360
FXUS65 KTFX 190410
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
910 PM MST WED DEC 18 2024
KEY MESSAGES
- STRONG WINDS CONTINUE TO DIMINISH OVERNIGHT TONIGHT.
- SNOW AND BLOWING SNOW OVER HILL AND BLAINE COUNTIES SLOWLY
DIMINISH THROUGH MIDNIGHT.
- MILD AND GENERALLY DRY CONDITIONS RETURN FOR MOST LOCATIONS FOR
THE SECOND HALF OF THE WEEK.
UPDATE
WINDS ARE BEGINNING TO DIMINISH, BUT STILL REMAIN STRONG AND GUSTY
EAST OF A GREAT FALLS TO HAVRE LINE, ALONG THE ROCKY MOUNTAIN
FRONT, AND OVER THE BIG BELT MOUNTAINS. I KEPT THE HIGH WIND
WARNING GOING TIL MIDNIGHT FOR THESE LOCATIONS, BUT CANNED THE
REMAINING AREAS WITH LIGHTER WINDS.
THE CANADIAN FRONT MOVING SOUTH THROUGH THE NORTH-CENTRAL PLAINS
HAS BEEN A LITTLE MORE ROBUST THAN EXPECTED. SNOW AND BLOWING SNOW
HAVE IMPACTED MUCH OF HILL AND BLAINE COUNTIES WITH ICY ROADS AND
LOW VISIBILITY. GIVEN THE SHORT NATURE OF THIS EVENT, I OPTED TO
CONTINUE TO SPECIAL WEATHER STATEMENT FOR THE REMAINDER OF THE
EVENING AND POPS WERE ADJUSTED ACCORDINGLY TO THE SITUATION.
ADDITIONALLY, TEMPERATURES ARE RAPIDLY FALLING INTO THE TEENS AND
20S BEHIND THE FRONT AND A LITTLE FARTHER SOUTH THAN MODEL
GUIDANCE PROJECTIONS. THE FRONT SHOULD LOSE ITS MOMENTUM AND
WHILE GETTING HUNG UP OVER THE CENTRAL ISLAND RANGES. THEREFORE,
LOW TEMPERATURES AND HOURLIES FOR TONIGHT WERE ADJUSTED DOWNWARD
FOR MOST NORTH- CENTRAL LOCATIONS ALONG AND NORTH OF THE HIGHWAY
200 CORRIDOR. A NORTHERLY WIND COMPONENT WAS ALSO ADDED TO THESE
AREAS. - RCG
DISCUSSION
/ISSUED 158 PM MST WED DEC 18 2024/
- METEOROLOGICAL OVERVIEW:
A COMPACT AND FAST MOVING SHORTWAVE WILL CONTINUE TO MOVE OVER THE
NORTHERN ROCKIES AND HIGH PLAINS THROUGH THIS EVENING, WITH A
PACIFIC COLD FRONT SWEEPING EAST ACROSS SOUTHWEST THROUGH NORTH
CENTRAL MONTANA DURING THE AFTERNOON. AS THE ATTENDANT SURFACE MOVES
EAST SOUTHEAST FROM SOUTHERN ALBERTA TO WESTERN NORTH DAKOTA THROUGH
THIS EVENING A RE-ENFORCING COLD FRONT WILL THEN CRASH SOUTH INTO
NORTH CENTRAL AND PORTIONS OF CENTRAL MONTANA. A FAIRLY PROGRESSIVE
PATTERN IS THEN EXPECTED THROUGH THE REMAINDER OF THE WORK WEEK,
WITH UPPER LEVEL RIDGING, CURRENTLY OVER THE EASTERN PACIFIC THIS
AFTERNOON, SLIDING EAST AND OVER THE NORTHERN ROCKIES THROUGH THE
DAY ON THURSDAY FOLLOWED BY ANOTHER FAST MOVING SHORTWAVE FOR THE
DAY ON FRIDAY. SURFACE HIGH PRESSURE IN WAKE OF TODAY'S SERIES OF
COLD FRONTS WILL GRADUALLY MOVE EAST OF THE NORTHERN ROCKIES DURING
THE DAY ON THURSDAY, WEAK ANOTHER WEAK SURFACE LOW SURFACE LOW
DEVELOPING IN LEE OF THE CANADIAN/NORTHERN ROCKIES ON FRIDAY MORNING
BEFORE MOVING SOUTHEAST TOWARDS THE DAKOTAS THROUGH FRIDAY NIGHT.
