418
FXUS63 KFSD 300304
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1004 PM CDT SUN MAR 29 2026
KEY MESSAGES
- DRY AND WARM CONDITIONS CONTINUE TO START THE NEW WORK WEEK,
LEADING TO PERSISTENT FIRE WEATHER CONCERNS. THOSE CONCERNS
GROW TOWARDS ELEVATED LEVELS MONDAY AFTERNOON AND CONTINUE
TUESDAY.
- A STRONG COLD FRONT ARRIVING TUESDAY MORNING MAY BRING A
BRIEF WINDOW OF 40 TO 50 MPH GUSTS AS IT MOVES THROUGH.
- PRECIPITATION CHANCES BEGIN TO RISE BY THE MIDDLE OF THE WEEK
WITH A GROWING POTENTIAL FOR ACCUMULATING SNOW WEDNESDAY INTO
THURSDAY. NO JOKE!
- GREATER RAIN CHANCES CONTINUE TO DEVELOP FRIDAY NIGHT INTO
SATURDAY WITH GUIDANCE SUGGESTING A 60% PROBABILITY OF
MEANINGFUL RAINFALL, WITH >1.0" PROBABILITIES AT 20% FAVORING
AREAS EAST AND SOUTHEAST OF I-29.
UPDATE
ISSUED AT 1002 PM CDT SUN MAR 29 2026
HIGH CLOUDS ARE SPREADING ACROSS THE AREA THIS EVENING, ESPECIALLY
ALONG AND NORTH OF THE I-90 CORRIDOR. THIS WILL HELP PREVENT MAXIMUM
COOLING FROM BEING REALIZED IN THOSE AREAS AND SO THE FORECAST
FOR LOWS IN THE UPPER 30S NORTH TO MID 40S SOUTH BY DAYBREAK
MONDAY REMAIN ON TRACK. ALSO STILL ON TRACK FOR MONDAY IS THE
AFTERNOON WARMTH. WE LOOK TO SEE HIGHS WELL ABOVE NORMAL INTO
THE 70S AND 80S ACROSS THE AREA. RECORD HIGHS RUN WARM FOR
MONDAY, RANGING FROM THE UPPER 80S TO LOWER 90S, SO WE ARE
UNLIKELY TO TIE OR BREAK RECORDS. MAIN FORECAST CONCERN FOR
MONDAY CONTINUES TO BE THE INCREASING FIRE THREAT, WITH THE
RETURN OF VERY HIGH GFDI FOR PARTS OF THE AREA. RELATIVE
HUMIDITY VALUES DROP BELOW 25% GENERALLY ALONG THE MISSOURI
RIVER VALLEY AND ADJACENT AREAS TO THE NORTH. WINDS STILL DON'T
LOOK TO BE OVERLY STRONG, BUT THE POTENTIAL IS THERE FOR
OCCASIONAL GUSTS OF 25+ MPH TO SWING THROUGH THE AREA DURING THE
DAY MONDAY. THE DURATION AND COVERAGE OF THESE HIGHER WIND
GUSTS PRECLUDE THE NEED FOR FIRE WEATHER HEADLINES AT THIS TIME,
BUT CONTINUE TO AVOID ANY ACTIVITIES THAT COULD CAUSE A SPARK.
HEADING INTO MONDAY EVENING AND MONDAY NIGHT, A WAVE MOVING THROUGH
SOUTH OF THE AREA WILL BRING A LOW CHANCE FOR A HIGH-BASED SHOWER OR
THUNDERSTORM MAINLY ALONG AND SOUTH OF HIGHWAY-20 AS SOME SOUNDINGS
INDICATE A BIT OF ELEVATED INSTABILITY. THE 30.00Z RUNS OF THE HRRR
AND THE NAM 4KM HAVE COME IN A BIT FARTHER SOUTH WITH THIS ACTIVITY
THAN COMPARED TO EARLIER RUNS, SO CHANCES FOR THIS STILL REMAIN LOW.
