133
FXUS63 KFSD 010742
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
242 AM CDT SUN JUN 1 2025
KEY MESSAGES
- HIGH LEVEL CANADIAN WILDFIRE SMOKE WILL CONTINUE INTO SUNDAY
NIGHT. GROUND LEVEL SMOKE/HAZE WILL PRODUCE WIDESPREAD REDUCED
AIR QUALITY INTO SUNDAY NIGHT. ALL THOSE SENSITIVE TO AIR
QUALITY SHOULD USE CAUTION.
- THUNDERSTORM RISKS RETURN LATE MONDAY AFTERNOON AND PEAK
MONDAY NIGHT. A NARROW CORRIDOR OF SEVERE WEATHER RISK IS
EXPECTED TO DEVELOP OVER EASTERN SOUTH DAKOTA AFTER 4PM
MONDAY. THIS RISK MAY EXTEND THROUGH MIDNIGHT.
- SEVERE WEATHER RISKS INCLUDE HAIL UP TO PING PONG BALL SIZE
AND BRIEF DOWNBURST WINDS OF 65 MPH. LOCALLY HEAVY RAINFALL IS
POSSIBLE, BUT ANY FLOODING RISK SHOULD BE CONTAINED TO URBAN
AREAS.
- TEMPERATURES COOL BACK TO SEASONAL NORMALS FOR THE REMAINDER
OF THE WEEK, WITH SOME POTENTIAL FOR WIDELY SCATTERED DIURNAL
SHOWERS/THUNDERSTORMS EACH DAY.
DISCUSSION
ISSUED AT 239 AM CDT SUN JUN 1 2025
THIS MORNING: WIDESPREAD WILDFIRE SMOKE REMAINS OVERHEAD THIS
MORNING, PRODUCING AN OVERCAST CLOUD DECK AT TIMES. AT THE SURFACE,
WE CONTINUE TO SEE VISIBILITY DROPS AS LOW AS 2 MILES IN A FEW
LOCATIONS. TEMPERATURES ARE EXPECTED TO REMAIN QUITE WARM THIS
MORNING, FALLING INTO THE LOWER TO MIDDLE 50S.
TODAY: PERSISTENT WILDFIRE SMOKE WILL REMAIN IN THE PLAINS THROUGH
THE DAY. SOME VISIBILITY REDUCTIONS WILL CONTINUE THROUGH THE DAY,
AND AIR QUALITY WILL REMAIN IMPACTED OVER A LARGE AREA. ANYONE THAT
IS SENSITIVE TO AIR QUALITY WILL WANT TO REDUCE OR LIMIT OUTDOOR
TIME TODAY. SMOKE HAS CONTINUED TO HAVE SOME IMPACT ON AFTERNOON
HIGH TEMPERATURES, AND THIS WILL BE EXPECTED AGAIN TODAY. HAVE
LOWERED NBM HIGHS SLIGHTLY, THOUGH A WARMER START TO THE DAY WILL
ALLOW US TO CLIMB CLOSER TO THE MIDDLE OR EVEN UPPER 80S.
TONIGHT: MID-LVL RIDGING WILL SLIDE EASTWARD TONIGHT, ALLOWING A
STRONGER SOUTHERLY LOW-LVL WIND TO DEVELOP LATER THIS EVENING AND
OVERNIGHT. THIS INCREASED WIND SHOULD PUSH SMOKE AT THE SURFACE AND
ALOFT EAST OF I-29 BY MIDNIGHT AND EAST OF THE CWA BY DAYBREAK
MONDAY. A PERSISTENT MIXY SOUTHWESTERLY SURFACE WIND THROUGH THE
NIGHT WILL HOLD TEMPERATURES CONSIDERABLY WARMER, WITH TEMPERATURES
BOTTOMING OUT NEAR OR ABOVE THE 60 DEGREE MARK.
