085
FXUS63 KFSD 272350
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
650 PM CDT TUE OCT 27 2026
KEY MESSAGES
- PATCHY FOG IS EXPECTED TO DEVELOP LATER TONIGHT AND INTO EARLY
WEDNESDAY MORNING. MODERATE TO HIGH (50-70%) CHANCES OF
VISIBILITY BELOW A MILE AT TIMES.
- RAIN AND ISOLATED STORM CHANCES RETURN WEDNESDAY INTO
WEDNESDAY EVENING. IF STORMS CAN DEVELOP, AN ISOLATED STRONGER
STORM CAPABLE OF HALF DOLLAR SIZED HAIL AND 60 MPH WIND GUSTS
IS POSSIBLE IN THE AFTERNOON AND EVENING.
- NEAR TO ABOVE NORMAL TEMPERATURES RETURN FROM WEDNESDAY ONWARD
WITH HIGHS IN THE 60S TO LOWER 70S.
- ADDITIONAL RAIN CHANCES RETURN LATE THIS WEEK INTO THE
WEEKEND.
DISCUSSION
ISSUED AT 314 PM CDT TUE OCT 27 2026
CLOUDS WILL CONTINUE TO GRADUALLY BECOME BROKEN FROM WEST TO EAST
FOR THE REMAINDER OF THIS AFTERNOON AND INTO THE EVENING. THOSE IN
CENTRAL SOUTH DAKOTA MAY GET A FEW GLIMPSES OF SUNSHINE YET. TONIGHT
WINDS WILL BE LIGHT OUT OF THE SOUTH, AND LOWS WILL BE IN THE 40S TO
LOW 50S. NEARLY CALM CONDITIONS MAY RESULT IN DENSE FOG DEVELOPMENT
OVERNIGHT. ENSEMBLE GUIDANCE INDICATES A BROAD AREA OF 50-70%
PROBABILITY OF VISIBILITY OF 2 MILES OR LESS. WHILE THE WORST
CONDITIONS LOOK TO REMAIN ALONG AND NORTH OF I-90, CAUTION SHOULD BE
USED EVERYWHERE. FOG MAY LINGER INTO THE MID-TO-LATE MORNING.
LOOKING ALOFT FOR WEDNESDAY WE SEE A BROAD WAVE TAKING SHAPE OVER
WESTERN CANADA, EXTENDING DOWN OVER THE CENTRAL HIGH PLAINS. AT THE
SURFACE A LOW PRESSURE WILL SETTLE OVER CENTRAL CANADA AND A COLD
FRONT WILL DEVELOP AND DRAPE FROM THERE THROUGH EASTERN NORTH
DAKOTA, CENTRAL SOUTH DAKOTA, AND INTO SOUTHEASTERN WYOMING.
MODERATE WARM AIR AND MOISTURE ADVECTION WILL POOL AHEAD OF THIS
FRONT, WORKING TO DESTABILIZE THE BOUNDARY LAYER. HIGHS WILL CLIMB
INTO THE 60S TO THE LOW 70S OVER NORTHWEST IOWA, WHILE DEWPOINTS
CLIMB INTO THE UPPER 50S AND LOW 60S. THOUGH SKIES WILL BE PARTLY
CLOUDY, SURFACE HEATING THROUGH BREAKS IN THE CLOUDS MAY WORK TO
FURTHER DESTABILIZE THE ENVIRONMENT, ESPECIALLY EAST OF I-29. MLCAPE
OF 500-1000 J/KG IS POSSIBLE. MID-LEVEL LAPSE RATES WILL BE MARGINAL
AT 6.5 TO 7.0 DEG C. HOWEVER, THE 0-6 KM BULK SHEAR WILL BE 40+ KTS,
ENOUGH TO SUPPORT A STRONGER THUNDERSTORM OR TWO. AS THE UPPER LEVEL
TROUGH, UPPER RIGHT JET ENTRANCE REGION, AND SURFACE FRONT MOVE TO
THE EAST SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM
OVER CENTRAL SOUTH DAKOTA IN THE LATE MORNING TO EARLY AFTERNOON. AS
THIS SYSTEM CONTINUES TO PIVOT, STORMS WILL EXPAND TO THE EAST
MOSTLY ALONG AND NORTH OF I-90. BY MID-TO-LATE AFTERNOON THE AXIS OF
THE UPPER TROUGH AND SURFACE FRONT WILL CROSS INTO THE AREA OF BEST
THERMODYNAMIC PARAMETERS EAST OF I-29. A FEW STRONGER, POSSIBLY
SEVERE THUNDERSTORMS MAY DEVELOP. WHILE CONDITIONS ARE FAVORABLE OF
SURFACE BASED SUPERCELLS, STRONG BOUNDARY LAYER CAPPING WILL LIKELY
KEEP MOST STORMS ELEVATED AND SUB-SEVERE PRODUCING SMALL HAIL AND
WIND GUSTS TO 45 MPH. SHOULD A STRONGER SURFACE BASED STORM DEVELOP,
IT COULD PRODUCE LARGE HAIL UP TO THE SIZE OF A HALF DOLLAR, AND
DAMAGING WIND GUSTS IN EXCESS OF 60 MPH. THIS MATCHES WELL WITH THE
LATEST SPC DAY 2 OUTLOOK WITH A MARGINAL (LEVEL 1 OF 5) RISK OF
SEVERE STORMS. DESPITE THE CHANCE FOR STRONGER STORMS, MOST WILL
ONLY SEE A FEW HUNDREDTH TO A COUPLE TENTHS OF ACCUMULATION. THOSE
UNDER ANY STRONGER STORMS COULD SEE UP TO AN INCH. STORMS SHOULD
PUSH EAST OF THE CWA BY MIDNIGHT THURSDAY MORNING. COLD AIR
ADVECTION BEHIND THE FRONT ON NORTHERLY WINDS WILL REDUCE OVERNIGHT
LOWS TO THE MID 30S TO 40S.
