752
FXUS63 KBIS 132321
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
621 PM CDT THU AUG 13 2026
KEY MESSAGES
- SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WEST AND NORTH
CENTRAL, WITH SHOWERS BECOMING WIDESPREAD THIS EVENING
THROUGH FRIDAY MORNING. LOCALLY HEAVY RAINFALL IS POSSIBLE.
- SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE SOUTHWEST
AND CENTRAL FRIDAY AND FRIDAY EVENING, THEN MAINLY DRY LATE
FRIDAY AND THROUGH THE WEEKEND.
- TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND
WITH HIGHS GENERALLY IN THE 70S. THE EXCEPTION BEING SOME 60S
NORTHWEST AND SOME LOWER 80S SOUTHEAST.
UPDATE
ISSUED AT 620 PM CDT THU AUG 13 2026
SCATTERED SHOWERS CONTINUE TO SKIM ACROSS PORTIONS OF
NORTHWESTERN NORTH DAKOTA AT THE TIME OF THIS EARLY EVENING
UPDATE. LITTLE TO NO THUNDERSTORM ACTIVITY HAS BEEN OBSERVED
WITH THE LIMITED CONVECTIVE ENVIRONMENT OVER THE FORECAST AREA,
THOUGH A FEW ISOLATED RUMBLES OF THUNDER CAN BE FOUND ACROSS
THE BORDER IN EASTERN MONTANA. FURTHER DOWNSTREAM IN NORTHERN
WYOMING, THE NEXT ROUND OF SHOWERS THAT IS EXPECTED TO LIFT
ACROSS INTO WESTERN AND NORTH CENTRAL NORTH DAKOTA HAVE BEGUN TO
DEVELOP. OVERALL, THE FORECAST REMAINS IN GOOD SHAPE AT THIS
TIME, WITH NO MAJOR ADJUSTMENTS REQUIRED.
DISCUSSION
ISSUED AT 245 PM CDT THU AUG 13 2026
CURRENTLY, BROAD UPPER LEVEL RIDGING ACROSS THE CENTRAL CONUS
WITH MUCH OF THE NORTHERN PLAINS IN THE RIGHT ENTRANCE REGION OF
A STRONG UPPER JET STREAK LOCATED NORTH OF THE GREAT LAKES
REGION AND OVER THE NEW ENGLAND AREA. OVERRUNNING FLOW ACROSS
WESTERN NORTH DAKOTA COUPLED WITH EMBEDDED MID LEVEL IMPULSES
RIDING OVER THE AFOREMENTIONED RIDGE CONTRIBUTING TO SCATTERED
SHOWERS THIS AFTERNOON WEST INTO NORTH CENTRAL. ONLY WEAK MUCAPE
ABOUT, ROUGHLY A FEW HUNDRED J/KG, BUT ENOUGH FOR A FEW
ISOLATED SHOWERS NOW POPPING UP OVER CENTRAL ND WHERE CLOUD
COVER DECREASED EARLIER ALLOWING FOR SOME SFC HEATING.
INSTABILITY AND SHEAR REMAIN WEAK THROUGH THE DAY, SO WHILE A
FEW THUNDERSTORMS ARE FORECAST, THE THREAT FOR SEVERE WEATHER IS
VERY LOW IF NOT ZERO.
