775
FXUS63 KFSD 260237
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
937 PM CDT MON MAY 25 2026
KEY MESSAGES
- ISOLATED TO SCATTERED THUNDERSTORM RISKS GROW THIS EVENING,
BUT FOCUS MORESO OVERNIGHT. PING-PONG BALL SIZE HAIL AND 60
MPH WINDS WILL BE POSSIBLE.
- QUIET AND WARM CONDITIONS CONTINUE THROUGH THE MIDDLE OF THE
WEEK.
- RAIN CHANCES INCREASE BY FRIDAY AND CONTINUE ON AND OFF
THROUGH NEXT WEEKEND THOUGH RECENT TRENDS HAVE BEEN DRIER.
SEVERE WEATHER RISKS REMAIN LOW AS TEMPERATURE LOWER BACK
TOWARD SEASONAL NORMALS.
UPDATE
ISSUED AT 922 PM CDT MON MAY 25 2026
NO MAJOR CHANGES WITH THE GOING FORECAST, WITH ISOLATED STRONG
TO SEVERE STORMS REMAINING POSSIBLE INTO TONIGHT. A BROKEN AREA
OF SHOWERS AND ISOLATED STORMS EXTEND FROM JACKSON, MN TO SIOUX
CITY, IA BEFORE BECOMING MORE ORGANIZED INTO NORTHERN NEBRASKA.
UPDRAFTS OVER NORTHWEST IOWA HAVE AT LEAST BEEN ABLE TO DROP
SMALL HAIL THUS FAR BUT HAVE BEEN STRUGGLING TO MAINTAIN
THEMSELVES LIKELY OWING TO A LACK OF DECENT BULK SHEAR
(GENERALLY LESS THAN 25 KTS.) HOWEVER, THE LOW LEVEL JET WILL
INCREASE ACROSS THE AREA THROUGH THE OVERNIGHT HOURS, AND WITH
1,000 TO 2,000 J/KG OF MLCAPE STILL IN PLACE, NEW DEVELOPMENT
MAY STILL OCCUR OVERNIGHT ALONG WITH THE STORMS OVER NORTHERN
NEBRASKA BEING SOMEWHAT MAINTAINED AS IT LIFTS NORTHWARD.
ISOLATED STRONG TO SEVERE STORMS WITH LARGE HAIL WILL CONTINUE
TO BE THE PRIMARY THREAT AS MID LEVEL LAPSE RATES REMAIN STEEP,
ON THE ORDER OF 7.5-8.5 DEGREES C/KM. BUT WITH GRADUALLY
DECREASING INSTABILITY AND CONTINUED WEAKER BULK SHEAR VALUES
(ESPECIALLY COMPARED TO LAST NIGHT), THE THREAT FOR SEVERE
WEATHER STILL REMAINS ISOLATED. LASTLY, WITH AMPLE DRY AIR IN
THE LOW LEVELS, A ROGUE 60 MPH WIND GUST WILL BE POSSIBLE IN THE
STRONGEST ACTIVITY.
DISCUSSION
ISSUED AT 1246 PM CDT MON MAY 25 2026
THIS AFTERNOON/EVENING: TEMPERATURES CONTINUE TO RISE THROUGH THE
80S THIS MORNING, ON THEIR WAY TO THE 90S IN A HANDFUL OF AREAS.
ALOFT, MID-LVL MOISTURE AOA 600 MB CONTINUES TO PIVOT EAST ACROSS
THE MO RIVER VALLEY INTO NW IOWA. FURTHER DEVELOPMENT CAN'T BE
RULED OUT, BUT PROFILES SUGGEST NO MORE THAN SPRINKLES AS THIS
AREA OF CLOUDS MOVE EAST. SOME SLIGHT MODIFICATION OF HIGH
TEMPERATURES OVER NW IOWA MAY BE POSSIBLE DUE TO THESE CLOUDS.
DEW POINTS HAVE RISEN INTO THE 60S IN PORTIONS OF THE AREA.
LATER THIS AFTERNOON WE'LL BEGIN TO WATCH CU FIELD EXPECTED TO
DEVELOP OVER CENTRAL AND WESTERN NEBRASKA WHERE INCREASED
SURFACE CONVERGENCE ALONG A WEAK BOUNDARY MAY SPARK A FEW
THUNDERSTORMS. FURTHER NORTHEAST, DESPITE THE INCREASE IN MID-
LVL LAPSE RATES AND RESULTANT MLCAPE NEAR 2000-2500 J/KG,
SOUNDINGS CONTINUE TO SHOW CONVECTIVE INHIBITION HANGING AROUND
NEAR 750MB INTO THE EARLY EVENING ALONG THE NORTHEASTERN EXTENT
OF THIS BOUNDARY WHICH MAY EXTEND INTO SOUTHWEST MINNESOTA BY
00Z. CAMS INDICATE SCATTERED NEBRASKA CONVECTION MAY TEND TO
DRIFT NORTHWARD INTO SOUTH CENTRAL SOUTH DAKOTA THIS EVENING AS
LOW-LVL LAPSE RATES ARE STEEPER AND INHIBITION IS LESS. THE
DEVELOPMENT FURTHER NORTHEAST INTO EASTERN SOUTH DAKOTA AND
SOUTHWEST MINNESOTA ALONG THE BOUNDARY IS MUCH LESS CERTAIN AND
MAY BE ISOLATED IF IT DOES FORM. THE CONSEQUENCE OF MIXING
DEEPER IN SOUTH CENTRAL SOUTH DAKOTA MAY RESULT IN LOWER HAIL
POTENTIAL, BUT MORE GUSTY OUTFLOW WITH HIGH INVERTED V
SOUNDINGS AS STORMS MOVE NORTHEAST.
