810
FXUS63 KFSD 312116
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
416 PM CDT THU JUL 31 2025
KEY MESSAGES
- SURFACE SMOKE WILL CONTINUE TO CAUSE VISIBILITY REDUCTIONS
AND HEALTH HAZARDS TO SENSITIVE GROUPS THROUGH FRIDAY.
- LOWER CONFIDENCE POTENTIAL FOR ISOLATED SEVERE STORMS SATURDAY
NIGHT INTO SUNDAY.
- ANOTHER CHANCE WILL COME TUESDAY NIGHT INTO WEDNESDAY. A BIT
MORE SHEAR AND INSTABILITY POTENTIAL WITH THIS EVENT SO
SOMETHING TO KEEP AN EYE ON.
DISCUSSION
ISSUED AT 354 PM CDT THU JUL 31 2025
SKIES ARE PARTLY CLOUDY AND SMOKY ACROSS THE AREA ON THIS MILD
THURSDAY AFTERNOON. A SURFACE HIGH PRESSURE SYSTEM IS SLIDING
EASTWARD THROUGH NORTHERN MINNESOTA, ALLOWING FOR THE RETURN OF
LIGHT SOUTHEASTERLY WINDS LOCALLY. A FIELD OF CUMULUS CLOUDS
STRETCHES FROM NORTHWEST IOWA TO CENTRAL SOUTH DAKOTA, AND WITH
SOUNDINGS INDICATING SOME ELEVATED INSTABILITY, COULD SEE A FEW
SPITS OF DRIZZLE WEST MAINLY WEST OF I-29 THIS AFTERNOON. HIGHS
TODAY ARE EXPECTED TO BE IN THE MIDDLE TO UPPER 70S. SHOWERS AND
ISOLATED THUNDERSHOWERS HAVE DEVELOPED IN WESTERN SOUTH DAKOTA THIS
AFTERNOON DUE TO A WEAK SHORTWAVE DRIFTING BY. SOME OF THIS ACTIVITY
MAY TRY TO CREEP INTO THE EASTERN SIDE OF THE MISSOURI, BUT WITH
MINIMAL INSTABILITY (TOPPING OUT AROUND 300-400 J/KG), NOT MUCH
ACTIVITY IS EXPECTED LOCALLY. A STRONGER SHORTWAVE WILL MOVE IN FROM
WESTERN WYOMING AND FIRE OFF MORE STORMS OVER WESTERN SOUTH DAKOTA
OVERNIGHT. THESE STORMS WILL PUSH EAST TOWARDS THE MISSOURI RIVER
AND WEAKEN AS INSTABILITY WANES. AS A RESULT, SOME SHOWERS WILL BE
POSSIBLE EARLY FRIDAY MORNING IN THE CHAMBERLAIN-AREA BUT LIKELY
WON'T AMOUNT TO MUCH. LOWS TONIGHT DROP INTO THE UPPER-50S TO LOW-
60S, WARMEST WEST WHERE THERE WILL BE MORE CLOUD COVER. THE LESS
CLOUD COVER FARTHER EAST COMBINED WITH WET GROUNDS WILL LEAD TO THE
POTENTIAL FOR PATCHY FOG EAST OF I-29, BUT MAJOR CONCERNS ARE NOT
EXPECTED.
MORE SURFACE SMOKE WILL BE IN PLACE ON FRIDAY, REDUCING VISIBILITIES
AT TIMES AND COULD CAUSE ISSUES FOR THOSE SENSITIVE TO SMOKE. HIGHS
WILL BE SLIGHTLY COOLER ON FRIDAY COMPARED TO TODAY AS THERE WILL BE
SLIGHTLY MORE CLOUD COVER OVERALL, ESPECIALLY IN THE MORNING.
ANOTHER WAVE WILL TRAVEL THROUGH THE REGION ON FRIDAY, WITH PERHAPS
SOME BETTER COVERAGE OF SHOWERS AND STORMS LATER FRIDAY WEST RIVER
AS THE LOW-LEVEL JET KICKS UP TO AROUND 35-40 KTS IN WEST-CENTRAL
SOUTH DAKOTA. THESE STORMS WILL LIKELY WEAKEN AS THEY CROSS THE
MISSOURI RIVER AS INSTABILITY DROPS OFF SHARPLY INTO OUR AREA
OVERNIGHT FRIDAY INTO SATURDAY.
