523
FXUS63 KFSD 301043
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
543 AM CDT TUE JUN 30 2026
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH
MID-TUESDAY MORNING.
- WARM AND HUMID TODAY WITH HIGHS IN THE 80S AND 90S. HEAT INDEX
VALUES WILL CLIMB INTO THE MID TO UPPER 90S. WHILE NO
HEADLINES ARE ANTICIPATED AT THIS TIME, PROPER HYDRATION AND
BREAKS OUT OF THE SUN REMAIN ESSENTIAL.
- AN ACTIVE PATTERN CONTINUES WITH CHANCES FOR STRONG TO SEVERE
THUNDERSTORMS NEARLY EVERY EVENING/OVERNIGHT FOR THE REST OF
THE WEEK. DETAILS REMAIN UNCERTAIN AS STORMS WILL DEPEND ON
HOW THE PREVIOUS DAY'S STORMS EVOLVED.
UPDATE
ISSUED AT 421 AM CDT TUE JUN 30 2026
ANOTHER ROUND OF STRONG TO SEVERE THUNDERSTORMS ARE ONGOING AS OF
4:00 AM CDT. THESE ARE THE RESULT OF A MID-LEVEL WAVE MOVING THROUGH
THE REGION OVERNIGHT. INCREASING MID-LEVEL LAPSE RATES AHEAD OF THE
WAVE IN AN ALREADY STRONGLY UNSTABLE ENVIRONMENT COUPLED WITH DEEP
LAYER SHEAR OF 40-50 KTS RESULT IN AN ENVIRONMENT CAPABLE OF
PRODUCING VERY STRONG WIND GUSTS OF 70-80 MPH AND HEAVY RAINFALL.
LARGE HAIL TO THE SIZE OF A PING-PONG BALL IS ALSO POSSIBLE. AREA
MOST AT RISK IS ALONG AND EAST OF I-29. STORMS ARE EXPECTED TO
CONTINUE THROUGH DAYBREAK.
TUESDAY SHOULD BE A MOSTLY SUNNY, LIGHTLY BREEZY DAY WITH HIGHS IN
THE MID 80S TO MID 90S. DEW POINT TEMPERATURES WILL BE IN THE 50S
FOR SOUTHEAST SOUTH DAKOTA AND SOUTHWEST MINNESOTA, AND IN THE MID
60S TO LOW 70S IN NORTHEAST NEBRASKA AND NORTHWEST IOWA. APPARENT
TEMPERATURES WILL ONCE AGAIN BE WARM IN THE LOW TO MID 90S FOR MOST
OF THE REGION, BUT IN THE MID TO UPPER 90S IN NORTHWEST IOWA. NOT
HIGH ENOUGH OR WIDESPREAD ENOUGH TO NEED A HEAT ADVISORY, BUT STILL
ENOUGH THAT PROPER HYDRATION AND BREAKS OUT OF THE HEAT WILL BE
NECESSARY.
