702
FXUS63 KBIS 122036
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
336 PM CDT FRI SEP 12 2025
KEY MESSAGES
- SEVERAL ROUNDS OF SCATTERED SHOWERS AND THUNDERSTORMS THROUGH
THE MIDDLE OF NEXT WEEK.
- MEDIUM TO HIGH PROBABILITIES FOR AT LEAST AN INCH OF RAIN
ACROSS THE WESTERN HALF OF THE STATE THROUGH THIS WEEKEND.
- ISOLATED TO SCATTERED SEVERE THUNDERSTORMS POSSIBLE LATE THIS
AFTERNOON THROUGH TONIGHT. ADDITIONAL ISOLATED SEVERE
THUNDERSTORMS POSSIBLE SATURDAY AND SUNDAY.
- TEMPERATURES FAVORED TO REMAIN NEAR TO ABOVE AVERAGE THROUGH
THE MIDDLE OF NEXT WEEK.
DISCUSSION
ISSUED AT 336 PM CDT FRI SEP 12 2025
THIS AFTERNOON, AN ELONGATED UPPER LEVEL LOW EXTENDED
SOUTHWEST-NORTHEAST ACROSS THE WESTERN CONUS, WITH THE BASE OF
A TROUGH DIGGING INTO THE SOUTHWEST, LEADING TO SOUTHWEST FLOW
ALOFT OVER THE DAKOTAS. A SURFACE LOW WAS ANALYZED TO OUR SOUTH,
WITH A WARM FRONT EXTENDING ACROSS FAR SOUTHEAST NORTH DAKOTA.
THERE WAS AN ADDITIONAL BOUNDARY AND ASSOCIATED WIND SHIFT
ACROSS THE NORTHWEST, AND A FEW THUNDERSTORMS HAVE BEEN
DEVELOPING ALONG THIS BOUNDARY. ALTHOUGH NOT SEVERE STORMS, ONE
DID PRODUCE A BRIEF TORNADO IN WILLIAMS COUNTY, LIKELY DUE TO
ENHANCED LOW- LEVEL VORTICITY ALONG THE BOUNDARY AND TAPPING
INTO SOME ELEVATED INSTABILITY, WITH SPC MESO PAGE SHOWING AN
UNCAPPED ENVIRONMENT ACROSS PARTS OF WESTERN NORTH DAKOTA. THERE
IS LOW CONFIDENCE IN STORM DEVELOPMENT AND LOCATION FOR THE
REST OF THE AFTERNOON, WITH NO PRONOUNCED SYNOPTIC FORCING.
ISOLATED STORMS ARE DEVELOPING IN SOUTHEAST MONTANA, ALTHOUGH
THEY ARE MOVING SLOWLY AND ARE PROGRESSING INTO AN ENVIRONMENT
THAT IS STILL RELATIVELY CAPPED. IF THESE CAN BE SUSTAINED,
THOUGH, THEY WILL BE MOVING INTO SOUTHWEST NORTH DAKOTA EARLIER
THAN EXPECTED. WE ALSO CAN'T RULE OUT A STORM OR TWO DEVELOPING
AHEAD OF THE MAIN WAVE, AND ANYTHING THAT FORMS COULD BE
POTENTIALLY STRONG TO SEVERE, ESPECIALLY IN THE AREA THAT IS
EITHER WEAKLY CAPPED OR NOT CAPPED AT ALL OUT WEST.
