938
FXUS63 KFSD 150158
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
858 PM CDT THU MAY 14 2026
KEY MESSAGES
- WINDS WEAKEN SLIGHTLY FRIDAY, BUT RELATIVE HUMIDITY AND
LINGERING AFTERNOON GUSTS ALONG HIGHWAY 14 LEAD TO CRITICAL FIRE
DANGER.
- RISK FOR CONVECTION GROW OVER THE UPCOMING DAYS, BUT REMAIN
CONDITIONAL THROUGH SATURDAY AFTERNOON.
- SIGNIFICANTLY HIGHER THUNDERSTORM RISKS DEVELOP SATURDAY NIGHT
THROUGH MONDAY. POTENTIAL FOR WIDESPREAD SEVERE STORMS IS
FOCUSED ON SUNDAY AFTERNOON AND EARLY EVENING. MONITOR THE
FORECAST!
UPDATE
ISSUED AT 857 PM CDT THU MAY 14 2026
LIGHT SHOWERS AND THUNDERSTORMS HAVE MOVED EAST OF THE REGION. A
COLD FRONT CURRENTLY LOCATED ROUGHLY ALONG I-29 WILL ALSO CONTINUE
TO MOVE EAST. BEHIND IT WINDS WILL BECOME NORTHWESTERLY AND CLOUDS
WILL CLEAR. OVERNIGHT WINDS WILL BECOME LIGHT AND VARIABLE.
FRIDAY MORNING WINDS WILL BECOME NORTH TO NORTHWEST AROUND 5-10 MPH.
WINDS HAVE CONTINUED TO TREND DOWN SLIGHTLY, HOWEVER CAMS AND
SOUNDINGS INDICATE A LOCALIZED ENHANCEMENT IN AREAS AT ELEVATION
ALONG THE BUFFALO RIDGE. FOR AREAS SOUTH OF HIGHWAY 14, GUSTS WILL
BE AROUND 15-20 MPH. ALONG AND NORTH AFTERNOON WINDS LOOK TO GUST
AROUND 20-25 MPH. HIGHS WILL BE HOT, IN THE 80S TO LOW 90S OVER
NORTHWEST IOWA. IN ADDITION, FRIDAY WILL BE ANOTHER DRY DAY WITH
AFTERNOON RELATIVE HUMIDITY FALLING TO 17-20% FOR MOST OF THE
REGION. SINCE WINDS CONTINUE TO LOOK MARGINAL THE CURRENT, MORE
FOCUSED RED FLAG WARNING LOOKS TO BE IN GOOD SHAPE.
A PERIOD OF MORE ACTIVE WEATHER LOOKS TO BEGIN FRIDAY NIGHT AND
CONTINUE INTO THE EARLY PORTION OF NEXT WEEK. SEE THE DISCUSSION
BELOW FOR FURTHER DETAILS.
DISCUSSION
ISSUED AT 158 PM CDT THU MAY 14 2026
THIS AFTERNOON: SYNOPTICALLY DRIVEN STRONG SOUTHWESTERLY WIND
GUSTS OF 30 TO 45 MPH CONTINUE TO DEVELOP AHEAD OF A SURFACE
FRONT MOVING EASTWARD GRADUALLY. WE'VE HAD QUITE A FEW REPORTS
OF ELEVATED DUST AS WELL AS BLOWING DUST IMPACTING WEST TO EAST
ROADWAYS THIS AFTERNOON. WHILE WIDESPREAD VISIBILITY REMAINS
ABOVE 5 MILES, VERY HIGHLY LOCALIZED VISIBILITY MAY DROP BELOW 1
MILE IN HIGHER GUSTS. WHILE TEMPERATURES ARE SLOWER TO RESPOND
TODAY WITH THE CLOUD COVER, WE'RE STILL HEADED TOWARDS CRITICAL
FIRE DANGER. SEE SEPARATE DISCUSSION FOR MORE DETAILS.
OTHERWISE, A FEW LINGERING HIGH BASED SHOWERS WILL REMAIN OVER
NW IOWA INTO THE LATE AFTERNOON, WITH ISOLATED SHOWER/TSRA
POSSIBLE ALONG THE AFOREMENTIONED FRONT MOVING EAST THROUGH
SUNSET.
TONIGHT: THE FRONTAL BOUNDARY WILL SLIDE INTO THE EASTERN CWA AFTER
DARK TONIGHT WITH SOME PERSISTENCE OF MID-LVL CLOUDS ALONG IT.
ELSEWHERE, WINDS DO TURN LIGHT AND VARIABLE AS TEMPERATURES
COOL INTO THE UPPER 40S AND 50S.
