470  
FXUS63 KFSD 192312  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
612 PM CDT SAT APR 19 2025  
   
KEY MESSAGES  
 
- A PLEASANT EVENING IS AHEAD.  
 
- RAIN RETURNS TO THE AREA ON SUNDAY, WITH THE BEST CHANCES  
RESIDING EAST OF I-29. A QUARTER TO A HALF AN INCH OF RAIN IS  
LIKELY, WITH HIGHER TOTALS FARTHER EAST.  
 
- TEMPERATURES LOOK TO BE SEASONABLE TO SEASONABLY WARM FOR  
MOST OF NEXT WEEK. CHANCES FOR RAIN CONTINUE THROUGHOUT THE  
WEEK BUT DETAILS ARE UNCERTAIN AT THIS TIME.  
 
 
   
DISCUSSION  
 
ISSUED AT 225 PM CDT SAT APR 19 2025  
 
THIS AFTERNOON/EVENING: A PLEASANT AFTERNOON FOLLOWED BY A PLEASANT  
EVENING TODAY. DETERMINISTIC MODELS HAVE HELD AFTERNOON SURFACE  
HIGHS STEADY FROM THE PREVIOUS FORECAST. AS OUR WINDS TURN WESTERLY  
TO SOUTHWESTERLY THIS AFTERNOON, 850 MB TEMPS WARM TO 2-4 DEG C. AT  
THE SURFACE WE CAN EXPECT HIGHS IN THE MID 50S TO LOW 60S. OVERNIGHT  
LOWS WILL DIP INTO THE MID TO UPPER 30S.  
 
LOOKING ALOFT A DEEP, POSITIVELY TILTED TROUGH HAS CLOSED OFF, AND A  
SURFACE LOW PRESSURE HAS DEVELOPED OVER THE FOUR CORNERS REGION.  
TONIGHT, THAT SURFACE LOW IS EXPECTED TO EJECT OUT ONTO THE SOUTHERN  
PLAINS AND ACCELERATE NORTHEASTWARD. AS IT DOES SO, THE MIDLEVEL  
WAVE TAKES ON A NEGATIVE TILT, INDICATIVE OF STRENGTHENING.  
 
SUNDAY: THE MAIN SURFACE LOW PRESSURE LOOKS TO MOVE PAST OUR REGION  
TO THE SOUTHEAST. HOWEVER, WE WILL STILL SEE SOME RAIN FROM THIS  
SYSTEM AS WE EXPERIENCE A STRONG NORTHWARD SURGE OF WAA. THIS WITH  
FRONTOGENETIC BANDING IN THE 700-600 MB LEVEL WILL TRIGGER  
SHOWERS AS MOISTURE WRAPS AROUND THE LOW. MOST GUIDANCE  
INDICATES THESE SHOWERS WILL BE CONFINED ALONG AND EAST OF I-29,  
WHICH IS THE MOST LIKELY SOLUTION. HOWEVER, THE 12Z RUN OF THE  
GFS HAS LIGHT SHOWERS PUSHING AS FAR WEST AS THE JAMES RIVER  
VALLEY. SO WILL KEEPS SOME VERY LOW POPS IN THAT AREA. AS YOU  
MOVE EAST, POPS INCREASE WITH THE HIGHEST CHANCE FOR RAIN (>60%)  
EAST OF A LINE FROM SIOUX CITY TO TRACEY MINNESOTA. WHILE  
STRONG STORMS ARE NOT EXPECTED, SOME VERY WEAK INSTABILITY IN  
THE MID LEVELS MAY RESULT IN A FEW RUMBLES OF THUNDER. WHILE  
MOST AREAS THAT SEE RAIN WILL BE LIGHT, AREAS UNDER THE  
FRONTOGENETIC BANDS MAY SEE BRIEF PERIODS OF HEAVIER RAINFALL.  
THIS IS AGAIN MOST LIKELY EAST OF THE SIOUX CITY TO TRACEY LINE.  
RAINFALL TOTALS WILL RANGE FROM A FEW SPRINKLES TO A COUPLE  
HUNDREDTHS WEST OF I-29, AND 0.25-0.5 INCHES EAST. ENSEMBLES  
TEND TO SUPPORT THIS WITH A 60-80% PROBABILITY OF 0.25 INCHES OR  
MORE. HIGHER TOTALS APPROACHING 0.75 INCHES ARE POSSIBLE EAST  
OF A LINE FROM SLOAN TO SPIRIT LAKE. HOWEVER, ENSEMBLE  
PROBABILITIES DROP OFF TO LESS THAN 50%. A NOTE ON RAIN TOTALS:  
IF THIS SYSTEM WOBBLES TO THE WEST OR EAST IT COULD HAVE A LARGE  
IMPACT ON RAIN TOTALS. A WOBBLE WEST COULD MEAN HIGHER, AND TO  
THE EAST LOWER. HIGHS FOR SUNDAY WILL DEPEND ON HOW MUCH CLOUD  
COVER AN AREA EXPERIENCES, AND WHETHER OR NOT IT RAINS AND  
EVAPORATIVE COOLING TAKES PLACE. IN GENERAL, WEST OF THE JAMES  
RIVER WILL SEE HIGHS IN THE LOW 60S, AND EAST WILL SEE 50S.  
SUNDAY NIGHT LOWS WILL BE IN THE 30S.  
 
