674
FXUS63 KFSD 091719
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1219 PM CDT FRI OCT 9 2026
KEY MESSAGES
- NEAR-RECORD HEAT AND STRONG WINDS: HIGH TEMPERATURES MAY
APPROACH RECORDS ALONGSIDE STRONG SOUTHWEST WINDS OF 35-45 MPH
SATURDAY. HIGHEST WINDS ALONG THE BUFFALO RIDGE.
- ELEVATED FIRE DANGER AND BLOWING DUST: SATURDAY'S HOT, DRY,
AND WINDY CONDITIONS WILL LEAD TO ELEVATED FIRE DANGER AND
BLOWING DUST POTENTIAL. FARMERS AND TRAVELERS SHOULD BE AWARE
OF LOCALIZED VISIBILITY REDUCTIONS AND INCREASED FIRE RISKS.
- SHARP TEMPERATURE DROP: A COLD FRONT ARRIVING LATE SUNDAY WILL
PUSH TEMPERATURES DOWNWARDS INTO EARLY NEXT WEEK, CLOSER TO
SEASONAL NORMALS.
- LATE WEEK RAIN AND TURNING COLDER: EXPECT DRY SEASONABLE
WEATHER THROUGH MID-WEEK BEFORE A STRONGER STORM ARRIVES
WEDNESDAY. A 60% PROBABILITY OF RAIN IS ALREADY IN THE
FORECAST BY THURSDAY WITH A POTENTIAL SHIFT TO MUCH COLDER
TEMPERATURES NEXT WEEKEND.
DISCUSSION
ISSUED AT 1211 PM CDT FRI OCT 9 2026
THIS AFTERNOON: A RATHER PLEASANT DAY ACROSS THE REGION AS A WEAK
STATIONARY BOUNDARY IS BEGINNING TO DRIFT NORTHWARD. WEAK
CONVERGENCE ALONG THIS BOUNDARY WILL KEEP A NARROW CORRIDOR OF MID
AND UPPER 50 DEWPOINTS DRIFTING NORTHWARD. ELSEWHERE, AS AFTERNOON
MIXING AND HEATING TAKE OVER, WE SHOULD SEE DEW POINTS MIX DOWNWARDS
SLIGHTLY.
TONIGHT: A BEAUTIFUL EVENING CAN BE EXPECTED THROUGH THE REGION AS
HIGH LEVEL CIRRUS PUSHES SOUTHEAST. WINDS WILL STAY LIGHT AND MIXY
THROUGH THE NIGHT AS THE AFOREMENTIONED FRONT LIFTS NORTHEAST. WHILE
SOME VALLEY AREAS MAY COOL INTO THE 50S, THE PREVAILING OVERNIGHT
LOW TEMPERATURES WILL STAY IN THE LOWER 60S IN MANY AREAS, ONLY A
FEW DEGREES OFF TYPICAL SEASONAL HIGH TEMPERATURES.
SATURDAY: NEAR TO RECORD HIGH TEMPERATURES WILL ARRIVE FOR SATURDAY,
ACCOMPANIED BY GUSTY SOUTHWESTERLY WINDS AND PLENTY OF DRY AIR.
