191
FXUS65 KBYZ 151019
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
319 AM MST FRI NOV 15 2024
KEY MESSAGES
- THERE IS A 50-75% CHANCE OF AT LEAST 2 INCHES OF SNOW FOR AREAS
ALONG THE BEARTOOTH/ABSAROKA AND CRAZY MOUNTAIN FOOTHILLS WITH
LIGHTER ACCUMULATIONS FOR LOWER ELEVATIONS.
- POTENTIAL WEATHER SYSTEM BRINGING COOLER AND WETTER CONDITIONS
FOR MONDAY/TUESDAY.
- STRONG WINDS LOOK TO RETURN OVER THE WESTERN MOUNTAINS AND
FOOTHILLS LATE SATURDAY INTO SUNDAY NIGHT.
DISCUSSION
TODAY THROUGH SATURDAY NIGHT...
CURRENT ANALYSIS DEPICTS SLIGHT RIDGING OVER MT AND NORTHERN WY
AHEAD OF TROUGHING OVER THE WEST COAST THAT WILL MOVE INTO THE
REGION THIS EVENING. ENSEMBLES ARE IN AGREEMENT THAT A CLOSED LOW
WILL MOVE ACROSS MT THIS EVENING BRINGING SNOWFALL WITH A FEW AREAS
OF RAINFALL. A SMALL CHANCE OF LIGHT SNOW IS POSSIBLE ACROSS THE
WEST THIS AFTERNOON, BUT WILL BECOME MORE WIDESPREAD INTO THE
EVENING. RAIN/SNOW SHOWERS ASSOCIATED WITH A FRONT WILL TRACK EAST
OVERNIGHT, EXITING THE REGION BY SATURDAY EVENING. THE
BEARTOOTH/ABSAROKAS, PRYORS AND NORTHERN BIGHORNS WILL SEE 7-10
INCHES IN THE HIGHEST PEAKS. MODERATE TO HIGH CHANCES EXIST FOR
AT LEAST TWO INCHES OF SNOW FOR FOOTHILLS ALONG THE CRAZY AND
BEARTOOTH/ABSAROKA MOUNTAINS. THEREFORE, A WINTER WEATHER ADVISORY
WAS ISSUED FOR 5 PM TODAY THROUGH 11 AM SATURDAY. AREAS OF HIGHER
SNOWFALL (UP TO 6-7 INCHES) ARE LIKELY UP INTO THE HIGHER
FOOTHILLS. THERE IS STILL SOME UNCERTAINTY IN THE FORECAST IN
REGARDS TO SNOW TOTALS, SPECIFICALLY TO THE EAST OF BILLINGS. THE
HREF (HIGH RESOLUTION ENSEMBLE FORECAST) CONTAINS A LOT OF
SPREAD, GIVING AREAS OF SOUTHERN BIG HORN, ROSEBUD AND CUSTER
COUNTIES A RANGE OF 0 TO 5 INCHES OF SNOW. WITH THIS, UNCERTAINTY
STILL REMAINS ON SNOW LEVELS AND PRECIP TYPE AREAS EAST OF
BILLINGS. KEEP AN EYE ON THE FORECAST IF YOU HAVE TRAVEL PLANS
FRIDAY NIGHT INTO SATURDAY.
INTO SATURDAY EVENING AS LEESIDE TROUGHING AND INCREASED 700 MB
WINDS SET UP OVER THE WESTERN FOOTHILLS, A GAP WIND PATTERN WILL
BEGIN TO BRING INCREASED WINDS TO THE LIVINGSTON AREA. MODELS
GENERALLY HAVE SURFACE PRESSURE GRADIENTS AND 700 MB WINDS
INCREASING THROUGH SATURDAY NIGHT. THE CHANCES FOR WIND GUSTS OF
AT LEAST 50 MPH BEGIN AROUND 9 PM AND INCREASE THROUGH THE
MORNING. FOR MORE INFORMATION ON WINDS SUNDAY MORNING, SEE
DISCUSSION BELOW.
HIGH TEMPERATURES WILL BE IN THE 40S TO LOW 50S TODAY, COOLING
INTO THE UPPER 30S TO 40S SATURDAY. LOWS WILL BE IN THE 20S TO LOW
30S THIS MORNING AND SATURDAY MORNING. TS
SUNDAY THROUGH THURSDAY...
WPC 500 MB CLUSTERS SHOW THAT THIS FORECAST PERIOD BEGINS WITH
GOOD MODEL AGREEMENT ON SUNDAY BUT THEN INTRODUCES NOTICEABLE
MODEL SPREAD BEGINNING MONDAY.
ON SUNDAY, A 500 MB TROUGH WILL MOVE EASTWARD FROM THE NORTHEAST
PACIFIC INTO THE PACIFIC NORTHWEST. THIS PATTERN EVOLUTION WILL
CAUSE STRONGER WINDS ALOFT TO MOVE OVER THE ROCKY MOUNTAINS AND
ASSOCIATED SURFACE LEE TROUGHING TO DEVELOP. THE LEE TROUGHING
WILL EVOLVE INTO A SURFACE LOW THAT MOVES EASTWARD FROM ALBERTA TO
SASKATCHEWAN SUNDAY INTO SUNDAY NIGHT. IN ACCORD WITH THIS
EVOLUTION, THE SEA- LEVEL PRESSURE GRADIENT WILL STRENGTHEN OVER
CENTRAL MT, AN INDICATION THAT STRONG GAP WINDS WILL DEVELOP IN
THE LIVINGSTON TO NYE CORRIDOR EARLY SUNDAY INTO SUNDAY EVENING.
