584
FXUS65 KBYZ 270854
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
254 AM MDT WED AUG 27 2025
KEY MESSAGES
- SEASONABLE TEMPERATURES THIS WEEK.
- THE CHANCE OF SHOWERS AND THUNDERSTORMS RETURNS TO THE MOUNTAINS
TODAY (MODERATE CHANCE) AND THE ENTIRE AREA THURSDAY INTO
SATURDAY (MODERATE TO HIGH CHANCE).
- SHOWERS AND THUNDERSTORMS THROUGH SATURDAY COULD PRODUCE LOCALLY
HEAVY RAINFALL. USE CAUTION IF RECREATING, ESPECIALLY NEAR
RECENT BURN SCARS.
DISCUSSION
TODAY THROUGH THURSDAY NIGHT...
CURRENT ANALYSIS SHOWS SOUTHWEST FLOW ALOFT WITH EASTERLY LOW
LEVEL WINDS BRINGING LIGHT SHOWERS TO THE MOUNTAINS IN
SOUTH CENTRAL MT. ENERGY ASSOCIATED WITH THIS SYSTEM IS EXPECTED
TO MOVE NORTHEAST THEN EAST AS WELL AS EXTEND EASTWARD. WITH
THIS, CAMS ARE SHOWING THE BEST INSTABILITY (MUCAPE UP TO 750
J/KG) THROUGH SOUTHERN PORTIONS OF BIG HORN, ROSEBUD, POWDER RIVER
AS WELL AS SHERIDAN CO WY COUNTIES THIS AFTERNOON. AS A RESULT,
THIS WILL BE THE PLACE TO WATCH FOR THUNDERSTORMS TO DEVELOP. WITH
CONTINUED CONFIDENCE IN ABOVE AVERAGE ATMOSPHERIC MOISTURE AND
SLOW MOVING STORMS, THESE THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAIN. AS THE WAVE SHIFTS EASTWARD INTO THURSDAY,
INSTABILITY WILL BE MORE WIDESPREAD, BUT OF SIMILAR VALUE AS
TODAY. THE SAME STORY WILL CONTINUE WITH THUNDERSTORMS CAPABLE OF
PRODUCING HEAVY RAIN. THERE IS UNCERTAINTY IN RAINFALL AMOUNTS AND
WHERE THE HEAVIEST RAIN WILL FALL CONSIDERING HEAVY RAIN WILL
LIKELY BE THUNDERSTORM DRIVEN. MAKE SURE TO PLAN AHEAD IF YOU ARE
RECREATING, ESPECIALLY NEAR ANY RECENT BURN SCARS (PORTIONS OF THE
NORTHERN BIGHORNS AND SOUTHERN ROSEBUD CO.). SMOKE FROM FIRES
WEST OF THE REGION SHOULD REMAIN OUT OF THE AREA AS CYCLONIC FLOW
PERSISTS. WITH EAST WINDS IN PLACE, SMOKE FROM LOCAL FIRE(S) EAST
OF BILLINGS COULD CREATE HAZY CONDITIONS, BUT THIS IS DEPENDENT ON
FIRE ACTIVITY.
HIGH TEMPERATURES TODAY AND THURSDAY WILL BE IN THE 70S WEST TO
MID 80S IN EASTERN MT WITH THURSDAY BEING SLIGHTLY COOLER. TS
FRIDAY THROUGH TUESDAY...
THERE IS MODERATE TO HIGH CONFIDENCE THAT ANOMALOUSLY HIGH
PRECIPITABLE WATERS AND SLOW-MOVING SHOWER/THUNDERSTORM ACTIVITY,
FRIDAY INTO SATURDAY. ENSEMBLES CONTINUE TO DEPICT PWAT VALUES 150
TO 200 PERCENT OF NORMAL, OR 1.00 TO 1.30", THANKS TO MONSOONAL
MOISTURE MOVING INTO THE REGION. MOVING THROUGH THE ONGOING RIDGE
WILL BE A SHORTWAVE FROM THE SOUTHWEST. THIS WAVE WILL HELP
PROVIDE ASCENT FOR SHOWERS AND THUNDERSTORMS. THUNDERSTORMS ARE
NOT EXPECTED TO BE SEVERE AT THIS TIME WITH VERY MINIMAL SHEAR.
