Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 15, NWS La Crosse, WI

July 11, 2017Clayton County, Iowa

NWS La Crosse, WI issued this tornado warning at Jul 11, 2017, 9:19 PM CDT for Clayton County, Iowa. It was in force for 26 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: Jul 11, 2017, 9:19 PM CDT (02:19 UTC)
Expired: Jul 11, 2017, 9:45 PM CDT
In force: 26 min
Issued by: NWS La Crosse, WI
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

County Clayton County, IA

The radar

The La Crosse radar (KARX), 113 km from the middle of the area, began a volume at 02:19 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
Jul 11, 9:50 PM CDT	TSTM WND DMG	Elkader, IA	POWER LINES DOWN IN ELKADER.
Jul 11, 9:50 PM CDT	HAIL 0.88	Garnavillo, IA
Jul 11, 9:53 PM CDT	HAIL 1.75	1 N Garber, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 2.3 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: 1096 J/kg
Mixed-layer CIN: -33 J/kg
Mixed-layer LCL: 755 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 268 m²/s²
0-3 km storm-relative helicity: 315 m²/s²
Significant tornado parameter: 1.5
Supercell composite: 7.6

Open this sounding in Storm Lab

The text

As transmitted.

053 
WFUS53 KARX 120219
TORARX
IAC043-120245-
/O.NEW.KARX.TO.W.0015.170712T0219Z-170712T0245Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service La Crosse WI
919 PM CDT TUE JUL 11 2017

The National Weather Service in La Crosse has issued a

* Tornado Warning for...
  Southwestern Clayton County in northeastern Iowa...

* Until 945 PM CDT
    
* At 919 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Elkader, moving southeast at 30 mph.

  HAZARD...Tornado and quarter size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This dangerous storm will be near...
  Garnavillo around 930 PM CDT. 

Other locations impacted by this tornadic thunderstorm include
Garber, Elkport, Mederville, Highway 13 And County C 24 and Osborne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4282 9153 4293 9144 4286 9112 4266 9133
TIME...MOT...LOC 0219Z 299DEG 26KT 4280 9139 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

CA

2 follow-up statements

940 
WWUS53 KARX 120229
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
929 PM CDT TUE JUL 11 2017

IAC043-120245-
/O.CON.KARX.TO.W.0015.000000T0000Z-170712T0245Z/
Clayton IA-
929 PM CDT TUE JUL 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 945 PM CDT FOR
SOUTHWESTERN CLAYTON COUNTY...
    
At 928 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Elkader, moving east at 20 mph.

HAZARD...Tornado and quarter size hail. 

SOURCE...Radar indicated rotation. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

This dangerous storm will be near...
  Garnavillo around 945 PM CDT. 

Other locations impacted by this tornadic thunderstorm include St.
Olaf, Garber, Elkport, Mederville and Highway 13 And County C 24.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4280 9151 4293 9142 4286 9112 4266 9133
TIME...MOT...LOC 0228Z 289DEG 16KT 4280 9135 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

CA

078 
WWUS53 KARX 120238
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
938 PM CDT TUE JUL 11 2017

IAC043-120245-
/O.CON.KARX.TO.W.0015.000000T0000Z-170712T0245Z/
Clayton IA-
938 PM CDT TUE JUL 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 945 PM CDT FOR
SOUTHWESTERN CLAYTON COUNTY...
    
At 937 PM CDT, a severe thunderstorm capable of producing a tornado
was located 8 miles south of Garnavillo, or 8 miles southeast of
Elkader, moving southeast at 25 mph.

HAZARD...Tornado and quarter size hail. 

SOURCE...Radar indicated rotation. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

This tornadic thunderstorm will remain over mainly rural areas of
southwestern Clayton County, including the following locations:
Garber, Elkport, Mederville, Wood and Motor.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4275 9145 4292 9138 4286 9112 4266 9133
TIME...MOT...LOC 0237Z 307DEG 21KT 4276 9130 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

CA

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 11, 7:46 PM CDT	Special Weather Statement	ARX	Clayton	44 min
Jul 11, 8:35 PM CDT	Special Weather Statement	ARX	Clayton	70 min
Jul 11, 9:14 PM CDT	Special Weather Statement	ARX	Allamakee	46 min
Jul 11, 9:26 PM CDT	Areal Flood Advisory	ARX	Clayton, Fayette	3 hr
Jul 11, 9:44 PM CDT	Severe Thunderstorm Warning	ARX	Clayton	61 min
Jul 11, 10:12 PM CDT	Tornado Warning	ARX	Clayton	18 min
Jul 11, 10:14 PM CDT	Flash Flood Warning Emergency	ARX	Clayton	6 hr
Jul 12, 1:40 AM CDT	River Flood Warning	ARX	Clayton	24 hr
Jul 12, 1:40 AM CDT	River Flood Warning	ARX	Clayton	24 hr
Jul 12, 4:22 AM CDT	Areal Flood Warning Emergency	ARX	Clayton	6 hr
Jul 12, 8:44 AM CDT	Special Weather Statement	ARX	Chickasaw, Clayton, Fayette	31 min
Jul 12, 9:13 AM CDT	Special Weather Statement	ARX	Clayton	17 min
Jul 12, 9:18 AM CDT	Severe Thunderstorm Warning	ARX	Clayton	42 min
Jul 12, 9:44 AM CDT	Severe Thunderstorm Warning	ARX	Clayton	22 min
Jul 12, 10:12 AM CDT	Areal Flood Warning	ARX	Clayton	3 hr
Jul 12, 5:46 PM CDT	Severe Thunderstorm Warning	ARX	Fayette	26 min

Nearby

Tornado Warnings in Iowa, 2017 Every tornado warning in 2017 Tornadoes in 2017

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.