609
FXUS65 KBYZ 171812
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
1112 AM MST WED DEC 17 2025
KEY MESSAGES
- A SIGNIFICANT AND WIDESPREAD HIGH WIND EVENT IS IN STORE TODAY
THROUGH TONIGHT. GUSTS ARE EXPECTED TO APPROACH 70 MPH AT LOWER
ELEVATIONS BY THIS AFTERNOON AND EVENING. THE HIGHEST GUSTS MAY
CAUSE DAMAGE TO TREES, POWER LINES AND SOME STRUCTURES!
- 5 TO 10 INCHES OF SNOWFALL EXPECTED LATE ON WEST ASPECTS OF THE
BEARTOOTH ABSAROKA AND CRAZY MOUNTAINS THROUGH TODAY.
- ANOTHER PERIOD OF GUSTY WINDS ALONG THE WESTERN FOOTHILLS
THURSDAY NIGHT INTO FRIDAY.
- PERIODS OF MODERATE TO HEAVY SNOWFALL OVER THE BEARTOOTH
ABSAROKA MOUNTAINS THURSDAY TO SATURDAY; 90 PERCENT CHANCE OF AT
LEAST A FOOT OF SNOW ON WEST ASPECTS.
DISCUSSION
TODAY THROUGH TUESDAY...
A WIDESPREAD HIGH WIND EVENT REMAINS ON TRACK TO AFFECT THE REGION
THROUGH TONIGHT. HIGH WIND WARNINGS ARE IN EFFECT THROUGH THIS
EVENING AND INTO TONIGHT ACROSS THE REGION. BE PREPARED FOR WIND
GUSTS HIGHER THAN "USUAL" WITH 60 TO 70 MPH GUSTS BEING COMMON
ACROSS THE LOWER ELEVATIONS STARTING AROUND MIDDAY TODAY. THE
HIGHEST GUSTS MAY CAUSE DAMAGE TO TREES, POWER LINES AND SOME
STRUCTURES. TRAVEL AND OUTDOOR ACTIVITIES WILL BE IMPACTED. SECURE
ANY LOOSE OUTDOOR ITEMS.
WINDS HAVE BEGUN INCREASING OVER PORTIONS OF THE WESTERN FOOTHILLS
EARLY THIS MORNING AHEAD OF AN APPROACHING WAVE AND ASSOCIATED
COLD FRONT. WINDS HAVE BEEN GUSTING INTO THE 70S MPH NEAR
LIVINGSTON SO FAR. CURRENTLY, THE IDA-LWT GRADIENT IS AROUND
13MB, AND IS EXPECTED TO TIGHTEN TOWARDS 16-19MB INTO THIS
MORNING. MID-LEVEL WINDS WILL INCREASE THROUGH THE MORNING (700MB
WINDS 60-70 KTS) AHEAD OF AND WITH A COLD FRONT PASSAGE. STRONG TO
DAMAGING WINDS ARE EXPECTED TO SPREAD FROM THE FOOTHILLS, EAST
ACROSS THE LOWER ELEVATIONS THROUGH THE DAY AS THE COLD FRONT
SWEEPS THROUGH THE REGION. AS WE HEAD INTO LATER THIS AFTERNOON
AND EVENING, 700 MB WINDS WILL STRENGTHEN TOWARDS 80-90 KTS ON THE
BACK SIDE OF A PASSING SHORTWAVE. THE VERY STRONG MID-LEVEL
WINDS, COMBINED WITH STRONG PRESSURE RISES AND SUBSIDENCE BEHIND
THE COLD FRONT WILL BRING STRENGTHENING WINDS INTO THE EVENING AND
NIGHT OVER CENTRAL AND EASTERN ZONES. THE STRONG WINDS MAY
PERSIST NEAR THE DAKOTAS BORDER INTO THURSDAY MORNING. ANY
LINGERING SNOW COVER COULD PRODUCE A SHALLOW SURFACE INVERSION
WHICH WOULD WORK AGAINST THE WIND TO A POINT, BUT SNOW HAS BEEN
RAPIDLY MELTING OVER THE PAST FEW DAYS. ALONG WITH THE WIND,
RAIN/SNOW SHOWERS WILL ACCOMPANY THE COLD FRONT, AND COULD HELP
MIX DOWN THE WINDS. LIGHT SNOWFALL IS EXPECTED TO WRAP AROUND THE
SHORTWAVE AND BACK INTO FAR SOUTHEAST MT TONIGHT, WHICH IN
COMBINATION WITH THE STRONG WINDS COULD RESULT IN LOWER VISIBILITY
IN BLOWING SNOW AS TEMPS FALL TO THE TEENS AND 20S. WARMER
CONDITIONS CAN BE EXPECTED OVER THE WEST.