MONDAY-TUESDAY: RAINS SHOWERS MOVE EAST EARLY MONDAY MORNING, AND  
CLOUDS WILL CLEAR. LIGHT NORTHERLY WINDS WILL BECOME SOUTHERLY AND  
SLIGHTLY BREEZY. WAA IN THE 850 MB LAYER BOOSTS TEMPERATURES  
THERE INTO THE 4-8 DEG C RANGE. MIXING DOWN TO THE SURFACE WE  
CAN EXPECT HIGHS IN THE 60S TO LOW 70S. BY MONDAY EVENING, A  
MID-TO-UPPER LEVEL SHORTWAVE AND ASSOCIATED SURFACE LOW WILL  
PUSH INTO THE AREA FROM THE WEST. WE WILL FIND OURSELVES IN THE  
WARM SECTOR WITH STRONG WAA TRIGGERING LIGHT SHOWERS EARLY  
TUESDAY MORNING. A BAND OF 750-700 MB FRONTOGENESIS WITH AROUND  
500 J/KG OF MUCAPE MAY BE ENOUGH TO TRIGGER SOME THUNDERSTORMS.  
LAPSE RATES ARE CONDITIONALLY STABLE, BETWEEN 7 AND 8 DEGREES  
C/KM. THIS SET UP MAY ALLOW FOR A FEW STRONGER THUNDERSTORMS  
THAT MAY CONTAIN SMALL HAIL AND GUSTY WINDS. ENOUGH DIFFERENCES  
IN GUIDANCE EXISTS THAT CONFIDENCE IN STRONGER STORMS IS LOW AT  
THIS POINT. SHOWERS CLEAR OUT BY TUESDAY AFTERNOON AND SKIES  
CLEAR. HIGHS WILL REACH THE 70S AND LOWS WILL FALL TO THE 40S.  
 
WEDNESDAY-AND-BEYOND: MOSTLY ZONAL FLOW ALOFT FOR WEDNESDAY WILL  
KEEP CONDITIONS PLEASANT, WITH HIGHS IN THE 60S-70S AND LOWS IN THE  
40S. BEGINNING THURSDAY A SERIES OF SHORT WAVES AND RIDGES WILL PASS  
THROUGH THE REGION, BRINGING PERIODIC CHANCES FOR RAIN. HIGHS WILL  
BE AVERAGE TO SEASONABLY WARM, IN THE MID TO UPPER 60S.  
 
NOTE ON FIRE CONDITIONS: GRASSLAND FIRE DANGER WILL GENERALLY BE IN  
THE MODERATE TO HIGH CATEGORY FOR THE UPCOMING WEEK. WITH  
PERIODICALLY BREEZY WINDS, AND RELATIVE HUMIDITY LEVELS DROPPING TO  
NEAR CRITICAL TO CRITICAL LEVELS AT TIMES, FIRE IS STILL A CONCERN.  
PLEASE CONTINUE TO BE CAUTIOUS WITH SOURCES OF IGNITION SUCH AS  
CIGARETTES, DRAGGING CHAINS, HOT BRAKES, AND HOT EXHAUSTS.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z MONDAY/  
 
ISSUED AT 605 PM CDT SAT APR 19 2025  
 
SOUTHEASTERLY WINDS OF 5 TO 10 KTS TONIGHT WILL INCREASE TO 10  
TO 15 KTS ON SUNDAY, GUSTING NEAR 20 KTS THROUGH SUNDAY  
AFTERNOON AND EVENING. RAIN SHOWERS ARE EXPECTED TO DEVELOP  
THROUGH AREAS PRIMARILY EAST OF THE INTERSTATE 29 CORRIDOR ON  
SUNDAY AFTERNOON. WITH THAT, CEILINGS AND VISIBILITIES WILL  
DECREASE INTO THE MVFR RANGE.  
 
 
   
FSD WATCHES/WARNINGS/ADVISORIES  
 
SD...NONE.  
MN...NONE.  
IA...NONE.  
NE...NONE.  
 
 
 
 
 
DISCUSSION...AJP  
AVIATION...JM  
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