515  
FXUS63 KFSD 100317  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
1017 PM CDT TUE SEP 9 2025  
   
KEY MESSAGES  
 
- FOG WILL DEVELOP OVERNIGHT INTO EARLY WEDNESDAY MORNING FOR  
AREAS MAINLY EAST OF THE JAMES RIVER VALLEY. POCKETS OF  
REDUCED VISIBILITY BELOW 1 MILE ARE POSSIBLE.  
 
- CANADIAN WILDFIRE SMOKE WILL LINGER ALOFT THROUGH WEDNESDAY  
AND BEGIN TO MOVE EAST WEDNESDAY NIGHT. ANY SURFACE IMPACT  
WILL BE MINIMAL.  
 
- TEMPERATURES WARM TO WELL ABOVE MID-SEPTEMBER NORMALS THURSDAY  
THROUGH SATURDAY.  
 
- THE NEXT BEST CHANCE FOR SHOWERS AND THUNDERSTORMS (30-50  
PERCENT) WILL BE SATURDAY NIGHT THROUGH SUNDAY.  
 
 
   
DISCUSSION  
 
ISSUED AT 257 PM CDT TUE SEP 9 2025  
 
09.1930Z WATER VAPOR SHOWS A COMPACT SHORT-WAVE MOVING EAST  
INTO CENTRAL MN/IA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS  
WITH THIS WAVE HAVE MOVED EAST OF THE FORECAST AREA AND EXPECT A  
DRY FORECAST FOR MOST THIS EVENING AND OVERNIGHT. THE EXCEPTION  
BEING AREAS EAST OF I-29 WHERE SOME ADDITIONAL DEVELOPMENT IS  
POSSIBLE AS ANOTHER WEAK AREA OF POSITIVE VORTICITY ADVECTION  
MOVES THROUGH THE EASTWARD ADVANCING TROUGH ALOFT. SEVERE  
WEATHER IS NOT EXPECTED WITH ANY ADDITIONAL STORMS THAT DEVELOP.  
 
ALSO MONITORING AREAS OF STUBBORN LOW STRATUS FROM THE JAMES  
RIVER VALLEY EAST AND ALONG AND SOUTH OF INTERSTATE 90. THESE  
CLOUDS SHOULD CONTINUE TO SLOWLY DISSIPATE AND LIFT WITH PEAK  
AFTERNOON HEATING. HOWEVER, RECENT GUIDANCE SUGGESTS THIS CLOUD  
COVER COULD EXPAND AGAIN OVERNIGHT GIVEN MOIST, WEAK LOW-LEVEL  
FLOW. THIS COULD ALSO MANIFEST ITSELF AS SOME AREAS OF FOG AS  
WELL. 12Z HREF SHOWS A 30-50 PERCENT CHANCE VISIBILITY DROPS  
BELOW 1 MILE BY DAYBREAK WEDNESDAY. FOR NOW, ADDED PATCHY FOG TO  
THE FORECAST, BUT SOMETHING TO WATCH. ANY CLOUD COVER/FOG  
TONIGHT WOULD HELP KEEP OVERNIGHT LOWS ELEVATED INTO THE UPPER  
50S TO LOW 60S.  
 
WEDNESDAY WILL BE WARMER AND DRY GIVEN BUILDING HEIGHTS ALOFT.  
HOWEVER, CANADIAN WILDFIRE SMOKE IS EXPECTED TO REMAIN,  
RESULTING IN MILKY SKIES. AT THIS TIME, SMOKE IS NOT EXPECTED TO  
REACH THE SURFACE. TEMPERATURES WILL TOP OUT IN THE UPPER 70S  
TO LOW 80S WITH LIGHT SOUTHEAST SURFACE WIND.  
 
THURSDAY THROUGH SATURDAY, THE MAIN STORY WILL BE SUMMER-LIKE  
TEMPERATURES WITH AN AMPLIFIED RIDGE ACROSS THE NATION'S MID-  
SECTION. AFTERNOON HIGHS WILL RISE A BIT EACH DAY WITH SOME  
AREAS ALONG AND SOUTH OF I-90 PUSHING THE 90 DEGREE MARK.  
AFOREMENTIONED RIDGE BEGINS TO SLIDE EAST SATURDAY, ALLOWING  
FLOW ALOFT TO TURN TO THE SOUTHWEST IN RESPONSE TO A LARGE  
PACIFIC NORTHWEST TROUGH. ELEVATED INSTABILITY/SHEAR MAY LEND  
ITSELF TO SOME STRONGER TO SEVERE STORMS, AS HINTED AT BY  
MACHINE LEARNING MODELS. HOWEVER, MANY DETAILS STILL NEED TO BE  
WORKED OUT, SO BROAD BRUSH 30-50 NBM POPS SATURDAY NIGHT THROUGH  
SUNDAY SEEM REASONABLE AT THIS TIME.  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/  
 
ISSUED AT 1015 PM CDT TUE SEP 9 2025  
 
THE MAIN CHALLENGES OVERNIGHT INTO WEDNESDAY MORNING WILL BE THE  
POTENTIAL FOR IFR AND POSSIBLY LIFR STRATUS AND FOG. EXPECT  
BOTH TO OCCUR, WITH LOCATIONS NEAR AND EAST OF THE JAMES RIVER  
SEEING THE BEST CHANCE. IMPROVEMENTS TO VFR SHOULD OCCUR IN MOST  
SPOTS BY LATE MORNING INTO EARLY WEDNESDAY AFTERNOON.  
 
 
   
FSD WATCHES/WARNINGS/ADVISORIES  
 
SD...NONE.  
MN...NONE.  
IA...NONE.  
NE...NONE.  
 
 
 
 
 
DISCUSSION...ROGERS  
AVIATION...08  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab SD Page
The Nexlab IA Page
The Nexlab MN Page
The Nexlab NE Page
Main Text Page