542
FXUS63 KFSD 091112
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
612 AM CDT THU APR 9 2026
KEY MESSAGES
- SCATTERED SHOWERS AND VERY ISOLATED THUNDERSTORMS EXPECTED
TODAY. SEVERE WEATHER IS NOT EXPECTED AND THE BETTER CHANCE
FOR THUNDER WILL BE IN NORTHWEST IA.
- PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED
SATURDAY INTO EARLY NEXT WEEK. A FEW STRONGER STORMS ARE
POSSIBLE SATURDAY AFTERNOON INTO EARLY SUNDAY MORNING AND
POSSIBLY AGAIN TUESDAY.
- A WARMUP IS EXPECTED FRIDAY INTO EARLY NEXT WEEK. MUCH ABOVE
AVERAGE TEMPERATURES ARE EXPECTED SUNDAY AND MONDAY. SUNDAY
MORNING LOWS COULD APPROACH RECORD WARM LEVELS.
UPDATE
ISSUED AT 249 AM CDT THU APR 9 2026
OVERALL VERY FEW CHANGES TO THE FORECAST TODAY AND TONIGHT.
LATEST MODELS STILL INDICATE A RELATIVELY WEAK, FAST MOVING
WAVE MOVING THROUGH TODAY. THE LATEST MODEL SOUNDINGS CONTINUE
THE TREND OF INDICATING SOME WEAK INSTABILITY, 300-500 J/KG
CAPE, WITH THE SLIGHTLY HIGHER VALUES IN NORTHWEST IA. THIS MAY
ALLOW FOR A FEW RUMBLES OF THUNDER, BUT SEVERE WEATHER IS NOT
EXPECTED. A FAIRLY DEEP STABLE LAYER BELOW THE ELEVATED
INSTABILITY WILL LIKELY PRECLUDE ANY STRONGER WINDS AT THE
SURFACE AND WITH THE FREEZING LEVEL AT ABOUT 8-9 KFT HAIL IS
ALSO VERY UNLIKELY.
LATER SATURDAY AFTERNOON INTO SATURDAY NIGHT MAY SEE SOME
ISOLATED SEVERE HAIL AS A STRONG LLJ DEVELOPS, BRINGING WARMER
AND MORE HUMID AIR INTO THE 850-800MB LAYER. IF THIS DOES
HAPPEN, INSTABILITY WILL INCREASE WITH CAPE VALUES AROUND 1250
J/KG POSSIBLE. THIS COULD LEAD TO A FEW STORMS POSSIBLY
PRODUCING QUARTER SIZED HAIL. WILL NEED TO MONITOR TRENDS ON
THIS LLJ SURGE.
DISCUSSION
ISSUED AT 118 PM CDT WED APR 8 2026
BREEZY NORTHWEST WINDS GUSTING 25-35 MPH WILL USHER IN A MUCH DRIER
AIR MASS THIS AFTERNOON. RELATIVE HUMIDITY LEVELS WILL FALL TO NEAR
CRITICAL TO CRITICAL FOR A BRIEF PERIOD THIS AFTERNOON. WHILE NO
FIRE HEADLINES ARE PLANNED AT THIS TIME, CAUTION IS STILL NEEDED TO
PREVENT THE SPREAD OF WILDFIRE. THIS AFTERNOON A LOW CHANCE (<25%)
OF ISOLATED TO SCATTERED LIGHT RAIN IS POSSIBLE OVER NORTHWEST IOWA.
IF SHOWERS CAN OVERCOME THE DRY BOUNDARY LAYER, VERY LITTLE IF ANY
ACCUMULATION IS EXPECTED. HIGHS THIS AFTERNOON WILL CLIMB INTO THE
50S TO 60S, WITH THE HIGHEST TEMPERATURES OVER NORTHWEST IOWA. WINDS
BECOME LIGHT AND VARIABLE OVERNIGHT WITH CLEAR SKIES. THIS WILL HELP
LOWS COOL DOWN TO THE 20S.
AN ACTIVE PATTERN LOOKS TO BE THE STORY FOR THE REST OF THE WEEK AND
INTO NEXT WEEK. THURSDAY A SHORTWAVE PASSES THROUGH THE REGION
BRINGING WEAK ELEVATED INSTABILITY AND MODERATE WAA IN THE MID-
LEVELS. THIS MAY BE ENOUGH TO TRIGGER SHOWERS AND POSSIBLY
THUNDERSTORMS. WHILE ISOLATED TO SCATTERED STORMS ARE POSSIBLE
ACROSS THE REGION, ANY THUNDERSTORMS WILL MOST LIKELY REMAIN ALONG
AND SOUTH OF HIGHWAY 20. SEVERE WEATHER IS NOT EXPECTED, HOWEVER A
FEW STRONGER STORMS MAY PRODUCE WIND GUSTS OF 40-50 MPH AND SMALL
HAIL TO THE SIZE OF DIMES.