THE STRONG SURFACE PRESSURE GRADIENT ALREADY PUSHING 15 TO 20
MPH SUSTAINED WINDS BY MID-MORNING WILL CONTINUE TO TIGHTEN
THROUGH THE AFTERNOON, BUT THE DEEPENING MIXING WILL PROMOTE
MIXDOWN OF THE 40+ KNOT LLJ THAT WILL PERSIST INTO THE MID-LATE
AFTERNOON HOURS. IN THESE SITUATIONS HISTORICALLY, DEEPER MIXING
MODELS WILL VERIFY BETTER FOR DEW POINTS AND WINDS, SO HAVE
MIXED BOTH THE HRRR/RAP INTO THE FORECAST THROUGH THE AFTERNOON
HOURS. THIS WILL PROMOTE OCCASIONAL WIND GUSTS OF 35 TO 45 MPH
(HIGHEST ALONG THE BUFFALO RIDGE), AND DEW POINTS DROPPING INTO
THE LOWER 50S. WHILE THE NBM HAS STARTED TO CATCH-UP TO RECENT
WARM TEMPERATURE BIAS, MAKING THE MEAN POPULATION A BIT MORE
REASONABLE, HAVE AGAIN BUMPED UP TEMPERATURES SLIGHTLY TOWARDS
THE 90TH PERCENTILE GIVEN SYNOPTIC POTENTIAL. THIS WILL PLACE
HIGH TEMPERATURES NEAR DAILY RECORDS. ONE THING TO WATCH FOR
SATURDAY WILL BE THE POTENTIAL FOR HARVEST RELATED BLOWING DUST,
WHICH COULD PRODUCE SOME VERY LOCALIZED VISIBILITY AND AQI
REDUCTIONS. THE COMBINATION OF HEAT, WIND, AND DRYING FUELS WILL
LEAD TO ELEVATED FIRE DANGER. PLEASE SEE SEPARATE DISCUSSION
FOR FURTHER DETAILS.
SUNDAY: WINDS WILL WEAKEN SATURDAY NIGHT AS A FRONTAL BOUNDARY
BEGINS TO APPROACH FROM THE WEST. HOWEVER CONTINUED MIXING AFTER A
VERY WARM AFTERNOON WILL KEEP OVERNIGHT LOW TEMPERATURES IN THE 60S.
THIS FRONT WILL BISECT THE CWA BY THE MIDDLE OF THE AFTERNOON,
PROMOTING ANOTHER DAY OF HIGHS IN THE 80S ALONG AND SOUTHEAST OF THE
BOUNDARY, BUT A QUICK DROP TOWARDS THE 60S TOWARDS CENTRAL SOUTH
DAKOTA. THERE WILL BE A SHARP INCREASE IN MID-LVL CLOUDS ALONG THE
BOUNDARY WHICH MAY IMPACT HEATING SLIGHTLY. THE FRONT SLOWLY SETTLES
SOUTHEAST INTO MONDAY MORNING, PULLING COOLER AIR INTO THE JAMES
RIVER VALLEY. THAT SAID, THERE'S HIGH POTENTIAL THAT WE'LL SET NEW
RECORD WARM MINIMUM TEMPERATURES SATURDAY AND POTENTIALLY AGAIN
SUNDAY.
MONDAY-WEDNESDAY: BROAD RIDGING OVER THE CENTRAL CONUS AND THE
REMNANTS OF HURRICANE ISAIAS WILL PREVENT ANY MEANINGFUL MOISTURE TO
BE ABLE TO ADVECT INTO THE TRI-STATE AREA BEHIND THE PASSAGE OF THE
SURFACE TROUGH MONDAY MORNING. THE END RESULT MAY BE AN INCREASE IN
MID-LVL CLOUDS AND OCCASIONAL VIRGA/SPRINKLES IN THE AFTERNOON.
CANADIAN HIGH PRESSURE SLIDES SOUTHEAST THROUGH THE MIDDLE OF THE
WEEK, KEEPING A DRY FORECAST GOING, AND DROPPING HIGH TEMPERATURES
CLOSER TO THEIR SEASONAL NORMALS FOR A FEW DAYS.
