373  
FXUS63 KFSD 041124  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
624 AM CDT FRI JUL 4 2025  
   
KEY MESSAGES
 
 
- SLIGHTLY LESS HOT BUT STILL HUMID FOR THIS 4TH OF JULY WITH  
PEAK HEAT INDEX VALUES IN THE 90S. TEMPERATURES MORE TYPICAL  
OF EARLY-MID JULY (HIGHS MOSTLY IN THE 80S) SETTLE IN FOR THE  
REST OF THE HOLIDAY WEEKEND THROUGH MUCH OF NEXT WEEK.  
 
- MARGINAL (LEVEL 1 OF 5) RISK FOR SEVERE STORMS TODAY/TONIGHT.  
MAIN CONCERN IS ISOLATED DAMAGING WIND GUSTS IN THE LATE  
AFTERNOON AND EVENING WEST OF THE I-29 CORRIDOR. LOWER BUT  
NON-ZERO RISK THAT A STRONGER STORM COULD DEVELOP DURING THE  
OVERNIGHT HOURS.  
 
- POCKETS OF HEAVY RAIN COULD ACCOMPANY STORMS THIS AFTERNOON  
INTO SATURDAY MORNING. THE RISK FOR WIDESPREAD FLASH FLOODING  
IS LOW, BUT LOCALIZED URBAN FLOODING IS POSSIBLE.  
 
- ADDITIONAL CHANCES FOR SHOWERS/STORMS FOCUSED ON SATURDAY AND  
NEXT MONDAY NIGHT-TUESDAY. SOME STRONGER STORMS ARE POSSIBLE  
EARLY NEXT WEEK, BUT DETAILS ARE UNCERTAIN.  
 

 
   
DISCUSSION
 
 
ISSUED AT 355 AM CDT FRI JUL 4 2025  
 
TODAY: TRANQUIL WEATHER WILL DOMINATE INTO THE EARLY AFTERNOON  
ON THIS INDEPENDENCE DAY HOLIDAY, THOUGH OUTDOOR ACTIVITIES MAY  
STILL BE IMPACTED BY HEAT & HUMIDITY AS HEAT INDEX VALUES CLIMB  
INTO THE 90S BY MIDDAY TO EARLY AFTERNOON. OVERALL, LOW LEVEL  
TEMPERATURES ARE A FEW DEGREES COOLER THAN YESTERDAY, SO EXPECT  
HIGHS IN THE UPPER 80S TO LOWER 90S FOR MOST. HOWEVER, SURFACE DEW  
POINTS REMAIN JUICY IN THE UPPER 60S TO LOWER/MID 70S WHICH WILL  
PRODUCE THE ELEVATED HEAT INDICES. THOSE WITH OUTDOOR PLANS WILL  
WANT TO TAKE PRECAUTIONS TO STAY SAFE FROM THE HEAT.  
 
LATE AFTERNOON-TONIGHT: A MODEST MID-LEVEL SHORTWAVE OVER THE  
CENTRAL ROCKIES EARLY THIS MORNING WILL SLIDE NORTHEAST INTO  
NEBRASKA AND THE DAKOTAS THIS AFTERNOON BEFORE PIVOTING EAST  
ACROSS MINNESOTA TONIGHT INTO SATURDAY MORNING. THIS WAVE WILL  
INTERACT WITH AN APPROACHING COOL FRONT OVER CENTRAL SOUTH DAKOTA  
BY MID-LATE AFTERNOON, SPARKING A LINE OF STORMS WHICH WILL THEN  
PROGRESS EAST WITH THE FRONT INTO THE EVENING AND NIGHTTIME HOURS.  
AHEAD OF STORM DEVELOPMENT, MLCAPE VALUES REACH 1000-1500 J/KG  
BUT MID-LEVEL LAPSE RATES ARE ON THE WEAKER SIDE AROUND 7C/KM OR  
LESS. COMBINE THIS WITH A DEEP WARM CLOUD LAYER (FREEZING LEVEL  
NEAR 14KFT AGL) AND DEEP LAYER SHEAR GENERALLY LESS THAN 30KT,  
AND THE HAIL RISK APPEARS TO BE LOW. THIS AGREES WITH THE SPC  
MARGINAL (LEVEL 1 OF 5) RISK WHICH HIGHLIGHTS MAINLY AN ISOLATED  
DAMAGING WIND THREAT IN TODAY'S OUTLOOK FOR OUR FORECAST AREA,  
WHICH IS SUPPORTED BY 1000+ J/KG OF DCAPE ACROSS THE AREA PRIOR TO  
STORM DEVELOPMENT.  
 