IF WE DO GET THIS ACTIVITY, AMPLE DRY AIR BENEATH THE CLOUDS WILL
PREVENT MOST IF NOT ALL RAINDROPS FROM REACHING THE SURFACE, BUT
THAT DRY AIR MAY ALSO MEAN A LOCALIZED HIGHER WIND GUST CAN BE
BROUGHT DOWN TO THE SURFACE. A PUSH OF WARM AIR ADVECTION OVERNIGHT
AS THE MAIN WAVE MOVES THROUGH MAY SET OFF A SLIGHTLY BETTER CHANCE
OF SHOWERS DEVELOPING AND REACHING THE GROUND OVERNIGHT AND INTO
EARLY TUESDAY MORNING. CAN'T RULE OUT A THUNDERSTORM OR TWO WITH
THIS ACTIVITY MAINLY SOUTH OF I-90 AND INTO PORTIONS OF NORTHWEST
IOWA AND SOUTHERN MINNESOTA AS THERE MAY BE SOME ELEVATED
INSTABILITY TO TAP INTO.
OTHERWISE, WINDS WILL GET QUITE GUSTY AS A STRONG PUSH OF COLD AIR
ADVECTION MOVES THROUGH THE AREA INTO TUESDAY MORNING. STILL LOOKING
FOR WIND GUSTS IN THE 40-50 MPH RANGE DURING THIS TIME, THOUGH
LOCALLY HIGHER GUSTS WILL BE POSSIBLE. FUTURE CONSIDERATIONS FOR
WIND HEADLINES WILL LIKELY BE NEEDED AS THE REST OF THE 30.00Z SUITE
OF GUIDANCE COMES IN. WINDS WILL DIMINISH A BIT HEADING INTO TUESDAY
AFTERNOON, BUT WE COULD STILL SEE GUSTS OF 25 TO 35 MPH THROUGH THE
AFTERNOON BEFORE WEAKENING FURTHER INTO THE EVENING. THESE STRONG
WINDS WILL LEAD TO ANOTHER DAY OF VERY HIGH GFDI, SO TUESDAY WILL BE
ANOTHER DAY TO WATCH FOR THE POTENTIAL OF CRITICAL TO NEAR CRITICAL
FIRE WEATHER.
DISCUSSION
ISSUED AT 1215 PM CDT SUN MAR 29 2026
THIS AFTERNOON: A WEAK FRONT CONTINUES TO SETTLE SOUTHWARD EARLY
THIS AFTERNOON SPREADING AN AREA OF LIGHT AND VARIABLE WINDS ACROSS
THE CWA. SOME STRONGER 15 TO 20 MPH WINDS WILL LINGER OVER NW IOWA
INTO LATE AFTERNOON, AND WITH RH VALUES NEAR 30% FIRE DANGER WILL
REMAIN ELEVATED. ELSEWHERE, TEMPERATURES WILL RISE INTO THE MIDDLE
TO UPPER 70S.
TONIGHT: MID-LVL VORTICITY INCREASES OVERNIGHT, LIKELY LEADING TO
AN EXPANSION OF UPR CLOUD COVER BY DAYBREAK. THIS CLOUD COVER
MAY PREVENT A SHARP DROP IN OVERNIGHT LOW TEMPERATURES DESPITE
LIGHT WINDS.
MONDAY: LOW-LVL TROUGHING INCREASES EARLY ON MONDAY, AS WARMER
TEMPERATURES BEGIN TO SURGE INTO THE I-90 CORRIDOR. GREATEST
CONCERNS THROUGH THE DAY REMAIN FOCUSED ON FIRE WEATHER. WHILE A
SLIGHTLY BUMP IN TDS CAN BE EXPECTED INTO MONDAY, THE RETURN OF A
SOUTHWESTERLY TO WESTERLY WIND BY MID-DAY MAY USHER IN LOWER DEW
POINTS AND DROP RH TOWARDS THE 20 TO 30% RANGE. WINDS REMAIN VERY
QUESTIONABLE THROUGH THE DAY, WITH SOME HINTS THAT A FRONTAL
BOUNDARY WILL APPROACH THE JAMES RIVER VALLEY AREAS BY EARLY
AFTERNOON. THE GREATEST FIRE WEATHER CONCERNS WOULD DEVELOP IN
THE AFTERNOON ACROSS NW IOWA INTO SOUTHERN MINNESOTA AHEAD OF
THIS BOUNDARY. THIS AREA WOULD HAVE THE BEST ALIGNMENT WITH THE
925:850 SW WINDS AHEAD OF THE TROUGH, AND GREATEST POTENTIAL TO
MIX THE 20 TO 30 MPH WIND DOWN TO THE SURFACE. WHILE RH IS
HIGHER IN THESE AREAS, EXPECTED ELEVATED TO NEAR CRITICAL FIRE
WEATHER CONDITIONS TO DEVELOP AS HIGHS RISE INTO THE LOWER 80S.
