383
FXUS65 KBYZ 051506
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
906 AM MDT SAT JUL 5 2025
KEY MESSAGES
- COOLER TEMPERATURES THROUGH SUNDAY.
- SCATTERED STRONG TO SEVERE THUNDERSTORMS POSSIBLE TODAY, STARTING
EARLIER IN THE DAY THAN USUAL. BE WEATHER AWARE AND HAVE PLANS
TO SEEK SHELTER IF STORMS APPROACH.
- HOT AND MAINLY DRY NEXT WEEK, 90S TO NEAR 100 DEGREES TUESDAY
AND WEDNESDAY.
UPDATE
THE AREA IS STILL ON TRACK TO SEE A PERIOD OF STRONG TO SEVERE
THUNDERSTORMS THIS AFTERNOON AND EVENING, AS A PACIFIC TROUGH
COMBINES WITH AMPLE INSTABILITY AND SHEAR OVER THE AREA. THE SPC
HAS UPGRADED PARTS OF THE AREA TO AN ENHANCED RISK FOR SEVERE
THUNDERSTORMS (3 OUT OF 5) FOR THIS AFTERNOON AND EVENING. HAVE
GONE AHEAD AND UPDATED POPS AND THUNDER PROBS TO LATEST GUIDANCE
AND TRENDS THROUGH THE EVENING. THE CURRENT GOING FORECAST REMAINS
IN GOOD SHAPE, AND THE PREVIOUS DISCUSSION COVERS THE SEVERE
THUNDERSTORM THREAT WELL. STAY WEATHER AWARE THIS AFTERNOON AND
EVENING. STP
DISCUSSION
THROUGH SUNDAY NIGHT...
MAIN FOCUS FOR THE SHORT TERM WILL BE THE SEVERE THUNDERSTORM
THREAT TODAY. BY NOON A BROAD AREA OF MUCAPE IN THE 1500-2500 J/KG
IS SITTING OVER MUCH OF THE AREA WITH BULK SHEAR OF 40 TO 55KTS
CO-LOCATED. THATS PLENTY OF ENERGY AND SHEAR TO GET STRONG
ROTATING UPDRAFTS FOR SUPERCELL DEVELOPMENT AS A DISTURBANCE MOVES
THROUGH ALOFT PROVIDING THE CONVECTIVE TRIGGER FOR STORMS. THE
ONE THING THAT MAY BE A SAVING GRACE IS THE EARLY START TO THIS
STORM EVENT (NOT ARRIVING AT PEAK HEATING/ENERGY TIME OF DAY)
WHICH MAY LIMIT WHAT THESE STORMS COULD HAVE BEEN OVER WESTERN
INTO CENTRAL ZONES. BY LATE AFTERNOON THOUGH STORMS WILL BE INTO
SE MONTANA WHERE DAYTIME HEATING WILL BE CLOSER TO PEAK AND STORMS
WILL LIKELY BE MORE INTENSE. 1 TO 2 INCH DIAMETER HAIL AND GUSTS
TO 70 MPH SEEM REASONABLE WITH STRONGER STORMS TODAY, AND AN
ISOLATED TORNADO CAN'T BE RULED OUT WITH ELEVATED VALUES FOR LOW
LEVEL EHI/VGP PARAMETERS ESPECIALLY IN THE EARLY PART OF THE
AFTERNOON.
THERE WILL BE A SECOND ROUND OF THUNDERSTORMS LATER INTO THE
AFTERNOON SATURDAY, ASSOCIATED WITH THE ACTUAL COLD FRONT. THIS
ACTIVITY SHOULD BE WEAKER THAN THE FIRST WITH THE ATMOSPHERE
HAVING ALREADY BEEN WORKED ON BY THE FIRST SET OF STORMS. THAT
SAID THERE COULD STILL BE A FEW STRONG TO MARGINALLY SEVERE STORMS
WITH THIS ROUND AS WELL.
LOCALLY HEAVY RAINFALL IS IN THE FORECAST FOR AREAS EAST OF
BILLINGS WITH THESE STORMS. A FEW MODELS ARE SHOWING PRECIPITATION
BULLSEYES OVER AN INCH AN A HALF OVER SE MONTANA, AND WPC HAS A
MARGINAL RISK FOR EXCESSIVE RAINFALL OVER THIS AREA.
STORMS WILL SHIFT OUT OF THE AREA TO THE EAST MID TO LATE EVENING,
WITH A CLEARING AND QUIET OVERNIGHT INTO SUNDAY MORNING.
SUNDAY LOOKS LIKE A NICE DAY TO GET OUTDOORS. PLENTY OF SUN AND
TEMPERATURES IN THE 75 TO 85 DEGREE RANGE AS THE FLOW ALOFT
BECOMES ZONAL AND LIGHT DOWNSLOPE DRYING WINDS DEVELOP. CAN'T
RULE OUT AN ISOLATED SHOWER OR STRAY THUNDERSTORM IN THE
AFTERNOON, BUT MODELS ARE KEEPING PROBABILITIES UNDER 15 PERCENT
AT THIS TIME. CHAMBERS
MONDAY THROUGH SATURDAY...
