744
FXUS63 KBIS 281505
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1005 AM CDT TUE JUL 28 2026
KEY MESSAGES
- HOT AND SMOKY CONDITIONS CONTINUE THROUGH AT LEAST THE MIDDLE
OF THE WEEK, WITH HIGHS AROUND 90 TO 100.
- MEDIUM TO HIGH CHANCES (40 TO 70 PERCENT) FOR SHOWERS AND
THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH THURSDAY. A FEW
STORMS COULD BE SEVERE.
UPDATE
ISSUED AT 1000 AM CDT TUE JUL 28 2026
THE DENSE FOG ADVISORY HAS BEEN ALLOWED TO EXPIRE. VISIBILITIES
CONTINUE TO IMPROVE, BUT THERE WILL BE SOME PATCHY LOWER
VISIBILITIES FOR THE NEXT HOUR OR SO. WE ALSO ADJUSTED SKY
COVER DOWN A BIT IN THE SOUTH THROUGH THE MORNING. MOTORING A
FEW SHOWERS APPROACHING THE BORDER FROM EASTERN MONTANA. THERE
ARE A COUPLE OF SHOWER THAT MAY ENTER SOUTHWEST MCKENZIE IN THE
NEXT HOUR BUT NOT SURE THEY WILL SURVIVE. ADDITIONAL SHOWERS A
LITTLE FARTHER WEST WILL TAKE A BIT LONGER TO REACH ND AND WE DO
HAVE SOME LOW POPS IN THE FAR WEST THIS AFTERNOON.
UPDATE
ISSUED AT 650 AM CDT TUE JUL 28 2026
ISOLATED SHOWERS CONTINUE ROAM THROUGH THE JAMES RIVER VALLEY
EARLY THIS MORNING. DO NOT ANTICIPATE THIS ACTIVITY TO PERSIST
INTO THE AFTERNOON, AND THE PROBABILITY OF A THUNDERSTORM IS
VERY LOW. DENSE FOG ALSO CONTINUES ACROSS NORTH CENTRAL NORTH
DAKOTA EARLY THIS MORNING. OBSERVATIONS SHOW LITTLE REMAINING
DENSE FOG IN BURKE COUNTY, BUT ESTEVAN RECENTLY REPORTED 1/8
MILE VISIBILITY. THE FOG HAS ALSO SPREAD SOUTH INTO NORTHERN
KIDDER AND STUTSMAN COUNTIES, BUT THERE IS LOWER COVERAGE OF
DENSE FOG THERE. NO CHANGES WERE MADE TO THE ADVISORY FOR THIS
UPDATE.
DISCUSSION
ISSUED AT 515 AM CDT TUE JUL 28 2026
UPPER LEVEL RIDGE AXIS LIES ACROSS EASTERN MONTANA/WYOMING
EARLY THIS MORNING. A BENIGN SURFACE PATTERN IS ANALYZED OVER
THE NORTHERN PLAINS, WITH MESOSCALE HIGH PRESSURE FROM SOUTHERN
MANITOBA INTO NORTHEAST NORTH DAKOTA. DENSE FOG HAS DEVELOPED
ALONG AND NORTHEAST OF HIGHWAY 52, AS FAR SOUTH AS THE HIGHWAY
200 CORRIDOR. A DENSE FOG ADVISORY REMAINS IN EFFECT FOR THESE
AREAS UNTIL 10 AM CDT. MEANWHILE, WEAK WARM AIR/MOISTURE
ADVECTION UNDERNEATH THE RIGHT ENTRANCE REGION OF AN UPPER LEVEL
JET HAS INITIATED ISOLATED SHOWERS WITH AN OCCASIONAL
THUNDERSTORM FROM THE NORTHERN JAMES RIVER VALLEY TO BETWEEN
LAKE OAHE AND THE SOUTHERN JAMES RIVER VALLEY. THIS CONVECTION
MAY CONTINUE MEANDERING THROUGH THIS PART OF THE STATE INTO THE
MID/LATE MORNING HOURS BEFORE DISSIPATING, BUT FORECAST
CONFIDENCE IS LOW AS THIS CONVECTION WAS NOT MODELED VERY WELL.
