000
FXUS63 KFSD 251728
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1228 PM CDT SAT APR 25 2026
KEY MESSAGES
- LIGHT RAIN WILL CONTINUE INTO THE EVENING THOUGH AMOUNTS ARE
EXPECTED TO BE RATHER LIGHT. OCCASIONAL SPITS OF
RAIN/DRIZZLE MAY PERSIST OVERNIGHT.
- NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS WILL DEVELOP
SUNDAY AFTERNOON. BRIEF POCKETS OF MODERATE RAIN WILL BE
POSSIBLE INTO THE EARLY OVERNIGHT, THOUGH STORM MOTION WILL
LIMIT FLOODING POTENTIAL.
- A STRONGER STORM OR TWO MAY DEVELOP SUNDAY EVENING AND
LINGER INTO THE EARLY OVERNIGHT HOURS SOUTH OF I-90. HAIL
WOULD BE THE PRIMARY RISK, BUT ISOLATED WIND GUSTS POSSIBLE
NEAR HIGHWAY 20.
- AFTER RAIN ENDS MONDAY AFTERNOON AN EXTENDED PERIOD OF
COOLER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH THE
WEEK WITH ONLY MINOR RAIN CHANCES LATE WEDNESDAY.
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 /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1219 PM CDT SAT APR 25 2026
LIGHT RAIN CONTINUES TO MOVE THROUGH THE TRI-STATE ARE THIS
AFTERNOON. WE'RE CONTINUE TO SEE GRADUAL LOWERING OF CEILINGS
TOWARDS MVFR LEVELS, AND POTENTIAL FOR DROPS TO IFR CONTINUE TO
POSSIBLE IN A NARROW CORRIDOR INTO THIS EVENING. VISIBILITY
GENERALLY REMAINS ABOVE 4SM.
WIDESPREAD LIGHT RAIN DISSIPATES EARLY THIS EVENING, ONLY TO BE
REPLACED BY OCCASIONAL VERY LIGHT ISOLATED SHOWERS OR DRIZZLE.
CEILINGS MAY FALL BELOW 1000 FT AGL IN A FEW POCKETS.
RAIN SHOWERS TRY TO REDEVELOP SUNDAY MORNING, THROUGH GREATER
COVERAGE WILL BE FOCUSED ON THE AFTERNOON. MVFR CEILINGS
EXPECTED TO CONTINUE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...DUX
AVIATION...DUX
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