223
FXUS65 KTFX 132337
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
437 PM MST SAT DEC 13 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- THE SHALLOW ARCTIC AIRMASS WILL CONTINUE TO SLOWLY
RETREAT NORTHEASTWARD TONIGHT, WITH MILD TEMPERATURES RETURNING
TO ALL AREAS BY SUNDAY.
- WINDS INCREASE AND BECOME STRONG ALONG THE ROCKY MOUNTAIN FRONT
ON SUNDAY AND SPREAD OVER PORTIONS OF THE CENTRAL AND NORTH-
CENTRAL MONTANA ON MONDAY.
- A STRONG PACIFIC FRONT LOOKS TO BRING WIDESPREAD STRONG,
GUSTY WINDS AND LOCALLY INTENSE SNOW SHOWERS ON WEDNESDAY.
- THE ARCTIC AIR BEGINS TO SAG SOUTHWARD HEADING INTO NEXT
WEEKEND, ALTHOUGH IT'S SOUTHERN EXTENT REMAINS UNCERTAIN AT
THIS TIME.
DISCUSSION
/ISSUED 250 PM MST SAT DEC 13 2025/
- METEOROLOGICAL OVERVIEW:
RIDGING ALOFT GRADUALLY REPLACES THE CURRENT COLD NORTHWESTERLY
FLOW WITH THE SHALLOW ARCTIC AIR CONTINUING TO THIN AND RETREAT
NORTHEASTWARD THROUGH SUNDAY MORNING. DESPITE THE RIDGING ALOFT
AND WELL ABOVE NORMAL TEMPERATURES DURING THE FIRST HALF OF THE
WEEK, WESTERLY FLOW ALOFT WILL REMAIN STRONG AND OFFER MULTIPLE
OPPORTUNITIES FOR STRONG, GUSTY SURFACE WINDS, MOST WIDESPREAD
MONDAY AND AGAIN ON WEDNESDAY.
MONDAY'S WINDS WILL BE DRIVEN BY 55 TO 75 KT H700 FLOW AHEAD OF
AN APPROACHING SHORTWAVE IN ADDITION TO A TIGHTENING SURFACE
PRESSURE GRADIENT AND MOUNTAIN WAVE ACTIVITY. ON WEDNESDAY, A
POTENT PACIFIC SHORTWAVE AND ATTENDANT COLD FRONT LOOK TO BRING
COLD AIR ADVECTION AND DEEP LAYER MIXING WHILE H700 FLOW EXCEEDS
75 KTS. THE SHARP FRONTOGENESIS WITH THIS SYSTEM QUICKLY DROPS
H700/H500 TEMPERATURES TO AROUND -15C/-30C BEHIND THE FRONT, WHICH
MAY ALSO ENCOURAGE LOCALLY INTENSE SNOW SHOWER/SQUALL DEVELOPMENT
IN ADDITION TO ADDING SUPPORT FOR STRONG WINDS. THIS PROPOSED
EVENT IS STILL FOUR DAYS AWAY AND THINGS COULD CHANGE, BUT IT
BEARS WATCHING.
THE ARCTIC AIR BEGINS TO SAG SOUTHWARD DURING THE SECOND HALF OF
THE WEEK WITH THE RETURN OF COLDER WESTERLY FLOW ALOFT; HOWEVER,
THE SOUTHWARD TRAJECTORY LOOKS TO BE WEAK, RESULTING IN NORTHERN
AREAS GETTING CLIPPED WITH THE COLDER AIR AT TIMES WHILE MILDER
AIR REMAINS IN PLACE IN THE SOUTHWEST. THE PASSAGE OF SHORTWAVES
WILL MAINTAIN PERIODS OF MOSTLY MOUNTAIN SNOW DURING THIS TIME.
- RCG
- FORECAST CONFIDENCE & SCENARIOS:
WINDS SUNDAY THROUGH WEDNESDAY...
PERIODS OF STRONG, GUSTY WINDS WILL ACCOMPANY THE RETURN OF
MILDER CONDITIONS THROUGH MID- WEEK. WINDS INITIALLY INCREASE AND
BECOME STRONG ALONG THE ROCKY MOUNTAIN FRONT AS EARLY AS SUNDAY
MORNING. H700 FLOW EXCEEDING 70 KTS COMBINED WITH LOCALIZED
MOUNTAIN WAVE ACTIVITY LOOKS TO BRING AT LEAST A BRIEF PERIOD OF
WINDS APPROACHING 80 MPH IN THE EAST GLACIER/BROWNING AREAS WHERE
PROBABILITIES FOR THE HIGH WIND CRITERIA GUSTS ARE NOW TOPPING
AROUND 70%. GIVEN THIS PROBABILITY IS FOR THE HIGHER 75 MPH
CRITERIA, A HIGH WIND WATCH HAS BEEN POSTED. OTHER NORTH-CENTRAL
MT LOCATIONS LOOK TO SEE WINDS MOSTLY GUSTING IN THE 25 TO 45 MPH
RANGE ON SUNDAY.
THERE IS SOME POTENTIAL FOR BLOWING/DRIFTING OF SNOW WITH THE
ONSET OF THE GUSTY WEST/SOUTHWEST WINDS ON SUNDAY. THIS WOULD
INITIALLY AFFECT AREAS ALONG THE ROCKY MOUNTAIN FRONT AND AREAS
NORTHEAST OF THE LITTLE BELTS AND HIGHWOODS BY SUNDAY AFTERNOON.
