Alert archive / Iowa / Flash Flood Warnings in 2018

Flash Flood Warning 9, NWS Sioux Falls, SD

June 24, 2018Plymouth County, Sioux County, Iowa; Clay County, Union County, South Dakota; Dixon County, Nebraska

NWS Sioux Falls, SD issued this flash flood warning at Jun 24, 2018, 7:53 PM CDT for Plymouth County, Sioux County, Iowa; Clay County, Union County, South Dakota; Dixon County, Nebraska. It was in force for 3 hr. 1 report 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: Jun 24, 2018, 7:53 PM CDT (00:53 UTC)
Expired: Jun 24, 2018, 11:00 PM CDT
In force: 3 hr
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Flood severity: None

Counties Plymouth County, IA, Sioux County, IA, Dixon County, NE, Clay County, SD, Union County, SD

The radar

The Sioux Falls radar (KFSD), 86 km from the middle of the area, began a volume at 00:54 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
Jun 24, 10:00 PM CDT	HEAVY RAIN 4.4	7 Se Westfield, IA	REPORT VIA SOCIAL MEDIA.

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

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.9 hours before the alert went out and 170 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: 2261 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 1209 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 120 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 3.9

Open this sounding in Storm Lab

The text

As transmitted.

929 
WGUS53 KFSD 250053
FFWFSD
IAC149-167-NEC051-SDC027-127-250400-
/O.NEW.KFSD.FF.W.0009.180625T0053Z-180625T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Sioux Falls SD
753 PM CDT SUN JUN 24 2018

The National Weather Service in Sioux Falls has issued a

* Flash Flood Warning for...
  Southwestern Sioux County in northwestern Iowa...
  Western Plymouth County in northwestern Iowa...
  Northern Dixon County in northeastern Nebraska...
  Southeastern Clay County in southeastern South Dakota...
  Union County in southeastern South Dakota...

* Until 1100 PM CDT.

* At 753 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Two to three inches of rain 
  has already fallen. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Vermillion, Hawarden, Elk Point, Akron, Alcester, Ireton,
  Jefferson, Newcastle, Maurice, Craig, Maskell, Union Grove State
  Park, Ponca State Park, Brunsville, Westfield and Chatsworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 4266 9702 4276 9701 4277 9704 4309 9670
      4308 9666 4297 9617 4256 9642

$$

Weisser

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 24, 8:36 PM CDT	Areal Flood Warning	FSD	Dickinson	12 hr
Jun 24, 9:05 PM CDT	Flash Flood Warning	FSD	Plymouth, Woodbury	3 hr
Jun 24, 9:52 PM CDT	Flash Flood Watch	FSD	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more	25 hr
Jun 24, 10:41 PM CDT	Flash Flood Warning Emergency	FSD	Plymouth, Woodbury	4 hr
Jun 24, 11:13 PM CDT	Flash Flood Warning	FSD	O'Brien, Plymouth, Sioux, Woodbury	4 hr
Jun 25, 2:40 AM CDT	Areal Flood Warning	FSD	Lyon, O'Brien, Osceola, Sioux	12 hr
Jun 25, 2:46 AM CDT	Areal Flood Warning	FSD	Cherokee, Plymouth, Woodbury	12 hr
Jun 25, 5:16 AM CDT	River Flood Warning	FSD	Plymouth	24 hr
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	O'Brien	38 hr
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	Plymouth	3 days
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	Plymouth	65 hr
Jun 24, 7:56 PM CDT	River Flood Warning	FSD	Minnehaha	14 days
Jun 25, 2:05 AM CDT	River Flood Warning	FSD	Clay	7 days
Jun 25, 2:05 AM CDT	River Flood Warning	FSD	Union	7 days
Jun 25, 5:29 AM CDT	Areal Flood Warning	FSD	Union	12 hr
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	Minnehaha	4 days
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	Union	4 days
Jun 25, 4:48 PM CDT	River Flood Warning	FSD	Minnehaha	4 days
Jun 25, 5:49 PM CDT	Flash Flood Warning	FSD	Dakota, Dixon	4 hr

Nearby

Flash Flood Warnings in Iowa, 2018 Flash Flood Warnings in South Dakota, 2018 Flash Flood Warnings in Nebraska, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.