339
FXUS65 KBYZ 050945
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
345 AM MDT MON MAY 5 2025
KEY MESSAGES
- COOL AND WET CONDITIONS WILL AFFECT THE AREA THROUGH TUESDAY.
SEVERAL INCHES OF SNOW CAN BE EXPECTED IN THE MOUNTAINS. WET
SNOWFALL ACCUMULATIONS ON GRASSY SURFACES IN THE FOOTHILLS.
- DRIER AND WARMER CONDITIONS WILL RETURN FOR THE SECOND HALF OF
THE WORK WEEK. ISOLATED SHOWERS ARE POSSIBLE THURSDAY AND
FRIDAY.
DISCUSSION
THROUGH TUESDAY NIGHT...
SHOWERS WERE SLOWLY SLIDING TO THE NORTH OVER WESTERN AREAS WHILE
ISOLATED SHOWERS AND THUNDERSTORMS WERE CONTINUING OVER PORTIONS
OF POWDER RIVER AND CUSTER COUNTIES EARLY THIS MORNING.
PRECIPITATION TOTALS HAVE RANGED FROM JUST A FEW HUNDREDTHS, TO
CLOSE TO 0.60 INCHES OVER WESTERN AREAS. SATELLITE SHOWED
DIFFLUENT FLOW OVER THE AREA, WITH A SHORTWAVE DROPPING INTO FAR
NW MONTANA. EXPECT PRECIPITATION TO INCREASE IN COVERAGE OVER THE
WEST THROUGH THE MORNING AS COLD AIR ADVECTION CONTINUES TO WORK
IN FROM THE NORTH AND NORTHWEST AND UPSLOPE FLOW DEEPENS. RAIN
AND MOUNTAIN SNOW WILL SPREAD SOUTH AND EAST THROUGH THE DAY AS
THE AFOREMENTIONED SHORTWAVE DROPS INTO THE AREA, EVENTUALLY
PHASING WITH ENERGY ASSOCIATED WITH AN UPPER LOW TO THE SOUTH.
HIGHS WILL RANGE FROM THE UPPER 30S TO THE 40S OVER THE WEST AND
CENTRAL ZONES TODAY, WITH 50S TO LOWER 60S OVER THE EAST. BREEZY
NORTH TO NORTHEAST WINDS ARE FORECAST. EXPECT PRECIPITATION TO
CONTINUE OVERNIGHT INTO TUESDAY, GRADUALLY DECREASING INTO TUESDAY
AFTERNOON.
LIQUID PRECIPITATION TOTALS LOOK TO RANGE FROM AROUND A TENTH OR
TWO IN THE NORTHEAST, TO 0.75 TO 1.5 INCHES OVER THE NORTHERLY
UPSLOPE AREAS OF THE SOUTHERN MOUNTAINS AND FOOTHILLS. GREATEST
PRECIPITATION WILL BE FOUND ALONG AND SOUTH OF A HARLOWTON TO
BILLINGS TO BROADUS LINE. SNOW LEVELS CURRENTLY RANGE FROM NEAR
6,000 FEET IN THE FAR NORTHWEST, TO AROUND 9,000 FEET IN THE
SOUTH. SNOW LEVELS ARE EXPECTED TO DROP TOWARDS 6,000 FEET OVER
THE AREA TODAY, DROPPING TO BETWEEN 4,500 TO 5,000 FEET TONIGHT
INTO TUESDAY MORNING. THE MAJORITY OF THE PRECIPITATION LOOKS TO
FALL THIS AFTERNOON INTO TUESDAY MORNING, WHEN SNOW LEVELS ARE
FALLING. TEMPERATURES IN THE FOOTHILLS WILL FALL INTO THE UPPER
20S TO LOWER 30S TONIGHT, ALLOWING FOR PRECIPITATION TO
TRANSITION TO SNOW. HIGHS ON TUESDAY WILL STRUGGLE TO CLIMB INTO
THE 40S TO LOWER 50S. CURRENT FORECAST IS FOR 10 TO 16 INCHES OF
SNOW ON THE NORTHEAST ASPECTS OF THE BEARTOOTH/ABSAROKA MOUNTAINS,
WITH 5 TO 10 INCHES IN THE BIGHORNS THROUGH TUESDAY. FOOTHILL
LOCATIONS FROM NYE TO RED LODGE AND STORY COULD SEE 2 TO 6 INCHES,
WITH SOME LIGHT ACCUMULATIONS ON GRASSY SURFACES DOWN TO 4,500
FEET. HAVE CONTINUED THE WINTER STORM WARNING FOR THE SOUTHWEST
MOUNTAINS AND ADDED A WINTER WEATHER ADVISORY FOR THE
BIGHORN/PRYOR MOUNTAINS AND THE BEARTOOTH AND RED LODGE FOOTHILLS.
