132
FXUS65 KBYZ 181049
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
349 AM MST MON NOV 18 2024
KEY MESSAGES
- MIXED PRECIPITATION AND SNOW TODAY INTO THIS EVENING, WITH
ACCUMULATING SNOW MAINLY IN THE FOOTHILLS AND MOUNTAINS.
- SURFACES WILL BECOME SLIPPERY LATE THIS AFTERNOON INTO THIS
EVENING IN SOUTHERN BIG HORN COUNTY, MT AND SHERIDAN COUNTY, WY
AS SNOW FALLS AND TEMPERATURES DROP.
- NORTHWEST WINDS IN SOUTHEAST MT WILL GUST TO 40-50 MPH TUESDAY
AND POTENTIALLY WEDNESDAY.
- HIGH UNCERTAINTY WITH LATE WEEK PATTERN CHANGE. MODELS ARE
HINTING AT A COLD AND WET SYSTEM.
DISCUSSION
THROUGH TUESDAY NIGHT...
500 MB TROUGH AND SURFACE COLD FRONT WILL MOVE EASTWARD ACROSS
THE NORTHERN ROCKIES TODAY INTO TONIGHT. THE TROUGH IS PRODUCING
LOWER PRESSURE OVER NW WY, REDUCING THE SEA-LEVEL PRESSURE
GRADIENT AND ASSOCIATED GAP FLOW WINDS IN THE LIVINGSTON AREA AND
BEARTOOTH FOOTHILLS. SO, HAVE CANCELLED THE WIND ADVISORY FOR
THIS AREA. FOCUS WILL NOW MOVE TO THE PRECIPITATION POTENTIAL FROM
THIS TROUGH. THE TROUGH WILL BRING SOME DYNAMICS/UPWARD MOTION
WITH IT AND PRODUCE LIGHT PRECIPITATION /GENERALLY LESS THAN 0.25
INCHES FOR MUCH OF THE AREA/, WITH 0.30-0.40 INCHES IN THE
BEARTOOTH/ABSAROKA AND BIGHORN MOUNTAINS.
THIS SYSTEM ONLY HAS SOMEWHAT COOLER AIR TO WORK WITH. IT WILL
NOT BRING ARCTIC AIR INTO THE AREA. SO, PRECIPITATION TYPE AND
SNOW ACCUMULATION ARE AGAIN GOING TO DEPEND ON ELEVATION OUTSIDE
OF THE MOUNTAINS. LOCATIONS WEST OF BILLINGS SHOULD SEE ALL SNOW,
BUT ACCUMULATION WILL OCCUR IN THE HIGHER ELEVATIONS OUTSIDE THE
YELLOWSTONE RIVER VALLEY FROM ABOUT BIG TIMBER EASTWARD. NEAR AND
EAST OF BILLINGS, PRECIPITATION COULD BEGIN AS RAIN THEN
TRANSITION TO A RAIN/SNOW MIX AND THEN EVENTUALLY WET SNOW. MUCH
OF THE SNOW ACCUMULATION, THOUGH, WILL BE LIMITED TO THE WESTERN
FOOTHILLS, SHERIDAN FOOTHILLS, SOUTHERN BIG HORN COUNTY (MT) AND
THE MOUNTAINS. THE FOOTHILL LOCATIONS AND SOUTHERN BIG HORN COUNTY
HAVE APPRECIABLE CHANCES OF RECEIVING AT LEAST 1 INCH OF SNOW FROM
THIS SYSTEM. NBM SHOWS THAT THE PROBABILITY OF RECEIVING AT LEAST
ONE INCH OF SNOW IS ABOUT 30-40% IN LIVINGSTON, 80-90% AT RED
LODGE, 70% AT ABERDEEN HILL, AND 40-50% IN SHERIDAN.
WE ARE NOT ANTICIPATING MUCH IN THE WAY OF IMPACTS IN THE WESTERN
FOOTHILLS AS SNOW SHOULD END BEFORE SUNSET. HOWEVER, FOR SOUTHERN
BIG HORN COUNTY AND THE SHERIDAN FOOTHILLS, APPRECIABLE DYNAMICS
IN THE FORM OF 700 MB FRONTOGENESIS LOOK TO PRODUCE SOME LIGHT TO
MODERATE SNOW AROUND SUNSET, WITH TEMPERATURES DROPPING. THIS
SCENARIO POSES A RISK OF WET SURFACES BECOMING ICY. IN THE BIGHORN
MOUNTAINS, NORTHWESTERLY UPSLOPE FLOW SHOULD PRODUCE GREATER
SNOWFALL TOTALS, WITH A 50% CHANCE OF RECEIVING AT LEAST 6 INCHES
OF SNOW THERE. IN ADDITION, THERE WILL BE SOME BLOWING SNOW AS
WINDS GUST TO NEAR 30 MPH. GIVEN THE ANTICIPATED IMPACTS, WE HAVE
ISSUED A WINTER WEATHER ADVISORY FOR SOUTHERN BIG HORN COUNTY
(MT), THE SHERIDAN FOOTHILLS, AND THE BIGHORN MOUNTAINS WITH
DIFFERENT START TIMES BUT ALL ENDING AT 10 PM MST TONIGHT.
