327
FXUS63 KFSD 220409
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1109 PM CDT SAT MAR 21 2026
KEY MESSAGES
- THE PASSAGE OF A FRONT SATURDAY NIGHT WILL BRING POTENTIAL FOR
40+ MPH WIND GUSTS INITIALLY, AND THEN WIND CHILLS BELOW
FREEZING BY DAYBREAK SUNDAY.
- A ROLLER COASTER RIDE OF TEMPERATURES AND WIND CAN BE
EXPECTED NEXT WEEK, INCREASING FIRE DANGER, BUT WITH LITTLE TO
NO RAIN ANTICIPATED.
UPDATE
ISSUED AT 1108 PM CDT SAT MAR 21 2026
THE COLD FRONT WE'VE BEEN TALKING ABOUT THE PAST SEVERAL FORECAST
PACKETS HAS PASSED TO THE SOUTH OF OUR CWA. WINDS ARE NORTHERLY AND
HAVE BEGUN TO INCREASE IN RESPONSE TO THE TIGHTENING SPG. STRONG CAA
FLOWING INTO THE REGION AS WELL WILL RESULT IN TEMPERATURES AT THE
SURFACE ARE FALLING RAPIDLY AT ROUGHLY 5-8 DEGREES PER HOUR.
OVERNIGHT LOWS ARE EXPECTED TO FALL TO THE LOW TO UPPER 30S, WITH
TEMPERATURES COLDEST ALONG HIGHWAY 14. IN ADDITION, A WEAK BAND OF
VORTICITY MAY TRIGGER A FEW SCATTERED LIGHT SPRINKLES FOR AREAS
NORTH OF I-90 THROUGH DAYBREAK. NO ACCUMULATION IS EXPECTED.
WIND GUSTS AS OF 11 PM CDT RANGE FROM 25 TO 38 MPH. EXPECT GUSTS TO
PEAK IN THE NEXT HOUR OR TWO BETWEEN 35-40 MPH WITH OCCASIONAL
GUSTS UP TO 45 MPH POSSIBLE. THE STRONG GUSTS ARE EXPECTED TO BE
SHORT LIVED AND SO HAVE DECIDED AGAINST A WIND HEADLINE. GUSTS
DECREASE RAPIDLY AS WE APPROACH SUNRISE, BUT WILL REMAIN ON THE
BREEZY SIDE FOR SUNDAY AROUND 20-25 MPH. WINDS CONTINUE TO
GRADUALLY DECREASE THROUGH THE AFTERNOON BECOMING LIGHT AND
VARIABLE SUNDAY EVENING. HIGHS FOR WILL BE COOLER BUT STILL
COMFORTABLE, IN THE 40S AND 50S. LOWS WILL FALL TO 20S BY MONDAY
MORNING. PLEASE SEE THE DISCUSSION BELOW FOR DETAILS ON THE
UPCOMING WEEK.
DISCUSSION
ISSUED AT 1214 PM CDT SAT MAR 21 2026
THIS AFTERNOON: NEAR TO RECORD TEMPERATURES CONTINUE TO REMAIN
POSSIBLE SATURDAY AFTERNOON AS TEMPERATURES SURGE INTO THE 80S.
QUITE A FEW LOCATIONS ALREADY SAW THEIR FIRST 80 DEGREE TEMPERATURE
OF THE YEAR ON FRIDAY, BUT OTHERS WILL SEE THESE TEMPERATURES TODAY.
THIS WILL MARK SOME OF THE EARLIEST 80 AND 90 DEGREE HIGHS ON
RECORD. A WEAK SURFACE FRONT REMAINS STALLED THROUGH THE HEART
OF THE CWA EARLY THIS AFTERNOON, LEADING TO A BIT OF A LULL OR
DROP IN WIND SPEEDS ALONG AND SOUTH OF I-90. HOWEVER, WE ARE
SEEING SOME MODEST INCREASE IN SOUTHWESTERLY FLOW THROUGH
EASTERN NEBRASKA, PUSHING INTO THE MISSOURI RIVER VALLEY REGION
BY MID- AFTERNOON AND THEN NW IOWA BY LATE AFTERNOON AND EARLY
EVENING. WINDS MAY BE A TAD LIGHTER THAN PREVIOUSLY EXPECTED,
BUT DANGEROUSLY LOW RH CONTINUE THE FIRE DANGER RISKS WITH RAPID
SPREAD INCREASED.
