871
FXUS63 KFSD 290531
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1231 AM CDT WED APR 29 2026
KEY MESSAGES
- SCATTERED CONVECTIVE SHOWERS AND ISOLATED THUNDERSTORMS MAY
DEVELOP THIS AFTERNOON INTO TONIGHT. SEVERE STORMS ARE NOT
EXPECTED, BUT A FEW WIND GUSTS TO 30+ MPH MAY BE POSSIBLE.
SCATTERED SPRINKLES TO SHOWERS POSSIBLE AGAIN THURSDAY.
- THE FROST/FREEZE WARNING PROGRAM HAS BEEN ACTIVATED FOR THE
AREA, WITH A FEW AREAS OF CONCERN THIS WEEK. THURSDAY NIGHT
MAY FEATURE THE MOST CONCERNING TEMPERATURES NEAR OR BELOW
FREEZING.
- TEMPERATURES WILL WARM ABOVE NORMAL BY THE UPCOMING WEEKEND
INTO EARLY NEXT WEEK.
UPDATE
ISSUED AT 925 PM CDT TUE APR 28 2026
AN AREA OF LIGHT RAIN WILL CONTINUE TO TREK EASTWARD ACROSS THE
FORECAST AREA THROUGH MIDNIGHT OR SHORTLY THEREAFTER. GENERALLY
TRACE AMOUNTS TO THIS POINT, BUT SOMEWHAT DEEPER SATURATION OVER
NORTHWEST IOWA MAY SUPPORT A STRAY HUNDREDTH OR TWO.
SECONDARY FOCUS FOR TONIGHT IS ON NIGHTTIME LOWS AND POTENTIAL
FOR FROST. PREVIOUS THINKING OF KEEPING TEMPERATURES SLIGHTLY
WARMER THAN NBM REMAINS ON TRACK THROUGH THE EARLY PART OF THE
EVENING GIVEN CLOUDS/SHOWERS. CLEARING HAS WORKED INTO THE FAR
WESTERN PORTIONS OF THE FORECAST AREA TOWARD CENTRAL SD, AND
HAVE NOT YET SEEN A DRAMATIC DROP IN TEMPERATURES GIVEN THIS
MORE OPTIMAL RADIATIVE SCENARIO, SO WILL MAINTAIN TEMPERATURES
SLIGHTLY WARMER THAN NBM GUIDANCE THROUGH TOMORROW MORNING. THIS
COULD STILL ALLOW FOR AREAS OF FROST ACROSS NORTHWEST PORTIONS
OF THE FORECAST AREA, SO THOSE WITH EARLY SEASON SENSITIVE
PLANTS OUTDOORS MAY WANT TO TAKE PRECAUTIONS.
NORTHWEST FLOW WILL CONTINUE THROUGH THE NEXT FEW DAYS, KEEPING
TEMPERATURES BELOW NORMAL AS WE TRANSITION TO MAY LATER THIS
WEEK. OCCASIONAL THREATS FOR LATE NIGHT/EARLY MORNING FROST WILL
CONTINUE THROUGH SATURDAY MORNING. SUBTLE WEAK WAVES SLIDING
THROUGH THE NORTHWEST FLOW WILL ALSO KEEP PERIODIC LOW CHANCES
FOR LIGHT SHOWERS AROUND INTO THURSDAY, WITH STEEP LAPSE RATES
AND WEAK INSTABILITY BELOW ROUGHLY 600MB SUPPORTING A POTENTIAL
FOR AN ISOLATED NON-SEVERE THUNDERSTORM DURING THE AFTERNOON TO
EARLY EVENING HOURS.
DISCUSSION
ISSUED AT 1222 PM CDT TUE APR 28 2026
THIS AFTERNOON: THE PASSAGE OF MID-LVL VORTICITY THROUGH THE CENTRAL
PLAINS WILL CONTINUE TO BRING A RISK FOR SPRINKLES TO VERY
LIGHT RAIN SHOWERS INTO THE TRI-STATE ARE INTO THE EARLY
OVERNIGHT HOURS.
TONIGHT: LINGERING SPRINKLES TO LIGHT SHOWERS MAY CONTINUE
THROUGH VERY EARLY WEDNESDAY MORNING, FOCUSING INTO NW IOWA AS
THE NIGHT MOVES ON. FURTHER NORTHWEST, DEPENDING ON CLEARING,
TEMPERATURES MAY FALL INTO THE 30S. HAVE TRENDED TEMPERATURES
SLIGHTLY WARMER THAN NBM GUIDANCE GIVEN INCREASED CLOUDS, AS
WELL AS THE OBSERVATION THAT WET GROUND HELD TEMPERATURES UP
1-3 DEGREES LAST NIGHT. NEVERTHELESS, IF TD SPREADS WERE A BIT
MORE SUFFICIENT, PATCHY FROST COULD DEVELOP.