ENSEMBLE CLUSTERS LARGELY FAVOR UPPER LEVEL RIDGING JUST TO THE EAST
OF THE NORTHERN ROCKIES THROUGH THE WEEKEND AND EARLY NEXT WEEK,
PLACING SOUTHWEST THROUGH NORTH CENTRAL MONTANA BENEATH SOUTHWEST
FLOW ALOFT (GENERALLY SPEAKING). ONE THING THE ENSEMBLE CLUSTERS
FAIL TO RESOLVE ARE INDIVIDUAL WEAK DISTURBANCES LIFTING NORTHEAST
WITHIN THIS SOUTHWESTERLY FLOW AS NOTED BY DETERMINISTIC GUIDANCE,
WITH SAID DETERMINISTIC GUIDANCE (I.E. GFS, ECMWF, AND CANADIAN)
HAVING SUBTLE TIMING AND MAGNITUDE DIFFERENCES. THESE TIMING AND
MAGNITUDE DIFFERENCE WILL ULTIMATELY IMPACT WHEN AND WHERE
PRECIPITATION FALL OVER THIS TIMEFRAME.
- FORECAST CONFIDENCE & SCENARIOS:
ACCUMULATING/BLOWING/DRIFTING SNOW THROUGH THIS EVENING :
SNOW, LIGHT TO MODERATE, WILL CONTINUE TO FALL ACROSS THE
CONTINENTAL DIVIDE THROUGH THIS EVENING, WITH THE HEAVIEST SNOW
FALLING ACROSS THE HIGHER TERRAIN OF GLACIER NATIONAL PARK.
ADDITIONAL SNOWFALL ACCUMULATIONS OF 1-3" ARE EXPECTED AT MARIAS
PASS THROUGH THIS EVENING, WITH UP TO 7" IN THE MOUNTAINS OF GLACIER
NATIONAL PARK. STRONG AND GUSTY WEST WINDS WILL CONTINUE TO
CONTRIBUTE TO THE POTENTIAL FOR BLOWING AND DRIFTING SNOW ACROSS THE
EAST GLACIER PARK REGION, MAINLY WEST OF EAST GLACIER PARK TO MARIAS
PASS AND ON US HWY 2 WHERE TEMPERATURES ARE HOVERING NEAR 35
DEGREES. GIVEN THE POTENTIAL FOR REDUCTIONS IN VISIBILITY DUE TO THE
COMBINATION OF FALLING AND BLOWING SNOW, WE WILL CONTINUE THE WINTER
STORM WARNING THROUGH MIDNIGHT TONIGHT FOR THE EAST GLACIER PARK
REGION.
