Alert archive / Nebraska / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 231, NWS Sioux Falls, SD

August 18, 2011Dakota County, Nebraska; Woodbury County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 18, 2011, 5:00 PM CDT for Dakota County, Nebraska; Woodbury County, Iowa. It was in force for 45 min. 2 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 18, 2011, 5:00 PM CDT (22:00 UTC)
Expired: Aug 18, 2011, 5:45 PM CDT
In force: 45 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 2.75 in
Wind: 70.0 mph

Counties Woodbury County, IA, Dakota County, NE

The radar

The Omaha radar (KOAX), 106 km from the middle of the area, began a volume at 22:03 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, 5:16 PM CDT	HAIL 2.5	Homer, NE
Aug 18, 5:20 PM CDT	HAIL 3	Homer, NE

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 18, 1:27 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.0 hours before the alert went out and 106 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.

128 
WUUS53 KFSD 182200
SVRFSD
IAC193-NEC043-182245-
/O.NEW.KFSD.SV.W.0231.110818T2200Z-110818T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
500 PM CDT THU AUG 18 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN WOODBURY COUNTY IN WEST CENTRAL IOWA...
  SOUTHEASTERN DAKOTA COUNTY IN NORTHEAST NEBRASKA...

* UNTIL 545 PM CDT

* AT 459 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING LARGE
  DESTRUCTIVE HAIL UP TO BASEBALL SIZE...AND DESTRUCTIVE WINDS IN
  EXCESS OF 70 MPH.  THIS STORM WAS LOCATED NEAR DAKOTA CITY...OR 7
  MILES SOUTH OF SIOUX CITY...AND MOVING SOUTHEAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  SALIX AROUND 515 PM CDT...
  SLOAN AROUND 530 PM CDT...
  HORNICK AROUND 540 PM CDT...
  SMITHLAND AROUND 545 PM CDT...

LARGEST HAIL UP TO BASEBALL SIZE IS EXPECTED TO OCCUR FOR AREAS
AROUND HUBBARD...HOMER...AND SOUTHWEST OF DAKOTA CITY...SALIX
AND SLOAN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR LARGE
HAIL AND DAMAGING WINDS. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM WINDOWS.

&&

LAT...LON 4221 9634 4223 9633 4227 9635 4227 9667
      4231 9673 4234 9673 4249 9646 4222 9579
      4220 9583
TIME...MOT...LOC 2159Z 310DEG 24KT 4239 9641
WIND...HAIL 70MPH 2.75IN

$$

CHAPMAN

2 follow-up statements

939 
WWUS53 KFSD 182228
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
528 PM CDT THU AUG 18 2011

IAC193-NEC043-182245-
/O.CON.KFSD.SV.W.0231.000000T0000Z-110818T2245Z/
WOODBURY IA-DAKOTA NE-
528 PM CDT THU AUG 18 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHEASTERN
DAKOTA AND SOUTHWESTERN WOODBURY COUNTIES UNTIL 545 PM CDT...

AT 528 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
HOMER...OR 15 MILES SOUTH OF SIOUX CITY...MOVING SOUTHEAST AT 15 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  SALIX AND SLOAN AROUND 545 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PREPARE IMMEDIATELY FOR LARGE HAIL AND DAMAGING WINDS IF YOU ARE IN
THE PATH OF THIS STORM. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM WINDOWS.

&&

LAT...LON 4221 9634 4223 9633 4227 9635 4227 9667
      4231 9662 4238 9653 4242 9646 4222 9579
      4220 9583
TIME...MOT...LOC 2228Z 303DEG 14KT 4229 9643
WIND...HAIL 60MPH 1.75IN

$$

CHAPMAN

595 
WWUS53 KFSD 182247
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
547 PM CDT THU AUG 18 2011

IAC193-NEC043-182258-
/O.EXP.KFSD.SV.W.0231.000000T0000Z-110818T2245Z/
WOODBURY IA-DAKOTA NE-
547 PM CDT THU AUG 18 2011

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN DAKOTA AND
SOUTHWESTERN WOODBURY COUNTIES HAS EXPIRED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED
AREA.

LAT...LON 4221 9634 4223 9633 4227 9635 4227 9667
      4231 9662 4238 9653 4242 9646 4222 9579
      4220 9583
TIME...MOT...LOC 2228Z 303DEG 14KT 4229 9643

$$

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, 5:22 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
Aug 18, 6:28 PM CDT	Flash Flood Warning	FSD	Dakota	4 hr
Aug 18, 2:00 PM CDT	Severe Thunderstorm Warning	FSD	Ida, Woodbury	45 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2011 Severe Thunderstorm Warnings in Iowa, 2011 Every severe thunderstorm 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.