Alert archive / South Dakota / Flash Flood Warnings in 2026

Flash Flood Warning 4, NWS Aberdeen, SD

July 30, 2026Day County, South Dakota

NWS Aberdeen, SD issued this flash flood warning at Jul 30, 2026, 4:17 PM CDT for Day County, South Dakota. It was in force for 6 hr. 5 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 30, 2026, 4:17 PM CDT (21:17 UTC)
Expired
Jul 30, 2026, 9:55 PM CDT
In force
6 hr
Issued by
NWS Aberdeen, SD
Area
Storm-based polygon
Flood severity
None

County Day County, SD

The radar

The Aberdeen radar (KABR), 50 km from the middle of the area, began a volume at 21:20 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Jul 30, 4:20 PM CDTRAIN 52 Se Roslyn, SD
Jul 30, 4:23 PM CDTRAIN 5Pierpont, SD
Jul 30, 4:58 PM CDTFLASH FLOODPierpont, SDDay County Emergency Manager reports SD Highway 27 is closed north of US-12. No additional specifics on location were given, so location is estimated based on the storm total precipitation. At the time of the report, roughly 4.5-5.5 inches of rain had fallen a
Jul 30, 4:58 PM CDTFLASH FLOODRoslyn, SDDay County Emergency Manager reported Highway 33 closed North of US-12 due to rainfall. No additional specifics on location were given, so location is placed based on the Storm Total Precipitation. At the time of the report, roughly 4-6 inches of rain had fall
Jul 30, 5:00 PM CDTRAIN 6Pierpont, SDMultiple reports of 5-6 inches of rain measured in Pierpont. Radar estimates as of 5 PM show pockets of 6-7 inches with more rain on the way.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this flash flood warning; the first came 41 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.3 hours before the alert went out and 335 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2026-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 190 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2026-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -75 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
190 J/kg
Mixed-layer CIN
-151 J/kg
Mixed-layer LCL
1065 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
-75 m²/s²
0-3 km storm-relative helicity
-44 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

491 
WGUS53 KABR 302117
FFWABR
SDC037-310315-
/O.NEW.KABR.FF.W.0004.260730T2117Z-260731T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Aberdeen SD
417 PM CDT Thu Jul 30 2026

The National Weather Service in Aberdeen has issued a

* Flash Flood Warning for...
  Northwestern Day County in northeastern South Dakota...

* Until 1015 PM CDT.

* At 417 PM CDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Between 3 and 5 inches of rain
  have fallen. Flash flooding is ongoing or expected to begin
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  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...
  Roslyn and Pierpont.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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 4548 9797 4557 9796 4557 9745 4542 9746
      4543 9783

FLASH FLOOD...RADAR INDICATED

$$

20
1 follow-up statement
741 
WGUS73 KABR 310255
FFSABR

Flash Flood Statement
National Weather Service Aberdeen SD
955 PM CDT Thu Jul 30 2026

SDC037-310305-
/O.CAN.KABR.FF.W.0004.000000T0000Z-260731T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Day SD-
955 PM CDT Thu Jul 30 2026

...FLASH FLOOD WARNING FOR NORTHWESTERN DAY COUNTY HAS BEEN REPLACED
WITH A FLOOD WARNING...

&&

LAT...LON 4548 9797 4557 9796 4557 9745 4542 9746
      4543 9783

$$

20

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Aberdeen, SD wrote its last area forecast discussion before this flash flood warning went out at Jul 30, 2:53 PM CDT, 1 hour 24 minutes earlier. Its key messages:

  • A Slight Risk (level 2 out of 5) for severe weather is in place over portions of central and south central SD this afternoon and tonight. A Marginal Risk (level 1 of 5) for severe weather is in place for the rest of the forecast area. The main hazard will be wind gusts of 60-70 mph and hail of one inch in diameter.
  • Through Friday morning, much of northeastern South Dakota and western Minnesota could see around 1.5"-2" of rain. Localized areas of 3" or more inches could be possible, and Flash Flooding will be possible in places that see these higher end rainfall totals.
  • Temperatures into the upper 90s to low 100s return over parts of central and north central South Dakota this weekend. Temperatures are set to cool down to below normal by the middle of next week.
Area forecast discussion, Jul 30, 2:53 PM CDT, 1 hour 24 minutes before
Area Forecast Discussion
National Weather Service Aberdeen SD
253 PM CDT Thu Jul 30 2026

.KEY MESSAGES...