OTHERWISE, MODELS APPEAR TO BE CONVERGING ON A SOLUTION WITH THE
500 MB LOW MOVING FAR ENOUGH EASTWARD THAT FALLON AND CARTER
COUNTIES RECEIVE LESS THAN ONE INCH OF SNOW. THE NBM SHOWS THAT
THE CHANCE OF BAKER RECEIVING MORE THAN 1 INCH OF SNOW HAS
DECREASED TO ABOUT 20%.
TUESDAY INTO TUESDAY NIGHT WILL BE DRY FOR MUCH OF THE AREA AS 500
MB SHORTWAVE RIDGING MOVES INTO THE REGION. THERE IS A 30-50%
CHANCE OF SNOW SHOWERS IN THE BEARTOOTH/ABSAROKA AND BIGHORN
MOUNTAINS ON TUESDAY BUT ANY ACCUMULATION WOULD BE LESS THAN ONE
INCH. SOUTHEAST MT WILL EXPERIENCE WIND GUSTS TO 40-50 MPH AS THE
AREA WILL BE IN A SURFACE PRESSURE GRADIENT BETWEEN HIGHER
PRESSURE TO THE WEST AND A DEEP SURFACE LOW OVER MINNESOTA.
HIGH TEMPERATURES WILL GENERALLY BE IN THE 30S AND 40S TODAY AND
TUESDAY. LOW TEMPERATURES WILL BE IN THE TEENS AND 20S TONIGHT
THEN MAINLY TEENS TUESDAY NIGHT. RMS
WEDNESDAY THROUGH SUNDAY...
INTO WEDNESDAY, ENSEMBLES DEPICT THE CLOSED LOW TRACKING EAST
FROM THE DAKOTAS INTO MINNESOTA WITH SHARP RIDGING OVER MT. THE
RESULTING SHARP GRADIENT OVER EASTERN MT WILL ALLOW FOR BREEZY
CONDITIONS TO CONTINUE THROUGH WEDNESDAY MORNING. MID TO LOW LEVEL
WINDS OF 45-55 MPH HAVE THE POTENTIAL TO MIX DOWN TO THE SURFACE
OVER FALLON AND CARTER COUNTIES. ENSEMBLES AND SOUNDINGS HAVE
WINDS DECREASING THROUGH THE AFTERNOON. RIDGING WILL LEAD TO
TEMPERATURES REBOUNDING INTO THE 30S TO MID 40S WEDNESDAY AND
THURSDAY. ENERGY RIDING ON THE WEST SIDE OF RIDGING WILL ALLOW FOR
LIGHT SNOW SHOWERS OVER THE BEARTOOTH/ABSAROKAS THURSDAY WITH
CHANCES FOR PRECIPITATION INCREASING FOR THE WEST (30-50%) LATE
THURSDAY. THE OVERALL PATTERN BECOMES MORE UNCERTAIN INTO THE END
OF THE WEEK AS ENSEMBLES GENERALLY SHOW A COOLER PATTERN, BUT THE
TIMING IS STILL YET TO BE IRONED OUT. WITH THIS, THERE IS SOME
SPREAD (10-15 DEGREES) IN HIGH TEMPERATURES FOR FRIDAY THROUGH THE
WEEKEND. HIGHS ARE CURRENTLY FORECASTED TO BE IN THE 30S TO LOW
50S FRIDAY AND SATURDAY, DROPPING TO THE 30S AND LOW 40S FOR
SUNDAY. TS
AVIATION
A COLD FRONT WILL BRING AREAS OF RAIN AND SNOW TO THE AREA TODAY
INTO THIS EVENING. THE RAIN AND SNOW COULD PRODUCE LOCAL MVFR-IFR
CONDITIONS. MOUNTAINS WILL BE OBSCURED IN SNOW. WINDS WILL BECOME
NORTHWESTERLY 10-15 KT AND GUST TO 25 KT BY THIS AFTERNOON,
CONTINUING INTO TONIGHT. RMS
PRELIMINARY POINT TEMP/POPS
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 043 024/039 018/039 025/044 024/037 025/042 024/038
7/O 10/U 00/U 01/E 33/J 22/W 33/J
LVM 039 015/034 013/044 029/049 030/050 030/049 024/040
7/S 11/U 01/B 13/W 64/W 33/W 64/J
HDN 046 024/041 016/040 020/044 021/039 021/042 019/038
8/R 31/U 00/U 01/B 23/W 22/W 34/J
MLS 044 026/039 018/036 016/039 019/033 019/039 019/034
7/O 21/N 00/U 00/B 12/J 11/E 23/J
4BQ 044 026/037 021/038 019/045 022/039 022/045 024/038
7/R 40/N 00/U 00/B 01/E 11/B 12/J
BHK 047 022/035 015/033 011/038 013/034 015/037 016/035
6/R 62/S 10/N 00/B 01/E 11/E 22/J
SHR 046 018/037 013/041 019/049 022/046 024/049 022/043
9/O 81/N 00/U 00/B 11/E 11/E 23/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
10 PM MST THIS EVENING FOR ZONE 138.
WINTER WEATHER ADVISORY IN EFFECT FROM 7 AM THIS MORNING TO
10 PM MST THIS EVENING FOR ZONE 171.
WY...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
10 PM MST THIS EVENING FOR ZONE 199.
WINTER WEATHER ADVISORY IN EFFECT FROM 7 AM THIS MORNING TO
10 PM MST THIS EVENING FOR ZONE 198.
WEATHER.GOV/BILLINGS
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