THROUGHOUT THE DAY MOISTURE RICH AIR WILL FLOW NORTH AND POOL ALONG
A STATIONARY FRONT DRAPED FROM SOUTH CENTRAL NEBRASKA NORTHEAST INTO
THE ARROWHEAD OF NORTHEAST MINNESOTA. STEEP MID-LEVEL LAPSE RATES,
2000-3000 J/KG OF MUCAPE, AND 30-40 KTS OF DEEP LAYER SHEAR WILL
WORK TOGETHER TO RESULT IN ANOTHER ENVIRONMENT CAPABLE OF PRODUCING
STRONG TO SEVERE THUNDERSTORMS. SPC DAY 1 OUTLOOK INCLUDES A
MARGINAL RISK (LEVEL 1 OF 5) FOR OUR CWA TUESDAY EVENING INTO THE
OVERNIGHT. SIMILAR TO THE PAST COUPLE OF DAYS, A STRONG CAP WILL BE
IN PLACE. HOWEVER, AS THE LLJ BEGINS TO RAMP UP IN THE MID TO LATE
EVENING A FEW DISCRETE SUPER CELLS ARE POSSIBLE IN NORTHEASTERN
NEBRASKA. WITH INITIAL STORM DEVELOPMENT LARGE HAIL UP TO 1 TO 1.5
INCHES ARE POSSIBLE. ONE THING TO NOTE, THE FREEZING LEVEL IS
GREATER THAN 13,000 FT AGL. THIS MAY HAVE AN IMPACT ON HAIL SIZE, AS
IT WILL HAVE PLENTY OF TIME TO MELT ON THE WAY DOWN. HEAVY RAIN AND
DAMAGING WIND GUSTS ARE ALSO POSSIBLE. STORMS ARE EXPECTED TO BECOME
ELEVATED AS THEY QUICKLY GROW UPSCALE INTO A QLCS, POSSIBLY WITH
BOWING SEGMENTS. AT THIS POINT THE THREATS WILL TRANSITION TO WIND,
WITH 70 MPH GUSTS POSSIBLE. STORMS WILL PROGRESS NORTHEAST THROUGH
THE OVERNIGHT INTO SOUTHWEST MINNESOTA WHERE THEY MAY LINGER THROUGH
ABOUT MID-DAY.
DISCUSSION
ISSUED AT 108 PM CDT MON JUN 29 2026
LATE THIS AFTERNOON AND TONIGHT:
AN UNSTABLE ENVIRONMENT WILL BE IN PLACE TODAY AS A WEAK FRONT WORKS
INTO AREAS BETWEEN ABOUT THE JAMES RIVER AND I-29 THIS AFTERNOON.
THIS MAY BE A FOCUS FOR ISOLATED THUNDERSTORMS AS A WEAK WAVE BEGINS
TO MOVE NORTHEAST FROM NEBRASKA AHEAD OF THE MAIN WAVE TO THE WEST
OF THE AREA. CAPE VALUES SITTING AROUND 3000 J/KG WITH THE 0-3KM AND
0-6KM SHEAR VALUES SITTING ABOUT 30-40 KNOTS. THE QUESTIONS FOR THE
LATE AFTERNOON AND EARLY EVENING ACTIVITY WILL BE GETTING ENOUGH
CONVERGENCE TO OVERCOME THE CAPPING INVERSION. HOWEVER, GIVEN THESE
PARAMETERS AND A QUICK LOOK AT THE MODEL SOUNDINGS SHOWING A DECENT
AMOUNT OF DRY AIR BELOW ABOUT 600MB, WIND AND HEAVY RAIN WILL BE THE
MAIN THREATS. WIND GUSTS TO 80 MPH AND LOCALLY HEAVY RAIN WILL BE
THE MAIN THREATS. HAIL TO HALF DOLLAR WILL BE A THREAT AS WELL.
CURRENT THOUGHTS ARE THAT THERE WILL LIKELY BE TWO AREAS OF
CONVECTION TO WATCH FOR. THE FIRST WILL BE FROM ROUGHLY 6 PM TO 9 PM
ALONG THE SURFACE FRONT AND MORE DRIVEN BY DAY TIME HEATING. THIS
WILL LIKELY BE NEAR I-29 AND IS A BIT LOWER CONFIDENCE GIVEN A
STRONG CAPPING INVERSION AND WEAK LOW LEVEL CONVERGENCE. THE NEXT,
INCREASINGLY MORE LIKELY THREAT WILL BE TIED TO A WEAK WAVE MOVING
OUT OF NEBRASKA AND AN INCREASING LLJ. THE BETTER CHANCES FOR THIS
WILL BE FROM ABOUT 11 PM TO 4 AM AND THIS IS ALSO WHEN THE THREAT
FOR THE HIGHEST WINDS IS EXPECTED.