HERE ARE SOME NOTABLE PROBABILITIES FOR SELECT CITIES:
BIL & MLS 80% CHANCE OF 60+ MPH, 45% CHANCE OF 70+ MPH
LVM 100% CHANCE OF 60+ MPH, 80% CHANCE OF 70+ MPH
SHR 90% CHANCE OF 60+ MPH, 55% CHANCE OF 70+ MPH
BHK 90% CHANCE OF 60+ MPH, 70% CHANCE OF 70+ MPH
SNOW WILL CONTINUE OVER THE WESTERN MOUNTAINS INTO THIS EVENING,
WITH 5 TO 10 INCHES OF SNOWFALL EXPECTED ON WEST FACING ASPECTS.
THURSDAY WILL BRING COOLER CONDITIONS THAN THE LAST SEVERAL DAYS
WITH HIGHS IN THE 20S OVER THE EAST TO THE LOWER 40S OVER THE
WEST. ANOTHER PERIOD OF GUSTY TO STRONG FOOTHILL WINDS IS POSSIBLE
THURSDAY NIGHT INTO FRIDAY WITH TIGHTENING PRESSURE GRADIENTS AND
700 MB WINDS OF 50 TO 60 KTS. CURRENT PROBABILITIES FOR WIND
GUSTS OF 60 MPH OR GREATER AT LIVINGSTON AND NYE IS AROUND 80%,
WHILE GUSTS OF 70 MPH IS AROUND 40%. THE PROBABILITY FOR WIND
GUSTS OF 50 MPH OR GREATER FOR THE 191 CORRIDOR IS AROUND 50%.
ANOTHER SURGE OF PACIFIC MOISTURE AND LOWER HEIGHTS WILL MOVE INTO
THE AREA LATE THURSDAY AND INTO THE END OF THE WEEK. THIS
TRANSLATES TO PERIODS OF ACCUMULATING MOUNTAIN SNOW (90% CHANCE OF
12+ INCHES OVER WEST ASPECTS OF THE BEARTOOTH ABSAROKAS THU-SAT)
AND RAIN/SNOW AT LOWER ELEVATIONS. COLD AIR ADVECTION WORKING IN
FROM THE NORTH COULD BRING A PERIOD OF UPSLOPE SNOW TO THE
FOOTHILLS AND LOWER ELEVATIONS FRIDAY NIGHT INTO SATURDAY MORNING.
LATEST NBM PROBS FOR AN INCH OF SNOW ARE ROUGHLY 20-40% FOR LOWER
ELEVATIONS AND 40-70% FOR THE FOOTHILLS DURING THIS TIME PERIOD.
HAVE ISSUED A WINTER STORM WATCH WITH THIS FORECAST PACKAGE FOR
THE BEARTOOTH/ABSAROKA MOUNTAINS FROM THURSDAY AFTERNOON THROUGH
FRIDAY NIGHT.