MONDAY: WE CONTINUE TO MONITOR THE POTENTIAL FOR STRONG TO SEVERE
STORMS TO DEVELOP LATE MONDAY AFTERNOON AND EVENING. EARLY IN THE
DAY WE'LL SEE A FRONTAL BOUNDARY BEGIN TO CROSS THE DAKOTAS FINDING
ITSELF ALONG A GREGORY TO HURON TO SISSETON BY MID-AFTERNOON. FOR
MOST OF THE DAY, SOUTHWESTERLY WINDS WILL BEGIN TO GUST AS HIGH AS
30 KNOTS, PROMOTING INCREASED MOISTURE ADVECTION INTO THE PRE-
FRONTAL ZONE, AND POTENTIALLY PUSHING DEW POINTS TOWARDS THE LOWER
TO MIDDLE 60S. A SUBTLE MID-LVL VORTICITY AREA MOVING THROUGH MID-
DAY COULD PROVIDE A BIT OF MID-LVL CLOUD COVER, BUT EVEN WITH THIS
CLOUD COVER WE SHOULD MIX TOWARDS THE UPPER 80S TO LOWER 90S AT PEAK
HEATING.
MODELS REMAIN IN REASONABLE AGREEMENT THAT ANY REMAINING INHIBITION
SHOULD BE OVERTAKEN AOA 4PM ALONG THE AFOREMENTIONED FRONTAL
BOUNDARY AS MODEST HIGH FALLS ARRIVE. A NARROW CORRIDOR OF 2000-
2500 J/KG MLCAPE SHOULD PROVIDE SUFFICIENT ENERGY FOR FAIRLY RAPID
UPSCALE GROWTH OF SEMI-DESCRETE STORMS ALONG THE BOUNDARY. HOWEVER,
BROAD SOUTHWESTERLY INCREASES OF MID-LVL FLOW RESIDE WELL TO THE
NORTHWEST OF THE FRONTAL BOUNDARY, SUGGESTING THAT WITH JUST 20-25
KNOTS OF EFFECTIVE SHEAR, ANY CONVECTION THAT DEVELOPS WILL STRUGGLE
TO REMAIN ORGANIZED AND INSTEAD FORMS INTO MULTICELL CLUSTERS. SLOW
SOUTHEASTWARD PROPAGATION OF CONVECTION INTO THE EVENING EVENTUALLY
OUTRUNS THE BEST CORRIDOR OF INSTABILITY BY LATE EVENING AS IT
APPROACHES WESTERN MN/IA.
HAZARDS: CONVECTIVE HAZARDS REMAIN CENTERED MOSTLY ON HAIL
WITHIN THE MATURING STAGE OF CONVECTION. 7-8 C/KM LAPSE RATES IN
THE MID- LVLS ALONG WITH MODERATE BUOYANCY COULD PROMOTE HAIL
UP TO PING PONG BALL SIZE, THOUGH SOME ANALOGS DO SUGGEST
ISOLATED POTENTIAL FOR 2" HAIL THOUGH LOWER EFFECTIVE SHEAR
SHOULD MITIGATE THIS SLIGHTLY. DCAPE REMAINS FAVORABLE AOA 1200
J/KG, WITH A FAIRLY WET SOUNDING (PWAT APPROACHING 1.6") COULD
FAVOR SOME LOCALIZED DOWNBURST WINDS.
THE FRONT TRACKS SLOWLY SOUTHEAST THROUGH THE OVERNIGHT HOURS INTO
TUESDAY MORNING. THE INCREASE OF THE LLJ AND PERSISTENCE OF
SOUTHWESTERLY FLOW ACROSS THE SLOW MOVING BOUNDARY WILL KEEP A RISK
OF CONVECTION THROUGH THE CWA INTO TUESDAY MORNING. HOWEVER,
MUCAPE SHOULD QUICKLY FALL THROUGH THE NIGHT, AOA 1000 J/KG, BUT
STILL MAY ALLOW A SLIGHTLY MARGINAL HAIL RISK TO PERSIST.
PRECIPITATION TOTALS: AS FAR AS QPF IS CONCERNED, WE'RE
BEGINNING TO SEE MORE INFLUENCE OF THE HIGHER RESOLUTION CAMS
INTO THE NBM WHICH HAS ALLOWED QPF TOTALS TO SHIFT SLIGHTLY.
