Flash Flood Warning 8, NWS Sioux Falls, SD

511 
WGUS73 KFSD 310717
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
217 AM CDT Fri Jul 31 2026

SDC077-310727-
/O.CAN.KFSD.FF.W.0008.000000T0000Z-260731T0730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kingsbury SD-
217 AM CDT Fri Jul 31 2026

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN KINGSBURY
COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.

&&

LAT...LON 4454 9749 4440 9776 4431 9757 4454 9722

$$

Weisser

Area Forecast Discussion
National Weather Service Sioux Falls SD
746 PM CDT Thu Jul 30 2026

.KEY MESSAGES...

- Showers and thunderstorms continue across the area through the
  overnight hours. Locally heavy rain, possibly as high as 4-5
  inches, remains he main concern. Severe weather threat
  continues to decrease this evening and tonight.

- While many locations will receive a beneficial half an inch to
  two inches of rainfall, the higher amounts could lead to localized
  flash flooding in urban and flood prone areas.

- Showers linger into the day on Friday, with increasing winds
  through Friday morning. Winds will gust to around 35 mph at
  times, though isolated pockets of gusts pushing 45 mph can't
  be ruled out Friday afternoon east of I-29.

- Dry conditions and seasonable temperatures return for the
  weekend. For next week, shower and storms chances will return
  Monday night into Tuesday.

&&

.UPDATE...
Issued at 745 PM CDT Thu Jul 30 2026

Sub-severe storms continue across northern NE this evening, with the
stronger storms now across central NE. Given the trends, have
cancelled the Severe Thunderstorm Watch for Brule, Charles Mix, and
Gregory counties early. Stratiform rain continues to slowly move
east across southeastern SD, with additional rain slowly moving
south out of northeastern SD toward US Hwy 14. Another line of
thunderstorms across west central SD is slowly moving east. Rainfall
amounts so far in our area have been under an inch, with a few sites
where storms tracked through south central SD near/above 2". Showers
and storm are expected to continue through the overnight; severe
risk continues to diminish through tonight.

Definitely keeping an eye on the latest guidance regarding the heavy
rain/isolated flash flood threat through the overnight into Friday.
Rainfall rates at times may exceed 1"/hr rates with ample moisture
transport as the low deepens overhead. Greatest concern will be for
any urban or flood prone areas which receive heavy rainfall. Be
extra cautious driving at night, as flooding is harder to see. Don't
drive through flooded roadways. See the previous discussion for more
details.

May see some patchy smoke at the surface, with higher concentrations
aloft as northerly flow returns through the day Friday and the low
pressure pushes off to the east. Not expecting significant impacts,
but those sensitive to the smoke may want to take additional
precautions.

&&

.DISCUSSION...
Issued at 229 PM CDT Thu Jul 30 2026

Scattered showers and storms are moving across areas mainly
near and east of the James River this afternoon, with some
clearing occurring behind this activity. This should allow for
greater destabilization in south-central South Dakota this
afternoon and thus have issued a Severe Thunderstorm Watch for
Brule, Gregory, and Charles Mix Counties. Damaging winds to 65
mph and quarter sized hail are the main threats locally through
the early evening hours. The greater severe weather risks looks
to be south and west of our area where the better instability
lies, but still be sure to remain weather aware. Elsewhere, the
environment has been pretty worked over and thus severe weather
is less likely. The one exception is over southwest Minnesota
where we've been able to warm to the low to middle 80s out ahead
of this early afternoon activity. However, with the current
rain and clouds moving in and growing increasingly thicker in
those areas, the threat for severe weather is diminishing there
as well. There's also some clearing over north-central South
Dakota, so this will be another area to watch for storm
development, with any activity there moving east-southeast
through the evening into tonight.

Heading into the night, the main wave will close off into an upper
level low, with a surface low developing east of I-29 by daybreak
Friday. This will all combine to keep rain and some storms in the
forecast tonight through Friday morning and potentially as late as
Friday afternoon near and east of I-29 as moisture wraps around the
low. Any severe threat will greatly diminish after midnight, so this
will transition to mostly a heavy rain threat as showers and storms
will continue to push through the area. This could lead to localized
flash flooding primarily in urban and flood prone areas, so be sure
to remain weather aware. For the good majority of the area though,
this should be beneficial rainfall, with additional totals generally
between a half an inch to two inches through Friday afternoon.
Locally higher pockets of 4+ inches remain possible, but that will
be for areas that see multiple thunderstorms move over that same
area. With recent dryness, those rainfall totals won't be much of a
concern for rural areas. But urban areas could see some flash
flooding with that kind of rainfall, so that will be the main
concern tonight. Another thing to note is that the aforementioned
surface low will be deepening over the area, so it will be a
bit breezy on Friday, with gusts to around 35 mph possible.
Isolated pockets of 40+ mph wind gusts can't be ruled out mainly
east of I-29 Friday afternoon, but doesn't look like it will be
widespread enough to warrant wind headlines at this time.

