648
FXUS63 KBIS 091703
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1203 PM CDT SAT MAY 9 2026
KEY MESSAGES
- COOLER AND BREEZY TODAY, WITH CRITICAL FIRE WEATHER CONDITIONS
IN NORTHWEST AND NORTH CENTRAL PARTS OF THE STATE AND NEAR-
CRITICAL CONDITIONS ELSEWHERE.
- SUB-FREEZING LOW TEMPERATURES ARE FORECAST ACROSS MUCH OF
WESTERN AND CENTRAL NORTH DAKOTA TONIGHT.
- WARMER AND WINDY WEATHER NEXT WEEK COULD LEAD TO DAILY
CRITICAL FIRE WEATHER CONDITIONS, ESPECIALLY MONDAY THROUGH
TUESDAY.
- ONLY OCCASIONAL LOW CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH THE END OF NEXT WEEK.
UPDATE
ISSUED AT 1150 AM CDT SAT MAY 9 2026
FOR MID-DAY UPDATE MAIN CHANGE WAS TO ISSUE A FREEZE
WARNING FOR ALMOST ALL OF OUR AREA FOR TONIGHT, WITH A FROST
ADVISORY OVER REMAINING AREAS. WITH THE WINDS LOOKING TO
DIMINISH AS A SURFACE HIGH SETTLES THROUGH, IT STILL REMAINED
VERY REASONABLE TO DROP LOW TEMPERATURES BELOW GUIDANCE ON
TRACK WITH WHAT THE PREVIOUS SHIFT DID. REMAINDER OF FORECAST
CONTINUES TO BE ON TRACK.
UPDATE ISSUED AT 917 AM CDT SAT MAY 9 2026
QUIET WEATHER REMAINS OVER THE AREA, WITH THE FORECAST REMAINING
ON TRACK.
UPDATE
ISSUED AT 643 AM CDT SAT MAY 9 2026
THE FORECAST REMAINS ON TRACK, ALTHOUGH EARLY MORNING
TEMPERATURES ACROSS PARTS OF NORTHERN NORTH DAKOTA HAVE NOW
FALLEN WELL BELOW FREEZING. COULD SEE SOME PATCHY, SHALLOW
GROUND FOG EARLY THIS MORNING, WITH NO IMPACTS ANTICIPATED.
DISCUSSION
ISSUED AT 525 AM CDT SAT MAY 9 2026
NORTHWEST FLOW PREVAILS OVER THE NORTHERN PLAINS EARLY THIS
MORNING, WITH WATER VAPOR IMAGERY SHOWING A SHORTWAVE MOVING
ACROSS THE GREAT LAKES. A COLD FRONT ATTENDANT TO THIS WAVE HAS
SAGGED INTO SOUTH DAKOTA AND IS USHERING IN ANOTHER COOL AND DRY
AIR MASS EMINATING FROM HIGH PRESSURE BUILDING OVER ALBERTA AND
SASKATCHEWAN. OVERNIGHT/EARLY MORNING TEMPERATURES HAVE FALLEN
INTO THE LOWER AND MID 30S ACROSS THE NORTHERN HALF OF THE STATE
WHERE A FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM CDT. DRIER
AND COOL WEATHER IS EXPECTED FOR THE REST OF TODAY, WITH HIGHS
IN THE MID 50S TO MID 60S. IT WILL NOT BE QUITE AS WINDY AS
YESTERDAY, BUT STILL EXPECTING NORTHWEST WINDS AROUND 15 TO 20
MPH WITH GUSTS TO NEAR 30 MPH THIS AFTERNOON. THE BREEZY
CONDITIONS COMBINED WITH LOW RH HAS PROMPTED THE ISSUANCE OF A
RED FLAG WARNING FOR PARTS OF NORTHWEST AND NORTH CENTRAL NORTH
DAKOTA THIS AFTERNOON AND EVENING. FOR ADDITIONAL DETAILS AND
INFORMATION, SEE THE FIRE WEATHER SECTION BELOW.
THE CANADIAN HIGH PRESSURE WILL EXPAND SOUTHEASTWARD TONIGHT.
