400
FXUS63 KBIS 110618
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
118 AM CDT FRI SEP 11 2026
KEY MESSAGES
- A COOLING TREND IS EXPECTED THIS COMING WEEKEND.
- WIDESPREAD PRECIPITATION CHANCES (60 TO 80%) RETURN SUNDAY
NIGHT INTO MONDAY MORNING, WITH LOW CHANCES BEFORE AND AFTER
THIS PERIOD.
UPDATE
ISSUED AT 111 AM CDT FRI SEP 11 2026
COLD FRONT HAS NOW ENTERED FAR NORTHERN PORTIONS OF THE AREA,
WITH WINDS SHIFTING NORTHERLY. NO CHANGES NEEDED TO THE FORECAST
AT THIS TIME.
UPDATE
ISSUED AT 835 PM CDT THU SEP 10 2026
RELATIVE HUMIDITIES ACROSS IN THE SOUTHWESTERN CORNER OF THE
STATE HAVE BEEN STEADILY IMPROVING INTO THE 20-30%. TREND WILL
CONTINUE UPWARD THROUGH THE NIGHT. WINDS HAVE SUBSIDED AS WELL.
THEREFORE, THE RED FLAG WARNING WAS ALLOWED TO EXPIRE AT 9 PM.
OTHERWISE, NO CHANGES TO THE FORECAST AND ESPECIALLY WITH THE
FRONTAL PASSAGE THAT WILL OCCUR LATE TONIGHT TO EARLY FRIDAY
MORNING.
UPDATE
ISSUED AT 620 PM CDT THU SEP 10 2026
WINDS HAVE ALREADY PEAKED INTENSITY FOR THE DAY AND THEY ARE
STARTING TO DECREASE FOR THE REST OF THE EVENING. MAX WIND GUST
HAS BEEN 35 MPH. RED FLAG WARNING IS STILL IN EFFECT DUE TO THE
VERY DRY AND BREEZY CONDITIONS FOR THE SOUTHWESTERN PORTION OF
THE STATE THROUGH 9 PM CENTRAL / 8 PM MOUNTAIN. OVERNIGHT
RELATIVE HUMIDITIES WILL BOUNCE BACK ABOVE 60 PERCENT IN THE
MIDDLE OF THE NIGHT WITH CONTINUE BREEZES. OTHERWISE, WE ARE
STILL ON TRACK FOR THE FRONTAL PASSAGE LATE TONIGHT, SHIFTING
WINDS TO MORE NORTHERLY TO NORTHWESTERLY.
DISCUSSION
ISSUED AT 320 PM CDT THU SEP 10 2026
CURRENTLY, ZONAL FLOW ALOFT IN THE WAKE OF A WEAK S/WV RIDGE AND
A DEVELOPING UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST.
CLOSED UPPER LEVEL LOW OVER CENTRAL CANADA WITH AN ASSOCIATED
SFC TROUGH/FRONTAL BOUNDARY STRETCHED FROM SOUTH CENTRAL CANADA
SOUTH/SOUTHWEST TO ACROSS THE NORTHERN HIGH PLAINS OF MT/WY TO
OUR WEST. THIS SURFACE PATTERN RESULTS IN A SOUTH/SOUTHWESTERLY
LOW/MID LEVEL FLOW ACROSS THE DAKOTAS, ALLOWING FOR VERY DRY
AIR TO ADVECT INTO MUCH OF WESTERN AND CENTRAL NORTH DAKOTA
THIS AFTERNOON. A RED FLAG WARNING REMAINS IN EFFECT FOR SEVERAL
MORE HOURS FOR AREAS SOUTH AND WEST OF THE MISSOURI RIVER, WHERE
LATEST OBSERVATIONS REPORT PERCENT RH VALUES AS LOW AS THE
LOWER TO MID TEENS TO LOWER 20S AND STEADY SOUTHWEST WINDS
SUSTAINED TO AT LEAST 15 KNOTS (SEE FIRE WEATHER DISCUSSION
BELOW).
UPPER LOW OVER CENTRAL CANADA CONTINUES EAST TONIGHT, AND WILL
DRIVE THE AFOREMENTIONED SFC TROUGH SOUTH ACROSS WESTERN AND
CENTRAL NORTH DAKOTA LATE TONIGHT THROUGH FRIDAY AM. WINDS WILL
SHIFT FROM SOUTH/SOUTHWESTERLY TO NORTHERLY BEHIND THE FROPA,
AND WILL BECOME GUSTY DURING THE DAY FRIDAY WITH A DECENT
PRESSURE GRADIENT AND MIXING PERSISTING. FRI AFT TEMPERATURES
DROP 10-20 DEGREES FROM TODAY, WITH A MIX OF SUN AND CLOUDS. ZONAL
FLOW TRANSITIONS TO A WEST/SOUTHWESTERLY FLOW ALOFT TONIGHT/FRI,
WITH AN EMBEDDED WAVE BRINGING SOME LIGHT SHOWER CHANCES TO
NORTHWEST AREAS OF THE STATE DURING THE DAY.
WE REMAIN IN A QUASI-ZONAL FLOW REGIME THROUGH SAT NIGHT, ALONG
WITH THE UPPER LEVEL JET STREAM SAGGING FARTHER TO THE SOUTH.
THIS RESULTS IN TEMPERATURES TRENDING COOLER/WELL BELOW NORMAL
FOR THE WEEKEND, WITH HIGHS IN THE 60S BOTH SATURDAY AND SUNDAY
AND LOWS WELL INTO THE 40S (30S ARE A SAFE BET FOR LOWER LYING
AREAS). FAIRLY POTENT UPPER LOW DEVELOPS INTO THE PACIFIC
NORTHWEST SAT/SAT NIGHT, WHICH FURTHER DEVELOPS INTO THE
NORTHERN ROCKIES SUNDAY BEFORE LIFTING EAST-NORTHEAST ACROSS
THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY. INCREASING
UPPER LEVEL DIVERGENCE AHEAD OF THIS WAVE, COUPLED WITH AN
INVERTED SFC TROUGH MOVING FROM WEST TO EAST ACROSS THE REGION.
THIS FEATURE WILL BRING ELEVATED WIDESPREAD PRECIPITATION
CHANCES TO OUR AREA, WITH FORECAST QPF RANGING FROM 0.5 - 1 INCH
SUN EVENING THROUGH MONDAY MORNING. INSTABILITY LIMITED DURING
THIS PERIOD, SO PERHAPS SOME EMBEDDED THUNDER THOUGH WITH
CHANCES FOR ANY SEVERE LOW.
THEREAFTER, MUCH OF NEXT WEEK IS FAVORED TO BE IN A
WEST/NORTHWEST FLOW PATTERN, WHICH WOULD SUPPORT A GRADUAL
MODERATION/WARMING OF TEMPERATURES AND MINIMAL CHANCES FOR
PRECIPITATION.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 111 AM CDT FRI SEP 11 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A COLD
FRONT WILL SHIFT THROUGH THE AREA OVERNIGHT INTO FRIDAY MORNING
FROM NORTHWEST TO SOUTHEAST, WITH WINDS BECOMING NORTHERLY IN
ITS WAKE. GUSTS TO 30 KTS POSSIBLE DURING THE DAY.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...JJS
DISCUSSION...NH
AVIATION...JJS
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