607
FXUS63 KFSD 311743
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1243 PM CDT THU JUL 31 2025
KEY MESSAGES
- PATCHY AREAS OF FOG WILL BE POSSIBLE THIS MORNING. WITH
VISIBILITIES OF 5 MILES OR LESS POSSIBLE THROUGH MID-MORNING,
BE PREPARED FOR RAPID CHANGES IN VISIBILITY OVER SHORT
DISTANCES.
- WILDFIRE SMOKE WILL CONTINUE TO PROGRESS THROUGH THE REGION
INTO THE WEEKEND. WHILE MOST OF IT WILL STAY ALOFT, SOME
LIMITED SURFACE IMPACTS WILL BE POSSIBLE.
- A FEW SCATTERED SHOWERS WITH AN OCCASIONAL RUMBLE OF THUNDER
WILL BE POSSIBLE THIS AFTERNOON MAINLY WEST OF THE JAMES RIVER
VALLEY. HOWEVER, SEVERE WEATHER IS NOT EXPECTED.
- MORE CONCENTRATED PRECIPITATION CHANCES (40%-60%) RETURN
BETWEEN SATURDAY AND SUNDAY. HOWEVER, UNCERTAINTY REMAINS ON
THE COVERAGE/SEVERE RISK.
DISCUSSION
ISSUED AT 314 AM CDT THU JUL 31 2025
TODAY & TONIGHT: A SLIGHTLY WARMER DAY AHEAD! TAKING A LOOK ACROSS
THE AREA, CLEARER CONDITIONS ARE STARTING TO RETURN NORTH OF I-90 AS
A MID TO LOW LEVEL CLOUD DECK CONTINUE TO PUSH SOUTHWARDS THIS
MORNING. HOWEVER, WE'RE ALSO STARTING TO SEE A MIX OF PATCH FOG AND
WILDFIRE SMOKE MOVE INTO THE AREA AS WELL LEADING TO OCCASIONAL
VISIBILITIES OF 5 MILES OR LESS AT TIMES. WHILE THE FOG WILL LIKELY
PERSIST THROUGH THE MID-MORNING BEFORE DISSIPATE, EXPECT THE AREAS
OF WILDFIRE SMOKE TO CONTINUE ALOFT FOR MOST OF THE DAY WITH LIMITED
SURFACE IMPACTS. BESIDES THAT, MOSTLY QUIET CONDITIONS ARE EXPECTED
FOR AT LEAST THE FIRST HALF OF THE DAY AS SOUTHEASTERLY SURFACE
WINDS HELP INCREASE OUR HIGHS TO THE MID 70S TO LOWER 80S FOR THE
DAY.
LOOKING AT THE SECOND HALF OF THE DAY, A SURFACE HIGH WILL SLIDE
DOWN FROM SASKATCHEWAN/MANITOBA KEEPING MOST AREAS EAST OF THE JAMES
RIVER VALLEY RAIN-FREE FOR THE DAY. AS FOR AREAS WEST OF THE
PREVIOUSLY MENTIONED AREA, SCATTERED SHOWERS WILL LIKELY DEVELOP IN
THE EARLY AFTERNOON AS A MID-LEVEL WAVE SLIDES ACROSS THE MISSOURI
RIVER VALLEY. WITH ABOUT 300-600 J/KG OF INSTABILITY AND 30-40 KTS
OF SHEAR, CAN'T RULE OUT AN OCCASIONAL RUMBLE OF THUNDER WITH THE
STRONGEST ACTIVITY. HOWEVER, SEVERE WEATHER IS NOT EXPECTED. SINCE
THIS ACTIVITY WILL BE RUNNING INTO A MORE STABLE AIRMASS EAST OF THE
JAMES, NOT EXPECTING THIS ACTIVITY TO PERSIST PAST THE EARLY EVENING
BEFORE DISSIPATING. SHIFTING GEARS HERE, WE'LL LIKELY HAVE TO WATCH
FOR ADDITIONAL AREAS OF FOG OVERNIGHT MAINLY EAST OF I-29 AS LIGHTER
SURFACE WINDS AND HIGHER DEW POINTS COULD LEAD TO SOME LOCALLY DENSE
AREAS. LASTLY, EXPECT ANOTHER COOL NIGHT WITH TEMPERATURES FALLING
INTO THE UPPER 50S TO LOW 60S
THE WEEKEND: LOOKING INTO THE WEEKEND, WE'LL LIKELY HAVE TO DEAL
WITH SOME ADDITIONAL SHOWERS AND THUNDERSTORMS WEST OF I-29 TO START
THE DAY ON FRIDAY AS ANOTHER MID-LEVEL WAVE TRACKS THROUGH THE AREA.