FRIDAY-FRIDAY NIGHT: WE'LL BEGIN TO SEE GRADUAL SHIFTS IN THE MID-
LVL PATTERN ON FRIDAY AS ZONAL FLOW DEVELOPS. TWO CONCERNS ON
FRIDAY, ONE BEING MARGINAL RFW CONDITIONS ALONG THE HIGHWAY 14
CORRIDOR IN THE AFTERNOON, AND THE SECOND BEING POTENTIAL CONVECTION
FORMING ALONG SURFACE CONVERGENCE ZONE OVER EASTERN NEBRASKA AND
WESTERN/NORTHWESTERN IOWA LATE IN THE AFTERNOON. SOUNDINGS ALONG
THE HIGHWAY 20 CORRIDOR SHOW SOME INHIBITION LINGERING AT MID-
AFTERNOON, BUT DISSIPATING AS CONVECTIVE TEMPS IN THE LOW 90S ARE
MET. WITH MID-LVL FLOW INCREASING LATE IN THE DAY, JUST ENOUGH
FORCING ON THE BOUNDARY COULD FORCE ISOLATED TO SCATTERED STORMS
ALONG AND SOUTH OF HIGHWAY 20 IN THE EVENING. MLCAPE AROUND 1000-
1500 J/KG COULD SUPPORT MARGINALLY SEVERE HAIL FOR A FEW HOURS
AS STORMS WILL TRACK SOUTHEAST WITH THE MEAN FLOW AWAY FROM THE
CWA. FURTHER NORTH, WEAKER LOW-LVL FLOW SHOULD PREVENT
WIDESPREAD CONVECTION FROM FORMING INTO SATURDAY MORNING, BUT
IT'S ALSO A NON-ZERO CHANCE.
SATURDAY: THE VAST MAJORITY OF THE DAYTIME HOURS OF SATURDAY IS
ANTICIPATED TO BE DRY AS BRIEF MID-LVL RIDGING SLIDES THROUGH THE
AREA. THE SURFACE FRONT THAT PASSES THROUGH THE AREA TODAY WILL
SETTLE NEAR OR NORTH OF I-80 BUT MAY MAKE A SLOW RETREAT NORTHWARD
IN THE AFTERNOON. BY EARLY EVENING DEEPER SYNOPTIC LIFT ASSOCIATED
WITH AN UPPER TROUGH EJECTING OUT OF THE CENTRAL ROCKIES WILL FOCUS
LOW-LVL CONVERGENCE AND STRONG THETA-E ADVECTION SOUTH OF I-90 OR
TOWARDS HIGHWAY 20. THIS IS WHERE SOME UNCERTAINTY BEGINS TO GROW
IN THE FORECAST. MODELS HAVE SOME VARIABILITY ON THE NORTHWARD
EXTENT OF SURFACE BASED ACTIVITY BUT STRONGLY SUPPORT ELEVATED STORM
DEVELOPMENT ACROSS NORTHERN NEBRASKA EASTWARD INTO NORTH CENTRAL
IOWA. THERE MAY BE SOME POTENTIAL GIVEN 40 KNOTS EFFECTIVE SHEAR,
FOR A FEW SUPERCELLS WITH VERY LARGE HAIL TO FORM INITIALLY. LATER
IN THE EVENING A POTENTIAL MCS MAY TRY TO FORM OVER NORTHERN
NEBRASKA AND LIFT NORTHEAST THROUGH THE NEARLY 1500 J/KG MUCAPE
BRINGING BOTH A RISK FOR VERY LARGE HAIL BUT SOME MODEST STRONG WIND
RISKS INTO THE TRI-STATE AREA INTO DAYBREAK. POCKETS OF HEAVY
RAIN WILL BE POSSIBLE IN THIS THUNDERSTORM ACTIVITY.
SUNDAY: WHILE SOME CONSIDERABLE UNCERTAINTIES REMAIN ON SUNDAY,
THERE CONTINUES TO BE INCREASED POTENTIAL FOR IMPACTFUL AND
POTENTIALLY WIDESPREAD SEVERE WEATHER IN THE AREA. AS ALLUDED TO
IN WEDNESDAY'S DISCUSSION, THE GREATEST UNCERTAINTY CONTINUES
TO REVOLVE AROUND THE EXTEND OF THE NORTHWARD ADVECTION OF THE
WARM SECTOR INTO THE PLAINS DURING THE DAY. OVERNIGHT AND
MORNING CONVECTION MAY PLAY A LARGE ROLE IN THIS PROCESS, BUT
ENSEMBLE DATA HAS TRENDED TOWARDS INSTABILITY SHIFTING FURTHER
NORTH OVER THE PAST 24 HOURS, EVEN SHOWING MLCAPE EXCEEDING 3000
J/KG OVER PORTIONS OF NW IOWA BY LATE AFTERNOON. THE OTHER
LIMITATION WE'LL NEED TO MONITOR IS THE EML THAT REMAINS IN
PLACE FOR MUCH OF THE DAYTIME HOURS ONCE MORNING CONVECTION
PASSES. A STUBBORN WARM LAYER CONTINUES TO PRESENT ITSELF IN
SOUNDINGS NEAR 700 MB DEEP INTO THE AFTERNOON, BUT THOUGHTS ARE
THE AMPLITUDE OF THE SLIGHTLY NEGATIVELY TILTED TROUGH MAY BE
ENOUGH TO OVERCOME THIS LIMITATION. GIVEN THE MAGNITUDE OF BULK
SHEAR, SUPPORTIVE MID- LVL LAPSE RATES, LOW-LVL HELICITY AND
BUOYANCY THERE IS CERTAINLY POTENTIAL FOR A HIGHER END SEVERE
WEATHER DAY WELL INTO THE EVENING/OVERNIGHT HOURS WHICH INCLUDES
ALL MODES. THIS THOUGHT IS BACKED UP BY AI-LEARNING OUTLOOK
PRODUCTS AND CIPS ANALOGS THAT SUPPORT A SIGNIFICANT SEVERE
WEATHER POTENTIAL. STILL QUITE A FEW ISSUES TO WORK THOUGH AND
PLENTY OF TIME FOR THINGS TO CHANGE, BUT IT'S TIME TO REALLY
START MONITORING THE FORECAST IF PLANS EXIST ON SUNDAY OR SUNDAY
NIGHT.