WEDNESDAY-THURSDAY: WE'LL REMAIN WITHIN THE INFLUENCE OF A
LARGE UPPER TROUGH ROTATING THROUGH CENTRAL CANADA AND MOVING
TOWARDS HUDSON BAY BY THE END OF THE WEEK. THIS TROUGH WILL KEEP
TEMPERATURES COOLER THAN NORMAL, BUT ALSO BRING RISKS FOR
SCATTERED SHOWERS THROUGH THURSDAY. A QUICK WARMUP WEDNESDAY
MORNING, COMBINED WITH INCREASING LOW-LVL CAA SHOULD ASSIST IN
THE DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS BY MID-DAY.
SOUNDINGS SHOW A RATHER STEEP LOW-LVL LAPSE RATE, WITH A POCKET
OF WEAK INSTABILITY SUGGESTING AT LEAST ISOLATED THUNDER
MENTIONING THROUGH THE AFTERNOON. WINDS AT THE TOP OF THE MIXED
LAYER ARE NOT ALL THAT STRONG, BUT A POCKET OF 30+ MPH WINDS IN
SHOWERS COULD BE POSSIBLE. A SIMILAR STORY FOR THURSDAY, WITH
RAIN CHANCES PERHAPS MORE FOCUSED IN THE MORNING HOURS AND AGAIN
LATE AFTERNOON. ONE HAZARD TO WATCH WILL BE THE OVERNIGHT LOW
TEMPERATURES WEDNESDAY NIGHT BUT ESPECIALLY THURSDAY NIGHT.
CLOUD COVER MAY PREVENT ANY STRONG DROP INTO THURSDAY, BUT WITH
LESS CLOUDS AND LIGHT WINDS FRIDAY MORNING POTENTIAL FOR
WIDESPREAD SUB-32 LOWS WILL BE POSSIBLE. THE PROBABILITIES OF
<32 DEGREE TEMPERATURES FROM BOTH THE HREF AND NBM ARE SITTING
AROUND 50% ALONG THE BUFFALO RIDGE THURSDAY MORNING. MORE
WIDESPREAD 40%-60% PROBABILITIES OF <32 PRESENT THEMSELVES
FRIDAY MORNING AREAWIDE WITH PROBABILITIES OF <35 DEGREES NEARLY
90+%. ALL THIS TO SAY, WITH THE ACTIVATION OF FROST/FREEZE
PROGRAM HEADLINES TODAY, POTENTIAL IS GROWING FOR HEADLINES INTO
FRIDAY.
FRIDAY-SUNDAY: THE LARGE UPPER TROUGH SWINGS FURTHER EAST
FRIDAY, REBOUNDING TEMPERATURES TOWARDS THE UPPER 50S WITH DRY
WEATHER. HEIGHTS SLOWLY RISE DURING THE UPCOMING WEEKEND,
SIGNALING A GRADUAL RISE IN TEMPERATURES EACH DAY. A PLEASANT
SATURDAY IS EXPECTED WITH HIGHS RISING THROUGH THE 60S. THE
PASSAGE OF A WEAK FRONT EARLY SUNDAY WILL HAVE MINIMAL IMPACTS
ON TEMPERATURES WITH HIGHS AGAIN RISING INTO THE UPPER 60S TO
LOWER 70S.
MONDAY-TUESDAY: MID-LVL FLOW PATTERNS REMAIN SPLIT, WITH A
DOMINANT SOUTHERN STREAM FLOW KEEPING THE RISKS FOR SEVERE
WEATHER AND EXTREME WARMUP OVER THE SOUTHERN US. FURTHER NORTH,
LINGERING INFLUENCE OF WEST TO NORTHWESTERLY UPPER FLOW KEEPS
TEMPERATURES NEAR TO SLIGHTLY ABOVE NORMAL. THE PASSAGE OF
ANOTHER WEAK FRONT MONDAY MAY BRING LOW RISKS FOR RAIN, WITH
GREATER POTENTIAL SHOWING UP IN EXTENDED MODEL GUIDANCE BY THE
MIDDLE OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1231 AM CDT WED APR 29 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH SCATTERED
SHOWERS/ISOLATED THUNDER POSSIBLE THIS AFTERNOON AND EVENING.
CONFIDENCE IN THUNDER IS TOO LOW TO MENTION IN TAFS AT THIS
TIME, BUT WOULD BE FAVORED AFTER 29/18Z THROUGH SUNSET. HIGHER
CLOUD BASES COULD SUPPORT ISOLATED ERRATIC WIND GUSTS UP TO 30KT
WITH SHOWERS. OTHERWISE WIND SPEEDS SHOULD GENERALLY REMAIN AT
OR BELOW 12KT THROUGH THE PERIOD WITH A FEW AFTERNOON GUSTS OF
15-20KT.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...JH
DISCUSSION...DUX
AVIATION...JH
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