715
FXUS63 KFSD 090320
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1020 PM CDT MON SEP 8 2025
KEY MESSAGES
- ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS MAY DEVELOP
(20-40% CHANCE) THIS EVENING THROUGH TUESDAY MORNING. ALTHOUGH
SEVERE WEATHER IS UNLIKELY, A FEW STORMS MAY PRODUCE SMALL
HAIL.
- CANADIAN WILDFIRE SMOKE BEGINS TO DRIFT INTO THE REGION TODAY, LINGERING
THROUGH AT LEAST MID-WEEK.
- LOW (<40%) RAIN CHANCES SPREAD IN THIS WEEKEND, BUT CONFIDENCE
IN ANY DETAILS IS LOW AT THIS TIME.
DISCUSSION
ISSUED AT 245 PM CDT MON SEP 8 2025
TONIGHT: SATELLITE IMAGES EARLY THIS AFTERNOON SHOW SCATTERED MID TO
HIGH CLOUDS IN THE REGION AS A FEW WEAK WAVES TRAVERSE THE REGION TO
OUR NORTH, SOUTH, AND NORTHWEST. A BREEZY SSW GRADIENT WIND PERSISTS
AS 925-850MB WINDS MIX DOWN GUSTS IN THE 20S TO MID 30S THROUGH
EARLY THIS EVENING. GUSTS WILL BE STRONGEST ATOP AND DOWNWIND
(NORTHEAST) OF THE MN BUFFALO RIDGE, PEAKING 35 TO 40 MPH. WINDS
WILL WEAKEN SOME AFTER SUNSET.
ATTENTION THEN TURNS TO RAIN CHANCES LATER THIS EVENING THROUGH
TUESDAY MORNING. A MID LEVEL DISTURBANCE, EVIDENT IN WATER VAPOR
IMAGERY ENTERING NORTHWEST SD, AND WEAK JET STREAK ALOFT WILL TRACK
ESE AND TRIGGER SCATTERED, ELEVATED SHOWERS AND OCCASIONAL
THUNDERSTORMS OVERNIGHT. MODELS ARE NOT HANDLING THIS MID LEVEL
"RIDGE RIDER" VERY WELL, BUT A COMBO OF WEAK WINDS ALOFT (<20 KTS AT
500MB) COUPLED WITH PROXIMITY FAR FROM THE BROADER ASCENT (UPPER
TROUGH NEAR INTERNATIONAL BORDER) SHOULD INHIBIT ORGANIZED STORMS
ENOUGH TO PREVENT SEVERE WEATHER. A "WORST CASE" SCENARIO IS SHOWN
WITH GREATER (SCATTERED) COVERAGE OF TSTORMS VIA THE 12Z GFS AND
HRRR, SUGGESTING UPWARDS OF 1500-2000 J/KG MUCAPE COULD ALLOW FOR
SMALL HAIL FROM A STRONGER "PULSE-Y" MULTICELLS, IF AT ALL.
TUESDAY: WILL NEED TO MONITOR OVERNIGHT MODEL GUIDANCE AS THERE ARE
SOME HINTS WARM AIR ADVECTION MAY BRING AREAS OF FOG DEVELOPMENT
EARLY TUESDAY MORNING. SCATTERED MID TO HIGH CLOUDS WILL LINGER
DURING THE DAY WITH PERIODIC SCATTERED SHOWERS AND RUMBLES OF
THUNDER NEAR AND EAST OF THE I-29 CORRIDOR AS SEVERAL
DISTURBANCES SLIDE THROUGH IN NORTHWEST FLOW ALOFT. WINDS ALOFT
REMAIN WEAK, SO AGAIN DO NOT EXPECT ORGANIZED CONVECTION, BUT
MODERATE INSTABILITY IN THE NARROW WARM SECTOR STILL ALLOWS FOR
RUMBLES OF THUNDER. ADDITIONALLY, DESPITE SOME CLEARING/DRYING
ALOFT THE FURTHER WEST YOU GO, THICK CANADIAN WILDFIRE SMOKE
ALOFT SHOULD MAKE FOR A MILKY APPEARANCE TO THE SKY TUESDAY INTO
WEDNESDAY. HRRR AND RAP GUIDANCE SUGGEST SMOKE MAY MIX DOWN TO
THE SURFACE AND REDUCE AIR QUALITY AT TIMES, MAINLY NORTH OF A
WORTHINGTON TO SIOUX FALLS TO LAKE ANDES LINE.
WEDNESDAY THROUGH THIS WEEKEND: WE'LL GET ANOTHER TASTE OF
SUMMER AS HOT BUT MOSTLY DRY WEATHER COMMENCES FOR THE SECOND
HALF OF THE WORK WEEK. ESAT TABLES SUGGEST STRONG UPPER RIDGING
(TOP 10TH PERCENTILE OF NAEFS CLIMATOLOGY) BUILDS EAST INTO THE
CENTRAL U.S., LINGERING THROUGH AT LEAST SATURDAY. HIGH
CONFIDENCE IN NEAR TO ABOVE NORMAL TEMPERATURES DURING THIS
PERIOD WITH HIGHS IN THE 80S TO 90S. FAVORED NON-GFS (OVER-
MIXING) GUIDANCE BUT MAINTAINED NBM FOR NOW.
NEXT CHANCES FOR SHOWERS AND STORMS DEVELOP FRIDAY THROUGH THE
WEEKEND, PROMPTED BY ANY DISTURBANCES IN SOUTHWESTERLY FLOW ALOFT AS
SUBSIDENCE FROM UPPER RIDGING SHIFTS EAST. LOW CONFIDENCE IN TIMING
ANY WAVES DURING THIS PERIOD, WHICH WILL BE OVER THE PACIFIC OCEAN
UNTIL MID WEEK, BUT CAN'T RULE OUT POTENTIAL FOR SEVERE WEATHER OVER
THE WEEKEND IF THE RIGHT INGREDIENTS ALIGN.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1019 PM CDT MON SEP 8 2025
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL REMAIN
POSSIBLE THROUGH THE PERIOD. CONFIDENCE IN TIMING AND LOCATION
REMAIN LOW. BETTER CHANCES REMAIN OVERNIGHT.
OTHERWISE THE POTENTIAL FOR IFR AND MVFR STRATUS BECOMES THE
MAIN CONCERN. EXPECT SOME IFR STRATUS TO DEVELOP LATER TONIGHT
INTO TUESDAY MORNING. THE BETTER CHANCES WILL BE EAST OF THE
JAMES RIVER VALLEY TOA ROUND I-29.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...BP
AVIATION...08
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