WE REMAIN ON TRACK FOR NUMEROUS SHOWERS AND A FEW THUNDERSTORMS
DEVELOPING TONIGHT INTO TOMORROW OVER WESTERN INTO NORTH CENTRAL
NORTH DAKOTA, WITH THE GREATEST PROBABILITY FOR HEAVIER RAINFALL
OVER THE FAR NORTHWEST. THIS MATERIALIZES AS A SURFACE TROUGH,
NOW DEVELOPING OVER SOUTHEASTERN MONTANA, DEVELOPS OVER EASTERN
MT INTO WESTERN ND LATE TONIGHT/FRIDAY AM, COUPLED WITH A WELL-
DEFINED EMBEDDED S/WV LIFTING NORTHEAST ACROSS EASTERN MT TO
ACROSS NORTHWEST NORTH DAKOTA 06Z TONIGHT THROUGH FRIDAY MORNING
12-18Z. ANY HEAVIER SHOWER/THUNDERSTORM WILL BE CAPABLE OF HEAVY
RAINFALL GIVEN ELEVATED PW VALUES, THOUGH MODELS IN PRETTY GOOD
AGREEMENT THAT THE BEST COMBINED FORCING WILL BE OVER NORTHWEST
NORTH DAKOTA, SO MAYBE POCKETS OF HEAVIER PRECIP OUTSIDE OF THIS
AREA. EFI VALUES REMAIN FOCUSED NORTHWEST AS WELL, NOW AT 90
PERCENT WITH SHIFT OF TAILS STILL AT A VALUE OF 2 (ALL POINTING
TO AN EXTREME QPF EVENT). WE OPTED TO MAINTAIN NO HYDRO
HEADLINES FOR THIS POTENTIAL EVENT, AS A BEST PRACTICE IS TO
TREAT THESE AS SHORT-FUSED PRODUCTS ONCE IT BECOMES MORE EVIDENT
THAT ELEVATED MESSAGING IS NEEDED. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
AFOREMENTIONED SFC TROUGH ADVANCES EAST ACROSS WESTERN AND
CENTRAL NORTH DAKOTA DURING THE DAY FRIDAY ALONG WITH A
CONTINUED UNSETTLED SOUTHWEST FLOW ALOFT WITH MULTIPLE EMBEDDED
IMPULSES PUSHING THROUGH. THIS WILL BRING DECENT CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS TO MOST AREAS FRIDAY MORNING AND
AFTERNOON, ENDING GRADUALLY FRIDAY NIGHT AS FORCING DECREASES
AND HIGH PRESSURE BUILDS IN FROM THE WEST. LOCALLY HEAVY PRECIP
REMAINS POSSIBLE WITH PW VALUES REMAINING ELEVATED UNTIL LATE
FRIDAY NIGHT.
THE REMAINDER OF THE WEEKEND WILL BE MAINLY DRY AND COOLER,
WITH SURFACE HIGH PRESSURE OVER THE REGION ALONG WITH ZONAL FLOW
ALOFT. EMBEDDED WAVES RIDING OVER A BROAD UPPER RIDGE BUILDING
OVER THE ROCKIES LOOK TO BRING SOME CHANCES FOR
SHOWERS/THUNDERSTORMS TO THE LOCAL REGION DURING THE DAY SUNDAY
INTO SUNDAY NIGHT.
A QUASI-ZONAL FLOW ALOFT IS ADVERTISED FOR THE FIRST HALF OF
NEXT WEEK, AND WILL RESULT IN TEMPERATURES TRENDING WARMER/MORE
SEASONAL, ALONG WITH DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 620 PM CDT THU AUG 13 2026
INCREASING COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS ACROSS
WESTERN AND NORTH CENTRAL NORTH DAKOTA WILL PROMOTE LOWERING
CEILINGS AND VISIBILITY THROUGH THE END OF THE TAF PERIOD, WITH
MVFR TO IFR CEILINGS EXPECTED AT KXWA, KMOT, AND KDIK. HAVE LEFT
MENTIONS OF THUNDERSTORM ACTIVITY OUT OF ALL SITES, AS
CONFIDENCE IN TIMING AND LOCATION IS VERY LOW. SHOWER ACTIVITY
ACROSS THE SOUTH CENTRAL IS EXPECTED TO BE MORE LIMITED, THUS
LOW VFR CEILINGS ARE EXPECTED AT KBIS AND KJMS THROUGHOUT THE
TAF PERIOD. EAST WINDS ARE EXPECTED TO BECOME LIGHT THIS EVENING
THROUGH TONIGHT, BEFORE TURNING SOUTHEASTERN AND STRENGTHENING
FRIDAY MORNING AND AFTERNOON. GUSTY WINDS SUSTAINED AROUND 15
KNOTS AND GUSTS UP TO 25 KNOTS ARE EXPECTED ACROSS PORTIONS OF
SOUTH CENTRAL NORTH DAKOTA FRIDAY AFTERNOON.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...ADAM/NH
DISCUSSION...NH
AVIATION...ADAM
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