150
FXUS65 KTFX 162017
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
217 PM MDT FRI OCT 16 2026
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.
DISCUSSION
- 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 LOW,
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 10TH PERCENTILE AND
90TH 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
16/18Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. GUSTY
SOUTH/SOUTHWESTERLY WINDS ARE EXPECTED TO CONTINUE AT KGTF THROUGH
THE REST OF THE AFTERNOON BEFORE TAPERING OFF SLIGHTLY OVERNIGHT
AND PICKING UP AGAIN SATURDAY MORNING AS A BROADER SPREAD OF GUSTY
WINDS FILLS IN ACROSS NORTH-CENTRAL AND CENTRAL MONTANA AS WELL AS
THE MADISON VALLEY (KEKS). THE STRONGEST WINDS WILL BE ALONG THE
ROCKY MOUNTAIN FRONT WITH GUSTS UP TO 55KTS POSSIBLE AT KCTB AND
UP TO 70KTS RIGHT ALONG THE MOUNTAINS.
FURTHER ACROSS THE HI-LINE, INCLUDING KHVR, SURFACE WINDS WILL BE
GUSTY BUT A SHALLOW INVERSION IS EXPECTED TO KEEP THE HIGH WINDS
JUST ABOVE THE SURFACE WHICH MAY LEAD TO INSTANCES OF LLWS THROUGH
SATURDAY EVENING. SHOULD THESE STRONGER WINDS BE ABLE TO MIX DOWN
TO THE SURFACE, EXPECT GUSTY WINDS UP TO 50KTS AT KHVR. BUT
CURRENTLY THE PROBABILITY OF OCCURRENCE IS AT 20%. -THOR
PRELIMINARY POINT TEMPS/POPS
GTF 46 71 42 61 / 0 0 0 0
CTB 44 68 35 57 / 0 0 0 0
HLN 33 71 35 62 / 0 0 0 0
BZN 32 65 33 59 / 0 0 0 0
WYS 21 56 22 58 / 0 0 0 0
DLN 32 64 33 60 / 0 0 0 0
HVR 41 76 37 62 / 0 0 0 0
LWT 45 72 39 60 / 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-NORTHERN HIGH PLAINS-SOUTHERN HIGH
PLAINS-SOUTHERN ROCKY MOUNTAIN FRONT.
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