623  
FXUS63 KFSD 102007  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
307 PM CDT THU JUL 10 2025  
   
KEY MESSAGES  
 
- SCATTERED STRONG TO SEVERE STORMS ARE POSSIBLE THIS EVENING,  
CAPABLE OF DAMAGING WIND GUSTS AND LARGE HAIL, AND POTENTIALLY  
A TORNADO. GREATEST THREAT LOCALLY IS ALONG AND SOUTH OF  
HIGHWAY-20.  
 
- A MARGINAL (LEVEL 1 OF 5) RISK OF SEVERE STORMS CONTINUES  
FRIDAY AFTERNOON AND EVENING, AS A FRONT BRINGS SCATTERED  
THUNDERSTORMS SOUTHWARD INTO THE EVENING AND EARLY OVERNIGHT  
HOURS. MARGINAL RISKS OF 1" HAIL, BRIEF STRONG WINDS, AND  
BRIEF HEAVY DOWNPOURS POSSIBLE.  
 
- TEMPERATURES COOL SATURDAY, BUT RETURN BACK TO ABOVE NORMAL  
LEVELS SUNDAY AND MONDAY. HUMIDITY IS EXPECTED TO BUILD EACH  
DAY.  
 
- THUNDERSTORM RISKS RETURN LATE MONDAY THROUGH TUESDAY, WITH  
SIGNALS FOR SEVERE WEATHER POTENTIAL PRESENT IN MOST DATA.  
 
 
   
DISCUSSION  
 
ISSUED AT 258 PM CDT THU JUL 10 2025  
 
A LINE OF ELEVATED THUNDERSTORMS IS CROSSING THE MISSOURI RIVER IN  
SOUTH DAKOTA THIS AFTERNOON IN AN ENVIRONMENT CHARACTERIZED BY  
AROUND 3000 J/KG OF MUCAPE AND MID-LEVEL LAPSE RATES OF 7.5-8 C/KM.  
HAIL WOULD BE THE MAIN THREAT WITH THIS ACTIVITY IF AN UPDRAFT ALONG  
THE LINE IS ABLE TO SUSTAIN ITSELF LONG ENOUGH. THESE STORMS ALSO  
HAVE AROUND 1000-1500 J/KG OF DCAPE TO WORK WITH; HOWEVER, THE  
ELEVATED NATURE OF THE STORMS MAY MAKE IT DIFFICULT FOR STRONG WINDS  
TO MAKE IT TO THE SURFACE. SO OVERALL, THIS ACTIVITY LOOKS MOSTLY  
LIKE A HEAVY RAIN AND LIGHTNING THREAT OVER THE NEXT FEW HOURS AS IT  
LIFTS SLOWLY EAST-NORTHEASTWARDS AND FADES AS IT CLOSES IN TOWARDS I-  
90.  
 
THE BIGGER QUESTION GOING INTO LATE THIS AFTERNOON WILL BE STORM  
DEVELOPMENT THAT IS EXPECTED TO OCCUR SOMEWHERE IN NORTH-CENTRAL  
NEBRASKA. THE AFOREMENTIONED STORMS CROSSING THE MISSOURI MAY ACT TO  
SUPPRESS THE GREATER THERMODYNAMICS SOUTH OF THE AREA THROUGH  
THIS EVENING, KEEPING THE GREATEST THREAT OF SEVERE WEATHER  
CLOSER TO THE I-80 CORRIDOR. STILL, THE GREATER SEVERE WEATHER  
THREAT LOCALLY WILL BE MAINLY ALONG AND SOUTH OF HIGHWAY-20.  
THESE STORMS WILL BE CAPABLE OF ALL MODES OF SEVERE WEATHER,  
MAINLY LARGE HAIL AND DAMAGING WINDS, THOUGH A BRIEF TORNADO  
CANNOT BE RULED OUT. HEAVY RAIN AND URBAN FLOODING MAY ALSO BE  
POSSIBLE, MORE ON THAT BELOW.  
 
