040
FXUS63 KFSD 260833
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
333 AM CDT SUN APR 26 2026
KEY MESSAGES
- NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS DEVELOP SUNDAY
AFTERNOON. BRIEF POCKETS OF MODERATE RAIN ARE POSSIBLE INTO
THE MONDAY MORNING, THOUGH STORM MOTION LIMITS FLOODING
POTENTIAL.
- A STRONGER STORM OR TWO MAY DEVELOP SUNDAY EVENING INTO THE
EARLY OVERNIGHT HOURS SOUTH OF I-90. HAIL TO QUARTER SIZE WOULD
BE THE PRIMARY RISK, BUT ISOLATED WIND GUSTS TO 60 MPH ARE
POSSIBLE NEAR HIGHWAY 20. RISK CONTINUES MONDAY EAST OF A
LINE FROM IDA GROVE TO WINDOM.
- AFTER RAIN ENDS MONDAY AFTERNOON, AN EXTENDED PERIOD OF
COOLER THAN NORMAL TEMPERATURES CONTINUES THROUGH THE WEEK
WITH ONLY MINOR RAIN CHANCES LATE WEDNESDAY.
UPDATE
ISSUED AT 331 AM CDT SUN APR 26 2026
TEMPERATURES REMAIN IN THE UPPER 30S TO MID 40S THIS MORNING, WITH
ISOLATED SHOWERS AND DRIZZLE. ALTHOUGH SOME HI-RES GUIDANCE HINTS AT
FOG WEST OF I-29, WINDS ARE ALREADY INCREASING AND CLOUD COVER
SHOULD PREVENT DEVELOPMENT SO WILL CONTINUE TO KEEP MENTION OUT OF
THE FORECAST.
FORECAST REMAINS ON TRACK FOR THE REST OF THE DAY, WITH INCREASING
WAA AND THE APPROACH OF THE MID LEVEL WAVE. ISOLATED RUMBLES OF
THUNDER ARE EXPECTED. NO SIGNIFICANT CHANGE TO THE DAY 1 SPC
OUTLOOK, WITH A MARGINAL (LEVEL 1 OF 5) RISK FOR AREAS EAST OF THE
JAMES RIVER AND SOUTH OF I-90 THROUGH THE US HWY 20 CORRIDOR. IF
STRONGER STORMS ARE ABLE TO DEVELOP, QUARTER SIZED HAIL IS THE MAIN
THREAT WITH ANY ELEVATED STORMS. ANY STRONGER SURFACE BASED STORMS
NEAR US HWY 20 MAY BE CAPABLE OF 60 MPH WIND GUSTS. ISOLATED SEVERE
THREAT EXISTS FROM ROUGHLY 7 PM TO 2 AM, WITH SOME CAMS SHOWING A
COUPLE ROUNDS OF STORMS.
FOR MONDAY, SPC HAS INTRODUCED A MARGINAL (LEVEL 1 OF 5) RISK FOR
SEVERE STORMS FOR OUR FAR EASTERN TIER OF COUNTIES (EAST OF A LINE
FROM IDA GROVE TO WINDOM). WINDOW FOR ANY SEVERE WEATHER LOOKS
LIMITED AS MOST GUIDANCE HAS THE COLD FRONT PUSHING EAST OF OUR AREA
BY MID AFTERNOON. THIS LEADS TO VERY LOW CONFIDENCE IN COVERAGE AND
SEVERE POTENTIAL DUE TO LIMITED INSTABILITY. IF A STRONGER STORM CAN
DEVELOP, QUARTER SIZED HAIL AND WIND GUSTS TO 60 MPH ARE POSSIBLE.
LOCALLY MODERATE TO HEAVY RAINFALL IS POSSIBLE INTO MONDAY, AS THE
AFOREMENTIONED TALL AND SKINNY CAPE PROFILES ARE SUPPORTIVE OF MORE
EFFICIENT RAINFALL RATES. PWATS TODAY THROUGH MONDAY ARE EXPECTED TO
BE AROUND OR ABOVE AN INCH. HOWEVER, 1 HOURLY FFG BETWEEN 1.5 TO 2+
INCHES FOR MOST OF THE AREA, ANTECEDENT CONDITIONS, AND PROGRESSIVE
STORM MOTION SHOULD LIMIT ANY FLASH FLOOD POTENTIAL. WOULD NOT BE
SURPRISED, THOUGH, TO SEE LOCALIZED PONDING WITH RAINFALL RATES AT
TIMES UP TO HALF AN INCH PER HOUR.