- A Slight Risk (level 2 out of 5) for severe weather is in place
over portions of central and south central SD this afternoon and
tonight. A Marginal Risk (level 1 of 5) for severe weather is in
place for the rest of the forecast area. The main hazard will be
wind gusts of 60-70 mph and hail of one inch in diameter.

- Through Friday morning, much of northeastern South Dakota and
western Minnesota could see around 1.5"-2" of rain. Localized areas
of 3" or more inches could be possible, and Flash Flooding will be
possible in places that see these higher end rainfall totals.

- Temperatures into the upper 90s to low 100s return over parts of
central and north central South Dakota this weekend. Temperatures
are set to cool down to below normal by the middle of next week.

&&

.DISCUSSION...
Issued at 253 PM CDT Thu Jul 30 2026

The main challenges in this forecast package will continue to
revolve around the chances for severe weather and locally heavy
rainfall the remainder of today into tonight and Friday morning. Mid
afternoon satellite/radar imagery indicate ongoing active weather
across this forecast area. Showers and thunderstorms have continued
to evolve across northeast SD/west central MN early this afternoon
while the area of showers/storms the moved across south central SD
through the first half of the day have shifted into southeast SD.
development of more robust convection has taken place over the last
hour or so across parts of far south central SD, south of the I-90
corridor. This activity appears to be shifting east-southeast and
may clip our far south/southwest zones this afternoon where a Severe
Thunderstorm Watch has been issued until 9 PM CDT tonight.

The disturbance partly responsible for this active pattern today is
in the form of a mid level shortwave trough that is working into
western SD this afternoon. The lead shortwave ahead of this feature
was responsible for this mornings activity has shifting east and
southeast. This upper level disturbance is encountering a modestly
unstable air mass with MLCAPE values ranging between 2000-3000 J/kg.
So, there's enough instability for storms to continue. However, deep
layer shear remains mostly lacking across most of our CWA, outside
of far southern zones and perhaps near the ND/SD border region where
0-6 KM bulk shear values range between 25-30 kts. Weak flow in the
low to mid levels of the atmosphere have played havoc on the
evolution of convection and thus hi-res guidance has had a tough
time discerning what comes of all of this. Also, outflow boundaries
created by existing or earlier convection is also playing or will
play a role in future storms as the latter half of the afternoon and
evening wear on. So, best chances for severe weather for the
remainder of this event the rest of today and tonight will be across
parts of central and south central SD. Initial discrete cells will
be capable of large hail but with time, storms will evolve into more
clusters or linear mode and the threat will become damaging winds.
Perhaps the more widespread threat across most of the forecast area
will be locally heavy rainfall. A Slight Risk for Excessive Rainfall
remains posted for most of the forecast area with our eastern half
of zones having the best chance for seeing 1-2 inches of rainfall.
Some localized amounts of 3 inches or more will be possible,
especially from parts of west central MN into east central SD south
and west into sections of the James Valley and far south central SD.
These area will have the best chance to see localized flash flooding
with any storms. The slow moving nature of this convection will only
help contribute further to the flooding possibilities.

The upper level disturbance shifts south and east of the area on
Friday. Lingering rains across our eastern zones will diminish by
midday leaving drier condition to settle in during the afternoon.
High pressure building in from the north will lead to breezy north
to northeast winds on Friday. Temperatures will remain close to
normal if not slightly below normal(especially eastern zones) on
Friday. Upper ridging is progged to build into the region through
the course of the upcoming weekend. This will bring back the heat to
the region, especially across central SD. Temperature progs indicate
those locations will be back into the 90s to around 100 degrees
Saturday into Sunday and to a certain extent on Monday. Southerly
flow returns and with a tighter gradient developing by late in the
weekend and a drier air mass, elevated fire weather conditions are
expected to develop across parts of central and north central SD.
After another fropa early next week, a cooler than normal air mass
will infiltrate the area by Tuesday through the middle of next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1238 PM CDT Thu Jul 30 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to prevail at all TAF sites through
this forecast period outside of times when showers and
thunderstorms will be moving through the 4 aerodromes.
Increasing coverage of showers and thunderstorms are expected
this afternoon into tonight. Low confidence remains on timing
and placement of this activity through the period. Tried to
leverage the timing in the direction of best chances for
SHRAs/TSRAs in prevailing groups while using PROB30 groups for
durations where activity could be more widely scattered. MVFR
cigs/vsbys will be possible in the heavier SHRAs/TSRAs with more
widespread MVFR/IFR cigs/vsbys developing overnight at
KABR/KATY due to low stratus and fog. Southerly winds will
eventually become north to northeast late tonight/early Friday
and become gusty by late in this forecast cycle.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.