UPPER LEVEL TROUGHINESS SLOWLY WORKS FROM WEST TO EAST ACROSS THE
AREA INTO SATURDAY. FOR THE MOST PART ANY INSTABILITY FRIDAY NIGHT
INTO SATURDAY SHOULD MOSTLY REMAIN BOTTLED UP NEAR AND WEST OF THE
JAMES RIVER. FAIRLY STABLE AIR TO THE EAST OF THIS AXIS OF
INSTABILITY IN CENTRAL SD WILL MAKE IT DIFFICULT FOR ANY STORMS TO
PROPAGATE EASTWARD ON SATURDAY. BY SATURDAY NIGHT THIS UPPER LEVEL
TROUGH SHIFTS EAST ENOUGH TO ALLOW SOME INSTABILITY TO SPREAD INTO
EASTERN SD WHICH SHOULD INCREASE THE CHANCES FOR SHOWERS AND
THUNDERSTORMS. WHILE OVERALL DEEPER LAYER SHEAR IS FAIRLY WEAK, THE
LOWER LEVEL SHEAR DOES INDICATE SOME TURNING WITH 20 TO 30 KNOTS IN
THE LOWEST 3 OR SO KM. THIS ON TOP OF THE POTENTIAL FOR 1500-2000
J/KG CAPE MAINLY WEST OF I-29 MAY SUPPORT SOME ISOLATED SEVERE
STORMS AND THE POTENTIAL FOR A SOUTHEAST PROPAGATING MCS DURING THE
EVENING AND OVERNIGHT. SUNDAY CONTINUES THIS THREAT FOR SHOWERS AND
THUNDERSTORMS WITH A FEW SEVERE STORMS POSSIBLE. STILL A LOT OF
QUESTION MARKS AS SOME MORNING ACTIVITY COULD BE IN PLACE WHICH
COULD ALTER EXPECTATIONS. OTHERWISE, FRIDAY, SATURDAY AND SUNDAY ALL
LOOK TO HAVE BELOW NORMAL TEMPERATURES WITH HIGHS IN THE 70S AND
LOWS IN THE 50S TO LOWER 60S.
SHOWER AND THUNDERSTORM POTENTIAL CONTINUES WEDNESDAY INTO THURSDAY
AS UPPER LEVEL HIGH PRESSURE BUILDS OVER THE SOUTHERN AND CENTRAL
PLAINS WITH SOUTHWEST FLOW ALOFT ACROSS THE NORTHERN PLAINS AND THE
POTENTIAL FOR MULTIPLE SMALLER WAVES TO RIDE THROUGH.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1240 PM CDT THU JUL 31 2025
BIGGEST FORECAST UNCERTAINTY THROUGH THE PERIOD WILL BE THE
VISIBILITY RESTRICTIONS POSSIBLE DUE TO SMOKE. SEVERAL LOCATIONS ARE
DOWN TO 4 TO 5 MILE VISIBILITIES ACROSS THE REGION TO START THE
PERIOD, AND THERE WAS ENOUGH CONFIDENCE TO GO WITH PREVAILING MVFR
CONDITIONS THROUGH THE AFTERNOON FOR ALL TAF SITES.
IMPROVEMENTS IN SMOKE-RELATED VISIBILITIES ARE EXPECTED GRADUALLY
THROUGH THIS EVENING, THOUGH SOME SURFACE SMOKE WILL STILL LINGER
THROUGH THE REST OF THE PERIOD. GUIDANCE INDICATES A CHANCE THE
SMOKE THICKENS UP AGAIN LATE TOMORROW MORNING, BUT CONFIDENCE WAS
NOT HIGH ENOUGH TO INCLUDE MVFR VISIBILITIES DURING THAT TIME
AS OF NOW. ALSO CAN'T RULE OUT SOME PATCHY FOG TONIGHT, BUT THE
GREATER CHANCES RESIDE EAST OF I-29.
A FEW SHOWERS WILL BE POSSIBLE MAINLY WEST OF THE JAMES RIVER IN AND
AROUND K9V9 LATE TONIGHT INTO EARLY TOMORROW MORNING. SOME THUNDER
IS POSSIBLE, BUT SEVERE WEATHER IS NOT EXPECTED. HIGH PRESSURE OVER
NORTHERN MINNESOTA WILL LEAD TO MAINLY LIGHT SOUTHEASTERLY
WINDS THROUGH THE PERIOD. AS THIS HIGH DRIFTS FARTHER EAST
TOMORROW, WIND WILL PICK UP A BIT TOWARDS KHON TO END THE
PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SAMET/08
AVIATION...SAMET
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