671
FXUS65 KBYZ 310719
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
119 AM MDT SAT MAY 31 2025
KEY MESSAGES
- WARM THROUGH THE WEEKEND WITH HIGHS IN THE 80S TODAY,
APPROACHING 90 DEGREES SE MONTANA ON SUNDAY.
- COLD FRONT DROPPING INTO THE REGION SUNDAY BRINGS A MARGINAL
CHANCE FOR STRONG TO SEVERE THUNDERSTORMS FROM BILLINGS WEST
INTO SUNDAY EVENING.
- UNSETTLED AND MUCH COOLER MONDAY THROUGH WEDNESDAY.
- SNOW IS FORECAST IN THE HIGHER ELEVATIONS OF THE
BEARTOOTH/ABSAROKA MOUNTAINS, WHICH MAY IMPACT TRAVEL OVER THE
BEARTOOTH HIGHWAY BEGINNING MONDAY NIGHT.
- RIVERS AND STREAMS ARE RUNNING HIGH AND FAST WITH SNOWMELT. NO
FLOODING IS FORECAST AT THIS TIME, BUT ADDITIONAL RISES ARE
EXPECTED THROUGH EARLY NEXT WEEK. PLEASE USE EXTRA CAUTION NEAR
WATERWAYS AND KEEP CHILDREN A SAFE DISTANCE AWAY FROM THE WATERS
EDGE.
DISCUSSION
THROUGH SUNDAY NIGHT...
RAPID TRANSITION FROM UPPER TROF TO UPPER RIDGE IS UNDERWAY ACROSS
THE FORECAST AREA THIS MORNING. CLEAR SKIES AND WARMER
TEMPERATURES ARE ON TAP FOR TODAY. EXPECT HIGH TEMPERATURES TO
REACH THE MID 80S ACROSS MOST OF THE FORECAST AREA WITH A
GENERALLY LIGHT SOUTHERLY WIND.
EXPECT A DRY AND WARM OVERNIGHT TONIGHT WITH THE BREEZY SOUTHERLY
WINDS KEEPING TEMPERATURES IN THE 55 TO 65 DEGREE RANGE ACROSS
MUCH OF THE FORECAST AREA.
SUNDAY WILL BE A CHANGE DAY, STARTING OFF WARM AND DRY WITH A
SOUTH TO SOUTHWESTERLY BREEZE. BY MID DAY WINDS TURN NORTHERLY AS
A COLD FRONT MOVES INTO THE WESTERN AND CENTRAL ZONES.
TEMPERATURES WILL START TO FALL, ESPECIALLY AS SHOWER AND
THUNDERSTORM ACTIVITY INCREASES THROUGH THE AFTERNOON. A FEW
STRONG THUNDERSTORMS ARE POSSIBLE OVER AND NEAR THE SOUTHWEST
MOUNTAINS WITH A MARGINAL SEVERE RISK POSTED BY SPC. EVEN THOUGH
THE MARGINAL RISK IS CONFINED TO THE SOUTHWEST CORNER OF THE
FORECAST AREA, THIS TIME OF YEAR JUST ABOUT ANY THUNDERSTORM HAS
THE POTENTIAL TO PRODUCE SMALL HAIL AND WIND GUSTS IN THE 50 MPH
RANGE. IF YOU HAVE OUTDOOR PLANS SUNDAY STAY WEATHER AWARE.
THE LATEST MODEL RUNS HAVE MOVED UP THE TIMING OF THE COLD FRONT
BY 6 HOURS OR SO. THIS WILL LIKELY HAVE AN IMPACT ON HIGH
TEMPERATURES SUNDAY, CONFINING THE HIGHER POTENTIAL FOR
TEMPERATURES OVER 85 DEGREES TO THE EASTERN HALF OF THE FORECAST
AREA. IF THIS TIMING HOLDS, WILL LIKELY SEE THE NBM TEMPERATURE
FORECASTS DROP FURTHER OVER WESTERN AND CENTRAL ZONES WITH
SUBSEQUENT FORECASTS. CURRENT PROBABILITIES FOR 90+ DEGREE HIGHS
ON SUNDAY ARE IN THE 40 TO 70 PERCENT RANGE ALONG AND EAST OF A
MILES CITY TO SHERIDAN WYOMING LINE, WHILE BILLINGS SHOWS AN 18
PERCENT CHANCE.
40 TO 80 PERCENT PRECIPITATION CHANCES SPREAD ACROSS THE FORECAST
AREA SUNDAY NIGHT. BEST CHANCES RESIDE ALONG THE MUSSELSHELL RIVER
VALLEY SOUTH INTO THE BEARTOOTH FRONT. SNOW LEVELS DROP FROM
AROUND 13KFT TO UNDER 10KFT SUNDAY NIGHT INTO EARLY MONDAY
MORNING. THIS SHOULD KEEP THE SNOW GENERALLY ABOVE THE BEARTOOTH
HIGHWAY UNTIL MONDAY AFTERNOON.
