240
FXUS65 KBYZ 292054
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
254 PM MDT THU MAY 29 2025
KEY MESSAGES
- SOME HAZY CONDITIONS ARE POSSIBLE OVER CENTRAL AND EASTERN
SECTIONS TODAY DUE TO CANADIAN WILDFIRE SMOKE.
- 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.
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 AFTERNOON AND EVENING OVER
SOUTHWESTERN AREAS, INCLUDING KLVM. LOCALIZED MVFR CONDITIONS ARE
POSSIBLE WITH THE SHOWERS/THUNDERSTORMS. CANADIAN WILDFIRE SMOKE
MOVING IN ALOFT OVER CENTRAL AND EASTERN AREAS MAY REDUCE SLANT
RANGE VISIBILITY AT TIMES INTO FRIDAY. STP
PRELIMINARY POINT TEMP/POPS
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 056/080 052/087 059/089 054/062 047/062 046/065 047/074
11/U 00/U 03/W 68/W 77/T 44/T 32/T
LVM 050/079 049/086 057/085 050/062 043/059 041/063 044/072
21/U 00/U 06/W 88/W 78/T 55/T 33/T
HDN 050/081 048/086 056/089 055/065 047/063 046/067 047/075
11/H 00/U 02/W 67/W 86/W 44/T 32/T
MLS 049/083 050/085 058/093 057/068 049/064 047/067 047/074
01/U 00/U 01/U 66/W 64/W 33/W 21/B
4BQ 048/080 052/082 057/090 057/070 048/060 046/063 047/070
00/H 00/U 00/U 44/W 74/W 33/T 32/W
BHK 044/081 049/081 052/088 053/068 045/061 042/064 044/070
00/H 00/U 00/U 44/W 63/W 22/W 22/W
SHR 050/075 048/081 054/088 052/065 042/059 041/064 042/070
01/H 10/U 02/W 47/T 87/T 45/T 33/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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