THE UPPER LEVEL RIDGE WILL REMAIN IN PLACE TODAY. HIGH
TEMPERATURES SHOULD RETURN TO THE 90S TO NEAR 100 WITH LESSER
CLOUD COVER THAN YESTERDAY. SMOKE ALOFT REMAINS A WILD CARD
THOUGH, AND COULD KEEP TEMPERATURES A FEW DEGREES COOLER. A
MENTION OF PATCHY SMOKE WAS MAINTAINED IN THE FORECAST THROUGH
TONIGHT IN CONTINUITY WITH HRRR/RAP NEAR-SURFACE SMOKE GUIDANCE,
ALTHOUGH THE CORRELATION BETWEEN MODELED SMOKE CONCENTRATIONS
AND OBSERVED VISIBILITY IS SUBJECTIVELY VERIFYING WITH MIXED
RESULTS AT BEST. NEVERTHELESS, CONFIDENCE REMAINS HIGH IN AT
LEAST SOME AMOUNT OF SMOKE IN THE AIR THROUGH THE MIDDLE OF THE
WEEK, WHETHER IT BE ALOFT OR AT THE SURFACE. THE UPPER RIDGE
CONTINUES TO BUILD AND PIVOTS EASTWARD ON WEDNESDAY AHEAD OF
SHORTWAVE ENERGY EJECTING OFF THE NORTHERN ROCKIES, BRINGING THE
THERMAL RIDGE BACK INTO THE WESTERN DAKOTAS. THE NBM SHOWS HIGH
CONFIDENCE IN HIGH TEMPERATURES AROUND 100 ACROSS MUCH OF
WESTERN AND CENTRAL NORTH DAKOTA, WITH MAXIMUM HEAT INDICES ALSO
AROUND 100 ALONG AND TO THE WEST AND SOUTH OF THE MISSOURI
RIVER VALLEY.
WITH WEAK DISTURBANCES CONTINUING TO ROUND THE TOP OF THE RIDGE
AND FORECAST HIGHS NEAR CONVECTIVE TEMPERATURES, OCCASIONAL
ISOLATED SHOWERS AND THUNDERSTORMS CANNOT BE RULED OUT THIS
AFTERNOON AND EVENING. WE ARE BROADLY NOT CARRYING MENTIONABLE
POPS, AS THE POINT-SPECIFIC PROBABILITY FOR A SHOWER OR STORM
AT ANY GIVEN LOCATION IS LESS THAN 15 PERCENT. BUT IN GENERAL,
CAMS WOULD INDICATE RELATIVELY HIGHER ODDS OF CONVECTION
INITIATING ACROSS SOUTHERN AND EASTERN NORTH DAKOTA THAN TO THE
NORTH AND WEST. CAPE IS FORECAST TO DECREASE ACROSS WESTERN
NORTH DAKOTA THIS AFTERNOON, BUT THE EASTERN HALF OF THE STATE
COULD SEE 1000-2000 J/KG CAPE WITH AROUND 25-30 KTS OF DEEP
LAYER SHEAR DURING THE LATE AFTERNOON AND EARLY EVENING.
THEREFORE, A STRONGER STORM CANNOT BE RULED OUT IN THE JAMES
RIVER VALLEY OVER THE AFOREMENTIONED TIMEFRAME, WHICH A COUPLE
CAMS HAVE BEEN CONSISTENTLY SIMULATING.
THROUGH WEDNESDAY MORNING, A TURNING OF THE LOW LEVEL WIND
FIELD TO SOUTHWESTERLY WILL BRING WARM AIR/MOISTURE ADVECTION
INTO WESTERN AND CENTRAL NORTH DAKOTA. CAMS INDICATE A LOW
PROBABILITY OF SHOWER AND THUNDERSTORM DEVELOPMENT IN RESPONSE
TO THIS FORCING, WITH ANY STORMS LIKELY REMAINING ELEVATED AND
SUB-SEVERE. THERE IS A VERY LOW PROBABILITY SCENARIO THOUGH
WHERE THIS ACTIVITY BECOMES ROOTED IN THE BOUNDARY LAYER BEFORE
DEPARTING INTO EASTERN NORTH DAKOTA EARLY WEDNESDAY AFTERNOON.
THE GREATER FOCUS FOR STRONG TO SEVERE CONVECTION WILL BE ALONG
A LEE TROUGH NEAR THE MT/ND BORDER MID WEDNESDAY AFTERNOON.
MODEL GUIDANCE IS CONSISTENT IN INITIATING DEEP MOIST CONVECTION
BY LATE AFTERNOON, ALBEIT WITH TIMING AND COVERAGE DISCREPANCIES.
