471
FXUS63 KFSD 290856
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
356 AM CDT THU MAY 29 2025
KEY MESSAGES
- PATCHY FOG EARLY THIS MORNING, BUT WIDESPREAD DENSE FOG IS
NOT EXPECTED.
- ISOLATED TO SCATTERED LIGHT SHOWERS ARE POSSIBLE AGAIN TODAY,
MAINLY NEAR/EAST OF I-29 CORRIDOR. POTENTIAL FOR WEAK FUNNELS
IS LOWER THAN PREVIOUS COUPLE OF DAYS, BUT SHOWERS MAY PRODUCE
GUSTY WINDS.
- WILL SEE INCREASE IN SMOKE ALOFT TONIGHT INTO FRIDAY FROM
CANADIAN WILDFIRES. SURFACE IMPACTS FROM SMOKE ARE NOT EXPECTED.
- WARMER WITH HIGHS IN THE 80S TO PERHAPS SOME LOWER 90S THIS
WEEKEND INTO MONDAY, THEN MODERATE (40-60%) CHANCES FOR SHOWERS
AND STORMS MONDAY NIGHT THROUGH WEDNESDAY. SOME POTENTIAL FOR
STRONG-SEVERE STORMS, THOUGH DETAILS ARE FAR FROM CERTAIN.
DISCUSSION
ISSUED AT 355 AM CDT THU MAY 29 2025
TODAY: MAIN MID-UPPER LEVEL LOW AS MOVED EAST INTO THE UPPER
MISSISSIPPI VALLEY, BUT AN ELONGATED TROUGH AXIS EXTENDS WESTWARD
INTO SD. MORE EXPANSIVE CLOUD COVER ASSOCIATED WITH THIS TROUGH
WILL SLIDE SOUTH ACROSS OUR FORECAST AREA THIS MORNING, THOUGH
SOME THINNING IS POSSIBLE WITH WEAK SUBSIDENCE BEHIND THE TROUGH
AS IT SHIFTS INTO NEBRASKA/IOWA. CANNOT RULE OUT SPOTTY SPRINKLES
WITH THIS FEATURE THIS MORNING, BUT NOT EXPECTING ANY MEASURABLE
RAINFALL. AS FAR AS EARLY MORNING FOG, SURFACE OBSERVATIONS SHOW
PATCHY REDUCED VISIBILITY, BUT AREA WEB CAMS ARE NOT SHOWING MUCH
OF CONCERN, PERHAPS SOME LOCALIZED LOWER VISIBILITY NEAR THE LOWER
MISSOURI/VERMILLION RIVER VALLEY AREA (GAYVILLE-VERMILLION-IRENE).
AT THIS TIME DO NOT ANTICIPATE ANY HEADLINES, BUT WILL HIGHLIGHT
POTENTIAL FOR PATCHY LOW VISIBILITY IN THE HWO.
BY THIS AFTERNOON, DAYTIME HEATING AIDED BY A TRAILING WEAK WAVE
WILL AGAIN PRODUCE DIURNAL CUMULUS AND THE POTENTIAL FOR ISOLATED
TO SCATTERED LIGHT SHOWERS. OVERALL, THOUGH, THE AIR MASS IS DRIER
THAN RECENT DAYS AND INSTABILITY IS WEAKER, SO ANTICIPATE LESSER
COVERAGE OF SHOWERS AND MINIMAL THUNDER THREAT (<10%). THE WEAKER
INSTABILITY AND SLIGHTLY STRONGER WINDS WITHIN THE CLOUD LAYER
CONTRIBUTE TO A MUCH LOWER ENHANCED STRETCHING POTENTIAL (ESP)
TODAY, SO CURRENTLY DO NOT EXPECT TO SEE THE WEAK FUNNELS AS WE
HAVE SEEN THE PAST COUPLE OF DAYS WHEN THE UPPER LOW WAS PARKED
OVERHEAD. HOWEVER, A DRY SUB-CLOUD LAYER COULD STILL RESULT IN
ERRATIC WIND GUSTS WITH THE SPOTTY SHOWERS/VIRGA THAT MAY DEVELOP.
