326
FXUS65 KBYZ 170245
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
745 PM MST TUE DEC 16 2025
KEY MESSAGES
- A SIGNIFICANT AND WIDESPREAD HIGH WIND EVENT IS IN STORE TONIGHT
THROUGH WEDNESDAY. GUSTS ARE EXPECTED TO APPROACH 70 MPH AT
LOWER ELEVATIONS TOMORROW 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 LATE TONIGHT AND
WEDNESDAY.
- 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.
UPDATE
ADDED THE BIGHORN AND PRYOR MOUNTAINS TO THE HIGH WIND WARNING FOR
HIGH WINDS OVERNIGHT TONIGHT THROUGH WEDNESDAY EVENING. HIGHEST
WINDS WILL BE IN THE NORTHERN BIGHORNS AND ALONG THE LEESIDE OF
THE BIGHORNS. RAIN SHOWERS ACROSS SOUTHEAST MT SHOULD MOVE EAST
AND DISSIPATE LATER THIS EVENING. TS
DISCUSSION
THROUGH NEXT TUESDAY...
HIGH WIND WARNINGS HAVE BEEN ISSUED ACROSS THE REGION FOR A PERIOD
OF VERY STRONG WINDS LATE TONIGHT THROUGH WEDNESDAY EVENING. BE
PREPARED FOR WIND GUSTS HIGHER THAN "USUAL" WITH 60 TO 70 MPH
GUSTS BEING COMMON ACROSS THE LOWER ELEVATIONS STARTING AROUND
MIDDAY TOMORROW. 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 DECREASED ALONG THE WESTERN FOOTHILLS SINCE THIS
MORNING AND HAVE CANCELLED ALL LINGERING HIGHLIGHTS FOR THE TODAY
PERIOD. THAT SAID, WE ARE STILL SEEING 40-55 MPH GUSTS AT BIG
TIMBER AND HARLOWTON. A DECREASING TREND WILL CONTINUE INTO THE
EVENING BEFORE THE NEXT PERIOD OF LEE SIDE PRESSURE FALLS BEGINS,
AND THE IDA-LWT GRADIENT IS EXPECTED TO TIGHTEN TO 16-19MB BY
EARLY WEDNESDAY. MID LEVEL WINDS WILL INCREASE TO 60-70 KNOTS
TOMORROW MORNING, BUT A STRENGTHENING TO 80-90 KNOTS AT 700MB IS
PROGGED TO OCCUR FROM NORTH CENTRAL TO SOUTHEAST MT ON THE BACK
SIDE OF A PASSING SHORTWAVE LATE WEDNESDAY AND WEDNESDAY NIGHT.
THIS COINCIDES WITH LATE DAY SYNOPTIC SUBSIDENCE AND IS A
REMARKABLE STRONG WIND SIGNAL FOR OUR PLAINS. ANY LINGERING SNOW
COVER COULD PRODUCE A SHALLOW SURFACE INVERSION WHICH WOULD WORK
AGAINST THE WIND TO A POINT, BUT SNOWMELT HAS BEEN RAPID AND WILL
CONTINUE FOR THE NEXT 24-30 HOURS (AND THUS THIS MAY NOT BE A
FACTOR). SHORTWAVE PASSAGE WILL PRODUCE A PERIOD OF RAIN TO MIXED
RAIN/SNOW SHOWERS THROUGH THE COURSE OF THE DAY, SO THERE MAY BE
DOWNDRAFT WIND ASSISTANCE AS WELL. PLEASE HEED THESE HIGH WIND
WARNINGS! BELOW ARE SOME NOTEWORTHY PROBABILITIES:
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, 65% CHANCE OF 70+ MPH
BHK 90% CHANCE OF 60+ MPH, 70% CHANCE OF 80+ MPH
PACIFIC SHORTWAVE WILL BRING A PERIOD OF SNOW TO OUR WESTERN
MOUNTAINS LATE TONIGHT AND WEDNESDAY, W/ A 5-10" ACCUMULATION
EXPECTED ON WEST ASPECTS. AN ADDITIONAL POTENTIAL IMPACT IS WITH
REGARD TO WRAP AROUND LIGHT SNOWFALL IN FAR SOUTHEAST MT WEDNESDAY
NIGHT, WHICH IN COMBINATION WITH THE STRONG WINDS COULD RESULT IN
LOWER VISIBILITY IN BLOWING SNOW AS TEMPS FALL TO THE TEENS AND
20S (PER BRIEF PUSH OF CANADIAN COLD ADVECTION, WHICH WILL NOT
AFFECT OUR WEST).
NOT TO BEAT A DEAD HORSE, BUT ANOTHER PERIOD OF GUSTY FOOTHILLS
WINDS LOOKS PROMISING LATE THURSDAY INTO FRIDAY. MID LEVEL WINDS
OF 50-60 KNOTS WOULD SUGGEST ADVISORY LEVEL GUSTS ARE LIKELY AT
THE GAP LOCATIONS (LIVINGSTON & NYE). BIG TIMBER AND HARLOWTON
SHOULD SEE 50-60 MPH GUSTS BEGINNING SOMETIME THURSDAY NIGHT.
