925
FXUS63 KFSD 221134
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
634 AM CDT THU OCT 22 2026
KEY MESSAGES
- PATCHY FOG, ESPECIALLY IN RIVER VALLEYS, WILL LEAD TO
VISIBILITY BELOW TWO MILES AT TIMES THROUGH MID MORNING.
LOCALIZED DENSE FOG IS POSSIBLE.
- WELL ABOVE NORMAL TEMPERATURES, INCREASING WINDS, AND DRYING
FUELS LEAD TO ELEVATED FIRE DANGER THURSDAY TO NEAR CRITICAL
FIRE DANGER FRIDAY. HARVEST ACTIVITY SHOULD USE EXTREME
CAUTION.
- A SIGNIFICANT COOLDOWN ARRIVES THIS WEEKEND AND CONTINUES
INTO NEXT WEEK WITH HIGHS BACK INTO THE 50S.
- THIS COOLDOWN BRINGS RAIN RISKS SATURDAY INTO MONDAY.
PROBABILITIES FOR >0.10" ARE NEAR 100%, WITH POTENTIAL FOR
>0.50" NEAR 70%, AND PROBABILITIES FOR >1.0" AS HIGH AS 50%.
UPDATE
ISSUED AT 322 AM CDT THU OCT 22 2026
BEGINNING TO SEE SOME FOG DEVELOP ACROSS THE AREA EARLY THIS
MORNING. OUTSIDE OF BRIEF VISIBILITY BELOW ONE MILE, MOST LOCATIONS
ARE REMAINING AT OR ABOVE TWO MILES. EXPECT FOG TO EXPAND OVER THE
AREA AS WINDS BECOME CALM AND TEMPERATURES FALL INTO THE 40S TO NEAR
50. FOG SHOULD QUICKLY MIX OUT BY MID MORNING AS SOUTHERLY WINDS
INCREASE.
SLIGHTLY INCREASED TEMPERATURES AGAIN WITH THE 90TH PERCENTILE FOR
THE NEXT COUPLE OF DAYS AS THE NBM CONTINUES TO UNDER PERFORM. OTHER
THAN THAT, NO SIGNIFICANT CHANGES TO THE FORECAST. SOUTHERLY WINDS
INCREASE TODAY, WITH GUSTS WEST OF I-29 THIS AFTERNOON AROUND 30 MPH
(TAPERING DOWN AS YOU HEAD EAST). ELEVATED FIRE DANGER IS EXPECTED,
ESPECIALLY ACROSS SOUTH CENTRAL SD. MORE DETAILS BELOW IN THE FIRE
WEATHER SECTION. WINDS REMAIN BREEZY OVERNIGHT WITH THE TIGHTENING
SPG WITH LOWS IN THE 50S.
LATEST HI-RES GUIDANCE CONTINUES TO SHOW LIGHT RAIN/SHOWERS MOVING
THROUGH FRIDAY MORNING ON AN INITIAL MID LEVEL WAVE/WAA. HOWEVER,
RAINFALL AMOUNTS WILL BE LIGHT WITH LOW (< 15%) CHANCES OF A TENTH
OF AN INCH OR MORE. MAIN CONCERN FRIDAY REMAINS THE STRONG SOUTHERLY
WINDS AND WARM TEMPERATURES, CREATING NEAR CRITICAL FIRE DANGER.
WIND GUSTS ACROSS THE AREA FROM 30 TO 45 MPH EXPECTED, HIGHEST WEST
OF US HIGHWAY 81. SOUNDINGS CONTINUE TO SHOW THE POTENTIAL FOR SOME
STRONGER GUSTS IN SOUTH CENTRAL SD, WITH NBM PROBABILITY OF OVER 50
MPH WIND GUSTS AROUND 30% IN GREGORY COUNTY. EXPECT NEAR CRITICAL
FIRE CONDITIONS, WITH THE LIMITING FACTOR HUMIDITY VALUES. MORE
DETAILS BELOW. THOSE COMPLETING HARVEST ACTIVITIES SHOULD TAKE EXTRA
CAUTION FRIDAY TO PREVENT SPARKS.