CONFIDENCE IS NOT HIGH ENOUGH FOR HEADLINES ATTM, BUT CONDITIONS
WILL NEED TO BE MONITORED CLOSELY GIVEN RECENT FIRE BEHAVIOR.
SOUNDINGS SHOW SOME ELEVATED MOISTURE STREAMING NORTHWARD MONDAY
AFTERNOON AND EVENING, BUT SOUNDINGS SHOW SURFACE BASED ACTIVITY
WOULD BE CAPPED OFF. THAT SAID, AN ELEVATED SHOWER/THUNDERSTORM
COULD NOT BE RULED OUT ALONG OR SOUTH OF HIGHWAY 20 AFTER 3PM.
TUESDAY: A DEEPER UPPER TROUGH CROSSING THE CANADIAN BORDER WILL
PUSH A COLD FRONT SOUTHWARDS THROUGH THE DAKOTAS MONDAY NIGHT INTO
TUESDAY. THIS FRONT, ARRIVING IN THE NORTHWESTERN CWA AFTER
MIDNIGHT, WILL SURGE SOUTHEAST BY DAYBREAK BRINGING STRONG LOW-LVL
COLD ADVECTION WITH IT. IN ADDITION TO A LOW POP FOR POTENTIAL
ELEVATED SHOWERS BEHIND THE FRONT, HAVE BOOSTED WIND GUSTS
SIGNIFICANTLY OVER NBM GUIDANCE. LATEST CAMS SUGGEST POTENTIAL FOR
40 TO 50 MPH GUSTS IMMEDIATELY BEHIND THE BOUNDARY, WITH WINDS
SETTLING DOWN INTO THE 25 TO 35 MPH RANGE THROUGH MOST OF THE
DAYTIME HOURS. TUESDAY WILL BE ANOTHER DAY WHERE THE COMBINATION
OF FALLING AFTERNOON RH AND PERSISTENT 20 TO 30 MPH AFTERNOON
GUSTS MAY LEAD TO WIDESPREAD ELEVATED FIRE WEATHER CONDITIONS.
WEDNESDAY-THURSDAY: WE'LL PREFACE THIS SECTION BY SAYING THAT IT'S
NOT AN APRIL FOOLS JOKE. WE'RE BEGINNING TO SEE A SHIFT IN MODEL
GUIDANCE AS WE APPROACH THE MIDDLE OF THE WEEK. LATEST RUNS OF THE
NAM/CMC/EC BOTH BRING A STRONGER UPPER TROUGH OUT OF THE FOUR
CORNERS REGION AND INTO THE CENTRAL PLAINS BY WEDNESDAY. THE 12Z
GFS HAS ALSO SHIFTED TOWARDS A FURTHER NORTH TRACK OF THIS
WAVE, BUT NOT NEARLY AS MUCH AS OTHER GUIDANCE. ENSEMBLES ARE
ALSO BECOMING MORE BULLISH ON QPF CHANCES LATE WEDNESDAY INTO
THURSDAY, SHIFTING PROBABILITIES OF >0.10" OF QPF 20 TO 40%
HIGHER THAN ON SATURDAY. WHAT THIS MEANS IS THAT DEPENDING ON
LOW-LVL TEMPERATURES, THE INCREASING DPVA COMBINED WITH
PERSISTENT LOW-LVL WARM ADVECTION AHEAD OF THIS WAVE COULD LEAD
TO DRASTICALLY INCREASED RISKS FOR SNOW/RAIN MIX WEDNESDAY
AFTERNOON INTO THURSDAY AND EVEN ACCUMULATING SNOW. LATEST
ENSEMBLE AND AI ENSEMBLE GUIDANCE FROM THE EC SUGGESTS A >60%
PROBABILITY OF MORE THAN 1" OF SNOW ALONG AND NORTH OF I-90 WITH
>3" PROBABILITIES IN THIS AREA NEAR 40%. THE NORTHWARD SHIFTS
IN THE GFS AND IT'S ENSEMBLES WOULD ALSO SUPPORT INCREASING
RAIN/SNOW CHANCES BUT IT STILL REMAINS SLIGHTLY FURTHER SOUTH