FRIDAY: LINGERING SHOWERS ARE LIKELY TO CONTINUE MOVING EAST OR  
SOUTHEAST IN THE MORNING AS RAPID SUBSIDENCE DEVELOPS BEHIND  
DEPARTING UPPER TROUGH. A LIGHT AND VARIABLE WIND COULD LEAD TO A  
BIT OF PATCHY VALLEY FOG INTO MID-MORNING. RECENT CAMS AND LOWER  
RESOLUTION GUIDANCE HAVE BACKED OFF POPS THROUGH MID-DAY, HOLDING  
OFF ON ANY DIURNALLY BASED CONVECTION UNTIL MID-AFTERNOON IN MOST  
LOCATIONS. BETTER FOCUS FOR CONVECTION IS EXPECTED TO DEVELOP ALONG  
A SLOWLY ADVANCING COLD FRONT SINKING THROUGH CENTRAL AND NORTHERN  
SOUTH DAKOTA IN THE MORNING ALONG WITH A WEAK PRE-FRONTAL TROUGH  
BISECTING THE CWA. SOUNDINGS WITHIN THE WARM SECTOR AHEAD AND NEAR  
THESE FEATURES CONTINUE TO INDICATE MODEST MLCAPE OF 1500-2000 J/KG,  
BUT UNIDIRECTIONAL SHEAR REMAINS VERY LIMITED. THIS WOULD SUGGEST  
ANY ACTIVITY THAT DEVELOPS WILL BE PULSY IN NATURE, BUT ALSO CAPABLE  
OF SMALLER HAIL AND BRIEF DOWNBURST WINDS.  
 
FRIDAY NIGHT: THE FRONT AND ACCOMPANYING CONVECTION WILL SLOWLY  
DRIFT THROUGH THE CWA OVERNIGHT, WITH ISENTROPIC DOWNGLIDE  
CLEARING OUT PRECIPITATION QUICKLY BY DAYBREAK. TEMPERATURES  
SATURDAY MORNING EXPECTED TO FALL INTO THE MIDDLE 50S TO LOWER  
60S.  
 
SATURDAY-SUNDAY: A PERFECT SATURDAY WILL BE IN STORE FOR THE REGION  
AS HIGH PRESSURE DRIFTS ACROSS THE AREA. COMBINED WITH LIGHT WINDS  
AND TEMPERATURES ONLY IN THE UPPER 70S TO LOWER 80S, THE AFTERNOON  
MAY FEEL QUITE COMFORTABLE. SOME ISOLATED HIGH BASED SHOWERS AND  
THUNDERSTORMS MAY DEVELOP WEST OF THE JAMES RIVER EARLY SUNDAY  
MORNING, SIGNALING THE RETURN OF WARMER AIR ALOFT. TEMPERATURES  
SUNDAY ARE EXPECTED TO CLIMB BACK INTO THE MID 80S TO LOWER 90S.  
 
MONDAY-WEDNESDAY: AS WE'VE BEEN DISCUSSING THE PAST DAYS, WE'LL KEEP  
OUR EYES ON A FRONTAL BOUNDARY DRAGGING ACROSS THE DAKOTAS MONDAY  
INTO TUESDAY. DEW POINTS WILL LIKELY SURGE HIGHER MONDAY AFTERNOON  
GIVEN THE SOUTHERLY FLOW BUT ALSO INCREASING EVAPOTRANSPIRATION OF  
THE SEASON. WILL LIKELY CONTINUE TO NEED TO BUMP DEW POINTS UPWARDS  
FROM NBM VALUES. A MID-LVL WAVE MOVING THROUGH EARLY TUESDAY WILL  
BRING OUR NEXT RISK OF CONVECTION, POSSIBLY STRONG TO SEVERE, TO THE  
REGION.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/  
 