RAIN CHANCES REMAIN ON TRACK FOR THE WEEKEND WITH COOLER
TEMPERATURES AHEAD.
DISCUSSION
ISSUED AT 1235 PM CDT WED OCT 21 2026
THIS AFTERNOON: AN ABSOLUTELY BEAUTIFUL MID-OCTOBER AFTERNOON
IS UNFOLDING AS WINDS HAVE REMAIN LIGHT, SKIES REMAIN CLEAR, AND
TEMPERATURES ARE RISING INTO THE 70S. DEW POINTS ARE MIXING
DOWN INTO THE MIDDLE 40S IN A FEW AREAS, WHICH COULD BE A SIGN
FOR LATER TONIGHT.
TONIGHT: A BIT OF HIGH LVL CIRRUS THAT CROSSES THE CWA LATER THIS
AFTERNOON AND EARLY EVENING WILL PREVENT A SHARP TEMPERATURE DROP-
OFF INITIALLY. HOWEVER NEARLY ALL GUIDANCE IS INDICATING THAT WE'LL
SEE A NIGHT WITH LIGHT TO CALM WINDS AND CLEAR SKIES. GIVEN THESE
CONDITIONS, WILL LOWER TEMPERATURES SIGNIFICANTLY IN MOST LOCATIONS,
WITH HRRR/RAP GUIDANCE INDICATING POTENTIAL FOR MID-40S. WITH
AFTERNOON DEW POINTS LIKELY FALLING A BIT FURTHER, THIS LEAVES CROSS-
OVER TEMPERATURES IN A FAVORABLE POSITION TO LEAD TO FOG
DEVELOPMENT. THE MAJORITY OF THIS FOG MAY BE CONFINED TO SHELTERED
RIVER/VALLEY AREAS, BUT GIVEN TEMPERATURE FALLS, SOME MAY SPILL OUT
INTO A BROADER AREA AND BECOME LOCALLY DENSE.
THURSDAY: TROUGHING SLIDING INTO THE CENTRAL ROCKIES WILL HELP
INTENSIFY THE SPG THROUGHOUT THE PLAINS ON THURSDAY. WINDS WILL
BEGIN TO INCREASE EARLY IN THE MORNING AND BY THE AFTERNOON WE'LL
SEE ROUTINE GUSTS 20 TO 30 MPH AT TIMES. SLOWLY DRYING FUELS AND
INCREASING WIND WILL LEAD TO INCREASED FIRE DANGER. SEE SEPARATE
DISCUSSION FOR FURTHER DETAILS.
FRIDAY: LATE THURSDAY NIGHT WE'LL BEGIN TO SEE AN INCREASE IN LOW-
LVL MOISTURE EMANATING FROM THE OKLAHOMA PANHANDLE. THIS
MOISTURE, WHEN COMBINED WITH CONVERGENCE ON A 40 KNOT LLJ AND
WEAK DPVA, MAY LEAD TO ISOLATED TO SCATTERED HIGH BASED SHOWERS
AFTER 3AM FRIDAY WHICH WILL CONTINUE LIFTING NORTHWARD FRIDAY
MORNING. A MINOR INCREASE IN ELEVATED INSTABILITY COULD LEAD TO
ISOLATED LIGHTNING STRIKES WITH THIS ACTIVITY. HOWEVER, THE
GREATER THREAT IN THE AFTERNOON AND EVENING WILL BE THE SURGING
HIGH TEMPERATURES AND INCREASING WIND GUSTS. LATEST GUIDANCE
STRONGLY SUPPORTS SUSTAINED WINDS 20 MPH IN MANY LOCATIONS, WITH
POTENTIAL FOR GUSTS OF 45 MPH AT TIMES. WHILE THE SE SURFACE
WIND DIRECTION IS A BIT MIS-ALIGNED WITH THE STRONGEST CORRIDOR
OF LOW-LVL SWLY FLOW, THE HIGHEST WIND CORRIDOR IS LIKELY TO
FALL ALONG AND WEST OF A BROOKINGS TO YANKTON LINE. THIS WILL
AGAIN INCREASE FIRE DANGER SO PLEASE READ SEPARATE DISCUSSION
FOR FURTHER DETAILS.
