649
FXUS65 KBYZ 231036
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
436 AM MDT WED SEP 23 2026
KEY MESSAGES
- SCATTERED SHOWERS AND STORMS EARLY THIS MORNING; ISOLATED
T-STORMS IN EASTERN MONTANA THIS AFTERNOON.
- WARM AND DRY END OF THE WORK WEEK; 80S RETURN.
- SLIGHT CHANCE (<30%) FOR SHOWERS AND THUNDERSTORMS FRIDAY INTO SATURDAY.
- UNSETTLED AND COOLER SUNDAY INTO EARLY NEXT WEEK.
UPDATE
AS EXPECTED, SHOWERS AND T-STORMS INTENSIFIED EARLY THIS MORNING
AS THE WAVE LIFTING OUT OF THE SOUTHWEST REACHED OUR FORECAST
AREA. LIGHTNING ACTIVITY JUMPED QUITE A BIT BETWEEN 07-08Z AS
850-700MB FRONTOGENESIS INCREASED, A RESULT OF BACKED/EASTERLY MID
LEVEL WINDS AND SUFFICIENT ELEVATED INSTABILITY. LOCALLY HEAVY
RAIN HAS OCCURRED AND IS STILL OCCURRING IN PLACES, WITH RADAR
ESTIMATE OF NEAR 0.75" OVER LOCKWOOD AND THE HEIGHTS. ANOTHER
SLOW-MOVING STORM MAY HAVE PRODUCED AN INCH OF RAIN IN SOUTHERN
TREASURE COUNTY. DEFINITELY A REFECTION OF THE ANOMALOUSLY HIGH
PWATS IN PLACE. NOW AT 10Z, MESOANALYSIS SHOWS THE WAVE AND
ASSOCIATED SHOWER ACTIVITY LIFTING INTO OUR NORTHERN CWA AS 700MB
COLD ADVECTION W/ SW-W FLOW SPREADS ACROSS NORTHERN WY AND ALONG
OUR SOUTHERN BORDER. BASED ON HOW THINGS ARE PROGRESSING, IT SEEMS
THE RISK OF SHOWERS WILL END A BIT SOONER THAN PREVIOUSLY THOUGHT,
AT LEAST OVER WEST/SOUTHWEST (INCLUDING BILLINGS). SOME SHOWERS
SHOULD PERSIST ACROSS OUR NORTH (MUSSELSHELL TO FALLON) BEYOND
SUNRISE, ON BACK SIDE OF THE DEPARTING SHORTWAVE. HAVE MADE SOME
POP/WX ADJUSTMENTS TO ACCOUNT FOR THE SOONER END TIME. THERE MAY
BE A FEW SHOWERS OR WEAK T-STORMS THIS AFTERNOON BUT LARGE SCALE
DESCENT ARRIVES BY THEN, SO THIS IS UNCERTAIN. LOOK FOR HIGHS IN
THE 70S TODAY.
BILLINGS AIRPORT PICKED UP 0.14" OF RAIN WITH THE RECENT
THUNDERSTORM, BRINGING THE SEPTEMBER TOTAL TO 4.63". THE SEPTEMBER
RECORD IS 4.99" IN 1941.
JKL
DISCUSSION
NEXT 7 DAYS...
