441
FXUS63 KBIS 241731
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1231 PM CDT MON AUG 24 2026
KEY MESSAGES
- ISOLATED TO SCATTERED SEVERE THUNDERSTORMS COULD DEVELOP IN
CENTRAL AND EASTERN NORTH DAKOTA THIS AFTERNOON AND EVENING.
THERE ARE HIGHER CHANCES FOR STORMS DEVELOPING IN EASTERN
NORTH DAKOTA THAN CENTRAL.
- POTENTIAL HAZARDS FROM SEVERE STORMS THIS AFTERNOON AND
EVENING INCLUDE LARGE HAIL UP TO 2 INCHES IN DIAMETER AND
DAMAGING WINDS UP TO 70 MPH, WITH A TORNADO POSSIBLE IN THE
JAMES RIVER VALLEY EARLY THIS EVENING.
- NEAR-CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED ACROSS MUCH
OF WESTERN NORTH DAKOTA THIS AFTERNOON AND EARLY EVENING, AND
COULD RETURN TO FAR SOUTHWEST PARTS OF THE STATE ON TUESDAY.
- A LITTLE WARMER TODAY, THEN COOLER AND WINDY ON TUESDAY. NEAR
TO SLIGHTLY ABOVE AVERAGE TEMPERATURES ARE FAVORED FROM THE
MIDDLE OF THE WEEK THROUGH THE WEEKEND.
DISCUSSION
ISSUED AT 520 AM CDT MON AUG 24 2026
A DEEP UPPER LOW IS SPINNING FROM SOUTHERN ALBERTA INTO
SOUTHERN SASKATCHEWAN EARLY THIS MORNING, WITH AN ATTENDANT
SURFACE TROUGH EXTENDING FROM THE SURFACE LOW OVER CENTRAL
SASKATCHEWAN THROUGH WESTERN NORTH DAKOTA. A PRECEDING LOWER-
AMPLITUDE SHORTWAVE IS TRAVELING ALONG THE NORTH DAKOTA-
MANITOBA BORDER AND HAS BEEN RESPONSIBLE FOR THUNDERSTORMS
PRODUCING EXCESSIVE RAINFALL, ESPECIALLY FROM AROUND BOTTINEAU
TO RUGBY. GROUND-TRUTH RAIN AMOUNTS AROUND 4 INCHES HAVE BEEN
REPORTED, AND MRMS IS ESTIMATING NEAR 6 INCHES LOCALLY. AS OF 5
AM CDT, THE THREAT FOR TORRENTIAL RAINFALL HAS EXITED OUR
FORECAST AREA. FARTHER UPSTREAM, ISOLATED SHOWERS AND STORMS
THAT ARE LIKELY BEING MAINTAINED BY A PLUME OF LOW LEVEL WARM
AIR ADVECTION ARE MOVING FROM NORTHWEST INTO NORTH CENTRAL
NORTH DAKOTA. THESE HAVE MOSTLY BEEN BENIGN AND WERE BEGINNING
TO RAPIDLY DIMINISH AS OF 5 AM CDT, BUT EARLIER IN THE NIGHT
THERE WAS A ROGUE 58 MPH WIND GUST AT AN NDAWN STATION NEAR
RAY. THE MAGNITUDE OF WARM AIR ADVECTION IS FORECAST TO
DECREASE LATER THIS MORNING, WHICH COULD ALLOW THIS ACTIVITY TO
CONTINUE TO DISSIPATE. A FEW CAMS HINT AT REDEVELOPMENT OF WEAK
ELEVATED CONVECTION IN NORTHWEST NORTH DAKOTA LATER THIS
MORNING, LIKELY IN RESPONSE TO HEIGHT FALLS FROM THE
SASKATCHEWAN LOW, BUT MORE RECENT CAMS HAVE BACKED OFF ON THIS
POTENTIAL.
STILL LOOKING AT A CONDITIONAL THREAT FOR SEVERE THUNDERSTORMS
IN CENTRAL AND EASTERN NORTH DAKOTA ALONG AND AHEAD OF THE
EASTWARD ADVANCING SURFACE TROUGH THIS AFTERNOON AND EVENING,
WITH UNCERTAINTY ROOTED IN WHETHER THERE WILL BE STRONG ENOUGH
FORCING TO OVERCOME CIN. THE MOST RECENT SUITE OF CAMS IS MORE
CONFIDENT THAT CONVECTIVE INITIATION WILL OCCUR AT SOME POINT
AND TIME, BUT IT MAY NOT BE UNTIL CLOSER TO EARLY EVENING WHEN
THE FRONTAL BOUNDARY REACHES THE JAMES RIVER VALLEY. THE SPC
HAS INTRODUCED A SLIGHT RISK (LEVEL 2 OUT OF 5) TO THE EASTERN
THIRD OF THE STATE, REACHING AS FAR WEST AS THE JAMES RIVER
VALLEY. A DISCRETE STORM MODE IS FAVORED, BUT SPLITTING
SUPERCELLS/STORM MERGERS COULD CONTRIBUTE TO UPSCALE GROWTH
AND/OR CLUSTERING OF STORMS. CAPE IN THE 2000-3000 J/KG RANGE
AND DEEP LAYER SHEAR AROUND 35-40 KTS WILL BE SUPPORTIVE OF
VERY LARGE HAIL TO AROUND 2 INCHES IN DIAMETER. THE AMOUNT OF
SHEAR AND HIGH FORECAST DCAPE ALSO LEAVES OUR MOST LIKELY
MAXIMUM WIND GUST FORECAST AT 70 MPH. DID ELECT TO BEGIN
MESSAGING A POSSIBLE TORNADO, WHICH WOULD MOST LIKELY BE
LIMITED TO THE JAMES RIVER VALLEY IN THE EARLY EVENING WHEN AND
WHERE THE COMBINATION OF STRONGER LOW LEVEL SHEAR/SRH AND
WEAKER MLCIN IS MAXIMIZED.