HIGH CONFIDENCE IN A MOSTLY CLEAR SKY AND LIGHT WINDS HAS
PROMPTED US TO BLEND OUR LOW TEMPERATURE FORECAST FOR TONIGHT
CLOSER TO THE 25TH PERCENTILE OF THE NBM DISTRIBUTION. THIS
GIVES SUB-FREEZING TEMPERATURES TO ALL BUT PARTS OF THE FAR
SOUTHWEST AND FAR SOUTH CENTRAL, AND FORECAST LOWS AS COLD AS
THE MID 20S ACROSS THE NORTHWEST AND NORTH CENTRAL. A FREEZE
WARNING WILL LIKELY BE NEEDED FOR MOST OF WESTERN AND CENTRAL
NORTH DAKOTA TONIGHT, BUT WILL HOLD OFF ON ISSUANCE UNTIL THE
ONGOING FROST ADVISORY RUNS ITS COURSE. AN UPPER LEVEL RIDGE
WILL BEGIN SHIFTING OFF THE NORTHERN ROCKIES TOWARDS THE
NORTHERN PLAINS ON SUNDAY AS THE SURFACE HIGH SLIDES THROUGH THE
RED AND UPPER MISSISSIPPI RIVER VALLEYS. THIS TURNS OFF THE
WIND MACHINE FOR A DAY AND PROVIDES A SLIGHT MOTHER'S DAY WARM
UP TO HIGHS AROUND 60 EAST TO 70 WEST.
A PROLONGED PERIOD OF DAILY CRITICAL FIRE WEATHER CONDITIONS
REMAINS IN THE FORECAST FOR THE UPCOMING WORK WEEK. SPECIFIC
DETAILS REGARDING THIS THREAT ARE DISCUSSED IN THE FIRE WEATHER
SECTION BELOW.
SOUTHERLY RETURN FLOW WILL COMMENCE OVER THE NORTHERN PLAINS BY
MONDAY MORNING AS THE TRANSIENT UPPER RIDGE SLIDES ACROSS THE
DAKOTAS AHEAD OF A POTENT SHORTWAVE EJECTING OFF THE SOUTHERN
CANADIAN ROCKIES. LATEST FORECAST GUIDANCE SHOWS SOUTH WINDS
COULD APPROACH ADVISORY CRITERIA MONDAY AFTERNOON, MAINLY ALONG
AND EAST OF HIGHWAY 83. LEE CYCLOGENESIS IS FORECAST OVER
SOUTHERN ALBERTA LATE SUNDAY NIGHT, AND THE ATTENDANT WARM
SECTOR/THERMAL RIDGE IS FORECAST TO REACH WESTERN NORTH DAKOTA
BY PEAK HEATING MONDAY AFTERNOON. MEDIAN NBM PERCENTILE HIGH
TEMPERATURES CONTINUE TO TREND WARMER, NOW FIRMLY IN THE LOWER
TO MID 80S WITH VERY LITTLE SPREAD IN THE FULL DISTRIBUTION
ACROSS WESTERN NORTH DAKOTA, AND STILL MOSTLY IN THE 70S EAST OF
HIGHWAY 83. THE COLD FRONT ATTENDANT TO THE LOW IS FORECAST TO
REACH WESTERN NORTH DAKOTA SOMETIME MONDAY AFTERNOON, BUT THERE
IS STILL SOME TIMING UNCERTAINTY TO BE WORKED OUT. DETERMINISTIC
AND ENSEMBLE GUIDANCE CONTINUES TO SHOW A NARROW RIBBON OF CAPE
AHEAD OF THE COLD FRONT, BUT THERE ARE QUESTIONS WHETHER IT
WILL BE SUFFICIENT TO SUPPORT DEEP MOIST CONVECTION AND ALSO
WHETHER A MID LEVEL CAPPING INVERSION WILL ERODE PRIOR TO THE
ARRIVAL OF STRONGEST FORCING. A REASONABLE WORST-CASE
ENVIRONMENT WOULD FEATURE AROUND 500 J/KG CAPE WITH UP TO 60 KTS
OF EFFECTIVE BULK SHEAR, WHICH WOULD BE SUFFICIENT TO AT LEAST
SUPPORT A DAMAGING WIND THREAT. NEVERTHELESS, ANY SHOWERS OR
SUB-SEVERE STORMS COULD MIX STRONG WIND GUSTS TO THE SURFACE
THROUGH EVAPORATIVE COOLING AND DOWNWARD MOMENTUM TRANSFER
MECHANISMS. THE NBM PROBABILITY OF ANY SHOWERS AND STORMS ALONG
AND TO THE WEST OF HIGHWAY 83 IS VERY LOW, BUT THE LATEST
ITERATION OF ENSEMBLE CLUSTERS PAINT A DIFFERENT PICTURE.