THURSDAY-FRIDAY: A BIT OF UNCERTAINTY DEVELOPS IN THE EXTENDED
PORTIONS OF THE FORECAST AS MEDIUM RANGE MODELS DEVELOP A DEEP
UPPER TROUGH OVER THE WESTERN CONUS. BY WEDNESDAY, THERE SEEMS
TO BE CONSENSUS IN BOTH ENSEMBLE AND AI BASED GUIDANCE THAT THE
ENERGY AT THE BASE OF THE TROUGH BEGINS TO EJECT IN TO THE
PLAINS. THE INCREASING NORTHWARD MOISTURE RETURN COMBINED WITH
LIFT FROM THE OPENING WAVE SUPPORTS HIGH POPS FROM THE NBM AT
THIS TIME. EC/GEFS PROBABILITIES FOR >0.10" OF QPF OVER 24 HOURS
IS ALREADY OVER 60% THROUGH THE REGION. WHILE IT'S STILL A BIT
OUT THERE, THE PASSAGE OF THIS TROUGH AND EVENTUAL DEEPENING OF
A LARGER LONGWAVE TROUGH THROUGH CENTRAL NORTH AMERICA COULD
SIGNAL AT LEAST A TEMPORARY SHIFT TOWARDS COLDER THAN NORMAL
TEMPERATURES INTO NEXT WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1155 AM CDT FRI OCT 9 2026
VFR CONDITIONS WILL CONTINUE INTO THE OVERNIGHT HOURS. WINDS
WILL REMAIN QUITE BREEZY INTO SATURDAY MORNING, WITH RAPID GUST
DEVELOPMENT THROUGH THE DAY. LLWS WILL BEGIN TO DEVELOP THIS
EVENING AND IS EXPECTED TO CONTINUE THROUGH MID-MORNING. VFR
CONDITIONS AND STRONG GUSTY WINDS BETWEEN 30 AND 40 MPH ARE
LIKELY THROUGH SATURDAY.
FIRE WEATHER
ISSUED AT 1211 PM CDT FRI OCT 9 2026
CONCERNS FOR FIRE WEATHER GROW ON SATURDAY AND CONTINUE
SATURDAY NIGHT. LATEST GUIDANCE CONTINUE TO SUPPORT FALLING
AFTERNOON RH INTO THE LOWER 30% RANGE, WITH NEAR RECORD HIGH
TEMPERATURES AND SEASONALLY STRONG WINDS NEAR 40 MPH. THE
PRIMARY ASPECT OF THE GFDI THAT IS KEEPING LEVELS IN THE "HIGH"
CATEGORY IN MOST AREAS IS THE RELATIVE PERCENT GREENNESS OF
FINE FUELS. RECENT RAINFALL AND WARM TEMPERATURES HAVE LED TO A
SLIGHT INCREASE IN PERCENT GREENNESS AND CONTINUES TO HOLD BACK
HIGHER END FIRE DANGER. HOWEVER, WE'RE ALSO NOW IN THE HEART OF
HARVEST SEASON WITH CROPS SIGNIFICANTLY DRY IN MANY AREAS. THIS
IS LIKELY WHERE THE GREATER CONCERN IS FOR SATURDAY, AS FIELD
ACTIVITIES MAY BE A DRIVING FORCE BEHIND ANY WILDFIRE POTENTIAL.
THE AGGFDI WOULD SUGGEST CONSIDERABLE CONCERN THROUGH THE TRI-
STATE AREA, SO EXTREME CAUTION SHOULD BE USED WHEN WORKING
OUTSIDE SATURDAY.
CLIMATE
ISSUED AT 1211 PM CDT FRI OCT 9 2026
RECORD HIGH TEMPERATURES:
OCTOBER 9: KFSD: 89/1980 KSUX: 87/1980 KHON: 90/1980 KMHE: 91/1928
OCTOBER 10: KFSD: 88/1928 KSUX: 92/1928 KHON: 92/1928 KMHE: 93/1928
OCTOBER 11: KFSD: 90/2015 KSUX: 91/2015 KHON: 91/1910 KMHE: 95/1910
RECORD HIGH MINIMUM TEMPERATURES:
OCTOBER 10: KFSD: 64/1928 KSUX: 66/1930 KHON: 60/1947
OCTOBER 11: KFSD: 67/1997 KSUX: 66/1997 KHON: 68/1997
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...DUX
AVIATION...DUX
FIRE WEATHER...DUX
CLIMATE...DUX
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