811
FXUS63 KBIS 280811
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
311 AM CDT TUE JUL 28 2026
KEY MESSAGES
- DENSE FOG ACROSS MUCH OF NORTHERN NORTH DAKOTA INTO THE
NORTHERN JAMES RIVER VALLEY THIS MORNING.
- HOT AND SMOKY CONDITIONS CONTINUE THROUGH AT LEAST THE MIDDLE
OF THE WEEK, WITH HIGHS AROUND 90 TO 100.
- MEDIUM TO HIGH CHANCES (30 TO 70 PERCENT) FOR SHOWERS AND
THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH THURSDAY. A FEW
STORMS COULD BE SEVERE.
UPDATE
ISSUED AT 311 AM CDT TUE JUL 28 2026
A DENSE FOG ADVISORY HAS BEEN ISSUED FOR FOR AREAS ALONG AND
EAST OF HIGHWAY 52 FROM THE CANADIAN BORDER TO THE HIGHWAY 200
CORRIDOR.
UPDATE
ISSUED AT 135 AM CDT TUE JUL 28 2026
FOG IS BEGINNING TO SETTLE IN ACROSS NORTH CENTRAL NORTH DAKOTA
FROM THE TURTLE MOUNTAINS TO THE NORTHERN JAMES RIVER VALLEY. A
SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR THESE AREAS, BUT
THIS COULD QUICKLY ESCALATE TO A DENSE FOG ADVISORY AS SUB-
QUARTER MILE VISIBILITY IS BECOMING MORE PREVALENT.
UPDATE
ISSUED AT 1003 PM CDT MON JUL 27 2026
EARLIER ELEVATED SHOWERS AND WEAK THUNDERSTORMS HAVE LARGELY
EXITED THE AREA, THOUGH WE WILL MAINTAIN LOW, ~20 PERCENT
CHANCES OF ADDITIONAL ACTIVITY OVERNIGHT IN PARTS OF CENTRAL ND
IN RESPECT TO MODEST MIDLEVEL WARM AIR ADVECTION THAT IS STILL
FORECAST TO REDEVELOP, ESPECIALLY AFTER 05Z. OTHERWISE, THE MAIN
CHANGE WITH THIS UPDATE WAS TO ADD PATCHY TO AREAS OF FOG INTO
THE FORECAST IN NORTHERN AND NORTH CENTRAL ND INTO PARTS OF THE
JAMES RIVER VALLEY. AS OF MID EVENING, TEMPERATURE-DEWPOINT
SPREADS IN THOSE AREAS ARE 5 F OR LESS, WITH SURFACE DEWPOINTS
AROUND 70 F. RECENT HRRR/RAP GUIDANCE ALSO HAS BEGUN SIMULATING
FOG DEVELOPMENT IN THOSE AREAS. WE WILL NEED TO MONITOR IN CASE
IT BECOMES MORE WIDESPREAD AND/OR DENSE, ESPECIALLY IN NORTH
CENTRAL ND, GIVEN THE WEAK SURFACE WINDS AND HIGH DEWPOINTS.
LASTLY, SIGNIFICANT AMOUNTS OF HIGH-LEVEL CLOUDS ARE SPREADING
EASTWARD OUT OF MT AROUND THE PERIPHERY OF THE UPPER-LEVEL RIDGE
AS OF MID EVENING TOO, WHICH WILL LIKELY LEAD TO CONSIDERABLE
CLOUD COVER OVERNIGHT. THIS MAY ACT TO KEEP LOW TEMPERATURES A
BIT WARMER THAN FORECAST, TOO.