&&

DISCUSSION...Vipond
AVIATION...Vipond
Hazardous weather outlook, Jul 30, 3:17 AM CDT, 13 hours before
Hazardous Weather Outlook
National Weather Service Aberdeen SD
317 AM CDT Thu Jul 30 2026

SDZ018-035>037-045-048-051-310830-
Spink-Hughes-Hyde-Hand-Jones-Lyman-Buffalo-
317 AM CDT Thu Jul 30 2026

This Hazardous Weather Outlook is for central South Dakota and
northeast South Dakota.

.DAY ONE...Today and tonight.

A Slight Risk for severe weather, a level 2 of 5 threat, is in place
today. Storms will be possible through the day, but the best chances
for severe weather come in the afternoon to evening time frame. The
main severe threat will be wind gusts of 60 to 70 miles per hour.
Hail of one inch in diameter will also be a threat west of the
Missouri River.

Additionally, storms may bring heavy rain to the region, potentially
leading to Flash Flooding. A Slight Risk for Excessive Rainfall, a
level 2 of 4 threat, is in place today. Through Friday morning, up to
1 to 2 inches of rain may fall, with some localized amounts up to 3
inches possible.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

MNZ039-046-SDZ005>011-016-017-019>023-034-310830-
Traverse-Big Stone-McPherson-Brown-Marshall-Roberts-Walworth-Edmunds-
Day-Potter-Faulk-Clark-Codington-Grant-Hamlin-Deuel-Sully-
317 AM CDT Thu Jul 30 2026

This Hazardous Weather Outlook is for west central Minnesota,
central South Dakota, north central South Dakota and northeast
South Dakota.

.DAY ONE...Today and tonight.

A Marginal Risk for severe weather, a level 1 of 5 threat, is in
place today. Storms will be possible through the day, but the best
chances for severe weather come in the afternoon to evening time
frame. The main severe threat will be wind gusts of 60 to 70 miles
per hour.

Additionally, storms may bring heavy rain to the region, potentially
leading to Flash Flooding. A Slight Risk for Excessive Rainfall, a
level 2 of 4 threat, is in place today. Through Friday morning, up to
1 to 2 inches of rain may fall, with some localized amounts up to 3
to 4 inches possible.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SDZ033-310830-
Stanley-
317 AM CDT Thu Jul 30 2026 /217 AM MDT Thu Jul 30 2026/

This Hazardous Weather Outlook is for central South Dakota.

.DAY ONE...Today and tonight.

A Slight Risk for severe weather, a level 2 of 5 threat, is in place
today. Storms will be possible through the day, but the best chances
for severe weather come in the afternoon to evening time frame. The
main severe threat will be wind gusts of 60 to 70 miles per hour.
Hail of one inch in diameter will also be a threat.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SDZ003-004-015-310830-
Corson-Campbell-Dewey-
317 AM CDT Thu Jul 30 2026 /217 AM MDT Thu Jul 30 2026/

This Hazardous Weather Outlook is for north central South Dakota.

.DAY ONE...Today and tonight.

A Marginal Risk for severe weather, a level 1 of 5 threat, is in
place today. Storms will be possible through the day, but the best
chances for severe weather come in the afternoon to evening time
frame. The main severe threat will be wind gusts of 60 to 70 miles
per hour. Hail of one inch in diameter will also be a threat.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

The office that day

Everything else NWS Aberdeen, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 29, 10:30 PM CDTSpecial Weather StatementABRStanley30 min
Jul 29, 10:34 PM CDTSevere Thunderstorm WarningABRDewey, Jones, Stanley42 min
Jul 29, 11:30 PM CDTSpecial Weather StatementABRJones, Stanley45 min
Jul 30, 12:07 AM CDTSpecial Weather StatementABRHughes, Stanley, Sully23 min
Jul 30, 3:22 PM CDTAreal Flood WarningABRDay3 hr
Jul 30, 4:09 PM CDTFlash Flood WarningABRLyman6 hr
Jul 30, 4:51 PM CDTFlash Flood WarningABRBrown, Day6 hr
Jul 30, 5:35 PM CDTAreal Flood WarningABRFaulk6 hr
Jul 30, 6:25 PM CDTFlash Flood WarningABRDay, Marshall, Roberts6 hr
Jul 30, 6:58 PM CDTAreal Flood WarningABRFaulk, Potter6 hr

Nearby

Flash Flood Warnings in South Dakota, 2026Every flash flood warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.