Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 49, NWS Sioux Falls, SD

May 4, 2012O'Brien County, Sioux County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 4, 2012, 10:12 PM CDT for O'Brien County, Sioux County, Iowa. It was in force for 16 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: May 4, 2012, 10:12 PM CDT (03:12 UTC)
Expired: May 4, 2012, 10:28 PM CDT
In force: 16 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

Counties O'Brien County, IA, Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 91 km from the middle of the area, began a volume at 03:15 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 watch it was issued in

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

Issued	Product	Office	Lasted
May 4, 2:00 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 3.2 hours before the alert went out and 190 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: 2635 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 1505 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 71 m²/s²
0-3 km storm-relative helicity: 173 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 8.5

Open this sounding in Storm Lab

The text

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

407 
WUUS53 KFSD 050312
SVRFSD
IAC141-167-050345-
/O.NEW.KFSD.SV.W.0049.120505T0312Z-120505T0345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1012 PM CDT FRI MAY 4 2012

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WEST CENTRAL O'BRIEN COUNTY IN NORTHWEST IOWA...
  SOUTHEASTERN SIOUX COUNTY IN NORTHWEST IOWA...

* UNTIL 1045 PM CDT

* AT 1012 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING HALF DOLLAR
  SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
  LOCATED 6 MILES EAST OF SIOUX CENTER...OR 6 MILES NORTH OF ORANGE
  CITY...AND MOVING SOUTHEAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  HOSPERS AND ALTON AROUND 1030 PM CDT...
  GRANVILLE AROUND 1045 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. SEEK SHELTER NOW
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS!

&&

LAT...LON 4291 9592 4291 9594 4308 9615 4317 9604
      4302 9576
TIME...MOT...LOC 0312Z 311DEG 17KT 4309 9604
WIND...HAIL 60MPH 1.25IN

$$

WILLIAMS

1 follow-up statement

348 
WWUS53 KFSD 050328
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1028 PM CDT FRI MAY 4 2012

IAC141-167-050338-
/O.CAN.KFSD.SV.W.0049.000000T0000Z-120505T0345Z/
SIOUX IA-O'BRIEN IA-
1028 PM CDT FRI MAY 4 2012

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL O'BRIEN AND
SOUTHEASTERN SIOUX COUNTIES IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR
PROPERTY...HOWEVER SMALL HAIL IS STILL POSSIBLE WITH THIS
THUNDERSTORM.

LAT...LON 4291 9592 4291 9594 4308 9615 4317 9604
      4302 9576
TIME...MOT...LOC 0328Z 311DEG 17KT 4304 9596

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
May 4, 9:39 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	36 min
May 5, 3:06 PM CDT	Flash Flood Watch	FSD	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more	13 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2012 Every severe thunderstorm warning in 2012

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.