693
FXUS63 KBIS 281754
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1254 PM CDT MON SEP 28 2026
KEY MESSAGES
- WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TODAY.
- EXCESSIVE RAINFALL COULD CAUSE LOCALIZED FLOODING FROM SOUTH
CENTRAL NORTH DAKOTA TO THE JAMES RIVER VALLEY THROUGH
TONIGHT.
- A FEW THUNDERSTORMS MAY BECOME STRONG, WITH HAIL UP TO NICKEL
SIZE, AND TORRENTIAL RAIN.
- MOSTLY DRY WITH NEAR NORMAL TEMPERATURES FROM TUESDAY INTO
THE WEEKEND.
UPDATE
ISSUED AT 1247 PM CDT MON SEP 28 2026
SHOWERS AND A FEW THUNDERSTORMS CONTINUE ACROSS THE CENTRAL AND
EAST. VERY HEAVY RAIN OVER THE LAST FEW HOURS IN EMMONS COUNTY
HAS PROMPTED A FLASH FLOOD ADVISORY. THUNDERSTORMS IN THAT AREA
ARE STARTING TO TRAIN AS WELL. ACROSS THE WEST AND CENTRAL A
FEW SMALL ISOLATED RAIN SHOWERS HAVE FORMED.
UPDATE
ISSUED AT 1018 AM CDT MON SEP 28 2026
FORECAST STILL REMAINS ON TRACK. WIDESPREAD SHOWERS CONTINUE IN
THE CENTRAL AND EAST, WHILE THE DRY SLOT OF THE SURFACE LOW
MOVES INTO THE SOUTHWEST. THE LATEST NBM WAS INGESTED INTO THE
FORECAST.
UPDATE
ISSUED AT 654 AM CDT MON SEP 28 2026
OVERALL, THE FORECAST REMAINS ON TRACK. OBSERVED AND RAPID
REFRESH MODEL TRENDS HAVE BEEN BLENDED INTO THE FORECAST. SOME
AREAS TO THE SOUTH AND EAST OF MINOT HAVE ALREADY RECEIVED CLOSE
TO 2 INCHES OF RAIN IN JUST THE PAST FEW HOURS.
DISCUSSION
ISSUED AT 502 AM CDT MON SEP 28 2026
SHORTWAVE ENERGY EJECTING FROM THE BASE OF A DEEP WESTERN CONUS
TROUGH IS SPREADING OVER THE NORTHERN PLAINS THIS MORNING WHILE
THE LOW LEVEL JET ADVECTS WARM AIR AND MOISTURE INTO THE
REGION. THESE FORCING MECHANISMS ARE RESPONSIBLE FOR AREAS OF
SHOWERS AND THUNDERSTORMS. AT 430 AM CDT, THERE WERE TWO
DISTINCT CLUSTERS OF CONVECTION: ONE OVER NORTH CENTRAL NORTH
DAKOTA AND ANOTHER MOVING INTO FAR SOUTHWEST AND SOUTH CENTRAL
NORTH DAKOTA, BOTH TRAVELING NORTHEASTWARD. THE SPACE BETWEEN
THESE TWO AREAS IS LIKELY TO FILL IN EVENTUALLY, BUT THIS MAY
NOT OCCUR UNTIL MID TO LATE MORNING OVER THE EASTERN THIRD OF
THE STATE. SPC MESOANALYSIS INDICATES 40 TO 50 KTS OF EFFECTIVE
BULK SHEAR, BUT THIS MAY BE TOO HIGH AND ANALYZED FROM THE BASE
OF AN INFLOW LAYER DIFFERENT FROM THAT OF REALITY. WHILE STORMS
HAVE BEEN STRONG AT TIMES, WOULD ANTICIPATE MORE INTENSE AND
SUSTAINED UPDRAFTS WITH THAT AMOUNT OF SHEAR AND UP TO 1000 J/KG
MUCAPE. THROUGH THE REST OF THIS MORNING AND INTO THE
AFTERNOON, THE BROADER EXPANSE OF SHOWERS AND STORMS WILL
PROPAGATE NORTHEASTWARD INTO THE RED RIVER VALLEY IN CONGRUENCE
WITH A MID LEVEL SHORTWAVE AND THE ATTENDANT LOW LEVEL WARM AIR
ADVECTION/MOISTURE TRANSPORT. RECENT GUIDANCE HAS TRENDED
TOWARDS A DRIER AFTERNOON ACROSS WESTERN AND CENTRAL NORTH
DAKOTA, ALTHOUGH SMALLER CLUSTERS OF MORE WIDELY SCATTERED
SHOWERS AND STORMS COULD BE MAINTAINED BY MID LEVEL
FRONTOGENESIS ACROSS THE SOUTH AND A POLEWARD ADVANCING SURFACE
WARM FRONT ACROSS THE NORTH.
