893
FXUS65 KTFX 170521
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1121 PM MDT FRI OCT 16 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- WINDY CONDITIONS TOMORROW ALONG THE NORTHERN ROCKY MOUNTAIN
FRONT, WITH GUSTS UP TO 85 MPH POSSIBLE.
- SLIGHTLY COOLER TEMPERATURES ON SUNDAY, FOLLOWED BY SEASONABLY
AVERAGE TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK.
- COOLER TEMPERATURES AND INCREASED CHANCES OF PRECIPITATION LATE
NEXT WEEK INTO NEXT WEEKEND.
UPDATE
/ISSUED 741 PM MDT FRI OCT 16 2026/
UPDATED FORECAST IS OUT. THE ONLY CHANGE THIS EVENING WAS TO ADD
EASTERN TOOLE COUNTY AND LIBERTY COUNTY TO THE HIGH WIND WARNING.
STRONG WINDS LOOK LIKE THEY SHOULD MIX DOWN IN THIS AREA,
ESPECIALLY NEAR THE SWEET GRASS HILLS. OTHERWISE THE CURRENT
FORECAST IS ON TRACK. MAIN CONCERN WILL BE THE STRONG WINDS ON
SATURDAY, WITH THE STRONGEST WINDS LIKELY OCCURRING SATURDAY
AFTERNOON. BRUSDA
DISCUSSION
/ISSUED 741 PM MDT FRI OCT 16 2026/
- METEOROLOGICAL OVERVIEW:
UPPER LEVEL RIDGING CONTINUES OVER THE REGION TODAY, BRINGING
MOSTLY SUNNY SKIES, DRY CONDITIONS AND ABOVE AVERAGE TEMPERATURES.
AS THIS AFTERNOON PROGRESSES, THE RIDGE WILL BEGIN TO FLATTEN,
INCREASING THE PRESSURE GRADIENT AND CREATING WINDY CONDITIONS,
MOSTLY CONFINED TO THE ROCKY MOUNTAIN FRONT. THE RIDGE CONTINUES
TO FLATTEN INTO SATURDAY, CAUSING THE PRESSURE GRADIENT TO TIGHTEN
EVEN MORE AS CONVERGENCE ALOFT INCREASES. THIS WILL BRING STRONG
UPPER LEVEL WINDS THAT, COMBINED WITH DIURNAL HEATING AND TERRAIN
INFLUENCES, WILL MIX DOWN TO THE SURFACE ALONG THE NORTHERN ROCKY
MOUNTAIN FRONT. THIS WILL BRING VERY WINDY CONDITIONS TO THE
NORTHERN ROCKY MOUNTAIN FRONT, SPECIFICALLY IN THE AREA NORTH OF
HIGHWAY 200 AND WEST OF I-15. THE GUSTY WINDS ARE EXPECTED TO
DISSIPATE BY LATE SATURDAY EVENING AS THE STRONGEST UPPER LEVEL
WINDS MOVE EAST AND DIURNAL HEATING SUBSIDES.
ZONAL FLOW ALOFT WILL BUILD AGAIN ON SUNDAY, ALLOWING FOR
SLIGHTLY COOLER TEMPERATURES AND CONTINUING THE STRETCH OF DRY
WEATHER. BY MONDAY MORNING, WEAK RIDGING TAKES ITS PLACE AS AN
UPPER LEVEL TROUGH BEGINS TO MOVE DOWN THE PACIFIC COAST TOWARDS
NORTHERN CALIFORNIA. THIS WILL CREATE SOUTHWESTERLY FLOW ALOFT BY
MONDAY EVENING, WHICH WILL LAST THROUGH THE MIDDLE OF NEXT WEEK,
ALLOWING FOR SEASONABLY AVERAGE TEMPERATURES.
BY THURSDAY, THE TROUGH WILL HAVE MOVED SOUTH OF THE GREAT BASIN,
CREATING A MORE DIRECT SOUTHERLY FLOW ALOFT, BEFORE MOVING
NORTHEAST TOWARDS WYOMING. THIS WILL ALLOW TEMPERATURES TO WARM ON
THURSDAY BEFORE COOLING DOWN ON FRIDAY. INCREASED MOISTURE ALOFT
WILL GET CARRIED NORTH BY THE UPPER LEVEL SOUTHERLY FLOW,
INCREASING PRECIPITATION CHANCES TOWARDS THE END OF NEXT WEEK INTO
NEXT WEEKEND. THERE REMAINS SHEARING AND SPLITTING IN THE TROUGH
LATE THURSDAY INTO NEXT WEEKEND, SO WHILE ONE CAN EXPECT COOLING
TEMPERATURES AND INCREASED PRECIPITATION CHANCES LATE IN THE
FORECAST PERIOD, CONFIDENCE IN THE FORECAST SPECIFICS FOR THIS
TIME REMAINS LOW.
