209
FXUS63 KFSD 301141
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
641 AM CDT SAT MAY 30 2026
KEY MESSAGES
- SCATTERED SHOWERS AND NON-SEVERE THUNDERSTORMS WILL MOVE NORTH
ACROSS THE AREA TODAY. A STRONGER STORM MAY PRODUCE PEA SIZED
HAIL, BUT OCCASIONAL LIGHTNING WILL BE THE BIGGEST RISK.
- STRONG TO SEVERE STORMS MAY RETURN TO THE AREA THIS WEEKEND.
THE FIRST CHANCE COMES LATE THIS EVENING AND OVERNIGHT ALONG
AND WEST OF THE JAMES RIVER WHERE AN INCOMING LINE OF STORMS
COULD BRING WIND GUSTS UP 65 MPH AND QUARTER SIZE (1 INCH)
HAIL.
- THE SECOND ROUND FOR SEVERE STORMS IS POSSIBLE LATER SUNDAY.
HOWEVER, THERE IS UNCERTAINTY REGARDING STORM POTENTIAL. IF
STORMS DO DEVELOP, LARGE HAIL UP TO 2 INCHES AND DAMAGING
WINDS TO 65 MPH WOULD BE THE MAIN HAZARDS. CONTINUE TO
MONITOR THE LATEST FORECAST FOR THE MOST UP TO DATE
INFORMATION.
- MODERATE CHANCES (30-60%) FOR RAIN WILL PERSIST THROUGH THE
BULK OF NEXT WEEK. HOWEVER, SEVERE STORM CHANCES CONTINUE TO
LOOK LOW (NEAR 5% OR LESS) THROUGH NEXT WEEK.
UPDATE
ISSUED AT 530 AM CDT SAT MAY 30 2026
WAVES OF SHOWERS AND ISOLATED THUNDERSTORMS WILL ROTATE NORTH
ACROSS THE REGION TODAY AS A COMPACT VORT LOBE IN NORTH CENTRAL
NEBRASKA LIFTS NORTH THROUGH EASTERN SOUTH DAKOTA. MUCH OF THIS
ACTIVITY WILL BE IN A REGION OF LIMITED INSTABILITY AND SHEAR,
SO SEVERE WEATHER IS NOT EXPECTED. HOWEVER, OCCASIONAL LIGHTNING
COULD IMPACT OUTDOOR ACTIVITIES AND STRONGER STORMS MAY PRODUCE
SMALL HAIL THIS AFTERNOON. OTHERWISE TEMPERATURES WILL BE NEAR
LATE MAY NORMALS IN THE UPPER 70S TO LOWER 80S WITH BREEZY
SOUTHEAST WINDS GUSTING 30-35 MPH THIS AFTERNOON.
MAIN SEVERE THREAT REPRESENTED BY THE LEVEL 1 OF 5 RISK WEST OF
THE JAMES RIVER VALLEY WILL COME LATE THIS EVENING, MORE LIKELY
AFTER MIDNIGHT, AS A LINE OF STORMS ROLLS EAST OUT OF WESTERN
SOUTH DAKOTA. STILL SOME DISCREPANCY AMONG HIGH-RES MODELS ON
THE TRACK AND INTENSITY OF THIS LINE AS IT MOVES INTO CENTRAL
SOUTH DAKOTA OVERNIGHT, BUT IF THE LINE MAINTAINS STRENGTH INTO
SOUTH-CENTRAL SOUTH DAKOTA, THE PRIMARY RISK WOULD BE ISOLATED
WIND GUSTS UP TO 65 MPH.
GREATER INSTABILITY AND BETTER DEEP LAYER SHEAR BUILDS INTO
PORTIONS OF OUR FORECAST AREA AHEAD OF A DRY LINE BY SUNDAY
AFTERNOON, THOUGH FORECAST SOUNDINGS DO DEPICT A WEAK CAPPING
INVERSION WHICH WILL HAVE TO BREAK TO TAP INTO THE INSTABILITY.
MID-LEVEL LIFT IS LIMITED IN THE WAKE OF DEPARTING MORNING
CONVECTION, BUT IF THE DRY LINE CAN PROVIDE ENOUGH FORCING TO
BREAK THE CAP, STEEP MID-LEVEL LAPSE RATES AND A POTENTIAL FOR
ROTATING UPDRAFTS WOULD SUPPORT LARGE HAIL, PERHAPS GOLF BALL
TO 2 INCHES IN DIAMETER.
