742
FXUS65 KBYZ 181608
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
908 AM MST THU DEC 18 2025
KEY MESSAGES
- ANOTHER PERIOD OF GUSTY WINDS ALONG THE WESTERN FOOTHILLS
STARTING THIS EVENING INTO FRIDAY.
- MOUNTAIN WAVE ACTIVITY COULD BRING STRONG AND ERRATIC WIND GUSTS
TO THE MOUNTAINS AND FOOTHILLS TONIGHT INTO FRIDAY MORNING.
- PERIODS OF MODERATE TO HEAVY SNOWFALL OVER THE BEARTOOTH
ABSAROKA MOUNTAINS TODAY INTO SATURDAY; 90 PERCENT CHANCE OF AT
LEAST A FOOT OF SNOW ON WEST ASPECTS, 60-70 PERCENT CHANCE FOR
AT LEAST 18 INCHES.
UPDATE
THE WINTER WEATHER ADVISORY FOR FALLON COUNTY HAS BEEN ALLOWED TO
EXPIRE THIS MORNING AS THE STRONG WINDS AND BLOWING SNOW IMPACTS
HAVE COME TO AN END. WITH THAT SAID, LINGERING BREEZY CONDITIONS
COMBINED WITH COLD AIR TEMPERATURES ARE LEADING TO WIND CHILL
VALUES IN THE SINGLE DIGITS TO TEENS BELOW ZERO THIS MORNING OVER
FAR EASTERN MONTANA (MAINLY FALLON AND CARTER COUNTIES). IN THESE
AREAS, LOOK FOR CONDITIONS TO WARM THROUGH THE DAY AS THE WINDS
CONTINUE TO DECREASE AND AIR TEMPERATURES WARM INTO THE 20S.
DISCUSSION
TODAY THROUGH WEDNESDAY...
STRONG TO DAMAGING WINDS HAVE BEEN GRADUALLY DECREASING FROM WEST
TO EAST OVERNIGHT AS A STRONG UPPER LOW SHIFTS EAST THROUGH THE
DAKOTAS. STRONG PRESSURE RISES AND MID-LEVEL WINDS (70-90 KTS)
HAVE KEPT WINDS GUSTING FROM 50-70 MPH FOR SHERIDAN COUNTY AND
AREAS NEAR THE DAKOTAS BORDER. WINDS WILL CONTINUE TO DECREASE
OVER THE AREA THROUGH THE MORNING. PRECIPITATION WRAPPING AROUND
THE LOW HAS BROUGHT LIGHT SNOW, AND THAT COMBINED WITH THE STRONG
WINDS HAS BROUGHT AREAS OF BLOWING SNOW, WITH THE WORST CONDITIONS
OVER FALLON COUNTY. THE SNOW/BLOWING SNOW IS EXPECTED TO DECREASE
THROUGH THE MORNING. COOLER CONDITIONS WILL PREVAIL OVER THE AREA
TODAY, WITH HIGHS RANGING FROM THE 20S OVER THE EAST TO THE 40S
OVER THE WEST.
BY THE TIME WE HEAD INTO THE LATE AFTERNOON AND EVENING, PRESSURE
GRADIENTS WILL BEGIN TIGHTENING BACK UP OVER THE WESTERN FOOTHILLS,
WITH MID-LEVEL WINDS INCREASING (700MB WINDS 50-75KTS). STRONG
WINDS ARE PROGGED TO DEVELOP IN THE WESTERN GAP AREAS FIRST
(LIVINGSTON AND NYE), SPREADING INTO THE US-191 CORRIDOR THURSDAY
EVENING/NIGHT. IDA-LWT PRESSURE GRADIENT IS PROGGED TO INCREASE TO
18-21 MB BY LATE TONIGHT/FRIDAY MORNING. GUSTY TO STRONG WINDS
ARE EXPECTED TO CONTINUE INTO FRIDAY OVER THE WESTERN FOOTHILLS,
SPREADING OUT ONTO CENTRAL AREAS AS A WARM FRONT LIFTS NORTHEAST
INDUCING DOWNSLOPE FLOW OVER THE AREA. WIND GUSTS OF 30 TO 45 MPH
WILL BE COMMON. SOUTHWEST TO WEST WINDS WILL DECREASE INTO THE
AFTERNOON AS A COLD FRONT APPROACHES FROM THE NORTH. WITH WINDS
ALOFT PERPENDICULAR TO THE MOUNTAINS AND PRESSURE GRADIENTS SET UP
ALONG THE FOOTHILLS, MOUNTAIN WAVE ACTIVITY IS POSSIBLE FOR NORTH
AND EAST FACING MOUNTAIN AND FOOTHILL LOCATIONS TONIGHT INTO
FRIDAY MORNING. THE PROBABILITY FOR WIND GUSTS OF 50 MPH AFFECTING
FOOTHILL LOCATIONS IS AROUND 60-80%, WHILE 60 MPH WINDS IS
CURRENTLY AROUND 50%. GUSTY AND ERRATIC WINDS ARE POSSIBLE FOR
LOCATIONS SUCH AS RED LODGE, FORT SMITH, DAYTON, SHERIDAN AND
STORY. HIGH WIND WARNINGS HAVE BEEN ISSUED FOR LIVINGSTON AND NYE
FROM THIS AFTERNOON INTO FRIDAY MORNING (SW GUSTS TO 75 MPH), AND
THE BIG TIMBER AREA FROM THIS EVENING THROUGH MID-DAY FRIDAY
(GUSTS UP TO 65 MPH). A HIGH WIND WATCH IS IN EFFECT FOR THE
WHEATLAND AND JUDITH GAP ZONES FROM TONIGHT THROUGH FRIDAY, WHERE
CONFIDENCE IN REACHING WARNING LEVEL WINDS IS LOWER (30-50%). HIGH
WIND WATCHES ARE IN EFFECT FOR THE RED LODGE FOOTHILLS AND THE
EAST SIDE OF THE BIGHORNS FROM LATE THIS EVENING THROUGH FRIDAY
MORNING.
