Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 27, NWS Sioux Falls, SD

May 1, 20126 counties in Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 1, 2012, 9:41 PM CDT for 6 counties in Iowa. It was in force for 34 min. 8 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: May 1, 2012, 9:41 PM CDT (02:41 UTC)
Expired: May 1, 2012, 10:15 PM CDT
In force: 34 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.0 in
Wind: 70.0 mph

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, O'Brien County, IA, Osceola County, IA

The radar

The Sioux Falls radar (KFSD), 139 km from the middle of the area, began a volume at 02:44 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, 9:44 PM CDT	TSTM WND GST 0	5 N Sutherland, IA	70-80 MPH WIND GUST
May 1, 9:44 PM CDT	TSTM WND GST 70	5 N Sutherland, IA
May 1, 9:44 PM CDT	TSTM WND GST 75	5 N Sutherland, IA	70-80 MPH WIND GUST
May 1, 9:55 PM CDT	TSTM WND GST 65	Se Spencer, IA	NUMEROUS TREES DOWN AND SOME WINDOWS BLOWN OUT OF BUILDINGS.
May 1, 9:56 PM CDT	TSTM WND GST 60	3 N Royal, IA
May 1, 10:06 PM CDT	TSTM WND GST 71	Spencer, IA	MEASURED BY RWIS.
May 1, 10:18 PM CDT	TSTM WND GST 65	3 Ne Dickens, IA	DAMAGE TO ROOF.
May 1, 10:22 PM CDT	HAIL 0.88	5 W Estherville, 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, 9:18 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.7 hours before the alert went out and 218 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: 1502 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 1477 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 122 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 5.2

Open this sounding in Storm Lab

The text

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

590 
WUUS53 KFSD 020241
SVRFSD
IAC021-035-041-059-141-143-020315-
/O.NEW.KFSD.SV.W.0027.120502T0241Z-120502T0315Z/

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

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN BUENA VISTA COUNTY IN NORTHWEST IOWA...
  NORTHEASTERN CHEROKEE COUNTY IN NORTHWEST IOWA...
  CLAY COUNTY IN NORTHWEST IOWA...
  DICKINSON COUNTY IN NORTHWEST IOWA...
  EASTERN O'BRIEN COUNTY IN NORTHWEST IOWA...
  EASTERN OSCEOLA COUNTY IN NORTHWEST IOWA...

* UNTIL 1015 PM CDT

* AT 942 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING
  DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED
  ALONG A LINE EXTENDING FROM LAKE PARK TO EVERLY TO LARRABEE...AND
  MOVING EAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  ROYAL...FOSTORIA...WEST OKOBOJI AND WAHPETON AROUND 950 PM CDT...
  MILFORD...SPENCER...PETERSON AND SPIRIT LAKE AROUND 955 PM CDT...
  GREENVILLE AROUND 1000 PM CDT...
  LINN GROVE AND TERRIL AROUND 1005 PM CDT...
  SIOUX RAPIDS AND SUPERIOR AROUND 1010 PM CDT...
  WEBB AND MARATHON AROUND 1015 PM CDT...

OTHER LOCATIONS IMPACTED BY THESE SEVERE THUNDERSTORMS INCLUDE
ROSSIE...DICKENS...REMBRANDT AND GILLETT GROVE.

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 4280 9492 4284 9561 4316 9544 4350 9545
      4350 9491 4289 9490
TIME...MOT...LOC 0242Z 272DEG 36KT 4349 9530 4317 9529
          4284 9557
WIND...HAIL 70MPH <1.00IN

$$

CJ

1 follow-up statement

419 
WWUS53 KFSD 020258
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
958 PM CDT TUE MAY 1 2012

IAC021-035-041-059-141-143-020315-
/O.CON.KFSD.SV.W.0027.000000T0000Z-120502T0315Z/
OSCEOLA IA-O'BRIEN IA-DICKINSON IA-BUENA VISTA IA-CHEROKEE IA-CLAY IA-
958 PM CDT TUE MAY 1 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR CLAY...
NORTHEASTERN CHEROKEE...NORTHERN BUENA VISTA...DICKINSON...EASTERN
O'BRIEN AND EASTERN OSCEOLA COUNTIES UNTIL 1015 PM CDT...

AT 958 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM ORLEANS TO SPENCER TO 6 MILES EAST OF LARRABEE...
MOVING EAST AT 40 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  LINN GROVE AND TERRIL AROUND 1005 PM CDT...
  SIOUX RAPIDS AND SUPERIOR AROUND 1010 PM CDT...
  WEBB AND MARATHON AROUND 1015 PM CDT...

OTHER LOCATIONS IMPACTED BY THIS LINE OF SEVERE THUNDERSTORMS INCLUDE
DICKENS...GILLETT GROVE AND REMBRANDT.

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 4280 9492 4284 9561 4316 9544 4350 9545
      4350 9491 4289 9490
TIME...MOT...LOC 0258Z 272DEG 36KT 4348 9508 4316 9508
          4283 9537
WIND...HAIL 70MPH <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, 9:22 PM CDT	Severe Thunderstorm Warning	FSD	Dickinson, Osceola	38 min
May 1, 9:29 PM CDT	Tornado Warning	FSD	Clay, O'Brien	46 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.