THE ADVISORY GOES INTO EFFECT LATER THIS AFTERNOON AND EVENING,
CONTINUING THROUGH NOON ON TUESDAY. STP
WEDNESDAY THROUGH MONDAY...
A BIT OF AN ODD SETUP IS FORECAST FOR THE SECOND HALF OF THE
WEEK. BY WEDNESDAY MORNING A CUTOFF LOW WILL BE SITUATED TO OUR
SOUTH OVER THE FOUR CORNERS REGION. WHILE THIS WILL BE THE
DOMINANT FEATURE IN THE CONUS, THE BIGGER PICTURE SHOWS AN ODD REX
BLOCK, OMEGA BLOCK HYBRID WITH A WEAKER LOW OVER THE NORTHEAST US
AND HIGH PRESSURE OVER THE NORTHERN PLAINS/MIDWEST. WHILE THIS
WILL STALL THE LARGER PATTERN ACROSS NORTH AMERICA, BOTH OF THE
LOWS ARE CUTOFF FROM THE MAIN FLOW. THEREFORE THIS SETUP SHOULD
NOT IMPEDE THE PROGRESSION OF THE ENERGY ALONG THE POLAR JET,
ALONG AND JUST NORTH OF THE CANADA/USA BORDER FOR THIS PERIOD.
ON WEDNESDAY, A RELATIVELY WEAK VORT MAX WILL DISLODGE FROM THE
CUTOFF LOW IN THE SW AND MIGRATE NORTHWARD THROUGH WY/MT BEFORE
GETTING PICKED UP BY A SHORTWAVE MOVING THROUGH THE MAIN POLAR
JET. THIS WILL BE ENOUGH LIFT, IN ASSOCIATION WITH THE WAA AND
MOISTURE ADVECTION, TO GIVE MUCH OF THE AREA THE POTENTIAL FOR
SOME SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON AND EVENING
BEFORE ALL OF THE ENERGY MIGRATES EASTWARD. THEN IMMEDIATELY
BEHIND THAT FEATURE, YET ANOTHER, ALBEIT WEAKER, SHORTWAVE FOLLOWS
RIGHT BEHIND THE FIRST. THIS WILL BRING ADDITIONAL CHANCES FOR
PRECIPITATION ACROSS THE REGION FRIDAY AFTERNOON.
FOLLOWING THE SPEEDY EXIT OF THAT FEATURE, A HIGH AMPLITUDE RIDGE
WILL BUILD IN FOR THE WESTERN CONUS SATURDAY. THIS WILL ALLOW MUCH
OF THE CWA TO HAVE A WARM AND MOSTLY DRY WEEKEND. WIDESPREAD HIGHS
IN THE UPPER 80S SUNDAY ARE POSSIBLE WITH THE CLEARING SKIES
UNDER THE RIDGE. ALTHOUGH THE RIDGE WILL BE THE DOMINANT FEATURE,
AS IT SLOWLY PROGRESSES EASTWARDS THE MOUNTAINS IN THE WESTERN
THIRD OF THE CWA GET IN A SW FLOW REGIME WHICH WOULD ALLOW FOR
SOME SCATTERED RAIN AND SNOW SHOWERS, EPICALLY ALONG SW FACING
ASPECTS, THROUGHOUT THE WEEKEND.