THE CHANCE FOR SHOWERS AND THUNDERSTORMS INCREASES THIS EVENING
AND INTO THE OVERNIGHT HOURS AS A STRONGER SHORTWAVE EJECTS OUT
OF THE TROUGH BASE, WITH PRECIPITATION CHANCES INCREASING TO 70
TO 90 PERCENT ACROSS SOUTHWEST NORTH DAKOTA TONIGHT. WE ARE ALSO
CARRYING A MENTION OF SCATTERED SEVERE THUNDERSTORMS (LEVEL 2
OUT OF 5) IN THIS AREA, AND ISOLATED SEVERE THUNDERSTORMS (LEVEL
1 OUT OF 5) ACROSS THE REMAINDER OF WESTERN AND CENTRAL NORTH
DAKOTA. HIGH-RES GUIDANCE IS GENERALLY AGREEING ON THE SAME
PROGRESSION ALTHOUGH SOME DIFFERENCES IN TIMING, WITH A BROAD
WINDOW OF 9 PM TO MIDNIGHT CDT FOR THE MAIN WAVE OF STORMS
MOVING INTO SOUTHWEST NORTH DAKOTA. THESE STORMS ARE PROJECTED
TO LIFT NORTH AS A MID-LEVEL WAVE ALIGNS WITH AN UPPER JET
STREAK, LEADING TO STRONG HEIGHT FALLS AND WIDESPREAD SHOWERS
AND THUNDERSTORMS. CURRENT HAZARDS WE ARE MESSAGING ARE HAIL UP
TO THE SIZE OF GOLF BALLS AND WIND GUSTS UP TO 60 MPH, WITH
SUFFICIENT BUOYANCY BUT WEAK SHEAR. 12Z HREF MAX UH TRACKS SHOW
A SMATTERING OF TRACKS TONIGHT INTO SATURDAY MORNING, ALTHOUGH
NONE VERY LONG OR PRONOUNCED, WHICH WOULD FIT WITH THE LACK OF
SHEAR BEING ADVERTISED IN GUIDANCE. WITH THE FREQUENT
BACKBUILDING AND RELATIVELY SLOW STORMS WE'VE BEEN SEEING
YESTERDAY AND TODAY SO FAR, ALSO HAVE TO CONSIDER HEAVY RAINFALL
AS A THREAT, WITH CONTINUED ABNORMALLY HIGH PWATS.
SHOWERS AND THUNDERSTORMS CONTINUE LIFTING NORTH THROUGH THE
MORNING SATURDAY BEFORE THERE WILL LIKELY BE A BIT OF A LULL, AT
LEAST IN THE AMOUNT OF WIDESPREAD CONVECTION. ADDITIONAL ROUNDS
OF PRECIPITATION ARE EXPECTED AS MORE WAVES EJECT FROM THE
TROUGH BASE THAT WILL SLOWLY BE ROTATING ACROSS THE REGION, WITH
PERSISTENT MEDIUM CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
MONDAY. WE ARE CARRYING A MENTION OF ISOLATED SEVERE STORMS ON
SATURDAY AND SUNDAY, WITH FORECAST INSTABILITY SLOWLY DECREASING
THROUGH THE WEEKEND. OF MORE CERTAINTY IS THE POTENTIAL FOR
WIDESPREAD RAIN AMOUNTS OF AT LEAST AN INCH, WITH CURRENT NBM
PROBABILITIES HIGHLIGHTING MEDIUM TO HIGH CHANCES FOR THIS
THRESHOLD THROUGH THE WEEKEND ACROSS THE WESTERN HALF OF THE
STATE. THE LIKELIHOOD OF AT LEAST 3 INCHES OF RAIN IS AROUND 10
PERCENT IN AN AREA FROM STANLEY TO LEMMON, ALTHOUGH OVERALL
RAINFALL AMOUNTS COULD BE QUITE VARIABLE FROM THUNDERSTORMS
MOVING THROUGH. WE CONTINUE TO SEE AN ELEVATED QPF SIGNAL IN THE
EFI, WITH A SHIFT OF TAILS OVER PARTS OF WESTERN AND CENTRAL
NORTH DAKOTA ON SATURDAY AND SUNDAY.
TEMPERATURE WISE, HIGHS SATURDAY THROUGH TUESDAY WILL BE IN THE
LOWER 70S TO LOWER 80S, BEFORE NBM TEMPERATURE PROBABILITIES
SHOW SIGNS OF A COOL DOWN FOR THE MIDDLE TO END OF NEXT WEEK AS
FLOW ALOFT TURNS MORE CYCLONIC. LOW PRECIPITATION CHANCES
CONTINUE FOR THE BACK HALF OF NEXT WEEK, ALTHOUGH NOT AS HIGH OR
AS WIDESPREAD AS WHAT WE'RE SEEING FOR THE NEXT FEW DAYS.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1242 PM CDT FRI SEP 12 2025
VFR TO START THE TAF PERIOD, AND CONTINUING INTO THE EVENING
HOURS AS CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE FOR THE
BACK HALF OF THE PERIOD. COULD BE SOME ISOLATED STORMS THIS
AFTERNOON SO CARRYING A TEMPO AT KXWA, BEFORE ADDING IN PROB30
GROUPS AT MOST TERMINALS OVERNIGHT. EXPECTING SHOWERS AND
THUNDERSTORMS TO BECOME PREVAILING AT ALL TERMINALS BUT KJMS
THROUGH SATURDAY MORNING. WINDS WILL BE RELATIVELY LIGHT THROUGH
THE PERIOD AND GENERALLY FROM THE NORTHEAST.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...JONES
AVIATION...JONES
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