TUESDAY INTO WEDNESDAY:
TUESDAY SHOULD PROVE TO BE A FAIRLY NICE, ALBEIT VERY WARM, SUMMER
DAY WITH LIGHTER WINDS AND DEW POINTS BACK INTO THE 50S AND 60S AND
HIGHS FROM THE UPPER 80S TO MID 90S. CURRENTLY DO NOT ANTICIPATE ANY
HEAT HEADLINES BUT PARTS OF NORTHWEST IOWA DO GET CLOSE TO A 100
HEAT INDEX SO THERE WILL BE SOME POTENTIAL AT LEAST.
MODEL OUTPUT CONTINUES TO POINT TO TUESDAY NIGHT INTO WEDNESDAY AS A
PERIOD WITH A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS. A WAVE WILL
ROTATE NORTHEAST THROUGH NEBRASKA AND BRING A STRONG INCREASE IN THE
LLJ INTO SOUTHERN SD BY ABOUT 6Z AND NORTHWEST IA AND SOUTHWEST MN
SHORTLY AFTER. GIVEN THE SHEAR PROFILE AND EXPECTED INSTABILITY
AROUND 2500 J/KG, A FEW SEVERE STORMS WILL BE POSSIBLE. THE LOW
LEVEL REMAIN FAIRLY DRY SO GIVEN THE AMOUNT OF INSTABILITY WE MAY
SEE SOME POTENTIAL FOR 75 TO 80 MPH WINDS AS WELL AS PIN PONG BALL
SIZED HAIL.
WEDNESDAY AFTERNOON AND EVENING MAY SEE SOME SCATTERED SHOWERS AND
STORMS WITH THE BETTER CHANCES IN NORTHWEST IA AS A FRONT LINGERS
AFTER THE LIKELY MORNING SHOWERS AND STORMS. WITH THE THREAT FOR
CLOUDS AND A POST OUTFLOW AIR MASS, HEAT HEADLINES ARE AGAIN NOT
EXPECTED.
THURSDAY INTO THE WEEKEND:
THE NEXT GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS MOVES IN THURSDAY
INTO THURSDAY NIGHT AS ANOTHER WELL AGREED UPON WAVE MOVES THROUGH.
WILL LIKELY CONTINUE THE THREAT FOR LOCALLY HEAVY RAIN AND ISOLATED
SEVERE THUNDERSTORMS DEPENDING UPON WHERE ANY OUTFLOW BOUNDARIES END
UP.
FRIDAY INTO THE WEEKEND CONTINUES THE TRENDS OF NEAR DAILY WAVES AS
THE UPPER LEVEL FLOW TRANSITIONS TO A BIT MORE WESTERLY DIRECTION.
THIS HINTS AT A CHANCE FOR SHOWERS AND STORMS FRIDAY AND SATURDAY
WITH A POTENTIAL BREAK BY SUNDAY INTO MONDAY AS A WEAK RIDGE ALOFT
BUILDS IN. FOR NOW THIS TIME FRAME IS PRETTY LOW CONFIDENCE GIVEN
ALL OF THE ACTIVITY TONIGHT THROUGH THURSDAY NIGHT.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 542 AM CDT TUE JUN 30 2026
LINGERING SHOWERS AND THUNDERSTORMS OVER NORTHWEST IOWA AND
SOUTHWEST MINNESOTA WILL TAPER OFF BY MID-MORNING. MOSTLY CLEAR
SKIES AND VFR CONDITIONS WILL PREVAIL FOR THE MAJORITY OF THE
PERIOD. WINDS WILL BE WEST-SOUTHWEST AND LIGHT. AFTER SUNSET WINDS
BECOME LIGHT AND VARIABLE.
CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN TONIGHT. STORMS WILL
PUSH INTO SOUTH CENTRAL SOUTH DAKOTA FROM NEBRASKA AROUND MIDNIGHT
AND PROGRESS NORTHEAST THROUGH APPROXIMATELY 01.15Z. STORMS HAVE THE
POTENTIAL TO BECOME STRONG TO SEVERE WITH HAIL UP TO 1.5 INCHES,
WIND GUSTS UP TO 70 MPH, AND HEAVY RAINFALL.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...08
AVIATION...AJP
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