SNOW WILL MOVE INTO THE WESTERN MOUNTAINS THIS AFTERNOON AS A
SURGE OF PACIFIC MOISTURE STREAMS INTO THE REGION. A PROLONGED
PERIOD OF ACCUMULATING SNOW IS EXPECTED FOR THE BEARTOOTH/ABSAROKA
MOUNTAINS THROUGH SATURDAY (90% CHANCE OF 12+ INCHES OVER WEST
ASPECTS, 60-70% CHANCE OF 18+ INCHES). A WINTER STORM WARNING
REMAINS IN EFFECT FOR THE BEARTOOTH/ABSAROKAS. RAIN/SNOW WILL
DEVELOP OVER THE LOWER ELEVATIONS FRIDAY AFTERNOON, SPREADING
SOUTH INTO THE UPSLOPE AREAS OF THE SOUTHERN MOUNTAINS AND
FOOTHILLS BY FRIDAY EVENING AS THE COLD FRONT DROPS THROUGH. LIGHT
SNOW ACCUMULATIONS ARE POSSIBLE, WITH THE PROBABILITY FOR 1 OR
MORE INCHES OF SNOW AT ROUGHLY 40-80% ALONG THE FOOTHILLS.
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. AS OF NOW, THERE DOES NOT LOOK
TO BE ANY PERIOD OF ACCUMULATING SNOW FOR THE LOWER ELEVATIONS FOR
THE NEXT SEVERAL DAYS. STP
AVIATION
WINDS ARE FORECAST TO SHIFT FROM NW TO SE FOR TERMINALS EAST OF
KBIL THIS AFTERNOON, THOUGH ONLY AROUND 15-20 KNOTS. WSW WINDS
WILL INCREASE ACROSS THE WESTERN FOOTHILLS THIS AFTERNOON/EVENING,
WITH GUSTS 45-65 KNOTS INTO FRIDAY MORNING. THE STRONGEST GUSTS
ARE FORECAST AROUND KLVM.
TONIGHT A MOUNTAIN WAVE MAY TAKE SHAPE ACROSS THE REGION. THIS
WILL HAVE THE MOST IMPACTS AT KSHR AND KRED WHERE THE WINDS AT
THE TERMINAL MAY PUSH 50KTS AND THERE MAY BE SIGNIFICANT LLWS. AT
KBIL, IMPACTS SUCH AS LLWS AND TURB ARE POSSIBLE AFTER 06Z BUT
SLIGHTLY LESS LIKELY.
MOUNTAINS WILL REMAIN PARTIALLY TO FULLY OBSCURED. THERE IS AN
ASOS POWER OUTAGE AT KLVM AND THUS IT HAS NOT REPORTED SINCE 19Z
WEDNESDAY. WMR/PM
PRELIMINARY POINT TEMP/POPS
TDY FRI SAT SUN MON TUE WED
-------------------------------------------------------
BIL 041 033/056 026/042 026/042 032/051 029/046 028/048
0/B 16/R 61/U 01/E 13/R 21/B 11/B
LVM 043 038/051 021/037 021/044 034/049 031/047 032/051
3/S 59/O 61/N 02/O 45/R 32/O 12/O
HDN 040 030/055 022/042 021/041 027/048 026/045 026/047
0/B 15/R 71/U 00/B 12/R 21/B 11/B
MLS 031 023/048 018/035 019/039 026/045 025/042 024/041
0/U 22/O 30/U 00/B 01/E 20/B 00/B
4BQ 034 028/054 024/038 023/043 031/049 028/046 028/049
0/U 11/E 60/U 00/B 01/E 10/B 00/B
BHK 025 014/048 013/030 015/040 024/045 023/041 022/042
0/N 21/N 30/U 00/B 01/E 10/B 00/B
SHR 037 028/057 017/038 016/042 027/050 025/047 026/052
0/B 12/R 92/S 00/B 01/B 10/B 00/B
BYZ WATCHES/WARNINGS/ADVISORIES
MT...HIGH WIND WATCH IN EFFECT FROM 8 PM MST THIS EVENING THROUGH
FRIDAY MORNING FOR ZONE 56.
HIGH WIND WATCH IN EFFECT FROM THIS EVENING THROUGH FRIDAY
AFTERNOON FOR ZONES 63-228.
HIGH WIND WARNING IN EFFECT FROM 2 PM THIS AFTERNOON TO 2 PM
MST FRIDAY FOR ZONES 65-66.
WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST SATURDAY FOR
ZONE 67.
HIGH WIND WATCH IN EFFECT FROM 8 PM MST THIS EVENING THROUGH
FRIDAY AFTERNOON FOR ZONES 138-169.
HIGH WIND WARNING IN EFFECT FROM 8 PM THIS EVENING TO 2 PM
MST FRIDAY FOR ZONES 141-172.
WY...HIGH WIND WATCH IN EFFECT FROM 8 PM MST THIS EVENING THROUGH
FRIDAY AFTERNOON FOR ZONE 199.
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