THURSDAY WILL BE DRY BUT COOLER AS FLOW ALOFT BECOMES QUASI-ZONAL
AND SURFACE HIGH PRESSURE PUSHES IN FROM THE NORTHWEST. AS THE HIGH
MOVES INTO CENTRAL MINNESOTA THROUGH THE AFTERNOON WINDS GRADUALLY
CHANGE FROM NORTHERLY TO EAST-SOUTHEASTERLY. SOUNDINGS INDICATE
MIXING WILL BE SHALLOW IN THE AFTERNOON, ONLY REACHING UP TO AROUND
THE 925 MB LAYER. TEMPERATURES IN THE 925 MB LAYER HAVE BEEN
TRENDING SLIGHTLY DOWN OVER THE PAST FEW MODEL RUNS. IN ADDITION,
LINGERING CLOUDS MAY ALSO LIMIT SURFACE HEATING. AFTER COLLABORATION
WITH NEIGHBORS HAVE OPTED TO REDUCE NBM HIGH TEMPERATURES A COUPLE
OF DEGREES BY BLENDING IT WITH CONSSHORT. HIGHS ARE NOW EXPECTED TO
CLIMB INTO THE 50S TO MID 60S.
FRIDAY WILL BE MOSTLY DRY AS WE WATCH THE APPROACH OF A STRONG UPPER
WAVE FROM THE SOUTHWEST. HIGHS WILL CLIMB INTO THE UPPER 50S AND MID
60S. FRIDAY LATE AFTERNOON INTO THE EVENING THE WAVE AND SURFACE LOW
WILL BEGIN PRODUCING SHOWERS AND THUNDERSTORMS THAT WILL SLOWLY MOVE
NORTH TO NORTHEAST THROUGH FRIDAY NIGHT AND MOST OF SATURDAY.
SATURDAY EVENING AND MOST OF SUNDAY WILL BE DRY WITH HIGHS IN THE
50S AND 60S. FOLLOWED BY ANOTHER STRONG UPPER WAVE THAT WILL BRING
EXTENDED CHANCES FOR RAIN INTO THE FIRST HALF OF NEXT WEEK. LONG
RANGE ENSEMBLES INDICATE A HIGH PROBABILITY (70-90%) OF TOTAL RAIN
EQUAL TO 1 INCH OR MORE FROM FRIDAY EVENING THROUGH NEXT
WEDNESDAY. FURTHER DETAILS ARE VAGUE AT THIS POINT AND THERE IS
MUCH UNCERTAINTY WITH TRACK AND EVOLUTION OF THESE WAVES.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 637 PM CDT TUE OCT 27 2026
MVFR AND IFR STRATUS IS CLEARING OVER PORTIONS OF THE AREA THIS
EVENING. HOWEVER, STRATUS LOOKS TO LINGER THROUGH THE OVERNIGHT,
POSSIBLY REDEVELOPING OVER AREAS WHICH HAVE CLEARED OUT. AREAS
THAT REMAIN CLEAR MAY SEE MVFR/IFR FOG DEVELOP OVERNIGHT INTO
EARLY WEDNESDAY MORNING, ALTHOUGH THE QUESTION WILL BE HOW
QUICKLY WINDS TAPER DOWN. IF WINDS STAY A LITTLE MORE ELEVATED,
WE MAY SEE MORE STRATUS AND CEILING REDUCTIONS THAN REDUCED
VISIBILITY. GREATEST CHANCES (50-70%) OF VISIBILITY BELOW ONE
MILE REMAINS NEAR/NORTH OF I-90.
FOG SHOULD LIFT BY MID TO LATE MORNING. GUIDANCE REMAINS SPLIT
ON HOW QUICKLY CEILINGS RETURN TO VFR CONDITIONS, BUT REMAINED A
BIT PESSIMISTIC. ADDITIONALLY, SHOWERS AND ISOLATED STORMS ARE
EXPECTED TOWARD I-29 TOWARD THE AFTERNOON HOURS, MOVING EAST
THROUGH THE AFTERNOON AND EVENING. FOR NOW, KEPT AS A PROB30 AT
KFSD DUE TO COVERAGE UNCERTAINTY AND KEPT OUT ANY TS MENTION DUE
TO LOWER CONFIDENCE.
WINDS INCREASE AND SHIFT WESTERLY LATER IN THE PERIOD BEHIND A
FRONT. GUSTS AROUND 20 KNOTS WEDNESDAY INTO THE EVENING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...AJP
AVIATION...SG
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