MONDAY: UNCERTAINTY GROWS FURTHER ON MONDAY AS MODELS DIVERGE ON THE
POSITIONING OF A COLD FRONT AND HOW FAR EAST IT MAY TRACK. ENSEMBLES
OF THESE MODELS ARE ALSO SPLIT WITH THE GFS SHOVING THE EFFECTIVE
BOUNDARY EAST. THE ECMWF/CMC BOTH STALL THE FRONT OVER THE EASTERN
CWA AND ALLOW IT TO RETREAT WESTWARD AS A SECONDARY TROUGH LIFT OUT
OF THE CENTRAL PLAINS. THESE DRASTICALLY DIFFERENT SCENARIOS MEAN A
BIG DIFFERENCE IN SEVERE WEATHER RISKS ESPECIALLY EAST OF I-29
MONDAY AFTERNOON AND EVENING.
QPF TOTALS: A WIDE ARRAY OF POTENTIAL QPF TOTALS REMAIN WITH THIS
SYSTEM WITH NBM CONTINUING TO SPREAD LOW PROBABILITIES OF HIGHER QPF
TOTALS, BUT EXPRESSING A WIDE ARRAY OF 10/90TH PERCENTILE POTENTIAL
BETWEEN 0.25-2". CONVECTION WILL ULTIMATELY DRIVE THE HIGHEST
TOTALS, AND WOULD NOT BE SURPRISED TO SEE POCKETS OF 2"+ BY
MONDAY EVENING.
TUESDAY-THURSDAY: BEHIND THIS TROUGH, COOLER WEATHER WILL ARRIVE
THROUGH THE MIDDLE OF THE WEEK WITH MINIMAL HAZARDS EXPECTED.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 623 PM CDT THU MAY 14 2026
EAST OF I-29 LIGHT SHOWERS TO THUNDERSTORMS ARE CONTINUING TO MOVE
EAST. STORMS SHOULD BE CLEAR OF THE REGION LATE THIS EVENING.
CEILINGS AROUND 7500 FT AGL WILL IMPROVE AS CLOUDS FLOW EAST WITH
THE SHOWERS. SKIES CLEAR RAPIDLY AFTER MIDNIGHT AND REMAIN MOSTLY
CLEAR FOR THE DURATION.
A COLD FRONT ROUGHLY DRAPED FROM AVON TO SPENCER TO ARLINGTON IN
SOUTH DAKOTA WILL CONTINUE TO GRADUALLY DRIFT EAST THIS EVENING.
WINDS HAVE ALREADY DROPPED BELOW 20 KTS OVER SOUTH CENTRAL SOUTH
DAKOTA. WINDS WILL CONTINUE TO DROP OFF RAPIDLY BEHIND THE FRONT
THROUGH THE EVENING, BECOMING LIGHT AND VARIABLE OVERNIGHT. FRIDAY
MORNING WINDS BECOME NORTHWEST AT 5-10 KTS. FOR AREAS ALONG AND
NORTH OF I-90 WIND GUSTS WILL INCREASE TO 15-20 KTS IN THE
AFTERNOON.
FIRE WEATHER
ISSUED AT 158 PM CDT THU MAY 14 2026
WINDS WILL DROP ON FRIDAY, BUT ALONG HIGHWAY 14 WILL INCREASE
ONCE AGAIN TOWARDS THE 15-25 MPH GUST RANGE EARLY IN THE
AFTERNOON. WIDESPREAD LOW RELATIVE HUMIDITY IS EXPECTED
THROUGHOUT THE TRI- STATE AREA WITH VALUES AS LOW AS 15 PERCENT.
A SMALLER, TARGETED RED FLAG WARNING IS IN EFFECT FOR AREAS
ALONG HIGHWAY 14.
WIDESPREAD RAIN WILL BE EXPECTED SATURDAY NIGHT THROUGH MONDAY.
FSD WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING FROM 9 AM TO 6 PM CDT FRIDAY FOR SDZ038>040.
MN...RED FLAG WARNING FROM 9 AM TO 6 PM CDT FRIDAY FOR MNZ071-072.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...DUX
AVIATION...AJP
FIRE WEATHER...DUX
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