HOWEVER, AS THIS DEVELOPING ACTIVITY GETS FURTHER AWAY FROM THE
BETTER INSTABILITY GRADIENT OVER WESTERN SD AND RUNS INTO A MORE
STABLE AIRMASS; SHOULD SEE THIS ACTIVITY GRADUALLY WEAKEN WITH
EASTWARD EXTENT. NONETHELESS, WE COULD SEE THIS PATTERN RINSE AND
REPEAT DURING THE AFTERNOON TO EVENING HOURS ON FRIDAY AS THE 850-
925 MB JET STRENGTHENS THOUGH SEVERE WEATHER IS NOT EXPECTED.
SHIFTING GEARS HERE, WE'LL LIKELY CONTINUE TO HAVE AREAS OF SMOKE
THROUGH AT LEAST THE WEEKEND AS CANADIAN WILDFIRE ROTATES AROUND THE
PREVIOUSLY MENTIONED SURFACE HIGH INTO OUR AREA. WHILE MOST OF THE
SMOKE WILL LIKELY STAY ALOFT, CAN'T RULE OUR AN OCCASIONAL "BURNING
SMELL" AT THE SURFACE ALONG WITH SLIGHT REDUCTION TO VISIBILITY IN
OUR HIGHER ELEVATION AREAS.
MORE CONCRETE PRECIPITATION CHANCES (40%-60%) LIKELY RETURN BETWEEN
SATURDAY AND SUNDAY AS THE SURFACE HIGH GRADUALLY PUSHES EASTWARDS
AND IS REPLACED BY A SURFACE WARM FRONT. SCATTERED SHOWERS AND
THUNDERSTORMS WILL LIKELY DEVELOP AS THIS BOUNDARY INTERACTS WITH AN
APPROACHING MID-LEVEL WAVE. WHILE THE SEVERE THREAT IS LARGELY
UNCERTAIN AT THIS POINT, WE'LL LIKELY HAVE TO WATCH THE SUNDAY
MORNING TIME FRAME FOR SOME ISOLATED POTENTIAL GIVEN THE INSTABILITY
AND BUOYANCY WITH APPROACHING WAVES. LASTLY, AS WARM AIR ADVECTION
(WAA) INCREASE AS THE WARM FRONT PUSHES INTO CENTRAL SD; WE'LL
LIKELY SEE TEMPERATURES TREND TOWARDS NORMAL HEADING INTO NEXT WEEK
WITH HIGH LIKELY IN THE 70S TO LOW 80S.
NEXT WEEK: HEADING INTO THE NEW WEEK, AN ACTIVE PATTERN WILL
CONTINUE ALOFT WITH MULTIPLE WAVES PASSING THROUGH BETWEEN MONDAY
AND WEDNESDAY. THE STRONGEST OF WHICH WILL LIKELY PASS THROUGH ON
WEDNESDAY. WITH LONG RANGE GUIDANCE DIVERGING IN TERMS OF THE
PLACEMENT OF SYNOPTIC SCALE FEATURES AND SUBSEQUENT BOUNDARIES, THE
COVERAGE AND SEVERE RISKS REMAIN LARGELY UNCERTAIN. LASTLY, EXPECT
TEMPERATURES TO CONTINUE THEIR WARMING TREND THROUGH WEDNESDAY WITH
HIGHS LARGELY IN THE 70S TO 80S WITH THE WARMEST CONDITIONS EXPECTED
BY WEDNESDAY WEST OF I-29.
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...05
AVIATION...SAMET
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