Alert archive / Nebraska / Flash Flood Warnings in 2011

Flash Flood Warning 35, NWS Sioux Falls, SD

August 18, 2011Dakota County, Nebraska

NWS Sioux Falls, SD issued this flash flood warning at Aug 18, 2011, 6:28 PM CDT for Dakota County, Nebraska. It was in force for 4 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: Aug 18, 2011, 6:28 PM CDT (23:28 UTC)
Expired: Aug 18, 2011, 10:30 PM CDT
In force: 4 hr
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Flood severity: None

County Dakota County, NE

The radar

The Omaha radar (KOAX), 114 km from the middle of the area, began a volume at 23:28 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 18, 7:20 PM CDT	FLASH FLOOD	1 Ene Hubbard, NE	PIDGEON CREEK OUT OF ITS BANK.

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 12:00Z, 11.5 hours before the alert went out and 114 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: 1181 J/kg
Mixed-layer CIN: -126 J/kg
Mixed-layer LCL: 683 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 385 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 11.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

898 
WGUS53 KFSD 182328
FFWFSD
NEC043-190330-
/O.NEW.KFSD.FF.W.0035.110818T2328Z-110819T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 PM CDT THU AUG 18 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL AND SOUTHERN DAKOTA COUNTY IN NORTHEAST NEBRASKA

* UNTIL 1030 PM CDT

* AT 620 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE WARNED AREA.
  DOPPLER RADAR ESTIMATED FROM ONE TO THREE INCHES RAINFALL DURING
  THE PAST THREE HOURS...AND WAS CURRENTLY ESTIMATING RATES OF ONE
  TO TWO INCHES PER HOUR WITH STORMS MOVING INTO THE AREA FROM THE
  WEST.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...HOMER
  AND HUBBARD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS...AS WELL AS FARMLAND ALONG THE
BANKS OF CREEKS AND STREAMS.

&&

LAT...LON 4228 9663 4240 9667 4245 9648 4240 9642
      4237 9641 4235 9642 4231 9637 4227 9636

$$
CHAPMAN

2 follow-up statements

401 
WGUS73 KFSD 190134
FFSFSD

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
834 PM CDT THU AUG 18 2011

NEC043-190330-
/O.CON.KFSD.FF.W.0035.000000T0000Z-110819T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DAKOTA NE-
834 PM CDT THU AUG 18 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR SOUTHERN DAKOTA COUNTY
UNTIL 1030 PM CDT...

AT 720 PM CDT...LOCAL LAW ENFORCEMENT OFFICIALS REPORTED THAT PIGEON 
CREEK WAS OUT OF ITS BANKS NEAR HIGHWAY 35 AND SOUTH BLUFF ROAD JUST 
NORTHEAST OF HUBBARD. THUNDERSTORMS HAD PRODUCED A DOPPLER RADAR 
ESTIMATED 2 TO 4 INCHES RAINFALL FROM LATE AFTERNOON INTO EARLY 
EVENING. CONTINUED RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE 
FLASH FLOODING TO OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE 
FLOODING INCLUDE...HOMER AND HUBBARD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLOODING IS OBSERVED...ACT QUICKLY. DO NOT
ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND. DO NOT
STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4228 9663 4240 9667 4245 9648 4240 9642
      4237 9641 4235 9642 4231 9637 4227 9636

$$

CHAPMAN

721 
WGUS73 KFSD 190330
FFSFSD

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1030 PM CDT THU AUG 18 2011

NEC043-190344-
/O.EXP.KFSD.FF.W.0035.000000T0000Z-110819T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DAKOTA NE-
1030 PM CDT THU AUG 18 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR SOUTHERN DAKOTA
COUNTY WILL BE ALLOWED TO EXPIRE AT 1030 PM CDT...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA HAVE RECEDED OR WERE BEGINNING TO
RECEDE...ENDING THE FLOOD THREAT. IF FLOODING HAS BEEN OBSERVED...
PLEASE REPORT IT TO YOUR LOCAL LAW ENFORCEMENT AGENCY.

LAT...LON 4228 9663 4240 9667 4245 9648 4240 9642
      4237 9641 4235 9642 4231 9637 4227 9636

$$

CHAPMAN

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 1:43 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	62 min
Aug 18, 2:48 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	27 min
Aug 18, 3:15 PM CDT	Severe Thunderstorm Warning	FSD	Dakota	18 min
Aug 18, 3:42 PM CDT	Severe Thunderstorm Warning	FSD	Dixon	48 min
Aug 18, 4:26 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	49 min
Aug 18, 5:00 PM CDT	Severe Thunderstorm Warning	FSD	Dakota	45 min
Aug 18, 5:22 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	23 min
Aug 18, 5:46 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	29 min
Aug 18, 5:57 PM CDT	Severe Thunderstorm Warning	FSD	Dixon	33 min
Aug 18, 6:26 PM CDT	Severe Thunderstorm Warning	FSD	Dakota, Dixon	34 min

Nearby

Flash Flood Warnings in Nebraska, 2011 Every flash flood warning in 2011

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.