SATURDAY-WEDNESDAY: A WARM OVERNIGHT IS ANTICIPATED INTO SATURDAY
AS THE SPG REALLY DOESN'T WEAKEN AND PROMOTES INCREASED MIXING
THROUGH THE NIGHT. BY SATURDAY MORNING, A COLD FRONT WILL SLOWLY
SLIDE EAST INTO CENTRAL SOUTH DAKOTA. WEAK LOW-LVL CONVERGENCE AND
MOISTURE STREAMING AHEAD OF THIS FRONT COULD LEAD TO HIGH BASED
SHOWERS INTO DAYBREAK. A SPLITTING UPPER TROUGH OVER THE ROCKIES
WILL PROMOTE TWO DISTINCT FEATURES, A PROGRESSIVE TROUGH LIFTING
NORTHEAST INTO SOUTHERN CANADA SATURDAY INTO SUNDAY, WITH A CUTOFF
AREA OF ENERGY STALLING OVER THE FOUR CORNERS. THE AFOREMENTIONED
FRONTAL BOUNDARY WILL GET NUDGED SOUTHEAST ON SATURDAY, BISECTING
THE CWA. WITH SIGNIFICANT COLD AIR LAGGING THIS FRONT, THE
TEMPERATURE GRADIENT IS NOT EXPECTED TO BE EXTREME. HOWEVER AN
INCREASE IN CLOUD COVER, ALONG WITH POTENTIAL FOR OCCASIONAL LIGHT
RAIN WILL PERSIST THROUGH SATURDAY AND INTO SATURDAY NIGHT.
ONE OR MORE WEAK IMPULSES TRAVELING NORTHEAST ALONG THE STALLED
FRONT WILL KEEP CLOUDS AND OCCASIONAL RAIN RISKS THROUGH THE CWA
SATURDAY NIGHT AND THROUGH SUNDAY. QPF AMOUNTS THROUGH SUNDAY
AFTERNOON MAY BE ON THE LIGHTER SIDE, WITH MOST AREAS SEEING LESS
THAN 0.25".
THAT EARLIER MENTIONED UPPER LOW OVER THE FOUR CORNERS BEGINS TO
EJECT NORTHEAST BY THE END OF THE WEEKEND AND INTO MONDAY. A STRONG
LOW-LVL FRONTAL ZONE IS EXPECTED TO DEVELOP ACROSS THE CWA AHEAD OF
THIS SYSTEM, PROMOTING INCREASING RAIN CHANCES. THE VERY SLOW
NORTHWARD MOVEMENT OF THE APPROACHING SW TROUGH WILL KEEP HIGH RAIN
CHANCES THROUGH THE CWA ON MONDAY AND WILL LIKELY CONTINUE INTO
EARLY TUESDAY. LATEST NBM PROBABILITIES SUGGEST HIGH RAIN
PROBABILITIES AT NEAR 100% FOR >0.10", POTENTIAL FOR >0.50" NEAR 70%-
80%, PROBABILITIES FOR >1.0" AS HIGH AS 50% AND PROBABILITIES
FOR 2.0" TOTALS AT 20%.
THE PASSAGE OF THIS SYSTEM, AND THEN THE COOLER AIR THAT FOLLOWS IT,
WILL PROMOTE A RETURN OF MORE TYPICAL MID-LATE OCTOBER TEMPERATURES.