MAINLY ZONAL FLOW WILL CONTINUE THROUGH THE WEEKEND AND INTO THE
FIRST PART OF NEXT WEEK. PACIFIC MOISTURE WILL CONTINUE STREAMING
INTO THE REGION AT TIMES BRINGING MOUNTAIN SNOWFALL. TEMPERATURES
WILL REMAIN ABOVE NORMAL, WITH HIGHS IN THE 30S TO NEAR 50 DEGREES
MOST DAYS, COLDEST OVER THE EAST. STP
AVIATION
THE MAIN HAZARD TO AVIATION OVER THE NEXT 24 HOURS IS EXTREME
WINDS. STRONG TO EXTREME WINDS WILL SPREAD EAST ACROSS SOUTHEAST
MONTANA THIS AFTERNOON. WIDESPREAD GUSTS OVER 50 KTS (>50% FOR
ALL TAF SITES) ARE EXPECTED WITH GUSTS OVER 60 KTS POSSIBLE
(10-60% FOR TAF SITES) ACROSS THE PLAINS. HIGHEST PROBABILITY FOR
GUSTS OVER 60 KT IS IN THE FOOTHILLS, AREAS NORTH OF KBIL, AND IN
SOUTHEAST MT. WINDS BEGIN TO DECREASE FROM WEST TO EAST AFTER
MIDNIGHT TONIGHT. STRONG WINDS ARE EXPECTED TO BE OUT OF THE
REGION BY 15Z THURSDAY. IN ADDITION, A BAND OF RAIN IS EXPECTED
TO MOVE ACROSS THE REGION THROUGH THIS AFTERNOON. STRONG WIND
GUSTS TO 60 KT CAN REACH THE SURFACE WITH THIS BAND OF RAIN. THERE
WILL ALSO BE SNOW AND BLOWING SNOW IN SOUTHEAST MT AFTER 03Z
TONIGHT, MAINLY NEAR AND EAST OF KMLS-K4BQ. THE GREATER IMPACTS TO
VISIBILITY FROM SNOW/BLOWING SNOW SHOULD OCCUR NEAR KBHK AND K97M.
TORGERSON/RMS
PRELIMINARY POINT TEMP/POPS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 055 027/041 033/055 026/041 023/041 028/046 027/042
6/W 00/B 15/O 82/S 11/B 12/O 21/B
LVM 052 026/043 034/051 026/039 022/043 031/050 030/046
5/J 13/S 58/O 82/S 12/O 34/R 32/O
HDN 055 020/039 030/056 024/041 020/040 025/045 024/042
6/W 10/B 15/O 83/S 11/B 12/R 21/B
MLS 049 011/032 026/048 018/033 019/036 023/041 022/037
6/W 30/N 12/O 61/B 10/B 11/E 11/B
4BQ 057 016/035 029/053 024/038 023/040 027/048 027/043
4/W 20/N 01/E 72/S 10/B 01/B 10/B
BHK 049 005/025 017/047 013/030 015/037 020/040 019/037
8/W 60/N 11/E 51/B 10/B 11/B 10/B
SHR 060 020/037 025/056 022/038 017/041 024/050 026/046
5/W 10/N 01/N 74/S 11/B 01/B 10/B
BYZ WATCHES/WARNINGS/ADVISORIES
MT...HIGH WIND WARNING IN EFFECT UNTIL 2 AM MST THURSDAY FOR ZONES
29-30-34-42-56-57-63-67-68-138-139-141-169>173-228-235.
HIGH WIND WARNING IN EFFECT UNTIL 5 AM MST THURSDAY FOR ZONES
31>33-36-37-58.
HIGH WIND WARNING IN EFFECT UNTIL 11 PM MST THIS EVENING FOR
ZONES 40-64>66.
WINTER STORM WATCH IN EFFECT FROM THURSDAY MORNING THROUGH
LATE FRIDAY NIGHT FOR ZONE 67.
WY...HIGH WIND WARNING IN EFFECT UNTIL 2 AM MST THURSDAY FOR ZONES
198-199.
WEATHER.GOV/BILLINGS
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