THE PROBABILITY OF 50 MPH+ GUSTS AT LIVINGSTON IS HIGH AT OVER
80%. THOSE PLANNING TO TRAVEL IN THE LIVINGSTON TO NYE CORRIDOR
WITH A HIGH-PROFILE VEHICLE SHOULD BE PREPARED FOR STRONG
CROSSWINDS. OTHERWISE, SUNDAY WILL BE A MILD AND DRY DAY FOR MUCH
OF THE AREA. THERE IS A 20% CHANCE OF SNOW SHOWERS IN THE
BEARTOOTH/ABSAROKA MOUNTAINS BUT ANY ACCUMULATION WOULD BE LIGHT.
MONDAY INTO TUESDAY, WPC 500 MB CLUSTERS GENERALLY AGREE ON LOWER
HEIGHTS OVER THE WESTERN US, BUT DIFFER ON THE AMPLITUDE OF THE
LOWER HEIGHTS. ONE CLUSTER SHOWS A SHARPER/MORE AMPLIFIED TROUGH
OVER THE PACIFIC NORTHWEST ON MONDAY THAT WOULD BE CAPABLE OF
PRODUCING SOME MEASURABLE PRECIPITATION IN THE LOWER ELEVATIONS,
SAY AROUND 0.10 INCHES OR SO IN CENTRAL AREAS. HOWEVER, THE OTHER
CLUSTERS SHOW A FLATTER TROUGH THAT WOULD PRODUCE LITTLE TO NO
PRECIPITATION IN THE LOWER ELEVATIONS. THEN ON TUESDAY, TWO
CLUSTERS SHOW A MORE AMPLIFIED TROUGH OVER OUR REGION WHICH WOULD
FAVOR ACCUMULATING SNOW OVER EASTERN MONTANA (ESPECIALLY EAST OF
MILES CITY-BROADUS). THE MOUNTAINS HAVE THE GREATER PROBABILITY OF
RECEIVING PRECIPITATION FROM ALL SCENARIOS. NBM REFLECTS THIS
FORECAST UNCERTAINTY WITH A 40-95% CHANCE OF PRECIPITATION
(GREATEST IN THE MOUNTAINS), AND A 30-50% CHANCE OF AT LEAST ONE
INCH OF SNOW FROM THE VALLEYS IN PARK COUNTY TO THE BEARTOOTH AND
RED LODGE FOOTHILLS, SOUTHERN BIG HORN COUNTY (MT), THE SHERIDAN
FOOTHILLS, AND SOUTHEAST MT. THERE IS ALSO A 20-30% CHANCE OF AT
LEAST 3 INCHES OF SNOW IN THESE AREAS EXCEPT THE LIVINGSTON AREA
AND SHIELDS VALLEY.
WEDNESDAY AND THURSDAY, MODEL CLUSTERS DIFFER ON AMPLITUDE OF THE
500 MB FLOW AND WHAT TO DO WITH A RIDGE SOMEWHERE IN WESTERN
NORTH AMERICA. SOME CLUSTERS BRING A RIDGE OVER OUR AREA WHICH
WOULD FAVOR MILD AND DRY CONDITIONS AND PROBABLY MORE STRONG GAP
WINDS. ANOTHER CLUSTER CENTERS A RIDGE OVER THE EASTERN PACIFIC
WITH NORTH/NORTHWESTERLY FLOW OVER OUR REGION WHICH WOULD
FACILITATE COLD AIR MOVING INTO OUR AREA.
HIGH TEMPERATURES WILL BE IN THE 40S TO LOWER 50S SUNDAY, THEN 30S
AND 40S MONDAY-WEDNESDAY. NBM THEN SHOWS THE UNCERTAINTY IN THE
HIGH TEMPERATURE INCREASING MARKEDLY ON THURSDAY, WHEN THE HIGH
TEMPERATURE AT BILLINGS COULD BE ANYWHERE FROM 32 TO 56, AS
SUGGESTED BY THE NBM 10TH TO 90TH PERCENTILES. RMS
AVIATION
SNOW SHOWERS WILL BEGIN TO MOVE INTO THE WESTERN FOOTHILLS MID
DAY TODAY AND BECOME MORE WIDESPREAD INTO KLVM INTO THE EVENING.
MOUNTAIN OBSCURATIONS WILL THEN BECOME LIKELY. RAIN/SNOW SHOWERS
WILL BEGIN AFTER MIDNIGHT FOR KBIL, WITH KSHR AND KMLS TO FOLLOW.
MVFR/IFR CONDITIONS ARE LIKELY DURING RAIN/SNOW SHOWERS. TS
PRELIMINARY POINT TEMP/POPS
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 045 033/044 027/049 033/044 024/039 018/040 024/048
1/E 97/W 00/B 15/O 31/B 10/U 11/U
LVM 044 028/041 024/047 028/040 017/036 012/041 023/052
2/J 96/J 01/N 47/S 41/B 11/U 12/R
HDN 048 028/044 023/052 028/046 023/041 017/040 018/047
1/E 89/W 00/B 16/O 32/S 11/U 12/O
MLS 050 030/039 023/050 028/046 023/038 016/036 017/044
1/E 49/W 00/U 03/O 32/S 21/U 11/B
4BQ 052 028/038 024/054 028/046 025/038 017/037 019/046
0/E 18/J 10/U 03/R 43/S 21/U 11/U
BHK 054 025/038 021/051 025/048 022/037 014/034 014/042
0/E 38/W 20/U 02/R 43/S 22/S 11/B
SHR 049 024/042 019/056 025/046 020/038 015/040 017/052
0/B 48/J 00/U 07/O 63/S 11/U 12/O
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 5 PM THIS AFTERNOON TO
11 AM MST SATURDAY FOR ZONES 56-64>66-172.
WY...NONE.
WEATHER.GOV/BILLINGS
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