706
FXUS65 KBYZ 300109
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
709 PM MDT THU MAY 29 2025
KEY MESSAGES
- MAINLY DRY AND WARM THROUGH THE WEEKEND; TEMPS PUSHING 80
DEGREES THROUGH SATURDAY; 90F IS POSSIBLE BY SUNDAY. MOUNTAIN
SNOWMELT WILL LEAD TO RISES ON AREA WATERWAYS.
- STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ON SUNDAY.
UNCERTAINTY REMAINS HIGH WITH TIMING AND LOCATION. MAIN THREATS
WOULD BE STRONG WINDS AND LARGE HAIL.
- UNCERTAINTY IS HIGH ON THE CHANCE FOR PRECIPITATION, TOTAL
PRECIPITATION AMOUNTS, AND OVERALL PATTERN PROGRESSION BEGINNING
SUNDAY.
UPDATE
SATELLITE IMAGERY SHOWS A WEAK SHORTWAVE MOVING INTO CENTRAL MT,
AND WHILE SKIES ACROSS OUR FORECAST ARE CLEAR (ALBEIT HAZY DUE TO
CANADIAN WILDFIRE SMOKE) THERE ARE A COUPLE OF T-STORMS
APPROACHING FROM THE WEST AS OF 7PM. ONE NEAR BOZEMAN PRODUCED A
38 MPH GUST AT ITS AIRPORT, THE OTHER IS CLOSER TO WHITE SULPHUR
SPRINGS. MESOANALYSIS SHOWS ENOUGH INSTABILITY FOR WEAK CONVECTION
TO GET INTO OUR FAR WEST OVER THE NEXT 1-2 HOURS. MAIN REGION OF
WEAK SYNOPTIC ASCENT ARRIVES OVERNIGHT AND TRACKS THRU THE AREA
FRIDAY. NEWER HIGH RES MODELS ARE A BIT MORE SUGGESTIVE OF
ISOLATED LIGHT SHOWERS OR SPRINKLES MAKING IT EAST OF THE
FOOTHILLS, POSSIBLE TO BILLINGS AND HARDIN LATE TONIGHT AND EARLY
TOMORROW. THIS COULD ALSO END UP BEING VIRGA AS LOW LEVELS ARE
DRY. HAVE MADE SOME MINOR POP/WX ADJUSTMENTS TO EXPAND AREA OF
ISOLATED SHOWERS OR SPRINKLES TONIGHT AND FRIDAY MORNING. POST-
FRONTAL W-NW WINDS WILL BE SOMEWHAT BREEZY TOMORROW, AND THERE
SHOULD BE LESS HAZE THAN THERE WAS TODAY DUE TO SHIFTING WINDS
ALOFT. FORECAST IS IN GOOD SHAPE. JKL
DISCUSSION
TODAY THROUGH FRIDAY NIGHT...
SEASONABLE AND DRY CONDITIONS WERE OBSERVED OVER MUCH OF THE AREA
TODAY, WITH A COUPLE ISOLATED SHOWERS BEGINNING TO FORM OVER THE
FAR SOUTHWEST MOUNTAINS THIS AFTERNOON. CANADIAN WILDFIRE SMOKE
WAS BRINGING HAZY SKIES TO CENTRAL AND EASTERN AREAS.
A WEAK SHORTWAVE AND ASSOCIATED FRONT WILL BRING ISOLATED SHOWERS
AND THUNDERSTORMS TO MAINLY WESTERN AREAS THIS AFTERNOON AND
EVENING, WITH WINDS SHIFTING AROUND TO THE WEST AND NORTHWEST
OVERNIGHT. VIRGA OR A FEW SPRINKLES ARE POSSIBLE LATE TONIGHT INTO
FRIDAY AS THE WAVE SHIFTS EAST THROUGH THE AREA. NORTHWEST WINDS
GUSTING 20 TO 30 MPH ARE POSSIBLE OVER PORTIONS OF THE AREA ON
FRIDAY. A FEW ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE OVER
THE BIGHORNS FRIDAY AFTERNOON/EVENING. HIGHS IN THE 70S TO LOWER
80S CAN BE EXPECTED ON FRIDAY. STP
SATURDAY THROUGH WEDNESDAY...
UPPER LEVEL RIDGING WILL CONTINUE SATURDAY AND MUCH OF SUNDAY. THE
WARMEST TEMPERATURES OF THE SEASON ARE CURRENTLY FORECAST, WITH
HIGHS IN THE 80S TO LOW 90S.
AS FOR PRECIPITATION, THERE CONTINUES TO BE VERY HIGH UNCERTAINTY
ON THE EXTENT AND TIMING. ENSEMBLES AND CLUSTERS HAVE GENERALLY
GOOD AGREEMENT ON THE OVERALL PATTERN CHANGE LATE SUNDAY INTO
MONDAY. A COLD FRONT IS DEPICTED SWINGING THROUGH THE FORECAST
AREA. SEVERAL MODELS DEPICT WIDESPREAD PRECIPITATION BEGINNING
SUNDAY WITH POTENTIALLY STRONG THUNDERSTORMS SUNDAY EVENING. OTHER
MODELS ARE SHOWING THE COLD FRONT COMING THROUGH SOUTHEASTERN
MONTANA WITH SOME SHOWERS AND THUNDERSTORMS AND NOT MUCH MORE INTO
THE NEW WEEK. THE CURRENT FORECAST HAS A MODERATE TO HIGH CHANCE
FOR PRECIPITATION ACROSS THE AREA, SUNDAY NIGHT THROUGH TUESDAY.