UPDATE
ISSUED AT 638 PM CDT MON JUL 27 2026
WEAK CONVECTION CONTINUES MOVING EASTWARD ACROSS CENTRAL ND AS
OF EARLY EVENING, DRIVEN BY BROAD MIDLEVEL WARM AIR ADVECTION,
AND THE INFLUENCE OF A MODEST JET STREAK ALOFT. BOUYANCY HAS
BEEN MEAGER OVER MOST OF WESTERN AND CENTRAL ND, AND LIGHTNING
HAS DWINDLED IN THE LAST 60 MINUTES. WE BELIEVE THE RISK OF A
STRONG STORM IS DIMINISHING, THOUGH AT LEAST BROAD/WEAK WARM AIR
ADVECTION IS FORECAST TO PERSIST OVER CENTRAL ND THROUGH THE
NIGHT, CONSTITUTING A LOW CHANCE OF ELEVATED SHOWERS OR A
THUNDERSTORM CONTINUING.
DISCUSSION
ISSUED AT 115 PM CDT MON JUL 27 2026
CURRENTLY, SCATTERED THUNDERSTORMS REMAIN JUST NORTH OF THE
INTERNATIONAL BORDER, IN NORTHWEST AND NORTH CENTRAL ND, BUT DO
EXTEND SOUTH AS YOU GET TO THE TURTLE MOUNTAINS AREA. ELSEWHERE,
ISOLATED SHOWERS AND THUNDERSTORMS WERE LOCATED OVER EASTERN
MONTANA.
FOR THIS AFTERNOON AND TONIGHT, THERE IS SOME ELEVATED
INSTABILITY ACROSS NORTHERN AND WESTERN PORTIONS OF THE
FORECAST AREA. THERE IS A MARGINAL RISK (LEVEL 1 OUT OF 5) OF
SEVERE STORMS OVER THE FAR SOUTHWEST (MAINLY BOWMAN AND ADAMS
COUNTIES). SURFACE LOW PRESSURE OVER SOUTHEAST MONTANA IS
FORECAST TO MOVE INTO SOUTHWEST ND LATER THIS AFTERNOON.
SOUTHWEST ND WILL BE IN AN AREA OF SURFACE CONVERGENCE AHEAD OF
THE LOW. THERE IS ON THE ORDER OF 500-1000 J/KG OF ELEVATED
CAPE ABOVE AN AREA OF GOOD CIN. THE FAR SOUTHWEST LOOKS TO BE
THE ONE AREA IN THE WEST WHICH COULD SEE MOST OF THE CIN ERODE
LATER THIS AFTERNOON INTO EARLY EVENING. EVERY SO OFTEN ONE OF
THE CAMS WILL SHOW A FEW STRONGER CELLS OVER THE FAR SOUTHWEST.
A COMBINATION OF THE DECREASED CIN AND SURFACE CONVERGENCE COULD
SUPPORT A STRONG TO SEVERE STORMS WITH THE MAIN THREAT BEING
WIND GUSTS TO 60 MPH. IN THE NORTH CONVECTION CONTINUES ALONG
THE INTERNATIONAL BORDER. INSTABILITY DOES INCREASE WITH GOOD
SHEAR AS YOU MOVE EAST ACROSS THE NORTH CENTRAL. THE SPC
MESOANALYSIS PAGE INDICATED INCREASING CIN OVER BOTH WESTERN AND
NORTHERN ND LATER THIS AFTERNOON INTO THIS EVENING. THEREFORE,
THE OVERALL THREAT FOR SEVERE STORMS LOOKS TO REMAIN LOW.
TONIGHT CAMS DO SHOW SCATTERED SHOWER/THUNDERSTORM ACTIVITY
SPREADING WEST TO EAST OVER THE SOUTHWEST AND SOUTH CENTRAL,
ALONG WITH SCATTERED CONVECTION ALONG THE NORTH SPREADING SOUTH
AND EAST. REALLY UNCERTAIN ABOUT OVERALL COVERAGE OF ANY
ACTIVITY TONIGHT GIVEN THE GENERAL STRONG CAPPING, SO STUCK MORE
TO A BROADBRUSH OF SLIGHT CHANCE POPS THROUGH TONIGHT.