NO SIGNIFICANT CHANGES TO THE MID-LONGER RANGE PERIODS OF THE
FORECAST, WITH LOWER RAIN CHANCES EARLY IN THE WORK WEEK RAMPING
UP AGAIN MID-LATE WEEK. TEMPERATURES LOOK FAIRLY CLOSE TO NORMAL
AS WE HEAD INTO JUNE, SLOWLY WARMING BY THE END OF THE WEEK.
DISCUSSION
ISSUED AT 215 PM CDT FRI MAY 29 2026
ABUNDANT CLOUD COVER AND LIGHT RAIN SHOWERS PERSIST THIS AFTERNOON.
THIS HAS KEPT HIGH TEMPERATURES IN THE UPPER 60S, 70S, AND LOW 80S
ALONG WITH SOME BREEZY SOUTHEASTERLY WINDS WITH GUSTS UP TO ABOUT 25
MPH. EXPECT ON AND OFF SHOWERS TO PERSIST FOR THE REST OF THE DAY AS
A WEAK UPPER LEVEL LOW MEANDERS THROUGH THE AREA. THROUGH THIS
EVENING, MINOR RAINFALL AMOUNTS BETWEEN A FEW HUNDREDTHS TO A FEW
TENTHS ARE EXPECTED. THE HIGHEST AMOUNTS WILL BE LOCALIZED AND WHERE
SHOWERS MORE FREQUENTLY TRACK OVER A GIVEN LOCATION. A BRIEF LULL IN
SHOWER ACTIVITY IS EXPECTED THIS EVENING BEFORE THE LOW LEVEL JET
(LLJ) BEGINS TO STRENGTHEN. WHILE THE JET WILL NOT BE THAT STRONG
WITH A MAGNITUDE UP TO ABOUT 20 TO 25 KNOTS, IT WILL BE STRONG
ENOUGH TO INITIATE A NEW ROUND OF SHOWERS AND SOME THUNDERSTORMS
AFTER MIDNIGHT. THESE SHOWERS AND STORMS LOOK TO DEVELOP SOUTH OF I-
90 INITIALLY BEFORE PUSHING NORTH OF THE INTERSTATE THROUGH THE REST
OF THE OVERNIGHT AND MORNING HOURS ON SATURDAY. SEVERE WEATHER IS
NOT EXPECTED BUT LIGHTING AND SMALL HAIL ARE POSSIBLE WITH THESE
STORMS.
THE MORNING SHOWERS AND A FEW THUNDERSTORMS WILL WANE THROUGH THE
AFTERNOON HOURS, SLOWLY DECREASING IN COVERAGE. SUNSHINE WILL
GRADUALLY RETURN TO THE AREA, ALLOWING FOR HIGH TEMPERATURES TO WARM
TO THE UPPER 70S TO LOW 80S. WHILE THE BULK OF THE LATE AFTERNOON
AND EVENING HOURS LOOK TO BE ON THE QUIET SIDE, STRONG TO SEVERE
THUNDERSTORMS LOOK TO DEVELOP ACROSS THE BLACK HILLS. THESE STORMS
WILL CONGEAL INTO A MESOSCALE CONVECTIVE SYSTEM (MCS) AND PUSH
EASTWARDS. THE WARM SECTOR SUPPORTING THE MCS'S INSTABILITY LOOKS TO
HAVE ITS EASTERN EDGE DRAPED ACROSS LOCATIONS WEST OF THE JAMES
RIVER SATURDAY EVENING. VERTICAL SHEAR WILL BE WEAKENING WITH
EASTWARD EXTENT. THUS, IT SEEMS THAT THE MCS WILL BE WEAKENING AS IT
ENTERS THE FORECAST AREA SATURDAY NIGHT. FOR NOW, THINK THAT 60 MPH
WINDS AND QUARTER SIZE (1 INCH) HAIL WILL BE THE MAIN HAZARDS AS THE
MCS MOVES INTO THE AREA. THE MCS SHOULD WEAKEN BELOW SEVERE LIMITS
WITH EASTERN EXTENT AS IT OUTRUNS THE INSTABILITY AND BETTER SHEAR.
COULD STILL SEE SOME SHOWERS AND THUNDERSTORMS PERSIST THROUGH THE
REST OF THE NIGHT BUT THESE STORMS ARE NOT EXPECTED TO BE SEVERE.