RECENTLY MODELS HAVE TRENDED A BIT STRONGER HERE.
A GREATER OPPORTUNITY FOR PRECIP EMERGES LATE IN THE WEEK WITH
ANOTHER SURGE OF PACIFIC MOISTURE AND LOWER HEIGHTS. 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. IN FACT, WE MAY TAP INTO ENOUGH
COOLER AIR FOR A LITTLE SNOW ACCUMULATION AT LOWER ELEVATIONS
FRIDAY NIGHT INTO SATURDAY. PLENTY OF MODEL SPREAD EXISTS, BUT
LATEST NBM PROBS FOR AN INCH OF SNOW ARE 15-25% FOR LOWER
ELEVATIONS AND 30-60% FOR THE FOOTHILLS DURING THIS TIME PERIOD.
ZONAL FLOW CONTINUES THRU THE WEEKEND AND FIRST PART OF NEXT WEEK.
THIS KEEPS TEMPS RUNNING ABOVE NORMAL BUT WITH POTENTIAL FOR
MOUNTAIN SNOWFALL AS WE MOVE INTO CHRISTMAS WEEK. WILL BILLINGS
SEE A WHITE CHRISTMAS IN 9 DAYS? THE ODDS CURRENTLY FAVOR NO.
JKL
AVIATION
00Z UPDATE:
A BRIEF BREAK IN THE WINDS ARE EXPECTED THROUGH THIS EVENING
ACROSS THE WESTERN FOOTHILLS, BUT ARE EXPECTED TO PICK UP AGAIN
OVERNIGHT TONIGHT AFTER 06Z (UP TO 70 KTS), LASTING THROUGH SUNSET
WEDNESDAY. OVERNIGHT TONIGHT INTO THE MORNING HOURS, THERE IS
HIGH CONFIDENCE FOR MOUNTAIN WAVE ACTIVITY ALONG THE
BEARTOOTH/ABSAROKAS (KRED) AND BIGHORN MOUNTAINS WITH GUSTS OF UP
TO 50-70 KTS POSSIBLE. SHOWERS WILL MOVE IN FROM THE WEST EARLY
MORNING WEDNESDAY (MOUNTAIN OBSCURATIONS EXPECTED), WITH AN
ADDITIONAL BAND MOVING ACROSS THE REGION MID MORNING, TRACKING
EAST THROUGH THE AFTERNOON. FOLLOWING THIS PRECIP, THAT'S WHEN THE
STRONGEST WINDS WILL OCCUR, AFFECTING ALL TAF SITES. WEST TO
NORTHWEST GUSTS OF 45-60 KTS CAN BE EXPECTED. TS
PRELIMINARY POINT TEMP/POPS
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 040/051 026/041 034/053 026/039 023/040 026/048 029/046
16/W 00/B 14/W 63/J 21/B 22/W 11/B
LVM 045/052 025/044 035/051 027/040 022/043 031/050 034/051
14/W 03/J 47/W 63/J 22/W 44/W 21/E
HDN 033/053 020/040 031/053 025/039 021/040 023/047 027/047
25/W 00/B 14/W 63/J 21/B 12/W 11/B
MLS 028/046 012/032 027/048 019/033 019/037 022/041 022/041
25/W 20/B 12/W 41/B 10/B 11/E 10/B
4BQ 032/054 018/036 030/053 025/037 024/041 027/049 028/047
25/W 20/N 02/W 52/J 11/B 01/B 10/B
BHK 027/046 005/027 018/045 014/029 014/037 019/042 020/038
16/W 50/N 12/W 41/B 10/B 11/B 10/B
SHR 030/057 019/038 026/056 023/039 019/043 024/053 028/051
06/W 10/N 02/W 53/J 21/B 01/B 10/B
BYZ WATCHES/WARNINGS/ADVISORIES
MT...HIGH WIND WARNING IN EFFECT FROM 8 AM WEDNESDAY TO 2 AM MST
THURSDAY FOR ZONES 29-30-34-42-57-139-170-173-235.
HIGH WIND WARNING IN EFFECT FROM 11 AM WEDNESDAY TO 5 AM MST
THURSDAY FOR ZONES 31>33-36-37-58.
HIGH WIND WARNING IN EFFECT FROM 2 AM WEDNESDAY TO 2 AM MST
THURSDAY FOR ZONES 56-63-138-141-169-171-172-228.
HIGH WIND WARNING IN EFFECT FROM 2 AM TO NOON MST WEDNESDAY
FOR ZONE 64.
HIGH WIND WARNING IN EFFECT UNTIL 11 PM MST WEDNESDAY FOR
ZONES 65-66.
HIGH WIND WARNING IN EFFECT FROM 11 PM THIS EVENING TO 2 AM
MST THURSDAY FOR ZONES 67-68.
WY...HIGH WIND WARNING IN EFFECT FROM 2 AM WEDNESDAY TO 2 AM MST
THURSDAY FOR ZONES 198-199.
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