778
FXUS63 KFSD 200520
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1220 AM CDT MON APR 20 2026
KEY MESSAGES
- NEAR CRITICAL FIRE WEATHER WILL RETURN ON MONDAY AND AGAIN ON
WEDNESDAY WITH MUCH WARMER TEMPERATURES AND BREEZY
CONDITIONS. WEDNESDAY MAY SEE NEAR RECORD HIGH TEMPERATURES.
- LIMITED PRECIPITATION CHANCES WILL CONTINUE THROUGH WEDNESDAY.
- SHOWER AND THUNDERSTORM CHANCES RETURN WEDNESDAY NIGHT INTO
THURSDAY NIGHT. SOME HINTS THAT MUCH OF THE AREA COULD BE
SPLIT BY STRONG UPPER LEVEL FORCING TO THE NORTHWEST AND
DEEPER INSTABILITY SOUTH AND EAST, KEEPING OUR PRECIPITATION
MORE ISOLATED TO SCATTERED.
- WHILE MONDAY THROUGH THURSDAY WILL SEE ABOVE NORMAL
TEMPERATURES, POSSIBLY APPROACHING RECORD HIGHS WEDNESDAY,
BELOW NORMAL TEMPERATURES ARE EXPECTED FRIDAY INTO NEXT
WEEKEND.
UPDATE
ISSUED AT 854 PM CDT SUN APR 19 2026
SURFACE RIDGING CONTINUES TO SLIDE THROUGH THE NORTHERN PLAINS THIS
EVENING. WINDS WILL REMAIN LIGHT BUT WILL SLOWLY TURN TO OUT OF
THE SOUTHEAST THROUGH THE OVERNIGHT HOURS. WITH CLEAR SKIES IN
PLACE, LOW TEMPERATURES WILL FALL TO EITHER SIDE OF FREEZING
OVERNIGHT. WINDS WILL TURN MORE SOUTHERLY FOR THE DAY TOMORROW
AND STRENGTHEN WITH GUSTS UP TO 20-30+ MPH. WARM AIR ADVECTION
(WAA) IS ON TRACK TO STRENGTHEN ALOFT TOMORROW, PUSHING HIGH
TEMPERATURES UP TO 60S AND 70S. PERHAPS A FEW LOCATIONS ACROSS
SOUTH CENTRAL SOUTH DAKOTA COULD SEE HIGHS TOUCH 80F. DEW POINTS
WILL REMAIN IN THE UPPER 20S AND 30S, RESULTING IN HUMIDITY
LEVELS FALLING TO CRITICAL LEVELS ACROSS THE VAST MAJORITY OF
THE AREA. THINK THE CURRENT FIRE WEATHER WATCH IS SUFFICIENT FOR
TOMORROWS FIRE DANGER AS THERE REMAINS A LITTLE UNCERTAINTY
REGARDING THE DURATION OF STRONGEST WINDS. AS OF NOW, SEEMS LIKE
WINDS WILL ONLY REACH CRITICAL LEVELS FOR A SHORT DURATION
OUTSIDE OF WHERE THE CURRENT WATCH IS. THUS, HAVE CONTINUED WITH
THE WATCH AND WILL MAKE ADJUSTMENTS WHEN CONFIDENCE INCREASES
IN THE AREAL EXTENT OF RED FLAG CONDITIONS. CRITICAL FIRE DANGER
WILL COME TO AN END MONDAY EVENING AS WINDS WEAKEN AND HUMIDITY
INCREASES. LOW TEMPERATURES WILL FALL TO NEAR TO JUST ABOVE
SEASONABLE LEVELS WITH TEMPERATURES IN THE UPPER 30S AND 40S.
TUESDAY WILL BE A QUIET DAY AS UPPER LEVEL RIDGING BUILDS OVER THE
EASTERN GRADIENT OF THE ROCKY MOUNTAIN. THIS WILL RESULT IN LARGE
SCALE SUBSIDENCE ACROSS THE PLAINS. LOOSER LOW LEVEL PRESSURE
GRADIENTS WILL RESULT IN LIGHT WINDS ACROSS THE FORECAST AREA. HIGHS
WILL STILL WARM TO THE 70S AND 80S, BUT WITH LIGHT WINDS IN PLACE,
FIRE DANGER IS NOT EXPECTED.
DISCUSSION
ISSUED AT 100 PM CDT SUN APR 19 2026
COOL HIGH PRESSURE SHIFTS EAST TONIGHT BRINGING SOUTHERLY FLOW BACK
TO THE AREA. LOWS WILL MAINLY BE FROM THE UPPER 20S TO LOWER 30S.
SOUTHERLY FLOW INCREASES ON MONDAY WITH GUSTS AROUND 25 TO 30 MPH
LIKELY THROUGH THE DAY. WITH FAIRLY DRY CONDITIONS EXPECTED
ONCE AGAIN, THIS CREATES ELEVATED TO NEAR CRITICAL FIRE WEATHER.