FRIDAY AN UPPER RIDGE AND SURFACE HIGH PRESSURE BUILD INTO THE
REGION. AS IT DOES SO WINDS WILL BECOME EASTERLY TO SOUTHEASTERLY.
SUBSIDING AIR WILL WARM AND DRY OUT CONDITIONS AT THE SURFACE.
MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO FALL TO AROUND 30%
FRIDAY AFTERNOON. HIGHS WILL BE IN THE 50S WITH LIGHT WINDS. THANKS
TO THE MILDER TEMPS AND LIGHT WINDS FIRE DANGER WILL REMAIN LOW TO
MODERATE FOR MOST OF THE FORECAST AREA. THE EXCEPTION WILL BE
SOUTH CENTRAL SOUTH DAKOTA, WHERE THE HIGH CATEGORY MAY BE
REACHED. THOUGH FIRE RISKS ARE LOWER, PLEASE CONTINUE TO USE
CAUTION.
ZOOMING OUT AND LOOKING AT THE OVERALL PATTERN WE SEE A LARGE TROUGH
DIGGING SOUTH OVER THE PACIFIC NORTHWEST. AS IT DOES SO, VORTICITY
WAVES PROPAGATE OFF THE PARENT WAVE, COMPRESSING THE PRESSURE
GRADIENTS FROM THE SURFACE THROUGH THE MID-LEVELS. THE LLJ AND
SURFACE WINDS WILL INCREASE IN RESPONSE. AFTERNOON WIND GUSTS OF 25-
35 MPH ARE EXPECTED WITH LOCALLY HIGHER GUSTS POSSIBLE. GOOD MIXING
AND WAA WILL HELP AFTERNOON HIGHS CLIMB INTO THE 60S AND 70S.
DEWPOINTS WILL ALSO INCREASE, REACHING THE MID TO UPPER 50S. IT MAY
BEGIN TO FEEL A BIT MUGGY BY SATURDAY AFTERNOON. IN ADDITION,
CHANCES FOR THUNDERSTORMS CREEP INTO THE AREA. THE GENERAL TREND
ACROSS MULTIPLE MODELS HAS BEEN AN INCREASE IN THE POTENTIAL
INSTABILITY ACROSS THE REGION. COUPLE THIS WITH MODERATE TO STEEP
LAPSE RATES, AND ROUGHLY 30 KTS OF 0-6 KM BULK SHEAR AND THE
POTENTIAL IS THERE FOR STRONG TO SEVERE THUNDERSTORMS SATURDAY
EVENING INTO SUNDAY MORNING.
STORMS CLEAR OUT FOR SUNDAY AFTERNOON AND MOST OF MONDAY. HIGHS
WILL CLIMB TO THE 70S AND 80S SUNDAY, SLIGHTLY COOLER IN THE
70S FOR MONDAY. MONDAY EVENING STORM CHANCES RETURN AGAIN, AND
CONTINUE PERIODICALLY THROUGH THE FIRST HALF OF NEXT WEEK AS THE
PREVIOUSLY MENTIONED UPPER TROUGH BEGINS TO MOVE OUT OVER THE
CENTRAL UNITED STATES. AT THIS TIME IT IS TOO EARLY TO SAY FOR
CERTAIN WHEN OR WHERE OR IF STORMS WILL BECOME SEVERE. BUT THE
POTENTIAL IS THERE BEGINNING THIS WEEKEND AND CONTINUING INTO
NEXT WEEK. THIS INCREASE IN THUNDERSTORM ACTIVITY IS TYPICAL FOR
APRIL IN THE MIDWEST. IT'S IMPORTANT THAT YOU KNOW HOW TO
RESPOND SHOULD SEVERE WEATHER APPROACH YOUR AREA. KNOW WHERE THE
NEAREST SHELTER IS LOCATED. HAVE MULTIPLE WAYS TO RECEIVE
WARNINGS, ESPECIALLY AT NIGHT HAVE AT LEAST ONE METHOD THAT WILL
WAKE YOU UP! IF YOU HAVE OUTDOOR PLANS BE SURE TO MONITOR THE
FORECAST CLOSELY FOR UPDATES.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 610 AM CDT THU APR 9 2026
VFR THROUGH THE PERIOD. AN MVFR CEILING WILL BE POSSIBLE NEAR
KMML THROUGH ABPOUT 15Z, BUT SHOULD DRIFT NORTH AFTER THIS.
OTHERWISE SOME SPOTTY SHOWERS WILL BE POSSIBLE AND A VERY
ISOLATED RUMBLE OF THUNDER WILL BE POSSIBLE NEAR KSUX AND KSLB
THIS AFTERNOON.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...08
DISCUSSION...AJP
AVIATION...08
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