669
FXUS63 KBIS 221935
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
235 PM CDT TUE SEP 22 2026
KEY MESSAGES
- SEASONABLE TEMPERATURES ARE FAVORED THROUGH THE WEEKEND, WITH
HIGHS MOSTLY IN THE 60S AND 70S AND LOWS IN THE 40S AND 50S.
- MEDIUM TO HIGH CHANCES FOR SHOWERS AND A FEW THUNDERSTORMS ON
WEDNESDAY. THEN, LOW TO MEDIUM CHANCES FOR MAINLY SHOWERS ON
FRIDAY.
DISCUSSION
ISSUED AT 235 PM CDT TUE SEP 22 2026
A SOMEWHAT CHAOTIC FLOW PATTERN IS FOUND OVER THE NORTHERN
PLAINS THIS AFTERNOON AS A DEVELOPING RIDGE TO THE WEST OF THE
FORECAST BUTTS UP AGAINST AN EXITING UPPER LEVEL LOW EXITING
INTO THE GREAT LAKES REGION. INCREASINGLY CLOUDY SKIES ARE
EXPECTED THROUGH THE AFTERNOON AND EVENING AS MOISTURE RETURNS
FROM THE GULF INCREASE ACROSS THE STATE. HIGHS TODAY WILL THUS
BE WARMEST IN THE UPPER 60S TO LOWER 70S ACROSS THE NORTHWEST
AND NORTH CENTRAL WHERE PARTLY CLOUDY TO MOSTLY CLEAR SKIES
LINGER THE LONGEST, WHILE THE SOUTHWEST AND SOUTH CENTRAL WILL
ONLY PEAK INTO THE LOWER TO MID 60S. BREEZY SOUTH TO
SOUTHEASTERLY WINDS, WITH SUSTAINED SPEEDS UP TO AROUND 25 MPH
AND GUSTS UP TO 35 MPH, WILL BE FOUND AS A MODEST PRESSURE
GRADIENT IS DRAPED ACROSS THE NORTHERN PLAINS AND WILL LINGER
OVERNIGHT INTO EARLY WEDNESDAY. OTHERWISE, THE INCREASING CLOUD
COVER AND PERSISTANT SOUTHERLY SURFACE FLOW ARE EXPECTED TO KEEP
LOW TEMPERATURES TONIGHT MAINLY IN THE MID 40S TO LOWER 50S.
UPPER LEVEL FLOW OVER THE NORTHERN PLAINS IS THEN EXPECTED TO
CONSOLIDATE AND TURN INCREASINGLY SOUTHWESTERLY LATE TONIGHT
INTO EARLY WEDNESDAY AS A SHORTWAVE PERTURBATION PASSES THROUGH
THE AREA. ALONG WITH THE INCREASING MOISTURE ACROSS THE AREA,
THIS WAVE WILL PROMOTE MEDIUM TO HIGH (50 TO 80 PERCENT) CHANCES
FOR SHOWERS ACROSS WESTERN AND CENTRAL NORTH DAKOTA STARTING
WEDNESDAY MORNING, WITH ISOLATED THUNDERSTORMS ALSO POSSIBLE (20
TO 30 PERCENT) WEDNESDAY AFTERNOON AND EVENING. WHILE THE
INITIAL CONVECTIVE ENVIRONMENT IS EXPECTED TO BE FAIRLY TAME,
WITH MUCAPE VALUES PEAKING ONLY AROUND 500-750 J/KG ABOVE THE
PREVAILING CLOUD LAYER AND COOLER SURFACE TEMPERATURES, THERE IS
SOME POTENTIAL FOR AN ISOLATED STRONGER STORM OVER THE
SOUTHWEST INTO THE SOUTH CENTRAL LATE WEDNESDAY AFTERNOON INTO
WEDNESDAY EVENING AS A WEAK COLD FRONT/SURFACE TROUGH IS PULLED
ACROSS THE AREA. THE OVERALL POTENTIAL FOR HAZARDS REMAINS LOW,
WITH SUB SEVERE WINDS AND MAYBE SOME SMALL EXPECTED WITH ANY
STRONGER STORM THAT DOES DEVELOP. STORM TOTAL RAIN THROUGH LATE
WEDNESDAY ARE ANTICIPATED TO BE LIGHT, WITH AMOUNTS GENERALLY
FROM AROUND 0.10" ACROSS THE WEST UP TO AROUND 0.25" TO 0.75"
CENTRAL. WHILE THE CURRENT CALIBRATED NBM CHANCE TO EXCEED 1.00"
IS LOW THROUGH THIS PERIOD, AROUND 15 TO 35 PERCENT ACROSS
PORTIONS OF THE NORTHERN JAMES RIVER VALLEY, HIGH MODEL PWATS
AROUND 1.25" INDICATE THAT LOCALLY HIGHER TOTALS CAN BE
ANTICIPATED WHERE AND WHEN THUNDERSTORMS DEVELOP. OTHERWISE, FOR
WEDNESDAY, HIGHS IN THE 60S TO LOWER 70S CAN BE ANTICIPATED AS
PREVAILING CLOUDS AND SHOWERS LIMIT DIURNAL HEATING POTENTIAL.