TODAY WILL BE SEASONABLY WARM, WITH HIGHS IN THE LOWER 80S TO
LOWER 90S. A MUCH DRIER AIR MASS AND GUSTY WEST-NORTHWEST WINDS
BEHIND THE SURFACE TROUGH WILL CREATE NEAR-CRITICAL FIRE
WEATHER CONDITIONS THIS AFTERNOON AND EARLY EVENING, ESPECIALLY
FROM NEAR WILLISTON TO BOWMAN. THE CANADIAN LOW WILL SPIN INTO
SOUTHERN MANITOBA ON TUESDAY BEFORE DIVING SOUTHEAST TOWARD THE
WESTERN GREAT LAKES. THIS WILL LEAVE COOLER TEMPERATURES AND
WINDY CONDITIONS OVER THE NORTHERN PLAINS ON TUESDAY, WITH
HIGHS IN THE MID 70S TO LOWER 80S AND NORTHWEST WINDS AROUND 20
TO 30 MPH, GUSTING AS HIGH AS 40 MPH. RH MAY FALL LOW ENOUGH IN
THE FAR SOUTHWEST FOR ANOTHER AFTERNOON OF NEAR-CRITICAL FIRE
WEATHER CONDITIONS ON TUESDAY. THERE COULD ALSO BE SOME
DIURNALLY-DRIVEN AFTERNOON SHOWERS IN THE CYCLONIC FLOW REGIME
ON TUESDAY. THE NBM LIMITS THIS POTENTIAL TO THE TURTLE
MOUNTAINS, BUT SOME RUNS OF THE HRRR HAVE BROUGHT ISOLATED
SHOWERS AS FAR SOUTH AS THE NORTHERN JAMES RIVER VALLEY.
BROAD SURFACE HIGH PRESSURE IS FORECAST OVER THE REGION ON
WEDNESDAY AS THE UPPER LEVEL RIDGE RE-AMPLIFIES OVER THE
ROCKIES. GUIDANCE THEN FAVORS THE RIDGE AXIS BEING SHOVED
EASTWARD ON THURSDAY AS A DEEPER TROUGH DIGS INTO THE PACIFIC
NORTHWEST. SHORTWAVE ENERGY EJECTING FROM THE BASE OF THAT
TROUGH BRINGS SHOWER AND THUNDERSTORM CHANCES BACK TO THE
REGION AS EARLY AS THURSDAY NIGHT, WITH NEAR-DAILY LOW TO
MEDIUM CHANCES CONTINUING THROUGH THE WEEKEND AS A MORE
PROGRESSIVE SYNOPTIC PATTERN EMERGES. TEMPERATURES ARE FAVORED
TO REMAIN NEAR AVERAGE OVERALL, BUT COULD TREND SLIGHTLY ABOVE
AVERAGE CLOSER TO THE END OF THE WEEK.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1216 PM CDT MON AUG 24 2026
EARLY THIS AFTERNOON, VFR CONDITIONS WERE DOMINATING MUCH OF
NORTHERN PLAINS. A SURFACE TROUGH WAS TRACKING EASTWARD ACROSS
WESTERN/CENTRAL NORTH DAKOTA WITH A FEW DISSIPATING SHOWERS
MOVING ALONG WITH IT. AS THIS TROUGH PASSES THROUGH THE REGION
FROM WEST TO EAST, SURFACE WINDS ARE SHIFTING FROM
SOUTH/SOUTHWESTERLY TO WEST/NORTHWESTERLY WITH WIND SPEEDS
AROUND 10-15 KNOTS. GUSTS UP TO 25 KNOTS ARE POSSIBLE ACROSS
WESTERN NORTH DAKOTA LATER THIS AFTERNOON.
LATE THIS AFTERNOON INTO THIS EVENING, ISOLATED TO SCATTERED
THUNDERSTORMS ARE POSSIBLE ACROSS THE EASTERN HALF OF THE STATE.
SOME OF THESE STORMS COULD BE SEVERE WITH LARGE HAIL AND
DAMAGING WINDS POSSIBLE. GIVEN SOME UNCERTAINTY IN STORM
COVERAGE, ELECTED TO MAINTAIN A PROB30 AT KJMS FOR THE POTENTIAL
OF A STRONG OR SEVERE STORM. CHANCES FOR THUNDERSTORMS SHOULD
COME TO AN END AFTER 04Z.
WINDY CONDITIONS ARE FORECAST IN THE WAKE OF THE SURFACE TROUGH
THROUGHOUT THE DAY ON TUESDAY WITH NORTHWEST WINDS SUSTAINED
AROUND 15 TO 20 KNOTS, AND GUSTS AROUND 25 TO 30 KNOTS ACROSS
MUCH OF THE FORECAST AREA. ADDITIONALLY, SOME PATCHY MVFR CIGS
ARE POSSIBLE THROUGH THE MORNING HOURS ACROSS NORTHERN NORTH
DAKOTA, THROUGH PROBS REMAIN A BIT TOO LOW FOR A PROB30 MENTION
AT KXWA AND KMOT AT THIS TIME.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HOLLAN
AVIATION...JC
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