THE OVERALL PATTERN FROM THE DETERMINISTICS HAS DRAMATICALLY
CHANGED OVER THE PAST FEW DAYS. THE GFS AND ECMWF SHOWED AN UPPER
LOW OFF THE COAST OF CALIFORNIA MOVING INTO THE SOUTHWESTERN US
AND THEN PHASING WITH TROUGH AND UPPER LOW ENERGY OVER THE
ROCKIES. NOT ONLY DO THE LATEST RUNS NO LONGER SHOW THIS, BUT
DETERMINISTIC AND ENSEMBLE RUNS DEPICT MUCH LESS LIQUID
PRECIPITATION TOTALS. THE CURRENT FORECAST HAS STORM TOTAL QPF
AMOUNTS OF .25" TO AN INCH ACROSS THE LOWER ELEVATIONS AND
FOOTHILLS, SUNDAY AFTERNOON THROUGH WEDNESDAY. IN THE MOUNTAINS,
UP TO 1.5" IS SHOWN.
THE POTENTIAL FOR STRONG TO MAYBE SEVERE THUNDERSTORMS ON SUNDAY
REMAINS UNCERTAIN. THE EC AND GFS DISAGREE ON COLD FRONT TIMING
AND SUBSEQUENTLY THE TIMING AND PLACEMENT OF STORMS. THE ECMWF
DEPICTS INCREASED MUCAPE IN THE FAR EAST WITH POTENTIAL
THUNDERSTORM DEVELOPMENT AHEAD OF THE COLD FRONT. MEANWHILE, THE
GFS IS SHOWING LITTLE TO NO PRE-FRONTAL CONVECTION AND INSTEAD
TYING IT WITH THE COLD FRONT AS IT MOVES WEST TO EAST. THE MAIN
THREAT WOULD LIKELY BE STRONG WINDS AND LARGE HAIL, WITH STEEP
LAPSE RATES (>7.0C/KM). ONE THING TO NOTE IS THE VARYING STRENGTH
OF 0-6KM SHEAR FROM WEST TO EAST. INITIAL STORM DEVELOPMENT IN
WESTERN AREAS WOULD BE WORKING WITH UPWARDS OF 50 KNOTS OF SHEAR,
WHILE ONLY 20-30 KNOTS IS SHOWN IN CENTRAL AND EASTERN AREAS.
CURRENTLY, COOLER TEMPERATURES ARE FORECAST MONDAY AND TUESDAY
WITH HIGHS IN THE 50S AND 60S. OVERNIGHT LOWS ARE FORECAST TO BE
IN THE 40S ACROSS LOWER ELEVATIONS WHILE AROUND OR BELOW FREEZING
IN THE HIGHER MOUNTAIN ELEVATIONS. ACCUMULATING SNOW IS FORECAST
ABOVE 8,000FT FOR ALL MOUNTAINS. THE LATEST FORECAST HAS SEVERAL
INCHES OF ACCUMULATION ALONG THE BEARTOOTH HIGHWAY. THOSE WITH
TRAVEL PLANS ALONG AND THROUGH US 212 SHOULD CONTINUE TO MONITOR
THE FORECAST AS WE HEAD INTO NEXT WEEK.
OVERNIGHT LOWS SATURDAY THROUGH SUNDAY WILL BE ABOVE FREEZING IN
THE MOUNTAINS, RESULTING IN RIVER AND STREAM RISES INTO NEXT WEEK.
WITH EVERYTHING SAID, UNCERTAINTY REMAINS HIGH WITH THE CHANCE FOR
PRECIPITATION, PRECIPITATION AMOUNTS, AND OVERALL PATTERN
PROGRESSION. THERE IS HIGH CERTAINTY OF ABOVE NORMAL TEMPERATURES
SATURDAY AND SUNDAY.
MATOS
AVIATION
IN GENERAL, VFR WILL PREVAIL THROUGH THE PERIOD. ISOLATED SHOWERS
AND THUNDERSTORMS ARE POSSIBLE THIS EVENING OVER WESTERN AREAS,
INCLUDING KLVM. LOCALIZED MVFR CONDITIONS AND ERRATIC WIND GUSTS
TO 40 MPH ARE POSSIBLE WITH THIS ACTIVITY. CANADIAN WILDFIRE
SMOKE OVER CENTRAL AND EASTERN AREAS MAY REDUCE SLANT RANGE
VISIBILITY AT TIMES INTO FRIDAY. W-NW WINDS WILL GUST 15-25 KNOTS
TOMORROW BEHIND A WEAK COLD FRONTAL PASSAGE. STP/JKL
PRELIMINARY POINT TEMP/POPS
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 057/080 052/087 059/088 055/063 046/062 046/069 048/076
11/U 00/U 03/T 68/T 77/T 44/T 22/T
LVM 053/078 049/086 057/085 049/062 041/059 040/066 044/073
20/U 00/U 07/T 88/T 78/T 55/T 22/T
HDN 052/079 048/086 056/088 054/064 046/063 045/069 047/076
11/U 00/U 02/T 67/T 76/W 44/T 22/T
MLS 049/081 050/085 058/091 056/067 048/066 046/070 048/076
01/U 00/U 01/U 66/T 64/W 33/W 21/B
4BQ 048/079 052/082 057/090 057/067 047/061 045/065 047/073
00/U 00/U 00/U 45/T 74/W 33/T 22/W
BHK 044/081 049/081 052/088 053/066 044/064 042/068 044/072
00/U 00/U 00/U 45/T 63/W 22/W 22/W
SHR 049/076 048/081 054/088 052/065 041/058 040/064 042/071
01/U 10/U 02/T 48/T 87/T 45/T 22/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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