796
FXUS65 KBYZ 242056
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
156 PM MST WED DEC 24 2025
KEY MESSAGES
- LOCALLY DENSE FOG THROUGH EARLY CHRISTMAS MORNING IN PORTIONS OF
NORTHERN ROSEBUD & CUSTER COUNTIES.
- ABOVE NORMAL TEMPERATURES THROUGH FRIDAY; SOME DAILY RECORDS MAY
BE BROKEN ON CHRISTMAS.
- CANADIAN COLD FRONT BRINGS A QUICK SHOT OF SNOW AND COLDER TEMPS
FOR THE WEEKEND. TRAVEL CONDITIONS MAY BE IMPACTED BY POOR
VISIBILITY AND SLICK ROADS, ESPECIALLY CLOSE TO THE FOOTHILLS.
- PERSISTENT LIGHT TO MODERATE ACCUMULATING SNOW FOR THE
BEARTOOTH/ABSAROKA MOUNTAINS TONIGHT THROUGH SATURDAY.
- FIRST HALF OF NEXT WEEK LOOKS WARM AND DRY.
DISCUSSION
THROUGH NEXT WEDNESDAY...
THE PRIMARY IMMEDIATE CONCERN IS FOG. DENSE FOG HAS PERSISTED INTO
THE AFTERNOON AT MILES CITY AND HAS SPREAD UPVALLEY THROUGH
FORSYTH AS OF 20Z. BOTH AIRPORTS ARE REPORTING VSBY OF 1/4SM OR
LESS, AND LOCAL WEB CAMERAS CORROBORATE THIS. MODELS HAVE HANDLED
TODAY'S FOG POORLY, BUT CONCEPTUALLY WITH A LIGHT EASTERLY WIND
THROUGH TONIGHT A SHALLOW DENSE FOG MAY PERSIST ALONG THE
YELLOWSTONE VALLEY INTO EARLY CHRISTMAS MORNING, AFTER WHICH A
WIND SHIFT WILL CERTAINLY CLEAR THINGS OUT. IT IS ALSO POSSIBLE
THAT INCREASING SSE 850MB WINDS WILL HELP TO ERODE THE FOG
TONIGHT. GIVEN THE FEW HOURS OF DENSE FOG THAT HAS ALREADY
HAPPENED, HAVE ISSUED A DENSE FOG ADVISORY FOR NORTHERN ROSEBUD
AND CUSTER COUNTIES THRU 15Z TOMORROW. CHRISTMAS EVE AND EARLY
MORNING TRAVELERS SHOULD USE CAUTION ON I-94 IN THIS AREA.
OTHERWISE, WEATHER TONIGHT WILL BE MOSTLY QUIET AS A MOISTENING SW
FLOW ALOFT AHEAD OF A DEEP PACIFIC COAST TROF BRINGS OROGRAPHIC
SNOW TO THE BEARTOOTH ABSAROKAS, WITH 1-3" EXPECTED ON FAVORED
ASPECTS BY 12Z. A WEAK PACIFIC FRONTAL PASSAGE COULD SPREAD SOME
LIGHT SHOWERS ACROSS LOWER ELEVATIONS CHRISTMAS MORNING, BUT THIS
WILL BE INSIGNIFICANT. THE BIGGER STORY IS REALLY THE WARM
TEMPERATURES. TODAY, ALTHOUGH THE LOWER YELLOWSTONE VALLEY IS
COLDER, TEMPS HAVE RISEN TO THE 40S & 50S TODAY, AND ACTUALLY
REACHED THE LOWER 60S AT BADGER PEAK AND LAME DEER DIVIDE. MIXING
SHOULD BE A BIT BETTER TOMORROW W/ WESTERLY WINDS, AND WE ARE
LOOKING AT NEAR RECORD WARMTH FOR MANY LOCATIONS ON CHRISTMAS DAY.
DAILY RECORDS AT LIVINGSTON (56F IN 2005), BILLINGS (56F IN 2005)
AND SHERIDAN (61 IN 1947) WILL BE CHALLENGED. AT THE VERY LEAST,
THIS WILL BE ONE OF THE WARMEST CHRISTMASES WE HAVE SEEN IN OUR
PERIOD OF RECORD. FRIDAY WILL SEE CONTINUED WARMTH WITH HIGHS IN
THE UPPER 40S TO MID 50S MOST PLACES.
MOIST PACIFIC FLOW VEERING FROM SW TO W WILL BRING PERSISTENT
PERIODS OF ACCUMULATING SNOWFALL TO OUR WESTERN MOUNTAINS THROUGH
SATURDAY. OVER THE MOUNTAINS AROUND COOKE CITY WE ARE LOOKING AT
1+ INCHES OF SWE AND 10-16" OF SNOW (60% CHANCE OF 12+ INCHES)
OVER THE NEXT 3 DAYS.