HYDROLOGY...SNOWMELT CONTINUES TO BE STRONG IN THE MOUNTAINS,
WITH RIVER LEVELS CONTINUING TO RISE ACROSS THE AREA. PEAK SPRING
FLOWS USUALLY ARRIVE BETWEEN NOW AND THE SECOND WEEK OF JUNE ON
OUR STREAMS. AT THIS TIME THERE IS NO INDICATION OF A FLOOD THREAT
OVER THE NEXT 5 DAYS, THOUGH WATER LEVELS ARE EXPECTED TO
CONTINUE TO RISE INTO EARLY NEXT WEEK. HOWEVER, EXTRA CAUTION
SHOULD BE EXERCISED NEAR WATERWAYS AT THIS TIME. BANK EROSION IS A
BIG CONCERN WITH RIVERS AND STREAMS AT THESE LEVELS. UNDERCUT
BANKS CAN FALL INTO THE WATER TAKING ANYONE STANDING THERE INTO
THE COLD, HIGH, AND FAST MOVING WATER WITH IT. MURKY FAST MOVING
WATER CONTAINS LARGE PIECES OF DEBRIS AND CAN HIDE OBSTRUCTIONS,
BOTH CAN BE DANGEROUS FOR BOATERS. CONSIDER STAYING OFF THE WATER
DURING THIS PERIOD OF HIGH FLOWS. KEEP A SAFE DISTANCE FROM THE
WATERS EDGE, THIS APPLIES ESPECIALLY FOR CHILDREN. CHAMBERS
MONDAY THROUGH FRIDAY...
GREAT UNCERTAINTY REMAINS REGARDING THE EARLY WEEK SYSTEM. THE
NBM 25TH-75TH TOTAL PRECIP SPREAD REMAINS IN EXCESS OF 0.5" FOR
BILLINGS AS OF THE LATEST RUN. THERE IS GOOD CONFIDENCE THAT THE
ENTIRE REGION WILL SEE RAIN AND SCATTERED THUNDERSTORMS MONDAY
INTO TUESDAY THOUGH. THE ENTIRE CWA HAS AT LEAST A 60% CHANCE OF
SEEING 0.1" AND A 30% CHANCE OF SEEING 0.25" THROUGH THE FIRST
PART OF THE WEEK WITH THE HIGHEST CHANCES IN THE MOUNTAIN
FOOTHILLS. SPEAKING OF MOUNTAINS; ALTHOUGH SNOW LEVELS WIL BE
NEAR OUR PEAKS TO START THIS EVENT, THEY WILL GRADUALLY FALL
DURING THE DAY MONDAY WITH A FROPA FROM THE NW. BY TUESDAY AM,
SNOW LEVELS ACROSS THE REGION WILL BE BETWEEN 7KFT AND 8KFT. WHILE
PRECIP WILL BE TAPERING OFF AT THIS TIME, A FEW INCHES OF SNOW
ACCUMULATION APPEAR POSSIBLE ABOVE 8KFT.
MOST LONG RANGE MODELS NOW SHOW AN ADDITIONAL SHORTWAVE MOVE
THROUGH THE AREA DURING THE DAY WEDNESDAY WHICH COULD HELP
PRODUCE SOME ADDITIONAL PRECIP ON THE TAIL END OF THE MAIN EVENT.
WITH THIS VORT MAX MOVING THROUGH AFTER THE MAIN TROUGH,
TEMPERATURES SHOULD BE COOL ENOUGH TO SUPPORT MOUNTAIN SNOW,
ALTHOUGH EXACT LEVELS ARE STILL UNCERTAIN.
THERE ARE SOME MODEL SOLUTIONS, ESPECIALLY THE 18Z GFS, THAT THEN
WANT TO HAVE A PARADE OF SHORTWAVES PUSH THROUGH MONTANA ONE AFTER
ANOTHER FOR THE REMAINDER OF THE WEEK. WHILE THIS IS POSSIBLE, THE NBM
ENSEMBLE MEAN KEEPS POPS UNDER 40% FOR THE REST OF THE WEEK. WHAT
DOES HAVE HIGHER CONFIDENCE THOUGH, IS A GRADUAL WARM UP WITH
HIGHS BACK INTO THE 70S APPEARING LIKELY ON FRIDAY. WMR
AVIATION
06Z DISCUSSION...
WINDS WILL REMAIN LIGHT OVERNIGHT (<10KTS). SKIES WILL ALSO STAY
MOSTLY CLEAR THROUGH THE ENTIRE PERIOD. WINDS BECOME PREDOMINANTLY
SOUTHEASTERLY AFTER 20Z ACROSS THE REGION. WMR
PRELIMINARY POINT TEMP/POPS
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 086 060/085 051/062 047/064 047/068 047/077 053/078
0/U 03/T 77/T 33/W 33/W 01/B 23/T
LVM 086 056/082 048/064 042/060 040/068 043/072 048/074
0/U 07/T 95/T 35/T 33/T 12/T 23/T
HDN 086 056/086 052/062 045/065 046/067 045/077 051/079
0/U 01/U 67/W 33/W 44/T 11/U 23/T
MLS 085 056/090 054/064 046/069 047/068 047/077 053/079
0/U 00/U 67/W 21/B 23/W 11/U 22/T
4BQ 082 054/090 054/062 046/064 047/061 045/073 051/077
0/U 00/U 44/W 21/E 34/W 11/U 11/B
BHK 080 052/090 052/063 041/067 042/065 043/072 048/075
0/K 00/U 45/W 11/B 12/W 11/B 12/T
SHR 081 053/087 050/061 042/059 041/060 040/072 046/075
0/U 01/U 47/T 56/W 66/T 11/U 13/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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