DISCUSSION
ISSUED AT 1219 PM CDT SAT APR 25 2026
THIS AFTERNOON: MID-LVL VORTICITY TRACKING THROUGH CENTRAL NE WILL
CONTINUE TO PRODUCE AREAS OF LIGHT RAIN INTO THE EVENING. GENERALLY
RAINFALL TOTALS HAVE BEEN RUNNING WELL SHORT OF CAM GUIDANCE THIS
MORNING, SUGGESTING GREATER IMPACT FROM LINGER DRY AIR. AS THE WAVE
SLOWLY SLIDES EAST, WE'LL CONTINUE TO SEE FORCING NEAR BOTH AREAS OF
850 AND 600MB FRONTOGENESIS. ABSENT ANY MEANINGFUL INSTABILITY,
RAINFALL RATES WILL REMAIN QUITE. ONE ITEM OF NOTE: WE HAVE
RECEIVED A COUPLE REPORTS OF SLEET ON THE WESTERN SIDE OF THE
PRECIPITATION AREA THIS AFTERNOON. THIS PROCESS SHOULD DIMINISH
AS STRONG WARM ADVECTION INCREASES.
TONIGHT: AFTER A LIGHT UPTICK IN ECHOS IN NW IOWA EARLY THIS
EVENING, THE INITIAL WAVE OF VORTICITY WILL MOVE EAST AFTER DARK. IN
IT'S WAKE, A VERY WEAK LOW-LVL WARM ADVECTION REGIME WILL STAY IN
PLACE. THE PERSISTENCE OF THIS WEAK LIFT MAY ALLOW SPRINKLES TO
ISOLATED SHOWERS TO LINGER INTO SUNDAY MORNING, BUT QPF AMOUNTS
WILL AGAIN BE VERY LIGHT.
SUNDAY-SUNDAY NIGHT: BROAD AND WEAK WARM ADVECTION PERSISTS SUNDAY
MORNING AGAIN ALLOWING THE DEVELOPMENT (OR REDEVELOPMENT) AND
NORTHWARD PROPAGATION OF SPRINKLES TO VERY LIGHT SHOWERS THROUGH
THE TRI- STATE AREA. BY THE AFTERNOON WE'LL BEGIN TO SEE A
SHIFT IN THE MID-LVL FLOW AS TROUGHING BEGINS TO EJECT OUT OF
THE CENTRAL ROCKIES. THE ADVECTION OF WEAK TO MODEST ELEVATED
INSTABILITY ALONG WITH BOTH THE INCREASING LOW-LVL CONVERGENCE
AND NOSE OF THE UPPER LVL JET ENERGY SHOULD ALLOW FOR NUMEROUS
SHOWERS AND THUNDERSTORMS TO FORM OVER NEBRASKA EARLY IN THE
AFTERNOON. THE INCREASE AND SLIGHT VEERING OF THE LLJ SHOULD
PUSH THIS ACTIVITY NORTHWARD INTO THE TRI-STATE AREA IN THE
EVENING. RAINFALL RATES BASED ON HREF GUIDANCE MAY RANGE
ANYWHERE FROM 0.10" TO AS MUCH 0.75" PER HOUR, BUT WITH THE FAST
NORTHEAST PROGRESSION OF RAIN ANY FLASH FLOOD RISK SHOULD BE
MINIMAL.
ONE HAZARD TO MONITOR WILL BE THE PROGRESSION AND NORTHWARD EXTENT
OF MOSTLY ELEVATED INSTABILITY LIFTING NORTHWARD SUNDAY EVENING.
LATEST GUIDANCE WOULD SUGGEST THE NORTHWARD ADVECTION OF MOSTLY
ELEVATED MUCAPE OF 400-800 J/KG SOUTH OF I-90. SOUNDINGS SUGGEST
THIS IS A TALL BUT THIN CAPE PROFILE, AND WHILE OVERALL SHEAR/WIND
PROFILE ISN'T ALL THAT STRONG, CAMS ARE SUGGESTING POTENTIAL FOR A
FEW BOWING SEGMENTS WITH SMALL HAIL MOSTLY NEAR THE HIGHWAY 20
CORRIDOR.
