959
FXUS63 KFSD 111715
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1215 PM CDT THU SEP 11 2025
KEY MESSAGES
- TEMPERATURES WARM TO WELL ABOVE MID-SEPTEMBER NORMALS HEADING
INTO THE WEEKEND AND INTO EARLY NEXT WEEK.
- RAIN/STORM CHANCES INCREASE THIS WEEKEND, WITH A 30-50% CHANCE
WEST OF I-29 SATURDAY NIGHT AND A 30-60% CHANCE AREA-WIDE
SUNDAY INTO SUNDAY NIGHT.
DISCUSSION
ISSUED AT 342 AM CDT THU SEP 11 2025
BEGINNING TO SEE PATCHY FOG DEVELOPMENT OVER SOUTHWESTERN MN VERY
EARLY THIS MORNING. WITH MOSTLY CLEAR SKIES AND LIGHT WINDS, THERE
WILL BE A POSSIBILITY OF ADDITIONAL FOG DEVELOPMENT EAST OF
INTERSTATE 29 THROUGH MID MORNING. FOR THE REMAINDER OF THE DAY,
UPPER LEVEL RIDGING WILL CONTINUE TO HAVE INFLUENCE ACROSS THE
REGION - WITH PARTLY CLOUDY SKIES AND WARMING TEMPERATURES AS HIGHS
RISE INTO THE LOWER TO MID 80S. WE MAY CONTINUE TO SEE A MILKY
APPEARANCE TO THE SKY WITH CANADIAN WILDFIRE SMOKE REMAINING
OVERHEAD, THOUGH THIS SHOULD FINALLY MOVE OUT OF THE AREA BY LATER
TONIGHT. IT LOOKS TO REMAIN DRY TONIGHT WITH LATEST HI-RES GUIDANCE
KEEPING ANY SHOWER/THUNDERSTORM ACTIVITY TO THE WEST OF OUR AREA.
WINDS WILL BE A LITTLE STRONGER TONIGHT (10-15 MPH) THAN RECENT
NIGHTS SO FOG SHOULD NOT BE AN ISSUE.
FOR FRIDAY AND SATURDAY, A DEEP UPPER LEVEL TROUGH TO OUR WEST
BEGINS TO SHIFT SLOWLY EASTWARD. EVEN SO, OUR AREA WILL REMAIN UNDER
THE INFLUENCE OF UPPER LEVEL RIDGING AND TEMPERATURES WILL CONTINUE
TO WARM. HIGHS ON FRIDAY LOOK TO BE IN THE MID TO UPPER 80S, THEN
UPPER 80S TO LOWER 90S FOR SATURDAY. THE NBM DID A LITTLE BETTER
WITH TEMPERATURES THIS RUN IN TERMS OF ITS WARM BIAS, BUT LIKE THE
PAST SEVERAL DAYS, CONTINUED TO BLEND A BIT OF THE NBM 50TH
PERCENTILE INTO THE GIVEN GUIDANCE TO ACCOUNT FOR THIS. THE CURRENT
FORECAST CONTINUES WITH MAINLY DRY CONDITIONS FOR FRIDAY INTO
SATURDAY WITH THE BETTER FORCING REMAINING TO OUR WEST.
INTERESTINGLY THOUGH, THE LATEST RUN OF THE HRRR, AND THE RAP TO A
LESSER DEGREE, WANT TO PRODUCE ISOLATED SHOWERS/THUNDERSTORMS ON
FRIDAY MORNING AS A SHORTWAVE LIFTS THROUGH THE REGION ON A
SOUTHWESTERLY UPPER LEVEL FLOW. KEPT IT DRY FOR NOW HOWEVER WITH
SOUNDINGS CONTINUING TO INDICATE STRONG CAPPING ACROSS THE AREA.
ALTHOUGH PRIMARILY DRY CONDITIONS WILL PREVAIL THROUGH THE PERIOD,
CANNOT COMPLETELY RULE OUT AN ISOLATED SHOWER/THUNDERSTORM MAKING IT
INTO OUR FAR WESTERN MOST CWA ON FRIDAY NIGHT AND SATURDAY IF THEY
MOVE OUT OF CENTRAL SD.
THE SHOWER AND THUNDERSTORM CHANCES WILL INCREASE AS WE MOVE INTO
SATURDAY NIGHT AND SUNDAY WHEN THE AFOREMENTIONED UPPER LEVEL TROUGH
FINALLY PUSHES INTO THE REGION - WITH THE MAIN FOCUS COMING LATER ON
SUNDAY INTO SUNDAY NIGHT. THE SEVERE WEATHER POTENTIAL IS STILL
UNCERTAIN WITH THE INSTABILITY BEING OFFSET FROM THE STRONGER SHEAR,
BUT THIS REMAINS A PERIOD TO KEEP AN EYE ON.
A SECONDARY UPPER LEVEL TROUGH AGAIN SLIDES INTO OUR REGION FOR THE
BEGINNING OF NEXT WEEK, KEEPING A POTENTIAL FOR SHOWERS AND
THUNDERSTORMS - MORE NOTABLE TOWARD THE MIDDLE OF THE WEEK.
TEMPERATURES LOOK TO REMAIN ABOVE NORMAL FOR MONDAY AND TUESDAY,
BEFORE DROPPING BACK CLOSER TO NORMAL FOR MIDWEEK.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1213 PM CDT THU SEP 11 2025
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. BREEZY CONDITIONS ARE
EXPECTED THIS AFTERNOON AND EVENING, WITH SOUTHEASTERLY GUSTS AROUND
20 KTS EXPECTED ALONG AND WEST OF I-29 TO THE JAMES RIVER,
INCREASING TO GUSTS OF 25-30 KTS ALONG AND WEST OF THE JAMES. WINDS
WILL GRADUALLY LESSEN TONIGHT, BUT THE LLJ WILL KICK UP AND CAUSE
LLWS CONCERNS AT TIMES OVERNIGHT AND INTO EARLY TOMORROW MORNING.
FOG IS NOT EXPECTED TO DEVELOP DUE TO ELEVATED WINDS (SOUTHEAST
AROUND 10 KTS) OVERNIGHT. SOUTHEASTERLY GUSTS OF 15-20 KTS WILL
RETURN ACROSS THE AREA THROUGH TOMORROW MORNING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JM
AVIATION...SAMET
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