THERE STILL REMAINS BROAD +80% PROBABILITIES FOR >0.50" OVER THE
ENTIRE AREA, WITH >1.0" PROBABILITIES FALLING TO NEAR 50%. THE
GREATEST FOCUS FOR HIGHER RAINFALL TOTALS OVER 2" WILL FOCUS
WITHIN THE INITIAL CORRIDOR OF CONVECTIVE DEVELOPMENT NEAR THE
FRONT. WHILE THERE WILL BE SLOW SOUTHEAST PROPAGATION OF
CONVECTION, OVERALL MEAN STORM MOTION WILL BE RELATIVELY
PARALLEL TO THE BOUNDARY, INCREASING THE POTENTIAL OF LOCALIZED
HEAVY RAIN BEFORE COLD POOLS DEVELOP. THIS SEEMS TO BE PICKED UP
WELL BY THE 30% PROBABILITIES OF >2" OF RAIN FOCUSED ALONG THE
IMMEDIATE FRONTAL ZONE WEST OF I-29. A FEW CAMS SUGGEST VERY
LOCALIZED 3-4" TOTALS, BUT PLENTY OF TIME TO REDEFINE THIS
CORRIDOR.
TUESDAY: ONE ITEM NOT MENTIONED EARLIER IS THE POTENTIAL FOR A
NARROW CORRIDOR OF SURFACE BASED SMOKE TO MIX DOWN BEHIND THE
PASSAGE OF THE FRONT INTO MONDAY NIGHT. BY TUESDAY MORNING, RAIN
GRADUALLY MOVES AWAY TO THE SOUTHEAST. THE REST OF THE DAY WILL
FEATURE COOLER TEMPERATURES WITH HIGHS ONLY IN THE 60S.
WEDNESDAY-FRIDAY: A BROAD POSITIVELY LONGWAVE UPPER TROUGH
EXTENDING FROM HUDSON BAY TO THE DESERT SOUTHWEST WILL PERSIST
THROUGH THE SECOND HALF OF THE WORK WEEK. WHILE NOT EVERY DAY WILL
BE WASHOUT, THE GENERALLY WEAK FLOW IN THE LOW AND MID-LVLS BUT
LINGERING MID-LVL VORTICITY SLIDING THROUGH THE REGION AT TIMES,
WILL PROMOTE WIDELY SCATTERED DIURNAL SHOWERS/STORMS AT TIMES. THE
GREATEST OR MORE WIDESPREAD RAIN POTENTIAL APPEARS ON FRIDAY.
TEMPERATURES WILL ALSO REMAIN NEAR SEASONAL NORMALS IN THE LOWER
TO MIDDLE 70S.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1045 PM CDT SAT MAY 31 2025
VFR AND MVFR VISIBILITIES ARE EXPECTED THROUGH THIS PERIOD.
REDUCTIONS IN VISIBILITY ARE THE RESULT OF THICKER PLUMES OF SMOKE
DRIFTING THROUGH THE REGION OVERNIGHT. LIGHT AND VARIABLE WINDS
OVERNIGHT WILL BECOME SOUTHWESTERLY, THEN SOUTHERLY AFTER DAY BREAK.
AS THEY DO SO THEY WILL PUSH SOME OF THE SMOKE OUT OF THE REGION AND
VISIBILITY SHOULD RETURN TO VFR. THOUGH SMOKE IS EXPECTED TO THIN,
IT WILL CONTINUE IMPACT THE REGION THROUGH SUNDAY.
WINDS WILL INCREASE SLIGHTLY BY MID-DAY WITH SOME GUSTS TO 15 KTS
POSSIBLE WEST OF THE MN/IA/SD BORDER. STRONGEST GUSTS ARE EXPECTED
OVER SOUTH CENTRAL SOUTH DAKOTA, WHERE GUSTS TO 20 KTS ARE POSSIBLE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...DUX
AVIATION...AJP
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