GUSTY NORTHWEST WINDS WILL TRAIL THE COLD FRONT, AND COULD
BECOME QUITE STRONG ON TUESDAY. ENSEMBLE CLUSTER MEAN 850 MB
WINDS IN THE POST FRONTAL AIR MASS HAVE TRENDED UPWARD CLOSER TO
35-40 KTS, AND THERE ARE NOW LOW PROBABILITIES FOR EXCEEDING 50
KTS IN EASTERN NORTH DAKOTA ON TUESDAY. THE EFI IS ALSO
BEGINNING TO SHOW A STRONGER WIND SIGNAL ACROSS THE EASTERN HALF
OF THE STATE ON TUESDAY. GIVEN THE TIME OF YEAR AND TRAJECTORY
OF THE SHORTWAVE/LOW, ONLY A MINOR DENT IN HIGH TEMPERATURES IS
PROJECTED FOR TUESDAY, RANGING FROM MID 60S NORTHEAST TO MID 70S
WEST. BEYOND TUESDAY, THERE IS NOW HIGHER ENSEMBLE CONFIDENCE
IN AN AMPLIFIED UPPER RIDGE PIVOTING INTO THE CENTRAL CONUS,
FOLLOWED BY TIMING UNCERTAINTY ON A TRANSITION TO A PROGRESSIVE
HIGH-AMPLITUDE WAVE PATTERN BY THE END OF THE WEEK. THIS
TRANSLATES TO ABOVE NORMAL TEMPERATURES BEING FAVORED AND,
HOPEFULLY, HIGHER AND MORE FREQUENT CHANCES FOR RAIN ONCE THE
RIDGE BREAKS DOWN. NBM TEMPERATURE SPREAD BECOMES LARGER FOR THE
SECOND HALF OF NEXT WEEK, BUT EVEN THE 25TH PERCENTILE OF HIGH
TEMPERATURES IS NEAR TO ABOVE NORMAL, AND THE 75TH PERCENTILE
BEGINS TO APPROACH 90 DEGREES.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 1150 AM CDT SAT MAY 9 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 525 AM CDT SAT MAY 9 2026
ALTHOUGH COOLER TEMPERATURES IN THE 50S AND 60S ARE EXPECTED
THIS AFTERNOON, DEWPOINTS IN THE 20S AND TEENS WILL YIELD
MINIMUM RH AROUND 15 TO 20 PERCENT ACROSS MUCH OF NORTHWEST AND
CENTRAL NORTH DAKOTA. THE WIND FORECAST FOR THIS AFTERNOON HAS
BACKED OFF SLIGHTLY, BUT STILL EXPECTING TO SEE NORTHWEST WINDS
AROUND 15 TO 20 MPH ACROSS MOST OF THE STATE. WITH FORECAST
CONDITIONS BARLEY TOUCHING ON OR JUST MARGINALLY EXCEEDING
CRITICAL VALUES, WE LIMITED THE SCOPE OF TODAY'S RED FLAG
WARNING TO 1) WHERE CONFIDENCE IS HIGHEST IN RH UNDER 20
PERCENT AND 2) WHERE THERE HAS BEEN OVER 200 DAYS SINCE THE
LAST DAILY PRECIPITATION OF OVER HALF AN INCH, WHICH LOCAL
RESEARCH INDICATES COULD BE A CORRELATING FACTOR TO LARGER
WILDFIRES. THE WARNING IS IN EFFECT FROM 1 PM TO 9 PM CDT FOR
DIVIDE, WILLIAMS, BURKE, MOUNTRAIL, RENVILLE, AND WARD COUNTIES.
SHOULD WINDS TREND HIGHER THAN WHAT IS FORECAST, A
SOUTHEASTWARD EXPANSION OF THE WARNING THROUGH THE MISSOURI
RIVER VALLEY WOULD NEED TO BE CONSIDERED.
FIRE WEATHER CONCERNS ARE RELATIVELY LOWEST ON SUNDAY, WITH
FORECAST MINIMUM RH AROUND 20 TO 30 PERCENT AND AFTERNOON WINDS
RANGING FROM NORTHERLY AROUND 10 MPH IN THE JAMES RIVER VALLEY
TO VARIABLE AROUND 5 MPH OR LESS ACROSS THE REST OF WESTERN AND
CENTRAL NORTH DAKOTA.