MAIN CONCERNS WITH PRECIPITATION WILL BE LOCALLY HEAVY RAINFALL
AND GUSTY OUTFLOW WINDS.
WPC HAS HIGHLIGHTED OUR AREA FOR A MARGINAL RISK OF EXCESSIVE
RAINFALL FRIDAY, GIVEN THE ABOVE NORMAL MOISTURE AND WEAK
INSTABILITY MENTIONED ABOVE. THE GREATEST PROBABILITIES FOR AT
LEAST A HALF INCH OF RAIN ARE OVER THE MOUNTAINS & FOOTHILLS AND
20-50% OVER THE PLAINS, LOWEST NORTHEAST OF BILLINGS. ACTUAL
PRECIP AMOUNTS WILL VARY GREATLY DUE TO THE CONVECTIVE NATURE.
POCKETS OF HEAVY RAIN UNDER STRONGER STORMS COUPLED WITH SLOW
STORM MOTION MAY RESULT IN SUBSTANTIAL PRECIP ACCUMULATIONS FOR
SOME AREAS WHILE NO SHOWERS OR STORMS DEVELOP OVER OTHERS.
SATURDAY SEEMS TO BE THE TRANSITION DAY TO A DRIER AIR MASS, BUT
AS ALREADY MENTIONED QUITE A BIT OF UNCERTAINTY EXISTS ON THE BACK
SIDE OF THE MAIN TROF. IN ADDITION TO THE ENHANCED PRECIP CHANCES
WILL COME COOLER TEMPS, WITH HIGHS IN THE 70S FRIDAY AND
SATURDAY.
SUNDAY & MONDAY LOOK TO TREND WARMER & DRIER WITH ENSEMBLE
CONSENSUS SHOWING SHORTWAVE RIDGING ON THESE DAYS. WITH ABOVE
NORMAL HEIGHTS PERSISTING THIS SHOULD PUSH TEMPS BACK TO THE 80S,
WHICH WOULD BE A LITTLE WARMER THAN NORMAL AS WE MOVE INTO EARLY
SEPTEMBER. THEN, BY THE MIDDLE OF THE WEEK, THERE ARE SIGNS OF THE
UPPER LEVEL PATTERN BECOMING MORE UNSETTLED.
JKL/PM
AVIATION
OVERALL VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL THROUGH
WEDNESDAY MORNING WITH ISOLATED LIGHT SHOWERS OVER SOUTHWEST
MOUNTAINS AND FOOTHILLS AT TIMES. BY WEDNESDAY AFTERNOON A
STRONGER EASTERLY WIND WILL DEVELOP (10 TO 20KTS). SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP FOR AREAS KBIL
AND KSHR WEST WITH LOCAL MVFR CONDITIONS NEAR AREAS OF HEAVY
RAINFALL. CONVECTION WILL BE VERTICAL AND SLOW MOVING, PULSEY IN
NATURE, MEANING PRECIPITATION COULD LINGER OVER AN AIRPORT FOR AN
EXTENDED PERIOD OF TIME. EXPECT CONVECTION TO LINGER LATE INTO
WEDNESDAY NIGHT. CHAMBERS/TS
PRELIMINARY POINT TEMP/POPS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 084 063/079 060/079 056/082 056/087 058/089 058/081
2/W 24/T 45/T 32/T 00/U 11/U 12/W
LVM 077 052/074 050/076 048/080 049/086 050/086 050/080
4/T 68/T 65/T 31/U 01/U 12/T 23/T
HDN 086 060/080 058/079 054/080 052/087 054/089 055/082
2/W 23/T 45/T 42/W 00/U 01/U 11/B
MLS 087 060/083 060/076 057/077 055/084 056/088 057/082
0/B 01/E 33/T 42/W 10/U 00/U 21/B
4BQ 085 061/077 059/075 058/075 056/082 056/086 058/081
2/W 22/W 55/T 43/T 10/U 00/U 11/B
BHK 085 053/084 056/077 053/076 051/080 052/084 053/080
0/U 00/B 23/W 43/T 20/U 00/U 11/B
SHR 082 055/076 052/075 050/076 049/082 052/086 052/079
4/T 46/T 66/T 54/T 10/U 01/U 12/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page