Alert archive / Iowa / Flash Flood Warnings in 2018

Flash Flood Warning 36, NWS Sioux Falls, SD

August 27, 2018Dickinson County, Iowa

NWS Sioux Falls, SD issued this flash flood warning at Aug 27, 2018, 4:27 PM CDT for Dickinson County, Iowa. It was in force for 85 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 27, 2018, 4:27 PM CDT (21:27 UTC)
Expired: Aug 27, 2018, 5:52 PM CDT
In force: 85 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Flood severity: None

County Dickinson County, IA

The radar

The Sioux Falls radar (KFSD), 130 km from the middle of the area, began a volume at 21:27 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.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.5 hours before the alert went out and 202 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: 1465 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 698 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 232 m²/s²
0-3 km storm-relative helicity: 249 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 4.7

Open this sounding in Storm Lab

The text

As transmitted.

071 
WGUS53 KFSD 272127
FFWFSD
IAC059-280030-
/O.NEW.KFSD.FF.W.0036.180827T2127Z-180828T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Sioux Falls SD
427 PM CDT MON AUG 27 2018

The National Weather Service in Sioux Falls has issued a

* Flash Flood Warning for...
  Northern Dickinson County in northwestern Iowa...

* Until 730 PM CDT.

* At 426 PM CDT, the public reported thunderstorms producing heavy 
  rain across the warned area. One to one and a half inches of rain 
  has already fallen. Flash flooding is expected to begin shortly as 
  more thunderstorms move over the warned area.

* Some locations that will experience flooding include...
  Spirit Lake, Milford, Arnolds Park, Okoboji, Orleans, Wahpeton and
  West Okoboji.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4334 9518 4343 9529 4350 9517 4350 9495
      4335 9504

$$

VandenBoogart

1 follow-up statement

683 
WGUS73 KFSD 272252
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
552 PM CDT MON AUG 27 2018

IAC059-272301-
/O.CAN.KFSD.FF.W.0036.000000T0000Z-180828T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Dickinson IA-
552 PM CDT MON AUG 27 2018

...THE FLASH FLOOD WARNING FOR NORTHERN DICKINSON COUNTY IS
CANCELLED...

Flood waters have receded as the thunderstorms have moved out of the 
area. Flooding is no longer expected to pose a threat. Please 
continue to heed any remaining road closures.

LAT...LON 4334 9518 4343 9529 4350 9517 4350 9495
      4335 9504

$$

VandenBoogart

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 27, 2:24 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	36 min
Aug 27, 2:51 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Plymouth, Sioux	39 min
Aug 27, 3:27 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, O'Brien	33 min
Aug 27, 3:30 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, O'Brien, Plymouth, Sioux	30 min
Aug 27, 3:51 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, O'Brien, Osceola	24 min
Aug 27, 3:57 PM CDT	Severe Thunderstorm Warning	FSD	Dickinson	18 min
Aug 27, 4:09 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, O'Brien, Osceola	20 min

Nearby

Flash Flood Warnings in Iowa, 2018 Every flash flood warning in 2018

Sources

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