BY EARLY EVENING, THE LEFT EXIT REGION OF AN UPPER LEVEL JET
WILL REACH SOUTH CENTRAL NORTH DAKOTA OVER LOWER TO MID LEVEL
CYCLOGENESIS ADJACENT TO A STRENGTHENING LOW LEVEL JET. THIS IS
EXPECTED TO PRODUCE ANOTHER ROUND OF WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS ACROSS CENTRAL AND EASTERN NORTH DAKOTA
THAT COULD PERSIST THROUGH TONIGHT. THIS APPEARS TO BE A
FAVORABLE SETUP FOR TRAINING CONVECTION THAT COULD PRODUCE
LOCALIZED AREAS OF FLASH FLOODING, WITH STORM MOTION AND DEEP
LAYER WIND VECTORS INTERSECTING THE LOW LEVEL JET AND MOISTURE
TRANSPORT VECTORS AT AN ANGLE GREATER THAN 45 DEGREES,
PRECIPITABLE WATER APPROACHING CLIMATOLOGICAL MAXIMUM VALUES,
HIGH DEEP LAYER RH, DEEP WARM CLOUD DEPTHS, AND SKINNY CAPE
PROFILES. NEARLY EVERY CAM PRODUCES A NARROW SWATH OF AT LEAST
3 TO 5 INCHES OF TOTAL RAINFALL THIS MORNING THROUGH TONIGHT.
THE MOST PROBABLE AREA FOR THIS TO OCCUR IS FROM THE MISSOURI
RIVER SOUTH OF LAKE SAKAKAWEA TO THE RED RIVER VALLEY NORTH OF
FARGO. BUT ONLY A SMALL FRACTION WITHIN THAT BROADER AREA WILL
SEE THE EXCESSIVELY HIGH RAIN AMOUNTS AND RISK FOR FLOODING.
WITH THE FORECAST TRANSITIONING TO A DRIER AFTERNOON AND MUCH
MORE ACTIVE EVENING AND OVERNIGHT TIME PERIOD, THE RISK FOR
SEVERE THUNDERSTORMS HAS DECREASED. BUT THERE AREA STILL A
HANDFUL OF CAMS IN BOTH THE HREF AND REFS THAT PRODUCE UH
TRACKS SUFFICIENT FOR SEVERE WEATHER DURING THE LATE AFTERNOON
AND EVENING FROM LAKE OAHE TO THE JAMES RIVER VALLEY. IF A
STORM IS ABLE TO BECOME SURFACE-BASED WITH NO INHIBITION LATE
THIS AFTERNOON, ALL HAZARDS INCLUDING A TORNADO WOULD BE
POSSIBLE. BUT THE PROBABILITY OF THIS OCCURRING IS TRENDING
LOWER. STRONG THUNDERSTORMS CAN STILL BE EXPECTED THOUGH, BOTH
THIS EVENING THROUGH TONIGHT AND ALSO WITH THE FIRST ROUND OF
CONVECTION THIS MORNING INTO THE EARLY AFTERNOON. THE MAIN
HAZARD WITH STRONGER STORMS (ASIDE FROM EXCESSIVE RAIN AND
LIGHTNING) IS EXPECTED TO BE HAIL UP TO NICKEL SIZE.
TODAY WILL BE COOLER BUT HUMID, WITH HIGHS IN THE UPPER 50S TO
UPPER 60S. FOG COULD DEVELOP ACROSS MUCH OF THE AREA TONIGHT
INTO TUESDAY MORNING AS A SURFACE RIDGE FORMS ACROSS WESTERN
AND NORTH CENTRAL NORTH DAKOTA. ASIDE FROM MORNING FOG AND A
FEW LINGERING EARLY MORNING SHOWERS, TUESDAY SHOULD BE DRY AND
SUNNIER WITH HIGHS RETURNING TO THE UPPER 60S TO UPPER 70S. DRY
WEATHER CONTINUES ON WEDNESDAY AS A DEEPENING TROUGH OVER
CENTRAL CANADA PUSHES A COOLER AIR MASS DOWN FROM THE NORTH.
THE TIMING OF THIS COLD FRONT HAS SPED UP FROM PREVIOUS
FORECASTS, WITH HIGHS ACROSS THE NORTH NOW ONLY PROJECTED TO
REACH THE LOWER TO MID 60S ON WEDNESDAY. THE WEDNESDAY NIGHT
LOW TEMPERATURE FORECAST HAS ALSO COOLED, WITH WIDESPREAD MID
30S TO LOWER 40S AND A POTENTIAL FOR PATCHY FROST TO DEVELOP IN
LOW-LYING, SHELTERED AREAS. THE COOLER BUT SEASONABLE AIR MASS
COULD HANG AROUND UNTIL A POTENTIAL CLIPPER ARRIVES THIS
WEEKEND, BUT THERE IS SOME ENSEMBLE SUPPORT FOR A BRIEF WARM UP
TO END THE WORK WEEK.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1247 PM CDT MON SEP 28 2026
IFR WITH RAIN IN THE EAST, TO VFR CIGS IN THE WEST. WIDESPREAD
RAIN SHOWERS WITH ISOLATED THUNDERSTORMS WILL CONTINUE IN THE
CENTRAL AND EAST THROUGH THE OVERNIGHT. THEN FOG COULD SPREAD
WEST TO EAST IN THE EARLY MORNING.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...SMITH
DISCUSSION...HOLLAN
AVIATION...SMITH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page