FOR THE END OF THE WORKWEEK, THE AMPLIFICATION OF A TRANSIENT
UPPER LEVEL RIDGE ACROSS THE NORTHERN PLAINS ON THURSDAY WILL
PROMOTE CLEARING SKIES, DRY WEATHER, AND WARMER TEMPERATURES IN
THE LOWER 70S AND 80S. THEN, HEADING INTO FRIDAY, LOW TO MEDIUM
CHANCES (30 TO 50 PERCENT) FOR SHOWERS WILL PASS ACROSS MUCH OF
WESTERN AND CENTRAL NORTH DAKOTA AS ANOTHER SHORTWAVE
PERTURBATION EJECTS OFF OF THE WESTERN ROCKIES AND PASSES NORTH
ACROSS THE FORECAST AREA. THE OVERALL POTENTIAL FOR
THUNDERSTORMS APPEARS TO BE FAIRLY LIMITED THROUGH THE DAY ON
FRIDAY, WITH ENSEMBLE MEMBERS ADVERTISING THE BETTER CONVECTIVE
ENVIRONMENT FURTHER TO THE SOUTH AND EAST OF THE FORECAST AREA.
WHILE IT WOULDN'T BE OVERLY SURPRISING TO SEE A RUMBLE OF
THUNDER OR TWO IN THE FAR SOUTHERN JAMES RIVER VALLEY, MAINLY
SHOWERS CAN BE ANTICIPATED AT THIS TIME. OVERALL QPF IS ALSO
EXPECTED TO BE FAIRLY LIMITED, WITH THE CALIBRATED NBM 5.0
PROBABILITY FOR MORE THAN 0.25" OF RAIN FAIRLY LOW (20 TO 40
PERCENT). OTHERWISE FOR FRIDAY, THE INCREASED CLOUD COVER
ASSOCIATED WITH THE SHOWERS WILL HELP PUT A DAMPER ON THE ABOVE
NORMAL TEMPERATURES PREVIOUSLY FORECAST IN EARLIER CYCLES, WITH
HIGHS NOW EXPECTED TO RANGE IN THE MID 60S TO MID 70S.
LOOKING AHEAD, THE WEEKEND IS GOING TO BE CHARACTERIZED THE
PASSAGE OF A STRONG PACIFIC TROUGH/CLOSED LOW ACROSS THE
CANADIAN PRAIRIES. MAINLY DRY AND WARM (HIGHS IN THE 60S AND
70S) CONDITIONS ARE EXPECTED AS FLOW OVER THE NORTHERN PLAINS
TURNS SOUTHWESTERLY ON THE LEADING EDGE OF THE TROUGH. THE
PREVAILING SOUTHEASTERLY WINDS OVER TURN NORTHWESTERLY ON
SATURDAY AS A COLD FRONT IS LOFTED THROUGH THE AREA, THOUGH POOR
SATURATION THROUGHOUT THE VERTICAL PROFILE WILL LIMIT OVERALL
CHANCES FOR PRECIPITATION. THE ENSEMBLE CONTINUES TO DELAY THE
ONSET PRECIPITATION OVER THE DAKOTAS COMPARED TO PREVIOUS
FORECAST CYCLES, DUE TO THE SLIGHTLY SLOWER EVOLUTION OF THIS
TROUGH. THERE IS FAIRLY STRONG AGREEMENT BETWEEN ENSEMBLE
MEMBERS FOR SHOWERS SOME TIME MONDAY THROUGH THE EARLY WORKWEEK,
THOUGH THERE IS A HINT IN SOME CLUSTERS (APPROX 30 PERCENT OF
MEMBERS) OF A MORE DIVERGENT FLOW PATTERN OVER THE NORTHERN
PLAINS. IN THIS PARTICULAR SCENARIO, MUCH OF THE FORECAST AREA
WOULD STRUGGLE TO SEE MUCH MEASURABLE PRECPITATION.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 235 PM CDT TUE SEP 22 2026
MVFR CEILINGS LINGER OVER PORTIONS OF SOUTHCENTRAL NORTH DAKOTA
TO BEGIN THE 18Z TAF PERIOD, WITH MVFR CEILINGS FOUND
ELSEWHERE. THROUGH THE LATE AFTERNOON AND EVENING, WIDESPREAD
MVFR CEILINGS ARE EXPECTED TO DEVELOP ACROSS THE FORECAST AREA
AND LINGER THROUGH THE END OF THE TAF PERIOD. CHANCES FOR
SHOWERS WILL INCREASE TONIGHT STARTING IN THE SOUTHWEST,
SPREADING TO CENTRAL NORTH DAKOTA WEDNESDAY MORNING THROUGH THE
END OF THE TAF PERIOD. WHEN AND WHERE SHOWERS DEVELOP, LOW MVFR
TO IFR CEILINGS ARE ANTICIPATED. THERE MAY BE SOME POTENTIAL FOR
PATCHY FOG OVER THE FAR SOUTHWEST LATE TONIGHT INTO EARLY
TOMORROW MORNING, THOUGH IS NOT ANTICIPATED TO IMPACT ANY GIVEN
TERMINAL AT THIS TIME. SOUTH TO SOUTHEAST WINDS ARE EXPECTED TO
CONTINUE TO STRENGTHEN THIS AFTERNOON THROUGH MUCH OF THE TAF
PERIOD, BECOMING GUSTY WITH SUSTAINED SPEEDS UP TO 25 KNOTS AND
GUSTS UP TO 35 KNOTS ACROSS THE WEST TODAY, THEN ACROSS THE
SOUTH CENTRAL WEDNESDAY MORNING.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...ADAM
AVIATION...ADAM
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