585
FXUS63 KFSD 272100 AAA
AFDFSD
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SIOUX FALLS SD
400 PM CDT WED AUG 27 2025
KEY MESSAGES
- SCATTERED SHOWERS AND STORMS ARE EXPECTED TO DEVELOP THIS
EVENING, MAINLY IN SOUTHWESTERN MINNESOTA. AN ISOLATED STRONG
TO SEVERE THUNDERSTORM OR TWO CANNOT BE RULED OUT THROUGH MID
EVENING.
- TEMPERATURES RETURN NEAR SEASONAL AVERAGES FOR TODAY AND
THURSDAY, WITH A SLIGHTLY COOLER DAY FRIDAY AND THROUGH THE
WEEKEND.
- MORE WIDESPREAD RAIN CHANCES AND COOLER CONDITIONS RETURN BY
FRIDAY NIGHT THROUGH THE UPCOMING HOLIDAY WEEKEND. DETAILS
REMAIN UNCERTAIN HEADING INTO THE WEEKEND SO CONTINUE TO
MONITOR THE LATEST FORECAST.
DISCUSSION
ISSUED AT 239 PM CDT WED AUG 27 2025
TODAY AND TONIGHT: WARMER TEMPERATURES TODAY AS SLIGHTLY BREEZY
SOUTHERLY WINDS BRING NORTHWARD A WARMER AIR MASS. TEMPERATURES IN
THE 850 MB LAYER WILL INCREASE TO 16-22 DEGREES C. AT THE SURFACE
THAT TRANSLATES INTO HIGHS IN THE UPPER 70S AND MID 80S. LOWS
TONIGHT WILL BE MILD, IN THE UPPER 50S.
LOOKING ALOFT, A WEAK NORTHWEST TO SOUTHEAST ORIENTATED JET STREAK
RIGHT ENTRANCE WILL BE SITUATED OVER OUR REGION. A WEAK MID-LEVEL
WAVE AND SURFACE LOW PRESSURE TROUGH AXIS WILL WORK TOGETHER TO
TRIGGER A ROUND OF SHOWERS AND POSSIBLY WEAK THUNDERSTORMS THIS
AFTERNOON INTO THE EARLY MORNING THURSDAY. MID-LEVEL LAPSE RATES ARE
WEAK AT 6.5 DEG C/KM OR LESS. INSTABILITY IS AROUND 1200-1500 J/KG
OF LONG AND SKINNY CAPE. THIS THERMAL PROFILE DOES NOT LEND ITSELF
TO STRONG STORMS. HOWEVER, 0-6 KM BULK SHEAR IS 30-40 KTS, WHICH
COULD SUPPORT A FEW ISOLATED STRONGER UPDRAFTS. THESE STRONGER
UPDRAFTS COULD PRODUCE HAIL UP TO THE SIZE OF A QUARTER AND WIND
GUSTS UP TO 60 MPH. THE AREA MOST LIKELY TO SEE ANY STRONGER STORMS
IS ALONG I-90 FROM MITCHELL, SD EAST TO JACKSON, MN AND NORTH. THIS
MATCHES WELL WITH THE SPC DAY 1 MARGINAL (LEVEL 1 OF 5) OUTLOOK. AS
FAR AS RAIN TOTALS ARE CONCERNED, A QUICK FEW HUNDREDTHS UP TO
AROUND A QUARTER OF AN INCH IS EXPECTED. DUE TO THE ISOLATED TO
SCATTERED NATURE OF THESE STORMS, NOT EVERYONE WILL SEE RAIN, WITH
THE MOST LIKELY AREA BEING SOUTHWEST MINNESOTA.
ONE FINAL CONSIDERATION FOR TONIGHT INTO EARLY THURSDAY MORNING IS
PATCHY DENSE FOG DEVELOPMENT. OVERNIGHT WINDS WILL BECOME LIGHT AND
VARIABLE AS THE BOUNDARY LAYER APPROACHES SATURATION. AS A RESULT,
PATCHY FOG MAY DEVELOP OVER CENTRAL SOUTH DAKOTA AND ALONG AND NORTH
OF I-90. PLEASE USE CAUTION DURING YOUR MORNING COMMUTES.