THAN OTHER GLOBAL ENSEMBLES. GIVEN THE SHIFTS IN RECENT ENSEMBLE
AND DETERMINISTIC GUIDANCE, THE LATEST NBM RUNS MAY GENERALLY
BE BIASED AND OPTIMISTICALLY WARM BOTH WEDNESDAY AND THURSDAY,
WITH A NOTED 10+ DEGREE SPREAD IN HIGH TEMPERATURES WEDNESDAY
AND NEARLY 15 DEGREE SPREAD ON THURSDAY. SHOULD COLDER AND
FURTHER NORTH SOLUTIONS VERIFY, HIGHS MAY INSTEAD REMAIN IN THE
30S. JUST ANOTHER REMINDER THAT WE CAN GO FROM 80 DEGREES TO
SNOW ANYTIME IN SPRING IN THE TRI-STATE AREA.
FRIDAY-SATURDAY: THIS INITIAL WAVE MOVES EAST OF THE AREA LATE
THURSDAY, BUT AS WE'VE BEEN TALKING THE PAST DAYS ABOUT, A SECONDARY
AND MUCH DEEPER TROUGH MOVES INTO THE ROCKIES BY FRIDAY. THIS
SECOND SYSTEM STILL WILL PROVIDE THE BEST CHANCE FOR WIDESPREAD
MEANINGFUL PRECIPITATION THROUGH MOST OF THE CENTRAL AND
NORTHERN UNITED STATES, BUT EXACT LOCATIONS REMAIN A BIT
UNCERTAIN. ENSEMBLES ARE HOWEVER POINTING TO IVT APPROACHING THE
90TH PERCENTILE OF CLIMATOLOGY FOR EARLY APRIL THROUGH THE
PLAINS AHEAD OF AN ADVANCING COLD FRONT. IT'S THE PLACEMENT OF
THIS FRONT, LIKELY DRIVEN BY THE DEPTH AND ORIENTATION OF THE
ROCKIES TROUGH, THAT WILL DETERMINE WHERE THE HEAVIEST
PRECIPITATION WILL OCCUR. ENSEMBLES CONTINUE TO SHOW HIGH
PROBABILITIES OF MEASURABLE RAIN >0.25" THROUGH THE PLAINS AND
UPPER MIDWEST, BUT ARE NOW STARTING TO NARROW DOWN THE CORRIDOR
OF HIGHER TOTALS >1.0 ALONG BUT ESPECIALLY EAST OF I-29. PLENTY
OF TIME FOR THINGS TO SHIFT OVER THE UPCOMING DAYS, BUT THIS
WOULD AT LEAST BE A SYSTEM TO MONITOR FOR MEANINGFUL RAINFALL
POTENTIAL.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 627 PM CDT SUN MAR 29 2026
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. WINDS TONIGHT WILL
BE MAINLY LIGHT AND VARIABLE, WITH WINDS INCREASING INTO THE DAY
MONDAY. A BOUNDARY WILL BE CROSSING THROUGH THE AREA THROUGH THE DAY
ON MONDAY, TURNING WINDS FROM THE SOUTHEAST TO START THE DAY AND
THEN TO THE WEST AND THEN OUT OF A NORTHERLY DIRECTION TO CLOSE THE
PERIOD. AN ISOLATED HIGH BASED SHOWER OR THUNDERSTORM CAN'T BE RULED
OUT MAINLY NEAR AND SOUTH OF US HIGHWAY 20 MONDAY AFTERNOON, BUT
CHANCES ARE TOO LOW (<15% CHANCE) TO WARRANT MENTIONING IN THE KSUX
TAF.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...DUX
AVIATION...SAMET
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