MONDAY THROUGH WEDNESDAY WILL SEE INCREASING 500 MB HEIGHTS
LEADING TO INCREASING TEMPERATURES AS WELL. THIS PERIOD IS ALSO
EXPECTED TO BE DRY. BY TUESDAY AND WEDNESDAY, 90 DEGREES F
TEMPERATURES WILL SPREAD ACROSS THE REGION. WEDNESDAY LOOKS TO BE
THE HOTTEST DAY WITH RIVER VALLEYS TO THE EAST OF BILLINGS HAVING
A 30-50% CHANCE OF GETTING A TEMPERATURE OVER 100 F. RELATIVE
HUMIDITY VALUES TUESDAY AND WEDNESDAY ARE EXPECTED DROP INTO THE
TEENS. WINDY CONDITIONS ARE NOT EXPECTED WITH THE HOT DRY WINDY
INDEX NOT SHOWING ANY PARTICULARLY IMPACTFUL FIRE DAYS. THIS HOT
AND DRY STRETCH WILL CONTINUE TO DRY OUT FUELS HOWEVER, LEADING TO
INCREASED FIRE CONCERN OVER THE LONG TERM.
ENSEMBLE SYSTEMS ARE IN AGREEMENT THAT THE END OF NEXT WEEK WILL
HAVE AN UPPER LEVEL TROUGH MOVING THROUGH THE REGION. THERE IS
A LOT OF UNCERTAINTY IN WHAT EXACTLY THIS WILL MEAN FOR THE
FORECAST. A LOOK AT DETERMINISTIC MODELS SHOWS THE GFS BRINGING A
COLD FRONT THROUGH THE REGION ON THURSDAY WITH THE ECMWF WAITING
UNTIL FRIDAY. THIS FRONT WILL BRING PRECIPITATION CHANCES, THOUGH
AT THIS TIME ENSEMBLE SYSTEMS AND DETERMINISTIC MODELS ARE KEEPING
VALUES LOW. THE NBM IS CURRENTLY GIVING A 20-30% CHANCE FOR
GREATER THAN 0.10 INCHES OF PRECIPITATION THURSDAY AND FRIDAY.
THE UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT MAY KNOCK
TEMPERATURES DOWN TO SEASONAL VALUES IN THE 80S BY FRIDAY. 500 MB
HEIGHTS HOWEVER WILL REMAIN NEAR TO SLIGHTLY ABOVE NORMAL
PREVENTING A SIGNIFICANT COOLDOWN AND LEAVING THE REGION
VULNERABLE TO A BOUNCE BACK TO ABOVE NORMAL TEMPERATURES LIKE LONG
TERM OUTLOOKS SUGGEST. TORGERSON
AVIATION
15Z DISCUSSION...
VFR CONDITIONS WIL PREVAIL THROUGH 18Z. AROUND 17-18Z TS FORM
OVER THE MOUNTAINS AND PUSH EAST. SOME STORMS ARE EXPECTED TO
BECOME SEVERE WITH WINDS POTENTIALLY GUSTING TO 60KTS AND LARGE
GR. ALL SITES HAVE THE POTENTIAL FOR SEVERE WEATHER TODAY,
HOWEVER, KMLS/KBHK/KBIL HAVE THE GREATEST POTENTIAL. MOUNTAINS
WILL BE PARTIALLY OBSCURED IN THESE STORMS. EXPECT PREVAILING
WINDS TO SHIFT OUT OF THE NW AFTER 00Z. WMR
PRELIMINARY POINT TEMP/POPS
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 082 055/083 058/087 061/097 063/097 063/087 056/083
6/T 50/U 00/U 00/U 00/U 11/U 32/T
LVM 077 045/081 048/086 052/093 056/092 054/083 048/082
7/T 30/U 00/U 00/U 11/U 11/U 22/T
HDN 086 054/084 055/089 059/097 061/098 060/088 055/085
6/T 60/U 10/U 00/U 00/U 11/U 32/T
MLS 086 058/082 058/087 062/097 065/099 065/089 057/083
6/T 81/U 11/U 00/U 00/U 11/B 21/B
4BQ 087 058/080 060/085 061/094 065/097 064/087 058/080
5/T 81/U 11/U 00/U 10/U 10/B 31/U
BHK 080 056/079 055/085 058/092 061/094 061/087 054/081
3/T 82/W 11/U 01/U 11/U 11/B 21/U
SHR 086 050/081 052/086 054/093 057/095 057/085 051/078
5/T 51/U 11/U 00/U 01/U 11/B 23/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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