Alert archive / Iowa / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 21, NWS Sioux Falls, SD

April 9, 20114 counties in Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Apr 9, 2011, 8:08 PM CDT for 4 counties in Iowa. It was in force for 37 min. 3 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: Apr 9, 2011, 8:08 PM CDT (01:08 UTC)
Expired: Apr 9, 2011, 8:45 PM CDT
In force: 37 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

Counties Buena Vista County, IA, Cherokee County, IA, Ida County, IA, Woodbury County, IA

The radar

The Sioux Falls radar (KFSD), 145 km from the middle of the area, began a volume at 01:09 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
Apr 9, 8:10 PM CDT	HAIL 1	2 Se Pierson, IA
Apr 9, 8:45 PM CDT	HAIL 1	2 S Galva, IA
Apr 9, 8:55 PM CDT	HAIL 1	6 Nnw Washta, 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
Apr 9, 5:48 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.1 hours before the alert went out and 152 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: 3327 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1533 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 270 m²/s²
0-3 km storm-relative helicity: 403 m²/s²
Significant tornado parameter: 3.7
Supercell composite: 19.0

Open this sounding in Storm Lab

The text

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

336 
WUUS53 KFSD 100108
SVRFSD
IAC021-035-093-193-100145-
/O.NEW.KFSD.SV.W.0021.110410T0108Z-110410T0145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
808 PM CDT SAT APR 9 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN BUENA VISTA COUNTY IN NORTHWEST IOWA...
  CHEROKEE COUNTY IN NORTHWEST IOWA...
  NORTHERN IDA COUNTY IN NORTHWEST IOWA...
  NORTHEASTERN WOODBURY COUNTY IN NORTHWEST IOWA...

* UNTIL 845 PM CDT

* AT 809 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING HALF
  DOLLAR SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE
  STORMS WERE LOCATED ALONG A LINE EXTENDING FROM 5 MILES EAST OF
  MOVILLE TO CORRECTIONVILLE TO 5 MILES SOUTH OF CUSHING...AND MOVING
  NORTHEAST AT 50 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  WASHTA AND HOLSTEIN AROUND 815 PM CDT...
  QUIMBY AND GALVA AROUND 820 PM CDT...
  CHEROKEE...AURELIA AND ALTA AROUND 835 PM CDT...
  STORM LAKE AND LAKESIDE AROUND 840 PM CDT...
  TRUESDALE AROUND 845 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.

&&

A TORNADO WATCH REMAINS IN EFFECT UNTIL 100 AM CDT SUNDAY MORNING FOR
NORTHWEST IOWA AND SOUTHWEST MINNESOTA AND NORTHEAST NEBRASKA AND
SOUTHEASTERN SOUTH DAKOTA.

LAT...LON 4248 9583 4251 9599 4256 9594 4257 9587
      4263 9587 4283 9566 4279 9521 4258 9514
      4255 9520 4256 9539 4247 9538 4235 9565
TIME...MOT...LOC 0109Z 235DEG 42KT 4254 9590 4253 9572
          4243 9559
WIND...HAIL 60MPH 1.25IN

$$

CJ

1 follow-up statement

227 
WWUS53 KFSD 100131
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
831 PM CDT SAT APR 9 2011

IAC093-193-100141-
/O.CAN.KFSD.SV.W.0021.000000T0000Z-110410T0145Z/
WOODBURY IA-IDA IA-
831 PM CDT SAT APR 9 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN IDA AND NORTHEASTERN
WOODBURY COUNTIES IS CANCELLED...

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

LAT...LON 4264 9534 4260 9539 4258 9543 4256 9575
      4258 9582 4256 9586 4263 9587 4283 9566
      4279 9539 4267 9527
TIME...MOT...LOC 0131Z 244DEG 48KT 4263 9576

$$

IAC021-035-100145-
/O.CON.KFSD.SV.W.0021.000000T0000Z-110410T0145Z/
CHEROKEE IA-BUENA VISTA IA-
831 PM CDT SAT APR 9 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR WEST CENTRAL
BUENA VISTA AND CHEROKEE COUNTIES UNTIL 845 PM CDT...

AT 831 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL.  THIS
STORM WAS LOCATED 5 MILES NORTHEAST OF PIERSON...OR 21 MILES
SOUTHEAST OF LE MARS...MOVING NORTHEAST AT 55 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  CHEROKEE AND AURELIA AROUND 845 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. TORNADOES CAN
DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. ALTHOUGH NOT IMMEDIATELY
LIKELY...IF A TORNADO IS SPOTTED ACT QUICKLY AND MOVE TO A PLACE OF
SAFETY INSIDE A STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL
INTERIOR ROOM.

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 4264 9534 4260 9539 4258 9543 4256 9575
      4258 9582 4256 9586 4263 9587 4283 9566
      4279 9539 4267 9527
TIME...MOT...LOC 0131Z 244DEG 48KT 4263 9576
WIND...HAIL <58MPH 1.00IN

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 9, 7:09 PM CDT	Severe Thunderstorm Warning	FSD	Ida, Woodbury	36 min
Apr 9, 7:31 PM CDT	Tornado Warning	FSD	Ida	29 min
Apr 9, 7:44 PM CDT	Severe Thunderstorm Warning	FSD	Ida	31 min
Apr 9, 7:46 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida, Woodbury	29 min
Apr 9, 7:56 PM CDT	Tornado Warning	FSD	Ida	34 min
Apr 9, 8:11 PM CDT	Severe Thunderstorm Warning	FSD	Ida	34 min
Apr 9, 8:19 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	41 min
Apr 9, 8:40 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	35 min
Apr 9, 8:41 PM CDT	Severe Thunderstorm Warning	FSD	Ida	19 min
Apr 9, 8:49 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	41 min
Apr 9, 8:55 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	35 min
Apr 9, 9:08 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	37 min
Apr 9, 9:09 PM CDT	Tornado Warning	FSD	Buena Vista	36 min
Apr 9, 9:15 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	30 min
Apr 9, 9:17 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	43 min
Apr 9, 9:24 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Plymouth, Woodbury	36 min
Apr 9, 9:25 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	20 min
Apr 9, 9:31 PM CDT	Tornado Warning	FSD	Plymouth, Woodbury	29 min
Apr 9, 9:36 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay	39 min
Apr 9, 9:46 PM CDT	Tornado Warning	FSD	Buena Vista	29 min
Apr 9, 9:48 PM CDT	Tornado Warning	FSD	Cherokee	27 min
Apr 9, 9:58 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	32 min
Apr 9, 10:02 PM CDT	Tornado Warning	FSD	Buena Vista	28 min
Apr 9, 10:09 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	36 min
Apr 9, 10:13 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee	47 min
Apr 9, 10:24 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, O'Brien, Plymouth, Sioux	36 min
Apr 9, 10:31 PM CDT	Tornado Warning	FSD	Cherokee	29 min
Apr 9, 10:35 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	30 min
Apr 9, 10:50 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee	40 min
Apr 9, 11:11 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	34 min
Apr 9, 11:27 PM CDT	Tornado Warning	FSD	Buena Vista, Clay	18 min
Apr 9, 11:39 PM CDT	Tornado Warning	FSD	Clay	21 min
Apr 10, 12:24 AM CDT	Severe Thunderstorm Warning	FSD	Woodbury	36 min
Apr 10, 12:47 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida	28 min

Nearby

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.