406
FXUS65 KBYZ 161830
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1230 PM MDT TUE SEP 16 2025
KEY MESSAGES
- RISK LEVEL 1 OF 4 FOR EXCESSIVE RAINFALL FOR LOCATIONS WEST OF
BILLINGS TODAY. LOCALIZED FLOODING POSSIBLE.
- THE BEST PRECIPITATION CHANCES SHIFT EAST OF BILLINGS WEDNESDAY
WITH A 30 TO 60 PERCENT CHANCE FOR RAINFALL OF 0.25 INCHES OR
MORE SOUTH OF A SHERIDAN TO BAKER LINE.
- LIGHT SNOW ACCUMULATIONS EXPECTED OVER THE BEARTOOTH MOUNTAINS
ABOVE 10KFT THROUGH WEDNESDAY MORNING. THIS SNOWFALL MAY IMPACT
TRAVEL OVER THE HIGHEST ELEVATIONS OF THE BEARTOOTH HIGHWAY.
- BECOMING DRIER WITH SEASONAL TEMPERATURES FOR THE END OF THE
WORK WEEK, WITH ABOVE NORMAL TEMPERATURES FOR THE WEEKEND.
DISCUSSION
A 500 MB TROUGH WILL CONTINUE TO DROP THROUGH THE REGION TONIGHT.
PRECIPITATION WEST OF BILLINGS TODAY WILL BEGIN TO SHIFT TO
LOCATIONS EAST OF BILLINGS OVERNIGHT. AS THE BAND OF PRECIPITATION
BEGINS TO MOVE OFF TO THE EAST, CONDITIONS WILL BECOME LESS
FAVORABLE FOR HIGH ELEVATION SNOW OVER THE BEARTOOTH HIGHWAY. WITH
MANY LOCATIONS IN THE BEARTOOTH/ABSAROKA MOUNTAINS AND SURROUNDING
FOOTHILLS HAVING RECEIVED OVER AN INCH OF RAINFALL OVER THE LAST
24 HOURS, AND THESE SAME LOCATIONS HAVING HIGH CHANCES (40-70%)
FOR AN ADDITIONAL 0.5 INCHES, A MARGINAL RISK FOR EXCESSIVE
RAINFALL HAS BEEN ISSUED FOR LOCATIONS WEST OF BILLINGS. THIS
COULD LEAD TO LOCALIZED FLOODING.
TOMORROW, AS THE UPPER LEVEL LOW CONTINUES TO MOVE EAST, IT WILL
SPIN UP A SURFACE LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS.
THIS LOW WILL ADVECT MOISTURE INTO EASTERN MONTANA BRINGING
PRECIPITATION CHANCES (30-60%) FOR LOCATIONS SOUTH AND EAST OF A
LINE FROM RED LODGE TO BAKER. THURSDAY, THE LOW WILL DRIFT INTO
THE NORTHERN PLAINS BRINGING LINGERING PRECIPITATION CHANCES
(20%) FOR LOCATIONS NEAR THE DAKOTAS BORDER. PRECIPITATION
THROUGHOUT THE NEXT FEW DAYS WILL BE SHOWERS AND GENERAL
THUNDERSTORMS. 6 PM TONIGHT TO 6 PM THURSDAY, LOCATIONS IN CARTER
COUNTY WILL HAVE THE HIGHEST CHANCES (20-50%) FOR GETTING GREATER
THAN 0.5 INCHES OF RAIN WITH <20% CHANCES ELSEWHERE.
THE 500 MB PATTERN WILL REMAIN ACTIVE FRIDAY THROUGH MONDAY WITH
MULTIPLE WAVES MOVING THROUGH. AT THIS TIME, DETERMINISTIC MODELS
AND ENSEMBLES ARE KEEPING THESE SYSTEMS TO THE NORTH WITH LITTLE
TO NO IMPACT OVER OUR REGION. WPC CLUSTERS ARE INDICATING UPPER
LEVEL RIDGING RETURNING NEXT WEEK, THOUGH DETAILS ARE UNCLEAR AT
THIS TIME.