- FORECAST CONFIDENCE & SCENARIOS:
CONFIDENCE HAS INCREASED ON STRONGER WINDS IMPACTING THE NORTHERN
ROCKY MOUNTAIN FRONT SATURDAY. MODELS ARE IN GOOD AGREEMENT ON AN
INCREASE IN THE 700 MB WINDS, NOW SHOWING AROUND 75-80 KTS, AND
VERTICAL CROSS SECTIONS SHOW THESE STRONG WINDS MIXING DOWN TO THE
SURFACE FROM LATE SATURDAY MORNING TO LATE SATURDAY NIGHT DUE TO
DIURNAL HEATING AND TURBULENT MIXING FROM THE TERRAIN OF THE ROCKY
MOUNTAINS. AS A RESULT, THERE IS ALSO MORE MODEL AGREEMENT ON THE
WIND GUSTS AT THE SURFACE, WITH THE SPREAD OF 14TH PERCENTILE AND
THE PERCENTILE WIND GUSTS ONLY BEING ABOUT A 10 MPH DIFFERENCE.
DUE TO THE STRONGER 700 MB WINDS AND INCREASED CONFIDENCE IN THEIR
TIMING AND LOCATION, THE HIGH WIND WATCH (ALONG THE NORTHERN
ROCKY MOUNTAIN FRONT) HAS NOW BEEN UPGRADED TO A HIGH WIND
WARNING, WITH GUSTS UP TO 85 MPH POSSIBLE.
CONFIDENCE WAS LOWER ON THESE STRONGER 700 MB WINDS MIXING TO THE
SURFACE ALONG THE REST OF THE HI-LINE. SOUNDINGS SHOWED A LOW
LEVEL INVERSION ACROSS THE HI-LINE, WHICH WOULD INHIBIT MIXING.
THIS IS SUPPORTED BY THE VERTICAL CROSS SECTIONS SHOWING THE
STRONGER WINDS ALOFT NOT MIXING DOWN TO THE SURFACE. WHILE WINDY
CONDITIONS WILL STILL BE PRESENT ACROSS THE HI-LINE TOMORROW, THE
LOWER CONFIDENCE IN THE STRONGEST WINDS BEING MIXED DOWN TO THE
SURFACE RESULTED IN THE HIGH WIND WATCH NOT BEING EXTENDED ACROSS
THE HI-LINE. -DZOMBA
AVIATION
17/06Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. HIGH WINDS
ARE EXPECTED ACROSS THE HI-LINE AND ROCK MOUNTAIN FRONT. TERMINAL
KCTB LOOKS OF GREATEST CONCERN WITH GUSTS OVER 50KTS LIKELY (>80%)
AND A MEDIUM CHANCE (50%) OF GUSTS OVER 60KTS. TERMINALS KHVR AND
KGTF WILL ALSO EXPERIENCE GUSTY WINDS WITH GUSTS 35-45KTS, MIXING
WILL LIMIT HIGHER END GUSTS BUT THERE IS A LOW (30%) CHANCE OF
GUSTS OVER 50KT AT BOTH TERMINALS. MOUNTAIN WAVE TURBULENCE WILL
ALSO BE OF CONCERN ACROSS THE DIVIDE AS WIND PICK UP THIS EVENING.
WINDS WILL BEGIN TO WEAKEN ACROSS ALL TERMINALS TOWARDS THE VERY
END OF THE TAF PERIOD.
LOW-LEVEL WIND SHEAR IS OF PARTICULAR CONCERN ACROSS TERMINALS
KCTB, KGTF, AND KHVR THROUGH THE NIGHT INTO THE MORNING AS
SURFACE WINDS WANE, BUT HIGHER LEVEL WINDS REMAIN STRONG. WIND
SHEAR SHOULD FALL BELOW 20KT BY 17/18Z ACROSS ALL MENTIONED TERMINALS
AS WINDS MIX TO THE SURFACE.
-JR
PRELIMINARY POINT TEMPS/POPS
GTF 67 46 71 42 / 0 0 0 0
CTB 66 44 68 35 / 0 0 0 0
HLN 61 33 71 35 / 0 0 0 0
BZN 59 32 65 33 / 0 0 0 0
WYS 56 21 56 22 / 0 0 0 0
DLN 58 32 64 33 / 0 0 0 0
HVR 67 41 76 37 / 0 0 0 0
LWT 68 45 72 39 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
HIGH WIND WARNING FROM 9 AM SATURDAY TO MIDNIGHT MDT SATURDAY
NIGHT 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.
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