THE GRADUAL RAMP-UP IN THE LLJ AFTER 00Z, BUT ESPECIALLY NEAR OR
AFTER 03Z MAY RESULT IN ADDITIONAL ISOLATED TO SCATTERED CONVECTION
INTO THE EARLY OVERNIGHT HOURS FURTHER NORTH TOWARDS I-90.
SHOULD THE BOUNDARY LAYER BE CUT-OFF ANY PARCEL LIFTED OFF THE
850MB SURFACE WOULD STILL HAVE 2000+ J/KG MUCAPE, HOWEVER
EFFECTIVE SHEAR MAY BE MARGINAL FOR ANY PERSISTENT ROTATING
STRUCTURES.
THE INCREASE IN WEAK DPVA THROUGH NORTHERN NEBRASKA INTO CENTRAL
SODAK MAY RESULT IN A BIT OF AN UPTICK IN CONVECTIVE RISK THROUGH
DAYBREAK. WHILE SHARPLY VEERING BY DAYBREAK, THE LLJ CONVERGENCE
FAVORS AREAS ALONG AND EAST OF I-29. MUCAPE LOWERS THROUGH
THE NIGHT, BUT THERE MAY STILL BE SUFFICIENT INSTABILITY FOR
ISOLATED HAILERS INTO DAYBREAK. THE LACK OF MEANINGFUL SHEAR
WILL KEEP ORGANIZED STORMS TO A SHORTER DURATION. HAZARDS THIS
EVENING AND OVERNIGHT INCLUDE PING-PONG BALL SIZE HAIL AND BRIEF
60+ MPH GUSTS THROUGH MID-LATE EVENING BEFORE BOUNDARY LAYER
STABILIZATION OCCURS.
TUESDAY: SOME ELEVATED CONVECTION MAY LINGER IN SW MINNESOTA THROUGH
MID-MORNING BUT RAPID DISSIPATION IS LIKELY AS FORCING MOVES OFF TO
THE EAST. A VERY WARM IS EXPECTED TUESDAY WITH TEMPERATURES RISING
INTO THE UPPER 80S TO 90S. DRIER AIR MIXING EASTWARD OFF THE WESTERN
PLAINS SHOULD LOWER DEWPOINTS SLIGHTLY, KEEPING HEAT INDEX VALUES
NEAR THEIR AIR TEMP.
WEDNESDAY-THURSDAY: AN ELONGATED NW TO SE ORIENTED MID-LVL RIDGE
BUILDS FROM CENTRAL CANADA INTO THE SOUTHEASTERN UNITED STATES.
WE'LL RESIDE UNDER THIS RIDGE AXIS THROUGH THURSDAY WHICH WILL KEEP
WINDS ALOFT VERY WEAK, AND TEMPERATURES IN THE MIDDLE 80S.
FRIDAY-SUNDAY: THE BRIEF OMEGA BLOCK WILL WEAKEN AS WE MOVE INTO
NEXT WEEKEND WITH A STRONGER WAVE ROTATING SOUTHWARD INTO THE
CENTRAL AND EASTERN GREAT LAKES BY FRIDAY AND SATURDAY. MEANWHILE,
MERIDIONAL LOW-LVL RETURN FLOW WILL BE FOCUSED MORE TOWARDS THE
WESTERN DAKOTAS AND NEBRASKA, KEEPING SHOWER AND THUNDERSTORM
CHANCES FOCUSED OVER THE WESTERN CWA INTO SATURDAY. PERHAPS THE BEST
RISK FOR ANY RAIN LOCALLY WILL MOVE IN SATURDAY INTO SUNDAY SHOULD
THE COOLER GREAT LAKES AIRMASS REACH THIS FAR TO THE WEST. THERE IS
QUITE A BIT OF SPREAD IN ENSEMBLE GUIDANCE FOR NEXT WEEKEND, WITH
THE GEFS/GFS SHOWING CONSIDERABLY MORE PRECIPITATION RISKS THAT THE
ECMWF/ECE. THE OFFICIAL FORECAST HAS LOWERED POPS FOR NEXT WEEKEND
TOWARDS THE 10-30% RANGE, WITH MINIMAL SHEAR REALLY PROHIBITING
ANY SEVERE RISKS. NBM MEAN TEMPERATURES STILL IN THE LOWER 80S
MAY BE A TOUCH WARM, BUT DO FALL RIGHT IN THE MIDDLE OF A
REASONABLE 25/75TH SPREAD FROM THE MID 70S TO THE MID 80S.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 640 PM CDT MON MAY 25 2026
CONCERNS TONIGHT ARE TWO-FOLD, BOTH WITHIN THE FIRST HALF OF
THIS TAF PERIOD. FIRST, STILL MONITORING POTENTIAL FOR ISOLATED
TO SCATTERED THUNDERSTORM DEVELOPMENT WITH LINGERING UNCERTAINTY
REGARDING TIMING AND COVERAGE. MOST MODELS FOCUS BETTER CHANCES
ACROSS FAR SOUTHEAST SD AND INTO THE I-90 CORRIDOR, INCLUDING
AROUND KFSD WITH LESSER CHANCES FOR KHON/KSUX. THUNDERSTORM
CHANCES DIMINISH AFTER SUNRISE WITH VFR CONDITIONS PREVAILING
FOR THE SECOND HALF OF THE TAF PERIOD.
AN INCREASING SOUTHWESTERLY LOW LEVEL JET ATOP A SHARP SURFACE
BASED INVERSION WILL BRING THE SECOND CONCERN, WITH A FEW HOURS
OF LOW LEVEL WIND SHEAR EXPECTED AT ALL LOCATIONS DURING THE
06Z-12Z WINDOW.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...DUX
AVIATION...JH
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