THE MOST CONCERNING PERIOD FOR FIRE WEATHER THIS COMING WEEK IS
MONDAY THROUGH TUESDAY. BY MIDDAY MONDAY, SOUTHERLY WINDS ARE
FORECAST TO INCREASE TO AROUND 20 TO 30 MPH, STRONGEST BETWEEN
THE MISSOURI AND JAMES RIVER VALLEYS WHERE GUSTS COULD APPROACH
45 MPH. EVEN THOUGH SOUTHERLY WINDS WILL BE RELATIVELY LIGHTER
IN WESTERN NORTH DAKOTA TO START THE DAY, A COLD FRONT IS
SCHEDULED TO ARRIVE FROM THE WEST BY MID AFTERNOON. THIS COLD
FRONT WILL SHIFT WINDS TO THE NORTHWEST AND COULD INCREASE
SPEEDS AS HIGH AS 30 MPH, WITH GUSTS TO 45 MPH. THIS WIND SHIFT
COULD OCCUR CLOSE TO THE TIMING OF LOWEST DIURNAL HUMIDITY,
WHICH COULD BE UNDER 20 PERCENT IN SOME AREAS. THERE IS HIGH
CONFIDENCE IN MINIMUM RH AROUND 20 PERCENT WEST TO 30 PERCENT
CENTRAL ON MONDAY. BUT EVEN WITH THE SLIGHTLY HIGHER RH IN
CENTRAL NORTH DAKOTA, THE SOUTHERLY WINDS COULD STILL BE STRONG
ENOUGH TO APPROACH CRITICAL FIRE WEATHER CONDITIONS.
THE COLD FRONT WILL CONTINUE TO PROGRESS EASTWARD ACROSS THE
STATE MONDAY EVENING, SHIFTING WINDS TO THE NORTHWEST. THE
STRENGTH OF GUSTS TRAILING THE FRONT BECOMES LESS CERTAIN WITH
THE LOSS OF DIURNAL HEATING, BUT DETERMINISTIC GUIDANCE DOES
SHOW MODEST VALUES OF COLD AIR ADVECTION AND PRESSURE RISES
PAIRED WITH AN INCREASING LOW LEVEL WRAP-AROUND JET. ENSEMBLES
CONTINUE TO TREND WINDIER FOR TUESDAY, WITH BROAD MEDIUM CHANCES
FOR NORTHWEST WINDS GUSTING IN EXCESS OF 50 MPH ACROSS THE
EASTERN HALF OF THE STATE. THE SUSTAINED WINDS OF 35 TO 40 MPH
PROJECTED BY THE LATEST ITERATION OF THE NBM MAY BE TOO HIGH,
BUT STILL RESEMBLE A REASONABLE WORST-CASE SCENARIO. THE MINIMUM
HUMIDITY FORECAST FOR TUESDAY IS AROUND 20 PERCENT FOR THE
WESTERN HALF OF THE STATE, WITH EVEN LOWER POCKETS IN THE FAR
WEST. FROM THE TURTLE MOUNTAINS THROUGH THE NORTHERN JAMES RIVER
VALLEY, MINIMUM RH IS CLOSER TO 30 PERCENT. EVEN THOUGH THE
STRONGEST WINDS MAY NOT OVERLAP WITH THE LOWEST RH ON TUESDAY,
THERE IS STILL POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS
ACROSS ALL OF WESTERN AND CENTRAL NORTH DAKOTA. AREAS OF
GREATEST CONCERN ON TUESDAY INCLUDE NORTHWEST PARTS OF THE
STATE ALONG AND NORTH OF THE MISSOURI RIVER, ALL OF CENTRAL
NORTH DAKOTA, AND ESPECIALLY AREAS FROM EAST OF LAKE OAHE TO
THE SOUTHERN JAMES RIVER VALLEY WHERE A STRONGER WIND OUTCOME
COULD PLACE THE ENTIRE AFTERNOON AND EARLY EVENING IN NON-STOP
CRITICAL CONDITIONS.
ON WEDNESDAY, LATEST FORECAST GUIDANCE PLACES THE HIGHEST FIRE
WEATHER CONCERNS BACK OVER WESTERN NORTH DAKOTA, WITH SOUTHERLY
WINDS PROJECTED TO INCREASE TO AROUND 25 MPH AND MINIMUM RH
AROUND 20 PERCENT. FORECAST DETAILS BECOME LESS CERTAIN TO END
THE WEEK, BUT EVERY DAY THROUGH AT LEAST SATURDAY HAS A
POTENTIAL FOR WARM TEMPERATURES, LOW RH, AND GUSTY WINDS.
BIS WATCHES/WARNINGS/ADVISORIES
RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR NDZ001>003-
009>011.
FREEZE WARNING FROM 1 AM CDT /MIDNIGHT MDT/ TO 9 AM CDT /8 AM
MDT/ SUNDAY FOR NDZ001>005-009-010-012-013-017>020-022-023-025-
033-035>037-046>048-050-051-055>060.
FROST ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ TO 9 AM CDT /8 AM
MDT/ SUNDAY FOR NDZ031-032-040>044-061-062.
UPDATE...JJS
DISCUSSION...HOLLAN
AVIATION...JJS
FIRE WEATHER...HOLLAN
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