TONIGHT: 12Z HIGH RESOLUTION CAMS ALL SHOW THE COLD FRONT, STEADILY
DROPPING SOUTHWARD THIS EVENING, BUT THE TRUE SURGE OF 925:850 CAA
NOT ARRIVING UNTIL LATE EVENING. THE ARRIVAL OF THIS COLD AIR,
INDUCING STEEP SURFACE TO 900MB LAPSE RATES, WILL ALLOW THE
DEVELOPMENT OF STRONG GUSTS UPWARDS OF 40 TO 45 MPH INTO THE
OVERNIGHT HOURS. THESE WINDS ARRIVE NEAR HIGHWAY 14 BY 9-10PM, I-90
BY 11PM, AND HIGHWAY 20 AFTER MIDNIGHT. HAVE MANUALLY INCREASED
GUSTS THROUGH THE OVERNIGHT TO ACCOUNT FOR THE WIND POTENTIAL. AT
THIS POINT, THE BREVITY OF THE HIGHER GUSTS DOES NOT REQUIRE A
WIND ADVISORY. AFTER A BEAUTIFUL DAY/EVENING, ANYONE THAT
BUILDS A BACKYARD FIRE SHOULD MAKE SURE THESE ARE EXTINGUISHED
AS THEY COULD PROVIDE EASY SPARKS FOR FIRE STARTS. FURTHER
BEHIND THE FRONT, WEAK 700:500 VORTICITY TRAVELING THROUGH THE
WESTERLY MID-LVL FLOW COULD LEAD TO SPRINKLES TO VERY LIGHT
SHOWERS TRACKING AS FAR SOUTH AS I- 90 BY SUNRISE.
SUNDAY: SUNDAY MORNING WE COMPLETE THE CIRCLE OF SEASONS BACK TO
WINTER AS WIND CHILLS FALL BELOW FREEZING THROUGH LATE MORNING. THE
GOOD NEWS IS THAT IT'S NOW LATE MARCH AND AS WINDS TURN LIGHT
THROUGH THE AFTERNOON, WE SHOULD AGAIN SEE TEMPERATURES BACK TO
NORMAL IN THE LOWER 50S.
MONDAY: AS WE'VE BEEN DISCUSSING THE PAST WEEK, MUCH OF THE
UPCOMING WORK WEEK WILL REMAIN QUIET AS THE MID-LVL PATTERN
CONTINUES TO BE DOMINATED BY AN ANOMALOUSLY STRONG UPPER RIDGE
OVER THE SOUTHWESTERN US. WHILE THIS RIDGE WILL BE WEAKENING
SLIGHTLY EARLY IN THE WEEK, IT IS EXPECTED TO REBUILD AS THE
WEEK MOVES FORWARD. BY MONDAY, WE'LL AGAIN SEE THE RETURN OF
LOW-LVL WARM ADVECTION WHICH WILL ALLOW A TONGUE OF MOISTURE TO
DRIFT THROUGH THE DAKOTAS. THIS MEAGER MOISTURE LAYER COMBINED
WITH WEAK TO MODEST LIFT COULD RESULT IN A FEW SCATTERED HIGH
BASED SHOWERS MOVING SW TO NE MONDAY AFTERNOON. THERE IS ONLY
AROUND 50 J/KG MUCAPE MOVING THROUGH, SO NOT ANTICIPATING MUCH
IN THE WAY OF LIGHTNING DEVELOPMENT. WIND WILL ALSO INCREASE IN
THE AFTERNOON, GUSTING OVER 25-30 MPH AT TIMES WEST OF I-90. RH
VALUES HOWEVER WILL REMAIN IN THE MID-30 PERCENT RANGE WHICH
WILL LOWER FIRE DANGER SLIGHTLY.
