Alert archive / Iowa / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 49, NWS La Crosse, WI

July 1, 2011Floyd County, Mitchell County, Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Jul 1, 2011, 9:39 PM CDT for Floyd County, Mitchell County, Iowa. It was in force for 66 min. 6 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
Jul 1, 2011, 9:39 PM CDT (02:39 UTC)
Expired
Jul 1, 2011, 10:45 PM CDT
In force
66 min
Issued by
NWS La Crosse, WI
Area
Storm-based polygon
Hail
0.5 in
Wind
60.0 mph

Counties Floyd County, IA, Mitchell County, IA

The radar

The La Crosse radar (KARX), 139 km from the middle of the area, began a volume at 02:42 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

TimeReportWhereRemark
Jul 1, 10:06 PM CDTTSTM WND DMG2 S Lyle, IALARGE TREE DOWN
Jul 1, 10:06 PM CDTTSTM WND DMG2 W St. Ansgar, IALARGE TREE DOWN
Jul 1, 10:06 PM CDTTSTM WND GST 02 S Lyle, IALARGE TREE DOWN
Jul 1, 10:06 PM CDTHAIL 0.54 W Osage, IA
Jul 1, 10:17 PM CDTTSTM WND DMGOsage, IAA FEW TREES BLOWN DOWN
Jul 1, 10:50 PM CDTHAIL 0.5Nora Springs, 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.

IssuedProductOfficeLasted
Jul 1, 8:07 PM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 2.7 hours before the alert went out and 185 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-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2011-07-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4059 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2011-07-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 178 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
4059 J/kg
Mixed-layer CIN
-22 J/kg
Mixed-layer LCL
1509 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
178 m²/s²
0-3 km storm-relative helicity
202 m²/s²
Significant tornado parameter
2.5
Supercell composite
20.8

Open this sounding in Storm Lab

The text

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

539 
WUUS53 KARX 020239
SVRARX
IAC067-131-020345-
/O.NEW.KARX.SV.W.0049.110702T0239Z-110702T0345Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE LA CROSSE WI
939 PM CDT FRI JUL 1 2011

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN FLOYD COUNTY IN NORTH CENTRAL IOWA...
  MITCHELL COUNTY IN NORTH CENTRAL IOWA...

* UNTIL 1045 PM CDT

* AT 937 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SEVERE THUNDERSTORMS ROUGHLY ALONG A LINE EXTENDING FROM LYLE TO 16
  MILES NORTHWEST OF NORA SPRINGS TO 10 MILES WEST OF MASON CITY...
  MOVING NORTHEAST AT 40 MPH. THESE STORMS CAN PRODUCE DAMAGING WINDS
  IN EXCESS OF 60 MPH.  

* THE SEVERE THUNDERSTORMS WILL BE NEAR...
  ST. ANSGAR AND NORA SPRINGS AROUND 1010 PM...
  ROCKFORD AND MARBLE ROCK AROUND 1015 PM...
  RUDD AROUND 1020 PM...
  STACYVILLE AROUND 1025 PM...
  OSAGE AROUND 1030 PM...
  FLOYD AROUND 1035 PM...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THESE STORMS...PREPARE IMMEDIATELY FOR
DAMAGING WINDS. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY
AWAY FROM WINDOWS.

&&

LAT...LON 4350 9303 4350 9256 4347 9255 4337 9260
      4335 9259 4330 9262 4315 9267 4292 9287
      4292 9303
TIME...MOT...LOC 0239Z 239DEG 34KT 4352 9304 4329 9325
          4294 9340
WIND...HAIL 60MPH <.50IN

$$

AJ
2 follow-up statements
900 
WWUS53 KARX 020248
SVSARX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
948 PM CDT FRI JUL 1 2011

IAC067-131-020345-
/O.CON.KARX.SV.W.0049.000000T0000Z-110702T0345Z/
MITCHELL IA-FLOYD IA-
948 PM CDT FRI JUL 1 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR WESTERN FLOYD
AND MITCHELL COUNTIES UNTIL 1045 PM CDT...

AT 943 PM...THE AUTOMATED OBSERVATION AT MASON CITY REPORTED WINDS 
OF 51 MPH WITH A LINE OF SEVERE THUNDERSTORMS.

AT 942 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THUNDERSTORMS WERE ROUGHLY ALONG A LINE EXTENDING FROM LYLE TO  
MASON CITY...MOVING NORTHEAST AT 40 MPH. THESE STORMS CAN PRODUCE 
DAMAGING WINDS IN EXCESS OF 60 MPH.

* THE SEVERE THUNDERSTORMS WILL BE NEAR...
  ST. ANSGAR AROUND 1010 PM...
  ROCKFORD AND NORA SPRINGS AROUND 1015 PM...
  RUDD AROUND 1020 PM...
  STACYVILLE AROUND 1025 PM...
  OSAGE AROUND 1030 PM...
  FLOYD AROUND 1035 PM...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THESE STORMS...PREPARE IMMEDIATELY FOR
DAMAGING WINDS. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY
AWAY FROM WINDOWS.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT. CONDITIONS REMAIN
FAVORABLE FOR ADDITIONAL SEVERE THUNDERSTORMS TO DEVELOP.

&&

LAT...LON 4350 9303 4350 9256 4347 9255 4337 9260
      4335 9259 4330 9262 4315 9267 4292 9287
      4292 9303
TIME...MOT...LOC 0247Z 239DEG 34KT 4356 9295 4333 9316
          4298 9331
WIND...HAIL 60MPH <.50IN

$$

AJ
801 
WWUS53 KARX 020321
SVSARX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
1021 PM CDT FRI JUL 1 2011

IAC067-131-020345-
/O.CON.KARX.SV.W.0049.000000T0000Z-110702T0345Z/
MITCHELL IA-FLOYD IA-
1021 PM CDT FRI JUL 1 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR WESTERN FLOYD
AND MITCHELL COUNTIES UNTIL 1045 PM CDT...

AT 1017 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WERE ROUGHLY ALONG A LINE EXTENDING FROM GRAND MEADOW
TO OSAGE TO 10 MILES SOUTHWEST OF ROCKFORD...MOVING NORTHEAST AT 40
MPH. THESE STORMS CAN PRODUCE DAMAGING WINDS IN EXCESS OF 60 MPH.

* THE SEVERE THUNDERSTORMS WILL BE NEAR...
  RUDD AROUND 1030 PM...
  MARBLE ROCK AND ROCKFORD AROUND 1035 PM...
  FLOYD AROUND 1045 PM...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THESE STORMS...PREPARE IMMEDIATELY FOR
DAMAGING WINDS. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY
AWAY FROM WINDOWS.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT. CONDITIONS REMAIN
FAVORABLE FOR ADDITIONAL SEVERE THUNDERSTORMS TO DEVELOP.

&&

LAT...LON 4350 9303 4350 9256 4347 9255 4337 9260
      4335 9259 4330 9262 4315 9267 4292 9287
      4292 9303
TIME...MOT...LOC 0321Z 239DEG 34KT 4372 9257 4336 9267
          4301 9309
WIND...HAIL 60MPH <.50IN

$$

AJ

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 1, 10:23 PM CDTSevere Thunderstorm WarningARXHoward37 min
Jul 1, 10:50 PM CDTSevere Thunderstorm WarningARXChickasaw, Floyd, Howard, Mitchell40 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2011Every 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.