MONDAY: UPPER TROUGHING EJECTS INTO THE PLAINS EARLY ON MONDAY,
KEEPING RAIN CHANCES HIGH THROUGHOUT THE DAYTIME HOURS. GREATEST
FOCUS FOR ISOLATED THUNDER WILL BE THROUGH THE MORNING HOURS BEFORE
MID-LVL DRY AIR ARRIVES. FURTHER WEST, THE DEEPENING UPPER TROUGH
WOULD SUGGEST A DEFORMATION BAND DEVELOPS WEST OF THE JAMES RIVER
EARLY AND THEN DRAGS ITSELF EASTWARD INTO THE EARLY EVENING. WITH
TEMPERATURES STUCK IN THE 40S, A RATHER RAW AND WINDY DAY MAY BE
EXPECTED.
TOTAL QPF POTENTIAL: THIS SYSTEM REMAINS ONE THAT SHOULD BRING SOME
RELIEF TO WHAT'S BEEN A VERY DRY SPRING SEASON. THE LATEST HREF
25/75TH PERCENTILE GUIDANCE SUGGESTS THAT BY 7AM MONDAY MOST SHOULD
SEE BETWEEN 0.75" AND 2". BY THE TIME THE DEFORMATION BAND TRACKS
THROUGH, SOME MODEL GUIDANCE SUGGESTING LOCALIZED 2.5-3" TOTALS MAY
NOT BE FAR OFF. OF COURSE, THE TRACK OF CONVECTION SUNDAY EVENING
WILL DETERMINE THE FINAL TOTALS.
TUESDAY-FRIDAY: CONFIDENCE REMAINS QUITE HIGH THAT THE REST OF
THIS WEEK WILL BE COOLER THAN NORMAL. DEEPENING LOW PRESSURE
OVER THE EASTERN THIRD OF THE CONUS WILL KEEP A PERSISTENT
NORTHWESTERLY LOW- LVL FLOW IN THE REGION. THE RESULTING HIGH
TEMPERATURES WILL CLIMB INTO THE UPPER 50S TO A FEW 60S, JUST A
SHADE BELOW NORMAL. THE ONLY MEANINGFUL RISK FOR ADDITIONAL RAIN
THIS WEEK WILL PRESENT ITSELF ON WEDNESDAY NIGHT INTO THURSDAY
AS A SUBTLE WAVE PASSES THROUGH THE NW FLOW. AT THIS TIME, WITH
NO INSTABILITY, ANY AMOUNTS WILL BE VERY LOW.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1242 AM CDT SUN APR 26 2026
ISOLATED LIGHT SHOWERS ARE MOVING THROUGH THE AREA TO START THE
PERIOD, BUT COVERAGE IS NOT GREAT ENOUGH TO INCLUDE IN ANY OF THE
TAFS FOR THE REST OF THE OVERNIGHT HOURS. LIGHT PATCHY FOG
CAN'T BE ENTIRELY RULED OUT THIS MORNING IN CENTRAL SOUTH DAKOTA
AS WINDS REMAIN LIGHT WITH AMPLE MOISTURE, BUT THE CLOUD COVER
OUT THERE WILL HELP KEEP THIS POTENTIAL LOW (<20%).
COVERAGE OF RAINFALL WILL INCREASE ESPECIALLY FROM LATE MORNING
ONWARDS, BRINGING MVFR TO IFR CEILINGS ALONG WITH IT. ACTIVITY
WILL GENERALLY BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH
THE DAY TODAY INTO THIS EVENING. A FEW THUNDERSTORMS WILL BE
POSSIBLE MAINLY SOUTH OF I-90 LATE SUNDAY AFTERNOON INTO SUNDAY
NIGHT, BUT CONFIDENCE WAS ONLY HIGH ENOUGH TO INCLUDE A PROB30
GROUP FOR -TSRA AT KSUX AT THIS TIME.
WINDS WILL GENERALLY BE OUT OF THE NORTHEAST THIS MORNING, WITH
WINDS TURNING MORE EASTERLY FOR MOST OF THE AREA HEADING INTO
THE AFTERNOON, BUT TURNING SOUTHEASTERLY OVER PORTIONS OF
NORTHWEST IOWA. WINDS WILL INCREASE FROM THE LATE MORNING INTO
THE AFTERNOON AND EVENING, WITH GUSTS UP TO 25 KTS POSSIBLE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SG
DISCUSSION...DUX
AVIATION...SAMET
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