TONIGHT-FRIDAY: MID-UPPER LEVEL FLOW WHICH HAS BEEN PREDOMINANTLY
EAST-NORTHEAST THE PAST FEW DAYS WILL TAKE ON A MORE NORTHERLY
TRAJECTORY AS THE UPPER TROUGH CONTINUES TO SWING OFF TO THE EAST
TONIGHT, AND A RIDGE BUILDS INTO THE HIGH PLAINS. ALAS, THIS WILL
BEGIN TO DRAW UPPER LEVEL SMOKE INTO THE REGION FROM CANADIAN
WILDFIRES, AND WILL BEGIN TO SEE MURKY/HAZY SKIES DEVELOP LATER
TONIGHT THROUGH AT LEAST FRIDAY EVENING. FORTUNATELY, AT LEAST
THROUGH FRIDAY, OUR SURFACE FLOW DOES NOT APPEAR TO TAP INTO THIS
ELEVATED SMOKE LAYER, SO SURFACE IMPACTS ARE NOT EXPECTED. MAY
HAVE TO MONITOR THIS INTO THE WEEKEND, THOUGH, AS DEEPER NORTHWEST
FLOW DEVELOPS ACROSS THE NORTHERN PLAINS.
SATURDAY-MONDAY: ASIDE FROM THE AFOREMENTIONED POTENTIAL FOR SMOKE
ISSUES, THIS PERIOD LOOKS TO BE RELATIVELY QUIET WITH THE UPPER
RIDGE PROVIDING OPPORTUNITY FOR OUR TEMPERATURES TO WARM TO ABOVE
SEASONAL NORMALS AS WE HEAD INTO METEOROLOGICAL SUMMER ON SUNDAY.
HIGHS IN THE 80S WILL BE MOST COMMON. HOWEVER, AS THE THERMAL
RIDGE CONTINUES TO STRENGTHEN EARLY NEXT WEEK, ENSEMBLES BEGIN TO
SHOW MODERATE (50-70%) PROBABILITIES FOR HIGHS TOPPING 90 DEGREES
IN SOME AREAS BY SUNDAY AND OVER A GREATER AREA ON MONDAY.
MONDAY NIGHT-WEDNESDAY: THE UPPER RIDGE SHIFTS EAST OF THE AREA
LATE MONDAY-MONDAY NIGHT, PLACING THE NORTHERN PLAINS IN A MORE
ACTIVE SOUTHWEST FLOW PATTERN MONDAY NIGHT. SOME MODELS MAINTAIN
THIS SOUTHWEST FLOW INTO THE MIDDLE OF NEXT WEEK, WHILE SOME
SOLUTIONS SHOW A MORE DOMINANT NORTHERN STREAM TROUGH PUSHING
EAST INTO THE NORTHERN PLAINS BY TUESDAY-WEDNESDAY. WHILE THE
TRANSITIONS TO SOUTHWEST OR WESTERLY FLOW WILL LESSEN OUR IMPACTS
FROM DISTANT WILDFIRE SMOKE, WE SHOULD SEE PERIODIC RAIN CHANCES
AS VARIOUS SHORTWAVES SLIDE ACROSS THE REGION. HOWEVER, THESE
AFOREMENTIONED DIFFERENCES IN PATTERN EVOLUTION LEAD TO A LOWER
CONFIDENCE FORECAST. THAT SAID, SOME MACHINE-LEARNING TOOLS DO
SUGGEST AT LEAST LOW PROBABILITIES (5-10%) FOR STRONG-SEVERE
STORMS DURING THE TUESDAY-WEDNESDAY TIMEFRAME. THOSE WITH OUTDOOR
PLANS WILL WANT TO MONITOR FORECAST TRENDS AS WE MOVE THROUGH THE
DAYS AHEAD.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1035 PM CDT WED MAY 28 2025
WINDS WILL BE LIGHT OVERNIGHT, AND THERE ARE LOW PROBABILITIES
(20-30%) FOR PATCHY FOG FORMATION - MAINLY FROM THE JAMES RIVER
VALLEY AND WESTWARD. WITH THE LOW CONFIDENCE, DID NOT INCLUDE
IN TAFS AT THIS TIME.
ISOLATED SHOWERS/THUNDERSTORMS WILL AGAIN BE POSSIBLE ON
THURSDAY. WINDS WILL REMAIN LIGHT.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JH
AVIATION...JM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page