROCKIES AND WESTERLY MID-LEVEL FLOW
OF 40-50 KNOTS WILL SUPPORT WIDESPREAD WINDY CONDITIONS, WITH
POTENTIAL FOR STRONG WINDS ALONG AND NEAR THE ROCKY MOUNTAIN
FRONT. PRECIPITATION WITH THIS SYSTEM WILL LIKELY BE SCATTERED FOR
MOST AREAS AND PRIMARILY OCCUR AFTER THE FRONTAL PASSAGE.
TEMPERATURES WILL COOL SLIGHTLY BUT REMAIN ABOVE SEASONAL AVERAGES
SUNDAY AND MONDAY. LONG-RANGE MODELS SUPPORT A RETURN TO UPPER-
LEVEL RIDGING AND ABOVE-AVERAGE WARMTH BEHIND THIS SYSTEM EARLY
NEXT WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
LINGERING SURFACE MOISTURE FROM RECENT PRECIPITATION WILL LIKELY
KEEP DEW POINTS SOMEWHAT ELEVATED THROUGH FRIDAY, POTENTIALLY
LEADING TO PATCHY FOG DEVELOPMENT TONIGHT IN AREAS WITH LIGHT
WINDS. THIS MOISTURE WILL ALSO CONTRIBUTE TO DAILY AFTERNOON
CUMULUS DEVELOPMENT, AND AN ISOLATED SHOWER OR THUNDERSTORM
CANNOT BE RULED OUT, MAINLY ACROSS THE ISLAND RANGES OF NORTH-
CENTRAL MONTANA.
THE PROBABILITY OF WIND GUSTS EXCEEDING 55 MPH ON SUNDAY IS
GREATER THAN 50% ONLY FOR AREAS ALONG THE IMMEDIATE EAST SLOPES OF
THE ROCKY MOUNTAIN FRONT AND GLACIER NATIONAL PARK. THERE IS UP
TO A 20% PROBABILITY FOR GUSTS OF THIS MAGNITUDE AS FAR EAST AS
CUT BANK. A 20-40% PROBABILITY EXISTS FOR WIND GUSTS TO EXCEED 45
MPH ACROSS MUCH OF NORTH-CENTRAL MONTANA. THEREFORE, HIGH WIND
PRODUCTS ARE NOT BEING CONSIDERED AT THIS TIME. HOWEVER, THIS IS
NOTABLE AS THE FIRST EVENT OF ITS TYPE FOR THE SEASON, WITH
POTENTIAL FOR ADDITIONAL IMPACTS FROM REMAINING DECIDUOUS TREE
FOLIAGE AND TO THOSE UNACCUSTOMED TO DRIVING IN STRONGER CROSS-
WINDS. HOENISCH
AVIATION
18/06Z TAF PERIOD
PRIMARY CONCERN THROUGH THE 1806/1906 TAF PERIOD WILL BE FOG, WITH
THE WINDOW FOR FOG DEVELOPMENT AT THE KWYS, KBZN, KHLN, AND KHVR
TERMINALS BEING BETWEEN 08-10Z AND PERSISTING THROUGH 15-17Z
THURSDAY. CONFIDENCE IN VIS AND/OR CIGS FALLING BELOW VFR DUE TO
THIS FOG CONTINUES TO BE LOW AT ALL OF THE AFOREMENTIONED
TERMINALS OUTSIDE OF KHVR WHERE LATEST HREF GUIDANCE SUPPORTS A
10% CHANCE FOR VIS TO FALL TO MVFR BETWEEN 13-16Z THURSDAY.
OTHERWISE THE REMAINDER OF THE TAF PERIOD WILL BE VFR, WITH NO
MOUNTIAN OBSCURATION. - MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 47 79 47 80 / 0 0 0 0
CTB 43 76 44 76 / 0 0 0 0
HLN 48 80 49 81 / 0 0 0 0
BZN 42 78 44 79 / 0 0 0 0
WYS 30 70 32 73 / 0 0 0 0
DLN 41 77 43 77 / 0 0 0 0
HVR 46 74 46 77 / 0 0 0 0
LWT 46 74 44 75 / 0 10 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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