THERE SHOULD BE A PERIOD OF PREFRONTAL ENHANCED SW-W WINDS ALONG
THE WESTERN FOOTHILLS LATE FRIDAY INTO EARLY SATURDAY. THE RISK OF
50+ MPH GUSTS IS ~50% AT LIVINGSTON, AND 20-40% AT BIG TIMBER AND
HARLOWTON. SOMETHING TO WATCH.
ANY IMPACTFUL WINTER WX OVER THE NEXT WEEK WILL BE TIED TO A
STRONGER FRONTAL PASSAGE AND BRIEF PERIOD OF SNOW ON SATURDAY.
TROF RESPONSIBLE FOR THIS IS CURRENTLY IN AK AND WILL TAP INTO A
PIECE OF THE VERY COLD AIR WHICH HAS EXISTED IN AK/YUKON OVER THE
PAST COUPLE WEEKS. THERE REMAIN MODEL DIFFERENCES WITH REGARD TO
SNOWFALL, WITH THE GFS CONTINUING TO SHOW A SHARPER TROF AND
STRONGER UPSLOPE SIGNAL THAN THE EC. ENSEMBLES SHOW GREAT SPREAD
IN POTENTIAL QPF. LATEST PROBABILITIES FOR 1+ INCHES OF SNOW RANGE
FROM 10% AT BILLINGS TO 50% ALONG THE SOUTHERN FOOTHILLS, AND
LOWER TO THE NORTH AND EAST. EVEN WITH JUST A BIT OF SNOW AFTER A
MILD FRIDAY NIGHT (FROPA ARRIVES SAT MORNING), RAPIDLY FALLING
TEMPS COULD RESULT IN ICY ROADS BY AFTERNOON. THERE ACTUALLY SEEMS
TO BE TWO FRONTAL PASSAGES, A PACIFIC FRONT EARLY THEN THE MUCH
COLDER CANADIAN ONE, AND THE TIMING OF THESE WILL NEED TO BE
MONITORED. WE ARE CONFIDENTLY LOOKING AT A SHARP COOL DOWN DURING
THE DAY ON SATURDAY FOLLOWED BY LOWS RANGING FROM NEAR -5F IN THE
EAST TO LOW-MID TEENS WEST SATURDAY NIGHT. WIND CHILLS MAY REACH
20 BELOW IN OUR EAST AS POST-FRONTAL NW WINDS WILL BE BRISK.
CHILLY AIR WILL REMAIN IN PLACE SUNDAY BEFORE WARMER WEATHER
RETURNS EARLY NEXT WEEK.
LOOKING AT NEXT WEEK, CONFIDENCE IS HIGH FOR ABOVE NORMAL HEIGHTS
WITH A BROAD NORTHERN ROCKIES RIDGE MONDAY TO WEDNESDAY. A FEW
ENSEMBLES SHOW BACKDOOR COOLING INTO OUR EAST IN THE TUESDAY NIGHT
TO WEDNESDAY PERIOD, BUT QUICK GLANCE AT CLUSTER ANALYSES SHOW
THAT THIS SOLUTION IS THE MUCH LOWER PROBABILITY. SO, LOOK FOR DRY
CONDITIONS WITH ABOVE NORMAL TEMPS (HIGHS IN 40S TO LOWER 50S) AS
WE APPROACH THE NEW YEAR.
JKL
AVIATION
LOCALLY DENSE FOG CONTINUES ALONG THE YELLOWSTONE RIVER VALLEY,
FROM K1S3 TO KMLS. THIS IS NOW FORECAST TO CONTINUE INTO THURSDAY
MORNING. EXPECT REDUCTIONS AS LOW AS VLIFR. FOR OTHER SITES, VFR
CONDITIONS ARE FORECAST THROUGH THE PERIOD. MATOS
PRELIMINARY POINT TEMP/POPS
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 036/057 039/055 031/038 011/034 021/043 028/049 028/047
12/W 00/B 04/J 10/B 00/B 01/B 11/B
LVM 042/054 038/050 027/036 015/034 019/042 027/048 030/049
54/W 23/W 24/J 10/B 00/U 00/B 10/U
HDN 030/053 032/057 029/039 006/029 013/042 023/048 023/044
11/B 10/B 05/W 10/U 00/B 01/B 21/B
MLS 027/045 028/050 025/034 002/018 006/037 023/043 021/038
01/F 00/B 02/J 10/U 00/B 01/B 21/B
4BQ 036/055 034/056 031/042 007/023 011/040 025/046 023/042
01/E 00/U 02/J 20/U 00/B 01/B 21/B
BHK 025/047 028/049 025/035 904/014 002/036 018/040 017/033
00/B 00/U 01/N 10/U 00/B 01/B 21/E
SHR 032/058 031/055 028/041 006/029 011/044 023/049 025/049
11/B 11/B 14/J 30/U 00/U 01/B 11/B
BYZ WATCHES/WARNINGS/ADVISORIES
MT...DENSE FOG ADVISORY IN EFFECT UNTIL 8 AM MST THURSDAY FOR
ZONES 31-32.
WY...NONE.
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