ELEVATED SMOKE LOOKS TO REMAIN OVER THE AREA FOR THE NEXT FEW
DAYS, SO KEPT A MENTION OF SMOKE IN THE FORECAST AND PUT A LOWER
LIMIT ON THE SKY COVER THROUGH TUESDAY.
TEMPERATURES CLIMB HIGHER TUESDAY AND WEDNESDAY. TUESDAY LOOKS
TO BE MOSTLY DRY WITH UPPER LEVEL RIDGING BUILDING OVER THE
AREA. THE LACK OF LOW LEVEL MOISTURE SHOULD ALSO KEEP HEAT INDEX
VALUES BELOW CRITICAL VALUES, EVEN AS SURFACE TEMPERATURES CLIMB
INTO THE UPPER 90S SOUTH AND WEST OF THE MISSOURI RIVER.
ON WEDNESDAY, TEMPERATURES ARE ABOUT THE SAME AS OR A LITTLE
HIGHER THAN TUESDAY. A SOUTHERLY RETURN FLOW SHOULD ALSO BUMP UP
DEW POINT TEMPERATURES A LITTLE. THIS COULD BUMP APPARENT
TEMPERATURES HIGH ENOUGH FOR A HEAT ADVISORY. HOWEVER, THE
UNCERTAINTY IS HIGH ENOUGH AT THIS TIME TO GIVE IT ANOTHER DAY.
CURRENTLY IT APPEARS THAT IT WOULD PROBABLY BE A LIMITED AREA
AND FOR A LIMITED DURATION SO WOULD MOST LIKELY PASS IF WE WERE
NEEDING TO MAKE A DECISION TODAY.
WEDNESDAY NIGHT AND THURSDAY WE SEE A SERIES OF WAVES
PROPAGATING THROUGH THE MEAN UPPER RIDGE, BRINGING US BETTER
CHANCES FOR SHOWERS AND THUNDERSTORMS THAN WE HAVE SEEN IN A
WHILE. RIGHT NOW THINGS LOOK A BIT MESSY WITH PERHAPS A SOUTHERN
STREAM AND A NORTHERN STREAM WAVE TRAVERSING THE FORECAST AREA
WITH A LOT OF UNCERTAINTY IN TIMING AND PLACEMENT OF SAID WAVES
AND RESULTING CONVECTION. NBM CONTINUES WITH IT'S BROADBRUSH
AREA OF MEDIUM TO HIGH POPS WEDNESDAY NIGHT AND THURSDAY. AS WAS
MENTIONED YESTERDAY, NOT OVERLY EXCITED ABOUT THE AREAL EXTENT
OF HIGH POPS BUT THIS FAR OUT. A BROADBRUSH APPROACH SEEMS
JUSTIFIED.
TEMPERATURES DO DROP A LITTLE AFTER WEDNESDAY, WITH HIGHS MAINLY
IN THE MID 80S TO MID 90S THURSDAY AND FRIDAY, FOLLOWED BY A
WARM-UP AS WE HEAD INTO THE WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 135 AM CDT TUE JUL 28 2026
FOG WAS DEVELOPING ACROSS NORTH CENTRAL AND EASTERN NORTH
DAKOTA TO START THE 06Z FORECAST PERIOD. CONFIDENCE IS LOW ON
WHETHER DENSE FOG WILL REACH KMOT OR KJMS. INCLUDED TEMPO
GROUPS FOR MVFR/IFR VISIBILITY AT EACH OF THESE TERMINALS FROM
09-13Z. VFR CONDITIONS ARE OTHERWISE EXPECTED THROUGH THE
FORECAST PERIOD, WITH WINDS REMAINING LIGHT. SMOKE FROM DISTANT
WILDFIRES WILL REMAIN PRESENT, 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
DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NDZ002>005-
012-013-022-023-025-055-056.
UPDATE...HOLLAN
DISCUSSION...TWH
AVIATION...HOLLAN
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