Flash Flood Warning 13, NWS Sioux Falls, SD

657 
WGUS73 KFSD 062052
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
352 PM CDT Sun Sep 6 2026

SDC011-099-101-062300-
/O.CON.KFSD.FF.W.0013.000000T0000Z-260906T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Brookings SD-Minnehaha SD-Moody SD-
352 PM CDT Sun Sep 6 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM CDT THIS EVENING
FOR SOUTHEASTERN BROOKINGS, EASTERN MOODY AND NORTHEASTERN MINNEHAHA
COUNTIES...

At 352 PM CDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain across the warned area. Between 2
and 4 inches of rain have fallen. The expected rainfall rate is up to
0.5 inches in 1 hour. Additional rainfall amounts up to 0.5 inches
are possible in the warned area. Flash flooding is ongoing or
expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Flandreau, Garretson, Elkton, White, Egan, Trent, Sherman,
  Palisades State Park, Bushnell and Flandreau Santee Sioux Tribal
  Nation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.

Please report observed flooding to local emergency services or law
enforcement and request they pass this information to the National
Weather Service when you can do so safely.

&&

LAT...LON 4385 9668 4443 9667 4444 9647 4364 9647
      4380 9668

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL RATE...0.5 INCHES IN 1 HOUR

$$

JH

353 
WGUS73 KFSD 062254
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
554 PM CDT Sun Sep 6 2026

SDC011-099-101-062304-
/O.EXP.KFSD.FF.W.0013.000000T0000Z-260906T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Brookings SD-Minnehaha SD-Moody SD-
554 PM CDT Sun Sep 6 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM CDT THIS EVENING FOR
SOUTHEASTERN BROOKINGS, EASTERN MOODY AND NORTHEASTERN MINNEHAHA
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a
threat.

A Flood Watch remains in effect until 1000 PM CDT for portions of
Iowa, southwest Minnesota, and southeast South Dakota.

&&

LAT...LON 4385 9668 4443 9667 4444 9647 4364 9647
      4380 9668

$$

Meyers

Area Forecast Discussion
National Weather Service Sioux Falls SD
1249 PM CDT Sun Sep 6 2026

.KEY MESSAGES...

- Isolated strong to severe storms remain possible into the
  late afternoon hours. Brief downburst winds of 50 to 60 mph
  will be possible over NW Iowa and adjacent SD/NE counties.

- Heavy rain will be the primary risk into the evening with
  rainfall rates of 1-3" per hour and local totals of 3-5"
  possible. A flood watch for flash flooding continues into late
  evening.

- Isolated strong to severe storms will again be possible late
  Monday afternoon into Tuesday morning. These risks may
  continue into NW Iowa Tuesday afternoon.

- Quiet but continued warm conditions are expected for the rest
  of the work week.

&&

.DISCUSSION...
Issued at 1246 PM CDT Sun Sep 6 2026

THIS AFTERNOON: Strong convection continues to develop in areas
along but mostly east of I-29 this afternoon.  The area continues to
reside in a moderately unstable environment, but lacks any
meaningful shear and mid-lvl lapse rates.  However, climatologically
significant PWATs are in place, with enough DCAPE to suggest an
increased risk for wet microbursts over the next 1-3 hours in a
narrow corridor from Madison to Sioux Falls, Sioux Center, Cherokee,
Storm Lake, Le Mars, and Sioux City. Rainfall may be the most
impactful hazard this afternoon with 1-2 hr totals of 3-4" already
in portions of southern Minnesota.  Additional convection is likely
to continue to produce 2-4" totals in pockets of NW Iowa, though
cold pool development may help push storms off an area before
extreme values may be produced.  The stronger MCV will also nudge
it's way northward later this afternoon, and may work to produce
additional northward/northeastward convection with it.

TONIGHT: This shortwave/MCV will drag it's feet eastward this
evening, with some expected weakening of convection with the lost of
daytime heating and general stabilization of the environment nearby.
However, an increased LLJ may begin to develop after 02Z which
could bring returning elevated showers and isolated
thunderstorms to the CWA late this evening and continuing into
the overnight hours. This activity will likely not be severe,
but any shower could still bring brief heavy rain.

MONDAY-TUESDAY: Elevated shower activity diminishes towards daybreak
as shortwave ridging arrives. An ejecting trough out of the Rockies
will bring additional elevated convection into central and northern
South Dakota into Monday afternoon, perhaps grazing the western CWA.
As the EML gradually erodes into south central SD late in the
afternoon, a few strong to severe storms may develop and track
east southeast into the early overnight hours. As the LLJ
increases after dark, elevated convection may expand in coverage
with continued low- end severe weather risks for Tuesday
morning.

More uncertainty for Tuesday, which is focused moreso on the
location of the surface front and impacts of overnight elevated
convection.  While the primary surface front settles in northwest
Iowa, a secondary stronger dew point gradient arrives later in the
afternoon. Should sufficient clearing develop, then a storm or two
could become stronger by mid-afternoon with activity quickly
tracking southeast by the evening.

EXTENDED: With ongoing convection, no forecast changes made to the
extended as a temporarily reprieve from active weather
develops. Temperatures may still remain near to above normal
for the rest of the work week.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1219 PM CDT Sun Sep 6 2026

Scattered convection will continue to develop early this
afternoon, and continue into early evening. In thunderstorms,
brief 40 to 60 mph wind will be possible, along with small hail,
and torrential rainfall. The coverage near the TAF sites
remains fairly uncertain, and impacts may be brief if they take
place.

Scattered showers and isolated thunderstorms continue south of
I-90 into the evening and early overnight hours. Again, brief
reduction to MVFR or IFR conditions are possible, but will be
driving by any sporadic updraft that passes through. Coverage in
SUX high enough to include prevailing wording ATTM.

VFR conditions may fall to MVFR levels into Monday morning,
though significant uncertainty remains as far as any stratus
development.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch until 10 PM CDT this evening for SDZ062-067-071.
MN...Flood Watch until 10 PM CDT this evening for MNZ080-081-089-
     090-097-098.
IA...Flood Watch until 10 PM CDT this evening for IAZ001>003-
     012>014-020>022-031-032.
NE...None.

&&

DISCUSSION...Dux
AVIATION...Dux

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
347 AM CDT Sun Sep 6 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-070900-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory-
Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-
Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-
Union-
347 AM CDT Sun Sep 6 2026

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, southwest Minnesota, northeast Nebraska, central South
Dakota, east central South Dakota, south central South Dakota and
southeast South Dakota.

.DAY ONE...Today and tonight.

Patchy fog may reduce visibility below a mile east of I-29 this
morning.

Thunderstorms return to the area by late morning, continuing through
the late afternoon and evening. Isolated strong storms may produce
hail to the size of a ping pong ball and wind gusts to 65 mph.

Locally heavy rainfall is possible Sunday with isolated totals of 2
to 4 inches. Some locations with multiple rounds of thunderstorms
may exceed 4 inches of rainfall through this evening.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Hot and humid again for Monday with Heat Index values in the 90s to
near 100 for areas along the southern Missouri River Valley.

Periodic storm chances continue into the middle part of the week.
Isolated severe storms and locally heavy rainfall possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed Sunday and again at times early
next week.