367
FXUS63 KBIS 172354
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
654 PM CDT MON AUG 17 2026
KEY MESSAGES
- SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS REMAIN POSSIBLE
TODAY (UP TO 40% CHANCE). ISOLATED SEVERE STORMS (LEVEL 1 OUT
OF 5) ARE POSSIBLE ACROSS FAR SOUTHERN AREAS OF THE STATE THIS
AFTERNOON THROUGH EARLY THIS EVENING.
- LOW TO MEDIUM CHANCES (20-40%) FOR SCATTERED SHOWERS AND
THUNDERSTORMS ON WEDNESDAY, THEN MAINLY DRY THURSDAY THROUGH
SATURDAY DAYTIME.
- MAINLY SEASONAL TEMPERATURES THIS WEEK, WITH ABOVE NORMAL HIGH
TEMPERATURES ON THURSDAY.
UPDATE
ISSUED AT 628 PM CDT MON AUG 17 2026
ISOLATED THUNDERSTORMS CONTINUE OVER SOUTHERN PORTIONS OF OUR
AREA AS A SHORT WAVE CONTINUES TO SWING AROUND BROAD UPPER LOW
CENTERED OVER FAR SOUTHWEST HUDSON BAY. ADDITIONAL SHORT WAVES
WRAPPING AROUND THE LOW CONTINUE TO PRODUCE ADDITIONAL STORMS
UPSTREAM IN EASTERN MONTANA. SO FAR THE OVERALL TREND HAS BEEN
THAT SOME STORMS GET A LITTLE STRONG FOR A BIT, BUT HAVE MAINLY
REMAINED SUB-SEVERE. WITH THAT SAID, INSTABILITY AND SHEAR
CONTINUE TO BE HIGH ENOUGH FOR A STORM TO POSSIBLY BECOME
SEVERE, MAINLY OVER OUR FAR SOUTHERN AREAS. THEREFORE, WILL
CONTINUE TO MONITOR THROUGH THE EVENING.
DISCUSSION
ISSUED AT 250 PM CDT MON AUG 17 2026
CURRENTLY, QUASI-ZONAL/WEST-NORTHWEST FLOW ALOFT WITH A LARGE
AREA OF UPPER LEVEL LOW PRESSURE OVER HUDSON BAY AND AN UPPER
LEVEL RIDGE OF HIGH PRESSURE EXTENDING FROM THE SOUTHERN ROCKIES
BACK NORTH-NORTHWEST INTO THE INTERMOUNTAIN WEST. COLD FRONT
SITUATED ROUGHLY FROM SOUTHWEST NORTH DAKOTA NORTHEAST INTO THE
NORTHERN RED RIVER VALLEY. EMBEDDED MID LEVEL IMPULSES
CONTRIBUTING TO TWO AREAS OF PRECIP ACTIVITY THIS AFTERNOON. THE
FIRST IS OVER NORTHWESTERN ND WHERE SCATTERED SHOWERS ARE MOVING
INTO, AND THE SECOND AREA IS OVER SOUTHWESTERN ND ALONG AND
AHEAD OF THE FRONTAL BOUNDARY AIDED BY LEFT EXIT REGION JET
DYNAMICS ALOFT. THERE IS ENOUGH EFFECTIVE WIND SHEAR (35-40
KNOTS) FOR A FEW STRONGER/MORE ORGANIZED UPDRAFTS OVER THE PAST
COUPLE HOURS, WITH ONE SEVERE STORM FIRING UP JUST ACROSS THE
BORDER IN NORTHWEST SOUTH DAKOTA. I OPTED TO MENTION THE ENTIRE
FAR SOUTH IN THE HWO, WITH THE MARGINAL (LEVEL 1 OF 5) OUTLOOK
NEAR OR OVER THIS AREA. THREAT FOR SEVERE WEATHER SHOULD
DECREASE WITH TIME AS WE LOSE DAYTIME HEATING AND AS THE FRONT
MOVES FARTHER TO THE SOUTH.
JET STREAK MOVING THROUGH ALOFT ALONG WITH ADDITIONAL MID LEVEL
IMPULSES WILL MAINTAIN CHANCES FOR SHOWERS AND PERHAPS A FEW
THUNDERSTORMS TONIGHT ACROSS THE LOCAL AREA. THREAT FOR SEVERE
WEATHER WILL BE VERY LOW AFTER PEAK HEATING AS THE MORE ROBUST
STORMS REMAIN MORE TO OUR SOUTH.
SURFACE HIGH PRESSURE BUILDS INTO WESTERN AND CENTRAL NORTH
DAKOTA TONIGHT INTO TOMORROW, AND WILL RESULT IN THE WEATHER
TRENDING DRY, LOWERING DEWPOINT TEMPERATURES, AND COOLER
TEMPERATURES MAINLY IN THE 70S TO AROUND 80.
INCREASING RETURN FLOW TUE NIGHT WEST AS SFC HIGH PRESSURE
SLIDES OFF TO THE EAST, WITH MODELS DEPICTING A MID LEVEL WAVE
ALSO APPROACHING TUE NIGHT THROUGH EARLY WED, RESULTING IN THE
NEXT CHANCE FOR PRECIPITATION. DESPITE NORTHWEST FLOW ALOFT,
TEMPERATURES WILL WARM MID-WEEK BACK INTO THE 80S ON WEDNESDAY,
THEN WELL INTO THE 80S AND LOWER 90S FOR THURSDAY AS THE
AFOREMENTIONED UPPER RIDGE BROADENS AND NUDGES EAST (INCREASING
SOUTHERLY MID LEVEL FLOW). MAINLY DRY WEATHER AND SEASONAL
TEMPERATURES TO END THE WEEK AS THE UPPER RIDGE CONTINUES TO
DEVELOP EAST INTO THE GREAT PLAINS. ENSEMBLES THEN SHOW THE
RIDGE BREAKING DOWN LATER IN THE WEEKEND INTO EARLY NEXT WEEK,
WITH SHOWER AND THUNDERSTORM CHANCES RETURNING TO THE FORECAST
AND CONTINUED SEASONAL TEMPERATURES.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 628 PM CDT MON AUG 17 2026
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL CONTINUE TO
MOVE THROUGH WESTERN AND SOUTH CENTRAL NORTH DAKOTA THIS EVENING
AND OVERNIGHT, CLEARING OUT TUESDAY MORNING. OTHERWISE, VFR
CONDITIONS ARE EXPECTED.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...
DISCUSSION...NH
AVIATION...JJS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page