We'll dry things out heading into Friday night, and depending on how
quickly clouds clear out, we could see widespread lows in the
50s by Saturday morning! If clouds take a little bit longer,
we'll still likely see some 50s west of I-29, it's just that
places east of there where clouds clear the latest may only drop
to the lower 60s. So still much cooler than we have been! Dry
and sunny conditions will be in store for the weekend, with a
pleasant Saturday expected with highs only in the upper 70s to
lower 80s across most of the area. Southerly flow returns on
Sunday, making for it to be a little hotter, though not nearly
as hot as it has been. Only south-central South Dakota has a
shot of reaching 90 degrees on Sunday, but heat indices there
will likely not stray too far from the air temperature. After
Friday, our next chance of appreciable rain/storms will be
Monday night into Tuesday as a cold front moves through the
area. Not a lot of time to look into details given the focus on
today and tonight's forecast, but it does look like there will
be enough instability and shear to at least have some strong to
severe thunderstorm risk, though details remain low. It does
look likely though that another round of cooler air will filter
in behind this front, making for an overall pleasant first week
of August.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 620 PM CDT Thu Jul 30 2026

A few aviation concerns through the period. First, a couple
rounds of showers and thunderstorms are expected to move east
across the area tonight into Friday morning, with some isolated
showers possibly lingering into the mid/late morning hours.
MVFR/IFR conditions are expected, with some locally heavy rain.
First round of showers/storms is pushing across SD and northern
NE at the time of this discussion, with additional areas across
west central and northeastern SD. Most areas should see a break
in the rounds of precipitation, which has made the timing a bit
tricky. Although risk is low, can't rule out a strong wind gust
around 55 knots across south central SD through this evening as
well as hail to the size of quarters.

MVFR/IFR stratus continues through the morning hours Friday,
with VFR conditions expected to return into the afternoon hours.
Winds increase and shift northerly, with gusts through the day
around 25-30 knots.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

UPDATE...SG
DISCUSSION...Samet
AVIATION...SG

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
758 PM CDT Thu Jul 30 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-010100-
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-
758 PM CDT Thu Jul 30 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...Tonight.

Periods of showers and thunderstorms continue through the overnight
hours and into Friday morning.

The main concern with these storms will be locally heavy rain,
possibly as high as 4 to 5 inches. Severe weather risk continues to
diminish late this evening into the early overnight hours.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Hazardous weather is not expected during this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed.

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
904 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0845 PM     Non-Tstm Wnd Gst Dante                   43.04N 98.19W
07/30/2026  M51 MPH          Charles Mix        SD   Mesonet

            Avon SD Mesonet report of a 51 mph wind
            gust.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
906 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0807 PM     Non-Tstm Wnd Gst 8 N Delmont             43.38N 98.16W
07/30/2026  M56 MPH          Douglas            SD   Public

            Personal weather station report of a 56 mph
            wind gust.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
917 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0906 PM     Non-Tstm Wnd Gst 4 NNE Freeman           43.40N 97.40W
07/30/2026  M50 MPH          Hutchinson         SD   Public

            Personal weather station reported a wind
            gust of 50 mph.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
933 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0917 PM     Non-Tstm Wnd Gst 5 ESE Tyndall           42.97N 97.77W
07/30/2026  M53 MPH          Bon Homme          SD   Dept of Highways

            SDDOT report of wind gust of 53 mph.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
935 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0910 PM     Non-Tstm Wnd Gst Springfield             42.86N 97.89W
07/30/2026  M52 MPH          Bon Homme          SD   Public

            Personal weather station report of a 52 mph
            wind gust.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
953 PM CDT Thu Jul 30 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0933 PM     Non-Tstm Wnd Gst 7 NE Lesterville        43.10N 97.50W
07/30/2026  M55 MPH          Yankton            SD   Public

            Personal weather station report of a 55 mph
            wind gust.

&&

AJP