STORM MODE COULD BE MIXED INITIALLY, WITH SHEAR VECTORS MORE
PERPENDICULAR TO THE LEE TROUGH IN SOUTHERN NORTH DAKOTA, BUT
MORE PARALLEL TO IT FARTHER NORTH. UPSCALE GROWTH INTO CLUSTERS
IS FAVORED AS STORMS PROPAGATE EASTWARD INTO CENTRAL NORTH
DAKOTA LATE WEDNESDAY EVENING INTO THE OVERNIGHT HOURS, WITH
MORE FAVORABLE MAINTENANCE OF CONVECTION ACROSS THE NORTH WHERE
BUOYANCY, SHEAR, AND FORCING COULD ALL BE STRONGER. THE TORNADO
RISK APPEARS VERY LOW, BUT A FAVORABLE SETUP COULD BRIEFLY
EMERGE IN FAR NORTHWEST NORTH DAKOTA EARLY WEDNESDAY EVENING.
HOWEVER, CURRENT HRRR/RAP HODOGRAPHS AT CROSBY SHOW CROSSWISE
VORTICITY IN THE 0-1 KM LAYER, RENDERING TORNADOGENESIS LESS
FAVORABLE.
MEDIUM CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUE ON
THURSDAY AS BROAD MID LEVEL SHORTWAVE TROUGHING IN THE MIDDLE
OF THE LONGWAVE RIDGE STALLS OVER THE NORTHERN PLAINS. A MEDIUM
TO HIGH CAPE AND LOW TO MODERATE SHEAR ENVIRONMENT COULD SUPPORT
A FEW SEVERE STORMS THURSDAY AFTERNOON AND EVENING, BUT DETAILS
REMAIN UNCERTAIN. A SLIGHT COOL DOWN IS EXPECTED ON THURSDAY,
BUT WITH HIGHS REMAINING IN THE MID 80S TO MID 90S. SIMILAR HIGH
TEMPERATURES CARRY INTO FRIDAY AS THE SHORTWAVE DIVES SOUTHEAST
INTO THE UPPER MISSISSIPPI AND LOWER MISSOURI RIVER VALLEYS.
THIS FORCES THE UPPER RIDGE BACK OVER THE WESTERN CONUS WHERE IT
LOOKS TO REBOUND, BUT THAT COULD BE TEMPORARILY INHIBITED BY
ANOTHER SHORTWAVE EJECTING OFF THE NORTHERN ROCKIES ON FRIDAY
WHICH COULD BRING A FEW THUNDERSTORMS INTO WESTERN NORTH DAKOTA
LATER IN THE DAY. THE UPSTREAM RIDGE IS FAVORED TO BECOME
HIGHLY-AMPLIFIED ONCE AGAIN OVER THE WEEKEND AND DEVELOP A
POSITIVE TILT AS A STRONG UPPER LOW DIGS INTO BRITISH COLUMBIA.
THE THERMAL RIDGE AXIS REACHES THE WESTERN DAKOTAS ON SUNDAY,
WHICH COULD ALLOW HIGH TEMPERATURES TO RETURN TO 100 TO 105. A
STRONG SOUTHERLY RETURN FLOW IS ALSO FORECAST ON SUNDAY, WHICH
COULD INCREASE FIRE WEATHER CONCERNS. A COLD FRONT IS FORECAST
TO MOVE THROUGH THE STATE LATE SUNDAY INTO MONDAY, WHICH MAY BE
ACCOMPANIED BY GUSTY WINDS AND SCATTERED SHOWERS AND
THUNDERSTORMS. THE POST-FRONTAL AIR MASS SHOULD BRING MUCH
COOLER TEMPERATURES TO START THE WORK WEEK, WITH HIGHS MOSTLY
IN THE 70S AND 80S. BUT THERE ARE SIGNS IN LONGER-RANGE
ENSEMBLES THAT THE UPPER RIDGE COULD TRY TO BUILD INTO THE
CENTRAL CONUS ONCE AGAIN LATER NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 650 AM CDT TUE JUL 28 2026
DENSE FOG CONTINUES ACROSS MUCH OF NORTH CENTRAL AND INTO
EASTERN NORTH DAKOTA EARLY THIS MORNING. KMOT AND KJMS REMAIN
JUST OUTSIDE THE DENSE FOG, BUT MVFR TO IFR VISIBILITY REMAINS
POSSIBLE THERE UNTIL AROUND 14-15Z. VFR CONDITIONS ARE OTHERWISE
ANTICIPATED THROUGH THE FORECAST PERIOD, WITH WINDS REMAINING
LIGHT. SMOKE FROM DISTANT WILDFIRES WILL REMAIN PRESENT TODAY,
BUT CATEGORICAL VISIBILITY RESTRICTIONS DUE TO SMOKE ALONE ARE
UNLIKELY. AN ISOLATED SHOWER OR THUNDERSTORM COULD DEVELOP FROM
TIME TO TIME THROUGHOUT THE FORECAST PERIOD, MAINLY ACROSS
SOUTHERN NORTH DAKOTA.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...TWH
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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