THURSDAY AND THE WEEKEND: AN UPPER LEVEL RIDGE KEEPS CONDITIONS
SEASONABLY WARM FOR THURSDAY. HIGHS WILL BE IN THE UPPER 70S TO MID
80S WITH LOWS IN THE MID 50S TO LOW 60S. WINDS WILL BE LIGHT OUT OF
THE EAST. A VERY LOW CHANCE (<20%) FOR LIGHT SHOWERS THURSDAY
MORNING OVER NORTHWESTERN IOWA AS A WEAK BOUNDARY TRIES TO TAKE
ADVANTAGE OF WHAT LITTLE MOISTURE IS AVAILABLE. HOWEVER, A DRY
SUBCLOUD LAYER WILL LIKELY EVAPORATE ANY MOISTURE BEFORE IT REACHES
THE GROUND.
FRIDAY WE SEE A MID-LEVEL SHORT WAVE AND SURFACE LOW PRESSURE BEGIN
TO MOVE INTO THE REGION. THERE REMAINS HIGH UNCERTAINTY IN THIS
SYSTEM DUE TO LOW MODEL AGREEMENT. THE GFS AND NAM HAVE WAA SHOWERS
BEGINNING A FULL 6-9 HOURS EARLIER THAN THE ARRIVAL OF THE MAIN
WAVE. MODELS COME INTO BETTER CONCENSUS AS THE MAIN WAVES MOVES
THROUGH SATURDAY. HOWEVER, TRACK OF THE SURFACE LOW VARIES BETWEEN
ALL FOUR MID-RANGE MODELS. WHAT THEY DO AGREE ON IS THE SLOW
EASTWARD PROGRESSION OF THE ENTIRE SYSTEM. WHAT THIS MEANS IS THE
WEEKEND IS LOOKING RATHER SOGGY AND DREARY. CONFIDENCE IN RAIN
TOTALS IS LOW DUE TO THE AFOREMENTIONED UNCERTAINTY. HOWEVER, THE
GFS AND EC LONG TERM GUIDANCE INDICATE 1-2 INCHES COULD BE POSSIBLE
THROUGH MONDAY MORNING, ESPECIALLY FOR AREAS OF SOUTHWESTERN
MINNESOTA. ALL METRICS USED TO DETERMINE SEVEREITY ARE LOW,
SUGGESTING THESE SHOULD REMAIN LIGHT TO MODERATE SHOWERS, WITH AN
OCCASSIONAL RUMBLE OF THUNDER POSSIBLE. PLEASE CONTINUE TO MONITOR
THE FORECAST FOR UPDATES AS DETAILS BECOME CLEAR. HIGHS FOR FRIDAY
THROUGH SUNDAY WILL BE IN THE UPPER 60S TO 70S WITH LOWS IN THE 50S.
NEXT WEEK: LONG TERM GUIDANCE FOR NEXT WEEK IS IN VERY LOW
AGREEMENT. THEY DO INDICATE MULTIPLE WAVES WILL PASS THROUGH
BRINGING RAIN CHANCES PERIODICALLY THROUGH AT LEAST MID-WEEK. BUT
OTHER THAN THAT DETAILS AT THIS TIME ARE SPARSE. HIGHS ARE EXPECTED
TO REMAIN SEASONABLE FOR THIS TIME OF YEAR, IN THE UPPER 70S TO LOW
80S.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1221 PM CDT WED AUG 27 2025
SLIGHTLY BREEZY SOUTHWESTERLY WINDS WILL DECREASE THROUGH THE
AFTERNOON AND EVENING HOURS, BECOMING LIGHT AND VARIABLE. THERE IS A
CHANCE FOR SOME PATCHY DENSE FOG TO DEVELOP OVERNIGHT, ESPECIALLY
OVER CENTRAL SOUTH DAKOTA AND ALONG AND NORTH OF I-90. FOG SHOULD
BEGIN TO BURN OFF SHORTLY AFTER SUNRISE THURSDAY.
KFSD MAY SEE A FEW LIGHT SHOWERS THIS EVENING INTO VERY EARLY
THURSDAY MORNING. SEVERE WEATHER IS NOT EXPECTED. CONFIDENCE IN
SHOWERS ACTUALLY IMPACTING THE TAF SITE IS LOW AND SO COVERED
SHOWER CHANCES WITH A PROB30 GROUP.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...AJP
AVIATION...AJP
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