RIGHT NOW A SHORTWAVE IS MOVING FROM SW TO NE OUT OF THE BIGHORN
BASIN INTO MT. AS THE MORNING GOES ON, MOISTURE WILL CONTINUE TO
BE ADVECTED INTO OUR CWA BY ESE WINDS OUT OF THE GREAT PLAINS
WHERE DEW POINTS ARE IN THE 50S TO 60S. THIS INCREASED MOISTURE
WILL ALLOW FOR SOME EMBEDDED CELLS TO PRODUCE LOCALLY HEAVY
RAINFALL THROUGH NOON, ESPECIALLY EAST OF BILLINGS. WHILE THERE
IS NOT MUCH CAPE AROUND THE AREA AT THE MOMENT, THERE IS BETWEEN
250-1000 J/KG LOCALLY ACROSS THE ENTIRE CWA. ALSO WITH THE
PREVIOUSLY MENTIONED ESE WINDS, THIS WILL ALSO BE ADVECTING IN
HIGHER THETA-E VALUES. ALL THAT TO SAY THAT LIGHTNING REMAINS A
POSSIBILITY WITH ANY AND ALL PRECIP THROUGH THE DAY TODAY, EVEN
BEFORE SUNRISE. THE ATMOSPHERE NEAR AND WEST/SOUTHWEST OF
BILLINGS IS A LITTLE DRIER AT THE SURFACE WHICH WOULD ALLOW FOR
SOME BREEZY WINDS UNDER THESE SHOWERS. THERE HAS ALREADY BEEN
GUSTS IN THE 30S AT SOME SITES AND THIS WILL CONTINUE. NO SEVERE
WINDS ARE EXPECTED. AS THE NEWLY DEVELOPED SURFACE LOW EXITS EAST-CENTERAL
MONTANA INTO ND THIS AFTERNOON, CAMS SHOW A FLARE UP IN
CONVECTION JUST AHEAD OF THE LOW. THERE IS VARYING DEGREES OF JUST
HOW STRONG A STORM OR TWO COULD GET AND JUST HOW FAST IT
INTENSIFIES BUT IT DOES APPEAR POSSIBLE. THIS WILL LIKELY DEPEND
ON HOW MUCH THETA-E ADVECTION THERE IS, OVERALL CAPE VALUES, AND
HOW FAST THE LOW CAN SPIN UP (WIND SHEAR). IT DOES APPEAR THAT IF
WE CAN GET A STRONG STORM GOING IT WILL NOT BE IN OUR FORECAST
AREA VERY LONG BEFORE EXITING INTO ND. THOSE IN CUSTER AND FALLON
COUNTIES SHOULD REMAIN WEATHER AWARE THIS AFTERNOON FOR THIS
POTENTIAL.
DUE TO TODAY'S FEATURE BEING OF SUB-TROPICAL ORIGIN, THERE WILL
BE VERY LITTLE TEMPERATURE COOL DOWN BEHIND IT. HIGHS IN THE UPPER
70S AND LOW 80S WILL REMAIN ACROSS THE CWA THROUGH FRIDAY.
LATE FRIDAY INTO EARLY SATURDAY, WE WILL SEE TWO SYSTEMS MOVE INTO
OUR AREA. THE SHORTWAVE TROUGH MOVING IN ALONG THE POLAR JET, AND
THEN A WEAKER VORT MAX MOVING ALMOST DUE NORTH ALONG THE ROCKY
MOUNTAIN FRONT. THE LATTER FEATURE SEEMED LIKE IT WOULD ACTUALLY
BRING MORE IMPACTS TO OUR CWA THAN THE FORMER. THIS IS CHANGING
SLIGHTLY WITH THE MOST RECENT MODEL RUNS. THIS SMALL LOW IS THE
SYSTEM THAT IS CURRENTLY IMPACTING PORTIONS OF NM AND DUMPING
LARGE AMOUNTS OF RAIN. WHILE IT WILL BE MODIFIED AND NOT PURELY
SUB-TROPICAL BY THE TIME IT REACHES EASTERN WY/MT, IT WILL STILL
BE CARRYING WITH IT A GOOD AMOUNT OF MOISTURE. THIS COULD GIVE
AREAS EAST OF BILLINGS A CHANCE TO GET A QUICK DOSE OF RAIN HEADED
INTO THE WEEKEND, ALTHOUGH THE MOST RECENT RUNS SHOW NEARLY ALL OF
THE MOISTURE STAYING TO THE EAST OF OUR CWA. THE MAIN SHORTWAVE
MOVING OUT OF THE PACIFIC COULD BE A WIND MAKER FOR SOME PLACES.
