523
FXUS63 KBIS 170538
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1238 AM CDT WED SEP 17 2025
KEY MESSAGES
- PATCHY FOG IS POSSIBLE ACROSS THE NORTH EARLY WEDNESDAY
MORNING.
- ON AND OFF SHOWERS AND ISOLATED THUNDERSTORMS REMAIN IN THE
FORECAST THROUGH FRIDAY. THE HIGHEST CHANCES (40 TO 60
PERCENT) ARE THURSDAY THROUGH FRIDAY.
- COOLER, BUT STILL SEASONABLE TEMPERATURES ARE ON TAP TO
FINISH OUT THE SECOND HALF OF THE WEEK.
UPDATE
ISSUED AT 1238 AM CDT WED SEP 17 2025
THE FORECAST REMAINS ON TRACK.
UPDATE
ISSUED AT 959 PM CDT TUE SEP 16 2025
THE FORECAST FOR TONIGHT REMAINS ON TRACK. ISOLATED SHOWERS
THAT DEVELOPED DURING THE LATE AFTERNOON HAVE SINCE DIMINISHED.
RECENT CAMS INFER A DELAY IN THE ARRIVAL/FORMATION OF SHOWERS
LATER TONIGHT, AND THIS IS SUPPORTED BY OBSERVED TRENDS. THE
INCREASE TO "CHANCE" POPS ALONG THE SOUTH DAKOTA BORDER PUSHED
BACK A FEW HOURS FOR THIS UPDATE.
UPDATE ISSUED AT 716 PM CDT TUE SEP 16 2025
ISOLATED SHOWERS WITH AN OCCASIONAL THUNDERSTORM HAVE DEVELOPED
ALONG A BROAD AREA OF LOW LEVEL CONVERGENCE FROM AROUND WILLISTON TO
BEACH TO BISMARCK TO GARRISON. THIS ACTIVITY IS UNLIKELY TO PERSIST
MORE THAN AN HOUR OR TWO PAST SUNSET, AND STRONG STORMS ARE NOT
EXPECTED GIVEN THE LACK OF SHEAR. THE MAIN FORECAST CHANGE FOR THIS
UPDATE WAS TO ALIGN POPS WITH OBSERVED TRENDS AND BLEND IN THE
LATEST ENSEMBLE MODEL GUIDANCE.
DISCUSSION
ISSUED AT 315 PM CDT TUE SEP 16 2025
CURRENTLY AN UPPER LEVEL LOW SITS OVER THE BORDER OF MONTANA AND
COLORADO. SOUTHWEST FLOW IS OVER THE DAKOTAS, WITH A
THUNDERSTORM COMPLEX IN WESTERN NEBRASKA AND SOUTHERN SOUTH
DAKOTA. AS THE UPPER LEVEL LOW PRESSURE SYSTEM SLIDES TO THE
EAST TONIGHT, SHOWERS AND THUNDERSTORMS ARE POSSIBLE AFTER
MIDNIGHT ACROSS THE SOUTHERN HALF OF THE STATE. SHOWER AND
THUNDERSTORM CHANCES WILL CONTINUE THROUGH FRIDAY AS THE UPPER
LEVEL LOW STALLS OVER THE DAKOTAS. SATURDAY THE LOW PRESSURE
SYSTEM GETS SHOVED INTO MINNESOTA BY A SHORT WAVE TROUGH FROM
THE ALBERTA AREA. SUNDAY SURFACE HIGH PRESSURE MOVES IN FROM THE
SOUTHWEST UNDER A QUASI-RIDGING PATTERN THROUGH MID NEXT WEEK.
THIS WILL MOSTLY CREATE DRY WEATHER. TONIGHT PATCHY FOG IS
POSSIBLE ACROSS THE NORTH WITH HIGH HUMIDITY AND LIGHT WINDS.
TEMPERATURES THROUGH THE FORECAST WILL COOL THIS WEEK AS THE
UPPER LEVEL LOW WRAPS IN COOLER AIR FROM CANADA. AS A RESULT OF
THIS, CAPE WILL LOWER. THIS WILL LIKELY RESULT IN A LOWER
CHANCE OF THUNDER IN THE OTHERWISE LIKELY CHANCE OF SHOWERS.
THURSDAY WILL BE THE LOWEST TEMPERATURES WITH WIDESPREAD HIGHS
IN THE UPPER 50S AND LOWER 60S. FRIDAY THAT COOLER AIR SLIDES
EAST AHEAD OF THE LOW, AND TEMPERATURES WARM BACK INTO THE UPPER
60S. THURSDAY AND FRIDAY WILL BE THE MOST RAINY DAY, ESPECIALLY
SOUTH AND CENTRAL NORTH DAKOTA. SATURDAY WHEN THE SHORTWAVE
MOVES IN, IT BRINGS WESTERLY FLOW ALOFT, RESULTING IN WARM AIR
ADVECTION FROM THE WEST. THIS WILL WARM TEMPERATURES INTO THE
70S AND 80S THROUGH EARLY NEXT WEEK AS THAT QUASI-RIDGING FLOW
CONTINUES.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1238 AM CDT WED SEP 17 2025
VFR CEILINGS AND VISIBILITY ARE PRESENT AT ALL TERMINALS.
HOWEVER, A SYSTEM WILL BEGIN ENCROACHING FROM THE SOUTH TONIGHT
THROUGH THE DAY WEDNESDAY BRINGING RAIN SHOWERS AND ISOLATED
THUNDERSTORMS TO MUCH OF THE STATE, ESPECIALLY THE SOUTHERN
HALF. TOWARDS THE END OF THE PERIOD, CEILING WILL LIKELY BEGIN
DROPPING TO MVFR/IFR LEVELS ESPECIALLY IN SOUTHWESTERN AND SOUTH
CENTRAL PARTS OF THE STATE. THE ONE OTHER THING OF NOTE IS THAT
PATCHY FOG MAY DEVELOP TONIGHT, MAINLY OVER NORTHWESTERN AND
NORTH CENTRAL ND. CONFIDENCE IN FOG DEVELOPMENT IS LOW, SO LEFT
MENTIONS OUT OF ALL TAFS FOR NOW.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...TELKEN
DISCUSSION...SMITH
AVIATION...TELKEN
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