AS THE WEEKEND COMES TO A CLOSE THE RIDGE GETS SHOVED EASTWARD BY
AN ADVANCING AND DIGGING TROUGH MOVING IN OFF OF THE PACIFIC.
PRECIPITATION COULD START AS EARLY AS SUNDAY AFTERNOON WITH THIS
SYSTEM, HOWEVER, IT IS FAR TOO EARLY TO TALK ANY DETAILS REGARDING
THIS EVENT. WMR
AVIATION
09Z DISCUSSION...
OVER THE COMING HOURS RA WILL CONTINUE TO FILL INTO THE WESTERN
FOOTHILLS INCLUDING KLVM, K6SO, ECT BEFORE PROGRESSING EASTWARDS
THROUGH THE ENTIRETY OF THE FORECAST AREA. ADDITIONALLY, CIGS WILL
BEGIN TO RAPIDLY DROP TO IFR ACROSS SOUTH CENTRAL MONTANA AND
NORTHERN WYOMING (INCLUDING KBIL), WHILE AREAS FURTHER EAST, SUCH
AS KMLS, SHOULD ONLY SEE MVFR CONDITIONS IN THIS TAF PERIOD. AFTER
00Z, SNOW/FREEZING LEVELS WILL DROP AND THUS RASN WAS INCLUDED IN
THE TAF FOR KLVM AND KSHR, HOWEVER, ALL SITES WHERE THE TERMINAL
SITS AT 4,000FT MSL OR HIGHER COULD SEE SOME SNOW MIX IN.
WINDS WILL ALSO BE GUSTY WITH A PRIMARILY NORTHERLY COMPONENT FOR
MOST OF THE PERIOD. SUSTAINED WINDS BETWEEN 15-20KTS WITH GUSTS
UP TO 30KTS LOOKS TO LINGER THROUGH AT LEAST 00Z AREA-WIDE. WHILE
KSHR DID SEE A GUST TO 49KTS WITH THE FRONTAL PASSAGE, WINDS
SHOULD NOT GUST THIS HIGH AGAIN. MOUNTAINS WILL BE OBSCURED
THROUGHOUT THE PERIOD. WMR
PRELIMINARY POINT TEMP/POPS
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 049 038/049 038/075 050/081 051/076 052/083 054/088
9/R 96/R 10/U 02/T 42/W 21/U 12/T
LVM 043 032/048 033/073 045/078 045/075 047/080 050/084
+/R 93/O 11/U 02/T 32/T 21/U 13/T
HDN 052 037/050 036/076 044/082 049/077 050/084 052/089
8/R 97/R 10/U 02/T 52/W 21/U 12/T
MLS 061 040/054 041/076 051/081 052/077 051/084 054/088
4/R 85/R 10/U 01/U 43/W 11/U 11/U
4BQ 063 039/050 041/072 050/079 051/075 049/081 054/086
3/R 96/R 21/B 00/U 33/W 30/U 11/U
BHK 066 038/055 039/073 047/079 048/075 046/078 050/086
3/R 73/R 10/B 00/U 23/W 00/U 11/U
SHR 051 033/045 034/071 041/078 046/073 046/080 049/086
8/R +8/R 31/B 02/T 33/T 31/U 12/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
NOON MDT TUESDAY FOR ZONES 56-66.
WINTER STORM WARNING IN EFFECT UNTIL NOON MDT TUESDAY FOR
ZONE 67.
WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
NOON MDT TUESDAY FOR ZONE 171.
WY...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
NOON MDT TUESDAY FOR ZONE 198.
WEATHER.GOV/BILLINGS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page