Alert archive / South Dakota / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Sioux Falls, SD

August 28, 2021Lincoln County, Minnehaha County, South Dakota

NWS Sioux Falls, SD issued this flash flood warning at Aug 28, 2021, 9:20 PM CDT for Lincoln County, Minnehaha County, South Dakota. It was in force for 85 min. 6 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: Aug 28, 2021, 9:20 PM CDT (02:20 UTC)
Expired: Aug 28, 2021, 10:45 PM CDT
In force: 85 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Flood severity: None

Counties Lincoln County, SD, Minnehaha County, SD

The radar

The Sioux Falls radar (KFSD), 11 km from the middle of the area, began a volume at 02:22 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

Time	Report	Where	Remark
Aug 28, 9:50 PM CDT	FLASH FLOOD	5 Wsw Rowena, SD	SEVERAL INCHES TO AROUND A FOOT OF WATER IN BACKYARD VIA SOCIAL MEDIA PICTURE.
Aug 28, 9:51 PM CDT	FLASH FLOOD	1 Ene Sioux Falls, SD	WATER OVER THE ROAD NEAR 6TH AND CLIFF. ESTIMATED ABOUT A FOOT DEEP VIA SOCIAL MEDIA PICTURE.
Aug 28, 9:54 PM CDT	FLASH FLOOD	5 Wsw Sioux Falls, SD	REPORT FROM MPING: RIVER/CREEK OVERFLOWING; CROPLAND/YARD/BASEMENT FLOODING.
Aug 28, 9:57 PM CDT	FLASH FLOOD	5 W Sioux Falls, SD	REPORT FROM MPING: RIVER/CREEK OVERFLOWING; CROPLAND/YARD/BASEMENT FLOODING.
Aug 28, 10:13 PM CDT	FLASH FLOOD	5 Wsw Sioux Falls, SD	REPORT FROM MPING: RIVER/CREEK OVERFLOWING; CROPLAND/YARD/BASEMENT FLOODING.
Aug 28, 10:14 PM CDT	FLASH FLOOD	Tea, SD	REPORT FROM MPING: STREET/ROAD FLOODING; STREET/ROAD CLOSED; VEHICLES STRANDED.

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

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 2.3 hours before the alert went out and 209 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 143 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 1242 m above ground
0-6 km bulk shear: 71 kt
0-1 km storm-relative helicity: -15 m²/s²
0-3 km storm-relative helicity: 268 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

As transmitted.

529 
WGUS53 KFSD 290220
FFWFSD
SDC083-099-290345-
/O.NEW.KFSD.FF.W.0002.210829T0220Z-210829T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Sioux Falls SD
920 PM CDT Sat Aug 28 2021

The National Weather Service in Sioux Falls has issued a

* Flash Flood Warning for...
  Northwestern Lincoln County in southeastern South Dakota...
  Southeastern Minnehaha County in southeastern South Dakota...

* Until 1045 PM CDT.

* At 920 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. The expected rainfall rate is 1 to 2 inches in 1 
  hour. Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  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...
  Sioux Falls, Brandon, Harrisburg, Tea, Lake Alvin State Recreation 
  Area and Rowena.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4363 9683 4361 9651 4350 9656 4350 9660
      4348 9658 4348 9659 4347 9658 4346 9660
      4344 9660 4343 9660 4345 9689

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

Schumacher

2 follow-up statements

066 
WGUS73 KFSD 290234
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
934 PM CDT Sat Aug 28 2021

SDC083-099-290345-
/O.CON.KFSD.FF.W.0002.000000T0000Z-210829T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lincoln SD-Minnehaha SD-
934 PM CDT Sat Aug 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM CDT THIS 
EVENING FOR NORTHWESTERN LINCOLN AND SOUTHEASTERN MINNEHAHA 
COUNTIES...

At 934 PM CDT, Doppler radar indicated thunderstorms producing heavy 
rain in Sioux Falls. Between 1 and 3 inches of rain have fallen. The 
expected rainfall rate is 1 to 2 inches in 1 hour. Flash flooding is 
already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public reports of several roads underwater including
         Willow Wood Rd near Fred Assam Elementary, the
         intersection of Minnesota and 26th St., the intersection
         of Minnesota and 33rd St., and Sycamore and 57th St.

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...
  Sioux Falls, Brandon, Harrisburg, Tea, Lake Alvin State Recreation 
  Area and Rowena.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4363 9683 4361 9651 4350 9656 4350 9660
      4348 9658 4348 9659 4347 9658 4346 9660
      4344 9660 4343 9660 4345 9689

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

Schumacher

671 
WGUS73 KFSD 290308
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
1008 PM CDT Sat Aug 28 2021

SDC083-099-290345-
/O.CON.KFSD.FF.W.0002.000000T0000Z-210829T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lincoln SD-Minnehaha SD-
1008 PM CDT Sat Aug 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM CDT THIS 
EVENING FOR NORTHWESTERN LINCOLN AND SOUTHEASTERN MINNEHAHA 
COUNTIES...

At 1008 PM CDT, the public reported thunderstorms producing heavy 
rain in Sioux Falls. Between 2 and 5 inches of rain have fallen. The 
expected rainfall rate is 2 inches in 1 hour. The heaviest rainfall 
will be south of 26th Street in Sioux Falls. Flash flooding is 
already occurring.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Public reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Sioux Falls, Brandon, Harrisburg, Tea, Lake Alvin State Recreation 
  Area and Rowena.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4363 9683 4361 9651 4350 9656 4350 9660
      4348 9658 4348 9659 4347 9658 4346 9660
      4344 9660 4343 9660 4345 9689

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...2 INCHES IN 1 HOUR

$$

Schumacher

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 28, 7:23 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lincoln	52 min
Aug 28, 7:25 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Hanson, Lake, McCook, Miner, Minnehaha, Moody	50 min
Aug 28, 7:27 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Hutchinson, Turner, Yankton	48 min
Aug 28, 7:48 PM CDT	Severe Thunderstorm Warning	FSD	Lake, McCook, Minnehaha, Moody, Turner	31 min
Aug 28, 7:50 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Clay, Hutchinson, Lincoln, Turner, Yankton	40 min
Aug 28, 8:52 PM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Minnehaha	23 min
Aug 28, 9:13 PM CDT	Severe Thunderstorm Warning	FSD	Lincoln	47 min
Aug 28, 9:29 PM CDT	Flash Flood Warning	FSD	Lincoln, Minnehaha	3 hr
Aug 28, 10:36 PM CDT	Flash Flood Warning	FSD	Lincoln, Minnehaha	114 min
Aug 28, 11:46 PM CDT	River Flood Warning	FSD	Lincoln, Minnehaha	8 hr
Aug 29, 7:44 AM CDT	River Flood Warning	FSD	Lincoln	15 hr

Nearby

Flash Flood Warnings in South Dakota, 2021 Every flash flood warning in 2021

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.