ISSUED AT 1251 PM CDT THU JUL 10 2025  
 
SCATTERED SHOWERS AND STORMS ARE SET TO DEVELOP NEAR AND ALONG THE  
MISSOURI RIVER VALLEY THIS AFTERNOON, BRINGING A RISK OF SEVERE  
WEATHER AND HEAVY RAINFALL. WITH THAT, THE BEST CHANCES OF  
THUNDERSTORM IMPACTS WILL BE FROM KYKN TO KSUX THROUGH THE EVENING  
HOURS, AND THUS HAVE A TEMPO GROUP IN KSUX FROM 00Z TO 03Z TO  
ACCOUNT FOR THIS. THE STRONGEST STORMS WILL BRING IFR VISIBILITIES  
AND THE POTENTIAL FOR SEVERE WIND GUSTS IN EXCESS OF 50 KTS. AFTER  
THE STORMS, SHOWERS MAY CONTINUE FOR AREAS MAINLY SOUTH OF  
I-90, BUT GUIDANCE VARIES LARGELY REGARDING ANY ACTIVITY THROUGH  
THE EARLY MORNING HOURS. WE'LL DRY OUT HEADING INTO FRIDAY  
MORNING, WITH ADDITIONAL THUNDERSTORM DEVELOPMENT POSSIBLE ON  
KHON'S DOORSTEP JUST AFTER THIS PERIOD.  
 
WINDS WILL BE MAINLY OUT OF THE SOUTHEAST THROUGH THIS EVENING,  
BEFORE TURNING LIGHTER AND MORE VARIABLE FRIDAY MORNING. WITH  
LESSENING WINDS AND MOISTURE LEFT BEHIND FROM THESE LAST ROUNDS  
OF RAIN, CAN'T ENTIRELY RULE OUT SOME PATCHY LIGHT FOG, BUT NOT  
ENOUGH CONFIDENCE TO INCLUDE IN THE TAFS AT THIS TIME. WINDS  
WILL PICK UP AGAIN LATER FRIDAY MORNING AS A COLD FRONT  
APPROACHES AND TURNS WINDS TO THE WEST-NORTHWEST FOR AREAS WEST  
OF THE JAMES RIVER AT THE END OF THE PERIOD.  
 
 
   
HYDROLOGY  
 
ISSUED AT 258 PM CDT THU JUL 10 2025  
 
THUNDERSTORM ARE EXPECTED TO TRACK EASTWARD THROUGH PORTIONS OF  
NORTHEASTERN NEBRASKA AND NORTHWESTERN AND WESTERN IOWA THIS  
EVENING. PWAT VALUES APPROACHING 2.0" ALONG WITH STORM MOTION  
ALONG AN ELEVATED BOUNDARY WILL LEAD TO AN INCREASED POTENTIAL  
FOR EXCESSIVE RAINFALL LATER THIS EVENING AND OVERNIGHT. HREF  
PMM INDICATE POTENTIAL FOR LOCALIZED 2 TO 5" OF RAIN ALONG, BUT  
ESPECIALLY SOUTH OF HIGHWAY 20 DURING THIS EVENT. WHILE  
PROBABILISTIC MODELS SUGGEST LOWER RIVER FLOODING IN SOUTHERN  
CWA BASINS THE GREATEST RISKS MAY RISE FROM URBAN AND SMALL  
STREAM FLOODING GIVEN POTENTIAL FOR 1 TO 3" PER HOUR RAINFALL  
RATES. THUS HAVE ISSUED A NARROW FLOOD WATCH FOR THE HIGHWAY 20  
CORRIDOR THIS EVENING INTO EARLY OVERNIGHT.  
 
 
   
FSD WATCHES/WARNINGS/ADVISORIES  
 
SD...NONE.  
MN...NONE.  
IA...FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY MORNING  
FOR IAZ031-032.  
NE...FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY MORNING  
FOR NEZ013-014.  
 
 
 
 
 
DISCUSSION...DUX/SAMET  
AVIATION...SAMET  
HYDROLOGY...DUX  
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