TUESDAY-WEDNESDAY: THAT SOUTHWESTERN RIDGE REALLY BEGINS TO INCREASE
ON TUESDAY, PUSHING WARMER LOW-LVL TEMPERATURES FURTHER EAST THROUGH
THE PLAINS AND TOWARDS THE GREAT LAKES. A SURFACE WARM FRONT IS
EXPECTED TO DEVELOP THROUGH THE DAKOTAS AND MINNESOTA BY TUESDAY,
ALLOWING WARMER AIR TO SURGE NORTHWARD AND KEEPING WINDS SOUTHERLY
BOTH DAYS. TUESDAY WILL AGAIN FEATURE INCREASED FIRE DANGER, AS
INCREASING LOW-LVL FLOW OFF THE WESTERN PLAINS INCREASES TO 40
KNOTS. AFTERNOON SOUNDINGS SHOW POTENTIAL FOR DEEPER MIXING AND
POTENTIAL FOR FURTHER DEW POINT/RH DROPS THAN THE DETERMINISTIC NBM
WOULD SUGGEST. IF WIND GUSTS CONTINUE TO INCREASE, THEN
ELEVATED FIRE DANGER MAY DEVELOP THROUGH THE AFTERNOON. THAT
AFOREMENTIONED WEAK FRONT WILL SETTLE SOUTHWARD ON WEDNESDAY,
THROUGH TEMPERATURES MAY ACTUALLY RISE EVEN FURTHER AS THE
FEEDBACK FROM DRY SPRING GROUND AND INCREASING MARCH SUN ANGLE
INCREASES. CURRENT PROJECTIONS PLACE HIGH TEMPERATURES IN THE
60S AND 70S IN MOST LOCATIONS, WITH WEAKER LOW-LVL FLOW REDUCING
GENERAL FIRE DANGER RISKS.
THURSDAY-FRIDAY: MID-LVL FLOW FLATTENS FOR THE SECOND HALF OF THE
WEEK ALLOWING A VERY PROGRESSIVE SHORTWAVE TO TRACK ALONG THE
US/CANADA BORDER ON THURSDAY. THIS SYSTEM IS EXPECTED TO PUSH A
STRONGER COLD FRONT SOUTHWARD THROUGH THE PLAINS, BRINGING BOTH NEAR
TO SLIGHTLY BELOW NORMAL TEMPERATURES TO END THE WEEK BUT ALSO
STRONG WIND GUSTS. WHILE QUITE A BIT OF AVERAGING IS TAKING PLACE,
LREF GUIDANCE INDICATES A 50% PROBABILITY OF 30+ MPH WIND GUSTS WITH
A 5% PROBABILITY OF NEAR ADVISORY LEVEL GUSTS THURSDAY. WITH
LOWERING AFTERNOON RH AND CONTINUATION OF GUSTS, THIS RAISES THE
POTENTIAL FOR FIRE WEATHER CONCERNS ALREADY SHOWING UP IN VERY HIGH
GFDI FORECASTS. WINDS ARE EXPECTED TO DECREASE FRIDAY AND CONTINUE
TO REMAIN LOW INTO THE WEEKEND. PRECIPITATION CHANCES WITH THIS
SYSTEM AND FRONT REMAIN LOW PARTIALLY DUE TO THE LACK OF LOW-LVL
MOISTURE, BUT MOSTLY THE TRACK OF THE UPPER WAVE TO THE NORTHEAST.