AFTERNOON RELATIVE HUMIDITY SHOULD VARY FROM THE TEENS IN
CENTRAL SD WHERE WINDS WILL BE A LITTLE LOWER DURING THE LOWEST
RELATIVE HUMIDITY WITH 20 TO 25 PERCENT OVER EASTERN SD INTO
SOUTHWEST MN. WILL HAVE A FIRE WEATHER WATCH OUT FOR SOUTHWEST
MN AND INTO BROOKINGS COUNTY. IF CONFIDENCE INCREASES ENOUGH IN
HIGHER WINDS TO THE SOUTHWEST OF THIS WATCH, A WATCH/WARNING MAY
BE NEEDED THERE AS WELL. THERE HAS BEEN A TREND FOR SLIGHTLY
STRONGER WINDS AND LOWER HUMIDITIES EACH DAY FOR THE PAST FEW
DAYS, SO SOMETHING TO TAKE INTO ACCOUNT.
A WEAK WAVE AND ASSOCIATED WEAK COLD FRONT AT THE SURFACE WILL MOVE
THROUGH MONDAY NIGHT, BRINGING WEAKER NORTHERLY AND EASTERLY
FLOW INTO THE AREA FOR TUESDAY. THIS WILL BRING WARM AND DRY
CONDITIONS TO THE AREA, BUT WITH WINDS MAINLY BELOW 15 MPH THE
FIRE WEATHER THREAT TUESDAY WILL REMAIN MUTED.
STRONG SOUTHERLY FLOW RETURNS ON WEDNESDAY, GUSTS 35 TO 40 MPH, WITH
TEMPERATURES SKY ROCKETING INTO THE 80S AND 90S. WHILE AFTERNOON
RELATIVE HUMIDITY WILL BE MARGINAL FOR FIRE WEATHER, THE POTENTIAL
FOR VERY STRONG WINDS WILL LEAD TO NEAR CRITICAL FIRE WEATHER
CONDITIONS.
LOW PRESSURE MOVES ONTO THE WESTERN HIGH PLAINS LATE WEDNESDAY NIGHT
AND MOVES NORTH AND DEEPENS OVER SOUTH CENTRAL SD. THIS SPREADS
INSTABILITY INTO THE AREA WEDNESDAY NIGHT BUT THE DEEPER WESTERLY
FLOW THAT DEVELOPS THURSDAY QUICKLY PUSHES THIS DEEPER INSTABILITY
TO THE EAST BY MID DAY THURSDAY. THERE MAY BE A SMALL MOMENT ON
THURSDAY AFTERNOON NEAR AND EAST OF A MARSHALL TO CORRECTIONVILLE
LINE WHERE A THUNDERSTORM COULD POP, BUT CONFIDENCE PRETTY LOW.
OTHERWISE COLDER AIR WILL MOVE IN THURSDAY AFTERNOON AND EVENING AND
LIKE BRING SOME PRETTY STRONG WINDS THURSDAY NIGHT.
FRIDAY THROUGH SUNDAY WILL SEE THIS LARGE LOW PRESSURE OVER SOUTHERN
CANADA KEEP GENERALLY DRY CONDITIONS AND BELOW NORMAL TEMPERATURES
IN PLACE. LOWS IN THE 30S AND HIGHS IN THE 50S.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1220 AM CDT MON APR 20 2026
VFR CONDITIONS ARE EXPECTED FOR THE TAF PERIOD. LIGHT EASTERLY WINDS
BEGIN THE PERIOD. THESE LIGHT WINDS WILL PERSIST THROUGH THE NIGHT
WHILE VEERING TO OUT OF THE SOUTH BY TOMORROW MORNING. THESE
SOUTHERLY WINDS WILL STRENGTHEN FOR THE AFTERNOON HOURS WITH GUSTS
UP TO 20-30 KNOTS. THE WINDS WILL BEGIN TO WEAKEN DURING THE EVENING
HOURS. AT THE SAME TIME, THE LOW LEVEL JET (LLJ) WILL BE
STRENGTHENING ALOFT, BRINGING LOW LEVEL WIND SHEAR (LLWS) TO
LOCATIONS SOUTH OF I-90 TO END THE TAF PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...FIRE WEATHER WATCH FROM 11 AM CDT THIS MORNING THROUGH THIS
EVENING FOR SDZ040.
MN...FIRE WEATHER WATCH FROM 11 AM CDT THIS MORNING THROUGH THIS
EVENING FOR MNZ071-072-080-081-089-090-097.
IA...NONE.
NE...NONE.
UPDATE...MEYERS
DISCUSSION...08
AVIATION...MEYERS
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