HIGH TEMPERATURES SUNDAY THROUGH WEDNESDAY ARE FAVORED TO BE IN THE
UPPER 40S TO MID 50S.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 628 AM CDT THU OCT 22 2026
MVFR TO IFR FOG CONTINUES THROUGH MID MORNING. A FEW SITES NEAR
AND ALONG THE MO RIVER (MAINLY NEAR KAGZ TO KVMR) HAVE BEEN MORE
PERSISTENT WITH VISIBILITY BELOW 1/2 SM; HOWEVER, OTHER SITES
HAVE BEEN MUCH MORE SPORADIC WITH VIS UNDER 1 SM. CONDITIONS
IMPROVE BY 14-15Z, WITH VFR CONDITIONS EXPECTED FOR THE REST OF
THE PERIOD.
LIGHT AND VARIABLE WINDS THIS MORNING INCREASE, WITH SOUTHERLY GUSTS
15-25 KNOTS THIS AFTERNOON AND EVENING. WINDS REMAIN BREEZY
OVERNIGHT, WITH GUSTS AROUND 30 KNOTS POSSIBLE BY DAYBREAK
FRIDAY IN SOUTH CENTRAL SD.
LIGHT RAIN SHOWERS DEVELOP TOWARD THE VERY END OF THE TAF
PERIOD BUT TOO LOW CONFIDENCE IN IMPACTS TO TERMINALS TO INCLUDE
AT THIS TIME.
FIRE WEATHER
ISSUED AT 322 AM CDT THU OCT 22 2026
WARM TEMPERATURES, INCREASING WINDS, AND DRY CONDITIONS TODAY WILL
LEAD TO ELEVATED FIRE CONCERNS - ESPECIALLY WEST OF I-29. BY THIS
AFTERNOON, SOUTHERLY WINDS INCREASE TO 10-15 MPH, WITH GUSTS 20-25
MPH AND AS HIGH AS 30 MPH IN SOUTH CENTRAL SD. HIGHS CLIMB TO THE
MID 70S AND NEAR 80 DEGREES. MINIMUM HUMIDITY VALUES ABOVE 40%
SHOULD TEMPER WIDESPREAD SIGNIFICANT CONCERNS TODAY.
MOSTLY DRY CONDITIONS CONTINUE FRIDAY AFTER SOME SCATTERED MORNING
SHOWERS/SPRINKLES. PROBABILITY OF MORE THAN A TENTH OF AN INCH OF
RAIN IS LOW (LESS THAN 15%). SOUTHERLY WINDS CONTINUE TO INCREASE
THROUGH THE MORNING HOURS WITH GUSTS BY THE AFTERNOON 30 TO 45 MPH,
HIGHEST TOWARD AND WEST OF US HIGHWAY 81. GUSTS AROUND 50 MPH ARE
POSSIBLE (30% OR LESS) IN SOUTH CENTRAL SD. THESE STRONG WINDS
COUPLED WITH DRYING FUELS/CROPS AND TEMPERATURES IN THE MID 70S TO
LOWER 80S, WILL LEAD TO NEAR CRITICAL FIRE CONDITIONS OVER THE
ENTIRE AREA. HUMIDITY VALUES SHOULD REMAIN ABOVE CRITICAL THRESHOLDS
(VALUES NEAR/ABOVE 35%); HOWEVER, GFDI VALUES CLIMB INTO THE HIGH
AND VERY HIGH CATEGORIES. ANY FIRE THAT STARTS WILL LIKELY QUICKLY
SPREAD GIVEN DRY GRASSES AND CROPS; USE EXTREME CAUTION TO PREVENT
SPARKS.
LOCALLY ELEVATED FIRE DANGER MAY CONTINUE INTO SATURDAY, ALTHOUGH
RAIN CHANCES WILL BE INCREASING AND TEMPERATURES COOLING AS A
BOUNDARY MOVES INTO THE AREA. RAIN CHANCES AND COOLER TEMPERATURES
PREVAIL INTO THE WEEKEND AND EARLY NEXT WEEK, TEMPERING FIRE
CONCERNS.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SG
DISCUSSION...DUX
AVIATION...SG
FIRE WEATHER...SG
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