FORTUNATELY, ABOVE FREEZING TEMPERATURES ARE LIKELY TO SETTLE THE
SNOWPACK ACROSS MOST AREAS BEFORE STRONGEST WINDS DEVELOP SUNDAY
NIGHT AND MONDAY.
AN APPROACHING SHORTWAVE WILL BRING STRONGER AND MORE WIDESPREAD
WINDS MONDAY THROUGH EARLY TUESDAY. WHILE MOST CENTRAL AND NORTH-
CENTRAL LOCATIONS WILL SEE WIDESPREAD GUSTS IN THE 35 TO 55 MPH
RANGE, THE ROCKY MOUNTAIN FRONT AND HIGH PLAINS WEST OF I15
CURRENTLY HAVE UP TO A 90% CHANCE FOR GUSTS EXCEEDING 55 MPH AND A
70 TO 80% CHANCE FOR 75 MPH GUSTS OR GREATER. ANOTHER AREA TO
CLOSELY WATCH WILL BE THE CENTRAL MT HIGHWAY 87/200 CORRIDOR WHERE
THE COMBINATION OF MOUNTAIN WAVE ACTIVITY AND STRONG FLOW ALOFT
PUSH THE CHANCES FOR GUSTS EXCEEDING 55 MPH TO THE 40 TO 60% MARK.
HIGH WIND WATCHES WERE SENT OUT FOR THESE NORMALLY HIGHER WIND
PRONE AREAS, INCLUDING THE ROCKY MOUNTAIN FRONT MOUNTAIN/PLAINS
ZONES, EASTERN TOOLE/LIBERTY ZONE, AND THE LOWER ELEVATIONS OF
CASCADE AND JUDITH BASIN COUNTIES. OTHER AREAS MAY BE ADDED BY
INCOMING SHIFTS AS CONFIDENCE INCREASES.
ON WEDNESDAY, A MUCH STRONGER AND DYNAMIC PACIFIC TROUGH AND
ATTENDANT COLD FRONT WILL BRING AN OPPORTUNITY FOR WIDESPREAD
STRONG WINDS AND SCATTERED LOCALLY INTENSE SNOW SHOWERS/SQUALLS.
DETERMINISTIC MODELS SEEM TO BECOME MORE AND MORE AGGRESSIVE WITH
THIS SYSTEM AS TIME GOES BY. AS OF THIS WRITING, IT CHECKS NEARLY
ALL THE BOXES FOR A HIGH IMPACT WIND EVENT ACROSS NORTH-CENTRAL
AND SOUTHWEST MT. IT LOOKS TO HAVE A VERTICALLY STACKED WIND
PROFILE GREATER THAN 70 KTS, STRONG COLD AIR ADVECTION, AND TIMING
NEAR THE TIME OF PEAK DIURNAL MIXING. WIDESPREAD STRONG TO
DAMAGING WINDS CAN BE EXPECTED SHOULD THIS EVENT UNFOLD AS
CURRENTLY ADVERTISED. IT'S IMPORTANT TO NOTE THAT THIS EVENT IS
FOUR DAYS AWAY AND BEFORE GETTING OVERLY EXCITED I'D LIKE TO SEE
MORE RUN TO RUN CONSISTENCY AMONG ENSEMBLE MEMBERS. SOME CAVEATS
THAT COULD WEAKEN OR PRECLUDE THE WINDS INCLUDE A STRONGER/FASTER
CANADIAN FRONT UNDERCUTTING THE STRONG WINDS ALOFT, MODELS OVER
FORECASTING UPPER LEVEL FLOW, AND FRONTAL PASSAGE TIMING SHIFTS.
THIS ONE WILL BE CLOSELY MONITORED OVER THE NEXT FEW DAYS. - RCG
AVIATION
14/00Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL ACROSS ALL TERMINALS DURING THE
DURATION OF THIS TAF PERIOD. AFTER 14/06Z WINDS WILL BEGIN TO
INCREASE AT THE KCTB, KGTF, AND KLWT TERMINALS. THERE WILL BE
INSTANCES OF LOW-LEVEL WIND SHEAR AND MOUNTAIN WAVE TURBULENCE
DURING THE DURATION OF THIS TAF PERIOD ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. -IG
PRELIMINARY POINT TEMPS/POPS
GTF 16 49 39 55 / 0 0 0 0
CTB 15 46 33 51 / 0 0 0 10
HLN 27 49 31 54 / 0 0 0 0
BZN 30 52 28 53 / 0 0 0 0
WYS 14 44 14 39 / 0 0 0 0
DLN 31 53 29 53 / 0 0 0 0
HVR 0 44 30 51 / 0 0 0 0
LWT 22 49 34 50 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
HIGH WIND WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
EAST GLACIER PARK REGION-NORTHERN HIGH PLAINS.
HIGH WIND WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR
EAST GLACIER PARK REGION-EASTERN GLACIER, WESTERN TOOLE, AND
CENTRAL PONDERA-EASTERN TOOLE AND LIBERTY-NORTHERN HIGH PLAINS-
SOUTHERN HIGH PLAINS-SOUTHERN ROCKY MOUNTAIN FRONT.
HIGH WIND WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING
FOR CASCADE COUNTY BELOW 5000FT-JUDITH BASIN COUNTY AND JUDITH
GAP.
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