TEMPERATURES WILL GENERALLY BE IN THE 70S F WEDNESDAY THROUGH
FRIDAY. TEMPERATURES INCREASE OVER THE WEEKEND WITH 80S F
RETURNING TO MUCH OF THE REGION. TORGERSON
AVIATION
UPPER AIR LOW PRESSURE WILL CONTINUE TO AFFECT THE SOUTHERN MT AND
NORTHERN WY REGION THROUGH WEDNESDAY IN THE FORM OF AREAS OF
LOWERED CLOUD DECKS, SHOWERS, AND ISOLATED THUNDERSTORMS. THROUGH
00Z WEDNESDAY, SHOWERS ARE LIKELY (70-90% CHANCE) OVER SOUTH
CENTRAL MT WITH LOWER CHANCES OF 50-60% NEAR KSHR AND 20-50% OVER
SOUTHEAST MT. THE HEAVIER SHOWERS OR THUNDERSTORMS CAN PRODUCE
MVFR VISIBILITY. PREVAILING CEILINGS WILL BE VFR BUT THERE WILL BE
PERIODS OF MVFR IN SOUTH CENTRAL MT.
TONIGHT, THE AREA WITH THE GREATEST CHANCE OF SHOWERS (50-60%
CHANCE) WILL SHIFT FROM SOUTH CENTRAL MT TO FAR SOUTHEAST MT.
12Z HREF SUGGESTS A 10-50% CHANCE OF FOG (VISIBILITY LESS THAN 1
MILE) IN SOUTHEAST MT 04Z-14Z WEDNESDAY.
ON WEDNESDAY, SHOWERS WILL AGAIN BE OVER SOUTHEAST MT AND NORTH
CENTRAL WY (20-70% CHANCE, GREATEST TO THE SOUTHEAST WITH LOWER
VALUES CLOSER TO SOUTH CENTRAL MT). THERE IS A 30% CHANCE OF
CEILINGS AT OR BELOW MVFR NEAR KBHK AND KSHR INCREASING TO ABOUT
60% CLOSER TO FAR SOUTHEAST MT. OTHERWISE, CEILINGS WILL BE VFR.
MOUNTAINS WILL BE OBSCURED ESPECIALLY THROUGH TONIGHT. ON
WEDNESDAY, CONDITIONS SHOULD IMPROVE FOR MOUNTAINS WEST AND
SOUTHWEST OF KBIL, BUT MOUNTAIN OBSCURATIONS WILL PERSIST OVER
THE BIGHORN MOUNTAINS. RMS
PRELIMINARY POINT TEMP/POPS
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 052/072 051/076 049/078 052/084 055/080 051/078 050/078
52/W 00/U 00/U 00/U 01/B 10/U 00/U
LVM 041/070 041/076 043/079 047/080 047/074 045/075 044/077
31/U 00/U 00/U 01/U 12/T 10/U 00/U
HDN 049/073 047/076 046/079 047/085 052/081 048/078 046/079
53/T 10/U 00/U 00/U 11/B 20/U 00/U
MLS 052/074 050/074 048/074 048/082 054/080 051/075 047/077
32/W 11/U 10/U 00/U 00/B 10/U 00/U
4BQ 052/069 050/069 046/073 048/080 053/078 051/074 049/076
44/T 21/B 10/U 00/U 00/U 10/U 00/U
BHK 050/073 047/069 045/071 045/079 049/079 049/074 044/076
62/T 12/W 21/B 00/U 00/B 10/U 00/U
SHR 043/067 042/071 042/075 045/081 049/078 046/075 044/078
56/T 21/U 00/U 00/U 11/B 21/U 00/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT MDT TONIGHT
FOR ZONE 67.
WY...NONE.
WEATHER.GOV/BILLINGS
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