AT THIS TIME, ENSEMBLES ONLY POINT TO A 20% PROBABILITY OF
MEASURABLE RAIN.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 655 PM CDT SAT MAR 21 2026
WINDS WILL BECOME NORTHERLY AND BEGIN TO INCREASE BEHIND A COLD
FRONT THIS EVENING AS MUCH COLDER AIR FLOWS INTO THE REGION. STRONG,
GUSTY WINDS ARE EXPECTED TO BEGIN TO IMPACT THE AREA ALONG HIGHWAY
14 AROUND 22.02Z, EXPANDING SOUTH INTO THE I-90 CORRIDOR AROUND
22.04Z, HIGHWAY 20 CORRIDOR AROUND 22.06Z. SUSTAINED WINDS OF 20-25
KTS WITH GUSTS 30-40 KTS ARE EXPECTED, WITH ISOLATED GUSTS TO 45 KTS
POSSIBLE. THE STRONGEST WINDS SHOULD BE SOUTH OF THE REGION AROUND
SUNRISE, GRADUALLY DECREASING THROUGH THE DAY. BY THE END OF THE
PERIOD WINDS WILL BECOME LIGHT AND VARIABLE.
CLOUDS BEGIN TO PUSH IN FROM THE NORTH AND LIGHT SPRINKLES BECOME
POSSIBLE AFTER 22.00Z. SPRINKLES ARE MOST LIKELY TO REMAIN ALONG AND
NORTH OF I-90. CEILINGS WILL DEGRADE TO MVFR WITH PATCHY IFR
POSSIBLE. LOWER CEILINGS LOOK TO REMAIN ALONG AND NORTH OF HIGHWAY
18. CEILINGS BEGIN TO IMPROVE IN THE MORNING AND SHOULD BE BACK TO
VFR AROUND 22.11Z AND FOR THE REST OF THE PERIOD.
FIRE WEATHER
ISSUED AT 1214 PM CDT SAT MAR 21 2026
FRONTAL BOUNDARY ARRIVING A BIT FASTER THAN PREVIOUSLY EXPECTED,
BRINGING LIGHTER WINDS TO AREAS SOUTH OF I-90 LATE THIS MORNING.
AT THIS POINT, THE STRONGEST SOUTHERLY WINDS MAY END UP JUST
SOUTH OF THE MISSOURI RIVER AND THEN EXTEND NORTHEAST INTO
SEVERAL NORTHWEST IOWA COUNTIES. WITH THAT SAID, WHILE RH VALUES
ARE GOING TO FALL NEAR 10-15%, GUSTS ARE LIKELY GOING TO FALL
SHORT OF RFW CRITERIA. WITH EXTREMELY LOW RH, ANY FIRE START
WILL SPREAD VERY QUICKLY DUE TO DRY FINE FUELS. WILL CONTINUE TO
MONITOR CONDITIONS OVER THE RFW, BUT AT THIS TIME NO CHANGES
ARE ANTICIPATED.
PERHAPS BIGGER CONCERNS ARRIVE AFTER SUNSET AS A STRONG COLD
FRONT WILL PUSH WINDS TOWARDS THE 30 TO 45 MPH MARK FOR A PERIOD
OF TIME OVERNIGHT. WHILE RH VALUES WILL BE RISING VERY QUICKLY
WITH THE COOLER AIR, ANY FIRE THAT WAS STARTED EARLIER IN THE
DAY COULD POSE A RISK FOR REIGNITING. SIMILARLY, FOR THOSE
ENJOYING A BACKYARD FIRE THIS EVENING GIVEN THE NICE WEATHER,
ENSURE THOSE FIRES ARE FULLY EXTINGUISHED.
LOOKING TO SUNDAY...DRY AND BREEZY CONDITIONS ARE AGAIN
EXPECTED, WITH GFDI VALUES RISING TOWARDS THE HIGH CATEGORY.
CLIMATE
ISSUED AT 1214 PM CDT SAT MAR 21 2026
RECORD HIGH TEMPERATURES:
MARCH 21:
KFSD: 83/1910, KSUX: 85/1910, KHON: 84/1907, KMHE: 88/1907
RECORD HIGH MINIMUM TEMPERATURES:
MARCH 21:
KFSD: 49/1938, KSUX: 48/2012, KHON: 45/1938
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...DUX
AVIATION...AJP
FIRE WEATHER...DUX
CLIMATE...DUX
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