OUR MAIN TIME WINDOW AND AREA OF CONCERN LOOKS TO BE 5PM-9PM IN  
AREAS WEST OF I-29, WITH STORMS WEAKENING AS THEY APPROACH THE  
I-29 CORRIDOR LATE IN THE EVENING. FOR THE OVERNIGHT HOURS, WILL  
HAVE TO WATCH A TRAILING WAVE SWINGING THROUGH THE BASE OF THE  
DEPARTING SHORTWAVE WHICH COULD SPARK ADDITIONAL STORMS ACROSS  
NORTHWEST IOWA AND SOUTHWEST MINNESOTA AFTER MIDNIGHT. SOME MODEL  
DISAGREEMENT REGARDING HOW MUCH INSTABILITY WILL BE AVAILABLE FOR  
THESE STORMS TO WORK WITH. THAT SAID, WE WILL BE LOOKING AT A  
LOCALLY HEAVY RAIN THREAT WITH ANY OF THE STORMS TONIGHT. STORM  
MOVEMENT LOOKS TO BE PROGRESSIVE, BUT THERE ARE SOME SIGNALS THAT  
POINT TO POTENTIAL BACKBUILDING STORMS, ESPECIALLY ALONG/EAST OF  
I-29 IN THE LATE EVENING-OVERNIGHT AS A LOW LEVEL JET INCREASES  
OVERHEAD. THE AIR MASS CERTAINLY IS SUPPORTIVE OF A LOCALIZED  
HEAVY RAIN THREAT, WITH PRECIPITABLE WATER (PWAT) VALUES NEAR 2  
INCHES, WHICH IS IN THE TOP 1% OF ENSEMBLE CLIMATOLOGY. ALTHOUGH  
DIFFICULT TO PINPOINT WHERE THE HEAVIEST RAIN MAY OCCUR, HREF  
LOCALIZED PROBABILITY MATCHED MEAN (LPMM) SHOWS POTENTIAL FOR  
POCKETS OF 1.5-2 INCH RAINFALL AMOUNTS WITH ISOLATED 3+ INCHES  
POSSIBLE. IF THIS HEAVIER RAINFALL OCCURS OVER AN URBAN AREA,  
CANNOT RULE OUT LOCALIZED FLASH/URBAN FLOODING, BUT OTHERWISE  
THINK SOILS IN RURAL AREAS SHOULD BE ABLE TO HANDLE THIS AMOUNT  
OF RAIN AND THE RISK FOR WIDESPREAD FLASH FLOODING IS LOW.  
 
SATURDAY-SUNDAY: THE REST OF THE HOLIDAY WEEKEND WILL FEATURE  
COOLER TEMPERATURES, PERHAPS EVEN A FEW DEGREES BELOW EARLY JULY  
NORMALS WITH SUB-80 DEGREE HIGHS POSSIBLE FOR SOME LOCATIONS.  
SHOWERS AND SCATTERED STORMS LINGER INTO SATURDAY, ESPECIALLY  
ACROSS THE EASTERN CWA AS THE MID-LEVEL WAVE IS SLOW TO SHIFT  
EAST AND WILL HAVE TO AGAIN WATCH FOR LOCALLY HEAVY RAINFALL.  
MOST LOCATIONS SHOULD SEE A DRIER DAY ON SUNDAY, THOUGH OUR NEXT  
WEAK WAVE MAY BRING A LOW CHANCE OF SHOWERS/STORMS TO AREAS WEST  
OF THE JAMES RIVER VALLEY.  
 
MONDAY-TUESDAY: AN UNSETTLED PATTERN PERSISTS INTO THE EARLY PART  
OF NEXT WEEK, THOUGH MODELS SHOW LIMITED AGREEMENT ON TIMING AND  
STRENGTH OF A WAVE MOVING THROUGH THE WESTERLY FLOW ALOFT THAT MAY  
TRIGGER THIS ACTIVITY. IF STORMS ARE TIMED FAVORABLY, WE COULD SEE  
SUFFICIENT INSTABILITY AND SHEAR LATE MONDAY-MONDAY EVENING FOR A  
FEW STRONG TO SEVERE STORMS, THOUGH CONFIDENCE IS LOW ON SPECIFIC  
DETAILS AT THIS TIME.  
 
WEDNESDAY-THURSDAY: A BROAD RIDGE BUILDING OVER THE ROCKIES WILL  
PLACE OUR FORECAST AREA IN NORTHWEST FLOW THROUGH THE MIDDLE PART  
OF THE WEEK. THIS SHOULD FAVOR GENERALLY LOW (<30%) RAIN CHANCES  
WITH SEASONABLE TEMPERATURES, AS MORE SIGNIFICANT WARMTH REMAINS  
TO OUR WEST.  
 

 
   
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
 
 
ISSUED AT 624 AM CDT FRI JUL 4 2025  
 
GUSTY SOUTH WINDS DEVELOP QUICKLY THIS MORNING, WITH FREQUENT  
GUSTS 25-30KT EXPECTED FROM LATE MORNING THROUGH SUNSET. A COLD  
FRONT WILL BRING A CHANCE OF THUNDERSTORMS TO MOST AREAS DURING  
THE LATTER HALF OF THIS TAF PERIOD, PERHAPS STARTING AS EARLY AS  
21-22Z TOWARD K9V9 AND KHON. ONLY MODERATE CONFIDENCE IN TIMING OF  
THE FRONT AND ASSOCIATED THUNDERSTORMS AT ANY SINGLE POINT, BUT  
TRIED TO NARROW DOWN POTENTIAL TO AT MOST A 4-HOUR WINDOW OF THE  
GREATEST CHANCES FOR EACH TAF SITE.  
 
THUNDERSTORMS MAY PRODUCE ERRATIC GUSTY WINDS IN EXCESS OF 40KT  
ALONG WITH MVFR-IFR VISIBILITY IN +TSRA. GOOD MODEL CONSENSUS THAT  
MVFR CEILINGS WILL FILTER INTO THE FORECAST AREA BEHIND THE STORMS  
TOWARD THE END OF THIS TAF PERIOD.  
 

 
   
FSD WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
MN...NONE.  
IA...NONE.  
NE...NONE.  
 

 
 

 
 
DISCUSSION...JH  
AVIATION...JH  
 
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