Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 26, NWS Sioux Falls, SD

May 1, 2012Dickinson County, Osceola County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 1, 2012, 9:22 PM CDT for Dickinson County, Osceola County, Iowa. It was in force for 38 min. 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: May 1, 2012, 9:22 PM CDT (02:22 UTC)
Expired: May 1, 2012, 10:00 PM CDT
In force: 38 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Dickinson County, IA, Osceola County, IA

The radar

The Sioux Falls radar (KFSD), 100 km from the middle of the area, began a volume at 02:25 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
May 1, 9:35 PM CDT	TSTM WND GST 70	1 S Ocheyedan, IA

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
May 1, 2:59 PM CDT	Tornado Watch	SPC	6 hr
May 1, 9:18 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 2.4 hours before the alert went out and 227 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: 279 J/kg
Mixed-layer CIN: -111 J/kg
Mixed-layer LCL: 1279 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 227 m²/s²
0-3 km storm-relative helicity: 393 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 4.9

Open this sounding in Storm Lab

The text

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

145 
WUUS53 KFSD 020222
SVRFSD
IAC059-143-020300-
/O.NEW.KFSD.SV.W.0026.120502T0222Z-120502T0300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
922 PM CDT TUE MAY 1 2012

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN DICKINSON COUNTY IN NORTHWEST IOWA...
  OSCEOLA COUNTY IN NORTHWEST IOWA...

* UNTIL 1000 PM CDT

* AT 923 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
  LOCATED 5 MILES NORTHWEST OF MELVIN...OR 20 MILES SOUTH OF
  WORTHINGTON...AND MOVING EAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  OCHEYEDAN AROUND 935 PM CDT...
  HARRIS AROUND 940 PM CDT...
  LAKE PARK AROUND 950 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.

&&

LAT...LON 4326 9577 4350 9575 4350 9521 4326 9518
TIME...MOT...LOC 0223Z 258DEG 31KT 4335 9564
WIND...HAIL 60MPH 1.00IN

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
May 1, 7:12 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	33 min
May 1, 7:27 PM CDT	Tornado Warning	FSD	Lyon, Sioux	33 min
May 1, 7:41 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	34 min
May 1, 7:57 PM CDT	Tornado Warning	FSD	Lyon	33 min
May 1, 8:09 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	36 min
May 1, 8:40 PM CDT	Flash Flood Warning	FSD	Lyon	3 hr
May 1, 9:15 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien, Plymouth, Sioux	30 min
May 1, 9:29 PM CDT	Tornado Warning	FSD	Clay, O'Brien	46 min
May 1, 9:41 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, Dickinson, O'Brien, Osceola	34 min
May 1, 9:44 PM CDT	Tornado Warning	FSD	Clay	31 min
May 1, 10:13 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, Dickinson	17 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.