ANOTHER ROUND FOR STRONG TO SEVERE STORMS IS POSSIBLE ON SUNDAY.
THERE REMAINS UNCERTAINTY REGARDING SEVERE STORM POTENTIAL THIS DAY
AS THE UPPER LEVEL WAVE RESPONSIBLE FOR SATURDAY'S SEVERE STORMS
WILL BE BE PUSHING OFF TO THE NORTH AND WEST, PROMOTING HEIGHT RISES
ACROSS THE FORECAST AREA AND THUS LITTLE FORCING FOR ASCENT. THE
WARM SECTOR COULD BE AFFECTED BY LINGERING SHOWERS FROM THE PREVIOUS
NIGHTS EVENT AS WELL. HOWEVER, LATEST GUIDANCE DOES SHOW THE
PREVIOUSLY MENTIONED WARM SECTOR GETTING PUSHED EASTWARDS THROUGHOUT
THE DAY. LATEST GUIDANCE IS SOMEWHAT SPLIT ON HOW STRONG THE CAP
WILL BE. LATEST REFS SHOWS A BROAD 30-60% CHANCE FOR CONVECTIVE
INHIBITION (CIN) TO REMAIN STRONGER (MORE NEGATIVE) THAN -10 J/KG,
THOUGH A FEW POCKETS OF MINIMAL CIN IS PRESENT. THIS SEEMS TO BE
SOMEWHAT SUPPORTED BY THE NAM3KM AND FV3 AS THESE TWO CAMS GO OUT
THROUGH SUNDAY AFTERNOON AND THEY BOTH DO NOT SHOW ANY STORMS. IF
STORMS ARE ABLE TO BREAK THE CAP AND DEVELOP, THEY COULD BE STRONG
TO SEVERE WITH LARGE HAIL UP TO HALF DOLLARS (1.25 INCHES) AND
DAMAGING WINDS TO 60 MPH. CONTINUE TO MONITOR THE LATEST FORECAST
FOR THE MOST UP TO DATE INFORMATION.
THE OMEGA BLOCK PATTERN LOOKS TO PERSIST ALOFT THROUGH MONDAY AND
TUESDAY BEFORE BEGINNING TO BREAK DOWN DURING THE MIDDLE OF THE
WEEK. THIS LOOKS TO BRING ZONAL FLOW BACK TO THE NORTHERN PLAINS.
HOWEVER, SOUTHERLY FLOW WILL KEEP DECENT LOW LEVEL MOISTURE IN THE
AREA AND CONTINUE TO CHANCE FOR DAILY SHOWERS AND THUNDERSTORMS. AS
OF NOW, THE ENSEMBLES SHOW A BROAD 30-60% CHANCE FOR RAINFALL
AMOUNTS TO EXCEED A TENTH OF AN INCH EACH DAY NEXT WEEK. GIVEN THE
WEAK FLOW ALOFT, QUESTIONS REMAIN REGARDING THE STRENGTH OF THE
VERTICAL SHEAR AND THUS OVERALL SEVERE STORM POTENTIAL. ASIDE FROM
RAIN CHANCES, HIGH TEMPERATURES LOOK TO REMAIN IN THE 80S WITH
OVERNIGHT LOWS FALLING TO THE UPPER 50S TO LOW 60S.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 632 AM CDT SAT MAY 30 2026
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL LIFT NORTH
ACROSS THE AREA THIS MORNING, WITH GREATEST COVERAGE NEAR TO
JUST NORTH OF THE MISSOURI RIVER VALLEY, INCLUDING KSUX. HEAVIER
SHOWERS WILL RESULT IN A PERIOD OF IFR VISIBILITY, BUT THUNDER
WILL BE LIMITED IN COVERAGE. A BROADER AREA OF MVFR CEILINGS
WILL ALSO LIFT NORTH, WITH CEILINGS VARYING BETWEEN MVFR AND VFR
THROUGH THIS PERIOD.
LATE IN THE TAF PERIOD, A LARGER COMPLEX OF SHOWERS AND STORMS
IS EXPECTED TO MOVE EAST OUT OF WESTERN SOUTH DAKOTA, BRINGING A
GREATER RISK OF THUNDERSTORMS TO TAF SITES AFTER 31/06Z. WHILE
EXACT TIMING IS UNCERTAIN, ATTEMPTED TO TARGET MOST LIKELY
WINDOW FOR THUNDER CHANCES LATE IN THE PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...JH
DISCUSSION...MEYERS
AVIATION...JH
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