HIGH WINDS THROUGH THIS EVENING :
WINDS CONTINUE TO INCREASE ACROSS SOUTHWEST THROUGH NORTH CENTRAL
MONTANA EARLY THIS AFTERNOON, WITH PEAK WIND GUSTS SO FAR
APPROACHING 80 MPH ALONG THE ROCKY MOUNTAIN FRONT AND NEAR 60 MPH
FOR AREAS AROUND ENNIS AND ALONG THE MT HWY 200 CORRIDOR. AS THE
REMAINDER OF THE AFTERNOON PROGRESSES I EXPECTED THESE WINDS TO
EXPAND FURTHER EASTWARD ACROSS THE REMAINDER OF CWA AS A PACIFIC
COLD FRONT SWEEPS EASTWARD IN TANDEM WITH A POTENT AND ANOMALOUS JET
MAX MOVING OVERHEAD. MAIN CHANGE WITH THE FORECAST THIS AFTERNOON
WAS TO ADD BEAVERHEAD AND WESTERN MADISON BELOW 6000FT AND NORTHWEST
BEAVERHEAD COUNTY TO THE HIGH WIND WARNING AS HIGH WINDS WERE
OCCURRING AT DILLON WITH THE APPROACH OF 2 PM MST, AND VERY NEAR
CRITERIA AT WISE RIVER. OTHERWISE THE REMAINING HIGH WIND WARNINGS
REMAIN ON TRACK, WITH WINDS EXPECTED TO DECREASE LATE THIS EVENING
AND THROUGH THURSDAY MORNING. ALONG WITH DAMAGE TO PROPERTY,
ISOLATED POWER OUTAGES, AND STRONG CROSS WINDS FOR HIGH PROFILE
VEHICLES THE STRONG WINDS WILL ALSO PRODUCE BLOWING DUST WHERE
CONDITIONS HAVE BEEN DRY SINCE MID-FALL. THE AREAS MOST SUSCEPTIBLE
TO BLOWING DUST ARE ALONG MT HWY 200 BETWEEN BELT AND GREAT FALLS
AND ON US HWY 87 FROM GREAT FALLS TO FORT BENTON, IN ADDITION TO THE
MADISON RIVER VALLEY IN SOUTHWEST MONTANA. - MOLDAN
AVIATION
19/00Z TAF PERIOD
A PASSING PACIFIC WEATHER SYSTEM AND ATTENDANT COLD FRONT WILL
CONTINUE TO BRING PERIODS OF STRONG WINDS, LOW LEVEL WIND SHEAR,
AND MOUNTAIN WAVE TURBULENCE OVER THE NEXT SEVERAL HOURS BEFORE
WINDS DIMINISH AND CONDITIONS BEGIN TO IMPROVE HEADING INTO THE
OVERNIGHT. THERE IS ALSO A CANADIAN FRONTAL BOUNDARY MOVING SOUTH
OUT OF AB/SK, SHIFTING WINDS TO A NORTHWESTERLY DIRECTION FOR KHVR
AND KCTB. PASSING LIGHT SHOWERS AND OR VIRGA IN ADDITION TO LOWER
VFR CLOUD LAYERS CAN ALSO EXPECTED FOR MOST LOCATIONS THROUGH
09/06Z OR SO. - RCG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 21 44 33 54 / 10 0 20 0
CTB 14 37 26 49 / 20 0 20 0
HLN 31 42 28 47 / 20 0 0 0
BZN 23 40 21 46 / 10 0 0 0
WYS 12 32 11 37 / 30 10 0 0
DLN 20 40 24 45 / 0 0 0 0
HVR 3 21 10 35 / 80 10 10 0
LWT 21 40 27 52 / 40 10 0 0
TFX WATCHES/WARNINGS/ADVISORIES
HIGH WIND WARNING UNTIL MIDNIGHT MST TONIGHT FOR BIG BELT,
BRIDGER AND CASTLE MOUNTAINS-EAST GLACIER PARK REGION-JUDITH
BASIN COUNTY AND JUDITH GAP-MEAGHER COUNTY VALLEYS-NORTHERN HIGH
PLAINS-SOUTHERN HIGH PLAINS-SOUTHERN ROCKY MOUNTAIN FRONT.
HIGH WIND WARNING UNTIL 5 AM MST THURSDAY FOR BEARS PAW
MOUNTAINS AND SOUTHERN BLAINE-FERGUS COUNTY BELOW 4500FT-HILL
COUNTY-NORTHERN BLAINE COUNTY-SNOWY AND JUDITH MOUNTAINS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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