638
FXUS63 KBIS 251138
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
638 AM CDT SAT JUL 25 2026
KEY MESSAGES
- VERY HOT CONDITIONS THROUGH THE WEEKEND, WITH DANGEROUSLY
HIGH TEMPERATURES AND HEAT INDEX VALUES AROUND 100 TO 105
DEGREES.
- SMOKE FROM DISTANT WILDFIRES WILL MAKE SKIES HAZY AND MAY
REDUCE SURFACE VISIBILITY TODAY.
- THE COMBINATION OF HOT, DRY, AND BREEZY CONDITIONS ON SUNDAY
MAY CAUSE NEAR-CRITICAL FIRE WEATHER CONDITIONS IN PARTS OF
WESTERN AND CENTRAL NORTH DAKOTA.
UPDATE
ISSUED AT 638 AM CDT SAT JUL 25 2026
WE ARE STARTING TO SEE MORE WIDELY SCATTERED LOW VISIBILITIES
FROM PATCHY FOG, ESPECIALLY IN PARTS OF THE NORTHWEST AND NORTH
CENTRAL, AS WELL AS THE JAMES RIVER VALLEY AREA. SOME OF THIS
FOG IS VERY SHALLOW GROUND FOG, WHICH IS WHAT WAS RECENTLY
OBSERVED AT THE OFFICE. THE EXPECTATION IS THIS SHOULD BURN OFF
THROUGH MID-MORNING BUT THOSE OUT AND ABOUT THIS MORNING COULD
ENCOUNTER SPORADIC REDUCED VISIBILITIES. A SPECIAL WEATHER
STATEMENT IS OUT UNTIL THE TOP OF THE HOUR BUT WILL LIKELY ISSUE
ANOTHER LARGER ONE TO COVER THIS HAZARD.
DISCUSSION
ISSUED AT 332 AM CDT SAT JUL 25 2026
THIS MORNING, THE SYNOPTIC PATTERN ACROSS THE CONUS WAS
CHARACTERIZED BY A STOUT UPPER HIGH OVER THE FOUR CORNERS
REGION, WITH THE RIDGE AXIS EXTENDING OVER THE NORTHERN ROCKIES
AND INTO THE SOUTHERN CANADIAN PRAIRIES. SURFACE HIGH PRESSURE
WAS CENTERED IN SOUTHWEST MANITOBA, WITH GENERALLY LIGHT AND
VARIABLE WINDS THAT AID IN THE POTENTIAL DEVELOPMENT OF FOG
ACROSS THE FORECAST AREA THIS MORNING. A FEW AUTOMATED SITES IN
THE NORTHWEST ARE STARTING TO REPORT MODERATELY REDUCED
VISIBILITY, BUT WEBCAMS LOOK PRETTY CLEAR, AT LEAST FOR NOW.
UNDERNEATH THE RIDGE, A POTENT LOW-LEVEL THERMAL RIDGE EXTENDS
ACROSS THE STATE, WITH 850MB TEMPERATURES AS WARM AS 29 DEGREES
C OVER SOUTHWEST NORTH DAKOTA. A HEAT ADVISORY IS IN EFFECT FOR
MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THIS AFTERNOON THROUGH
SUNDAY, WITH THE EXCEPTION OF OUR NORTHERN TWO TIERS OF
COUNTIES. AMBIENT AIR TEMPERATURES WILL GENERALLY RANGE FROM 95
TO 105 TODAY, WITH HEAT INDICES AT A SIMILAR LEVEL.
HRRR SMOKE MODEL OUTPUT IS SIMILAR TO YESTERDAY, ALTHOUGH
SKY OBSERVATIONS DIDN'T SEEM TO SHOW QUITE AS MUCH SMOKE AS WE
WOULD HAVE EXPECTED BASED ON LEVELS THE MODEL WAS ADVERTISING.
HOWEVER, STILL CARRYING MENTION OF PATCHY SMOKE, WITH SOME
POTENTIAL FOR MINOR SURFACE IMPACTS. OTHERWISE, MAINLY SUNNY
TODAY, JUST COULD BE HAZY SUNSHINE DEPENDING ON HOW THICK THE
SMOKE ALOFT ENDS UP.
A TRANSIENT SHORTWAVE AND WEAK SURFACE LOW ARE PROGGED TO TRACK
THROUGH NORTHERN SOUTH DAKOTA, WITH LOW POPS SKIRTING OUR
SOUTHERN COUNTIES. SPC ISOLATED THUNDERSTORMS AREA (LEVEL 1 OUT
OF 5) TAGS OUR EXTREME FAR SOUTHWEST, BUT THINKING ANY POTENTIAL
FOR STRONGER TO SEVERE STORMS IS PRETTY LOW, WITH DETERMINISTIC
GUIDANCE SHOWING INSTABILITY AT 1000 J/KG OR LESS.
HOT AND DRY WEATHER CONTINUES ON SUNDAY, WITH SIMILAR HIGH
TEMPERATURES AS TODAY AND THE HEAT ADVISORY CONTINUING. MAIN
FORECAST CONCERN ON SUNDAY IS NEAR CRITICAL FIRE WEATHER
CONDITIONS, GENERALLY FOR AREAS SOUTH AND WEST OF THE MISSOURI
RIVER. MINIMUM RELATIVE HUMIDITY WILL BE IN THE MID TO UPPER
TEENS FOR THIS AREA, BUT BREEZY NORTHWEST WINDS AROUND 20 MPH
ARE ENOUGH TO LIKELY REACH NEAR CRITICAL CONDITIONS.
NOT MANY CHANGES ARE EXPECTED LOOKING AHEAD TO THE FORECAST FOR
NEXT WORK WEEK. NBM TEMPERATURE PERCENTILE SPREADS ARE
RELATIVELY SMALL, INDICATING HIGH CONFIDENCE IN MAX TEMPERATURES
STAYING IN THE 90S, IF NOT AROUND 100 DEGREES F. THERE ARE ON
AND OFF CHANCES FOR SHOWERS AND THUNDERSTORMS AS EMBEDDED WAVES
MOVE THROUGH AND THE RIDGE AXIS SHIFTS AROUND THE REGION, BUT NO
ONE DAY STANDS OUT IN PARTICULAR. THERE IS POTENTIAL FOR STORMS
TO BE STRONG TO SEVERE DURING THIS PERIOD PER NSSL AND CSU
MACHINE LEARNING PROBABILITIES.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 638 AM CDT SAT JUL 25 2026
GENERALLY VFR CONDITIONS AT ALL TERMINALS THROUGH THE TAF
PERIOD. WE ARE SEEING SOME PATCHY FOG TO START THE TAF PERIOD,
WITH SOME OF IT VERY SHALLOW GROUND FOG, SO INCLUDED TEMPO
GROUNDS AT KBIS, KJMS, AND KMOT. ALSO HAVE HIGH-LEVEL SMOKE
CONTINUING TO FILTER THROUGH THE REGION, WHICH COULD
OCCASIONALLY LEAD TO MINOR SURFACE VISIBILITY REDUCTIONS.
GENERALLY LIGHT AND VARIABLE WINDS THIS MORNING WILL BE
WESTERLY THROUGH THE DAY TODAY BEFORE BECOMING MORE
SOUTHEASTERLY LATE IN THE TAF PERIOD, AND SHOULD BE STAYING
AROUND 10 KNOTS OR LESS.
BIS WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 9 PM
CDT /8 PM MDT/ SUNDAY FOR NDZ017>020-022-023-025-031>033-
035>037-040>044-046>048-050-051-057>062.
UPDATE...JONES
DISCUSSION...JONES
AVIATION...JONES
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