AS OF RIGHT NOW, NEARLY ALL MODELS HAVE THE WEAK FEATURE FROM NM SHOVING
THE SHORTWAVE JUST POLEWARD ENOUGH TO KEEP THE 700MB JET INTO THE
TFX AND GGW CWAS. IF THIS DOES NOT HAPPEN THOUGH, OR IS NOT
SHOVED POLEWARD AS MUCH, SATURDAY COULD BE A WINDY DAY ACROSS THE
REGION. EVEN IF THE LESS WINDY SCENARIO PLAYS OUT, GUSTS IN THE
30S MPH WILL PROBABLY OCCUR IN THE WEST GAP WIND PRONE LOCATIONS
(BIG TIMBER, HARLOWTON). BE SURE TO CHECK FUTURE FORECASTS IF YOU
HAVE PLANS FOR THE FIRST HALF OF THE WEEKEND.
BOTH THE ECMWF AND THE GFS KEEP OUR AREA IN A PROGRESSIVE PATTERN
THROUGH THE FIRST PART OF NEXT WEEK WITH SEVERAL SHORTWAVES COMING
OFF OF THE PACIFIC AND MOVING THROUGH MONTANA. THE MAIN QUESTION
FOR NEXT WEEK'S FORECAST WILL BE WHAT HAPPENS WITH A HANDFUL OF
TROPICAL SYSTEMS. THE FIRST IS FORMER TYPHOON DUJUAN WHICH IS NOW
IN THE POLAR JET STREAM. THERE COULD ALSO BE A FEW MAJOR
HURRICANES THAT FORM IN THE EASTERN PACIFIC OVER THE NEXT WEEK
WHICH COULD ALTER THE TROPICAL BRANCH OF THE JET AND/OR ADVECT A
LOT OF MOISTURE INTO THE MID-LATITUDES. WMR
AVIATION
10Z DISCUSSION.
A DISTURBANCE LIFTING THRU THE AREA FROM THE SOUTHWEST WILL BRING
SHOWERS AND ISOLATED T-STORMS EARLY THIS MORNING, ESPECIALLY NORTH
AND NORTHEAST OF KBIL. SOME ACTIVITY MAY LINGER IN THE EAST INTO
THE AFTERNOON BUT THIS IS UNCERTAIN. HEAVIER SHOWERS ARE PRODUCING
ERRATIC WIND GUSTS OF 15-25 KNOTS AND LOCAL MVFR. ANY DIURNAL
CONVECTION THIS AFTERNOON WILL END IN THE EARLY EVENING. EXPECT
CLEARING/VFR ACROSS THE REGION TONIGHT.
STRATUS/FOG CONTINUES TO IMPACT FAR SOUTHEAST MT (MAINLY FALLON &
CARTER COUNTIES) WITH MVFR/IFR, AND THIS WILL LINGER UNTIL ~18Z.
SHOWERS AND ONSET OF DOWNSLOPE WINDS WILL PREVENT FOG DEVELOPMENT
FURTHER WEST EARLY TODAY.
JKL
PRELIMINARY POINT TEMP/POPS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 076 052/079 052/080 055/067 048/064 049/062 046/064
2/W 00/U 00/B 00/B 01/B 33/W 21/B
LVM 074 042/079 047/083 048/067 042/066 042/062 039/065
1/B 00/U 00/U 00/U 01/B 44/T 21/B
HDN 075 046/082 051/081 051/069 044/068 046/063 042/065
3/W 00/U 00/B 00/U 01/B 34/W 31/B
MLS 073 049/081 055/078 054/069 047/069 050/065 045/065
7/T 00/U 00/B 00/U 00/B 34/W 21/B
4BQ 075 049/079 054/077 054/070 049/073 051/066 046/066
2/U 00/U 00/B 00/U 01/B 55/W 42/W
BHK 074 046/081 050/076 050/072 045/072 047/067 042/065
7/T 10/U 01/N 00/U 10/U 55/T 32/W
SHR 072 041/078 048/079 050/071 043/071 046/064 040/065
2/W 00/U 00/B 00/U 01/B 36/W 42/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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