Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 47, NWS Quad Cities, IA

July 11, 2017Iowa County, Johnson County, Iowa

NWS Quad Cities, IA issued this tornado warning at Jul 11, 2017, 5:51 PM CDT for Iowa County, Johnson County, Iowa. It was in force for 39 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: Jul 11, 2017, 5:51 PM CDT (22:51 UTC)
Expired: Jul 11, 2017, 6:30 PM CDT
In force: 39 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Tornado: Observed
Hail: 0.75 in

Counties Iowa County, IA, Johnson County, IA

The radar

The Quad Cities radar (KDVN), 99 km from the middle of the area, began a volume at 22:53 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, 5:52 PM CDT	TORNADO	3 Ne Conroy, IA	TROOPER WAS FLYING IN AIRPLANE WITH VISUAL.

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 12:00Z, 10.9 hours before the alert went out and 105 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: 1146 J/kg
Mixed-layer CIN: -134 J/kg
Mixed-layer LCL: 952 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 107 m²/s²
0-3 km storm-relative helicity: 223 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

682 
WFUS53 KDVN 112251
TORDVN
IAC095-103-112330-
/O.NEW.KDVN.TO.W.0047.170711T2251Z-170711T2330Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Quad Cities IA/IL
551 PM CDT TUE JUL 11 2017

The National Weather Service in the Quad Cities has issued a

* Tornado Warning for...
  Northwestern Johnson County in east central Iowa...
  Northeastern Iowa County in east central Iowa...

* Until 630 PM CDT

* At 551 PM CDT, a confirmed tornado was located near Conroy, or 8
  miles southeast of Marengo, moving east at 15 mph.

  HAZARD...Damaging tornado. 

  SOURCE...Weather spotters confirmed tornado. 

  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. 

* The tornado will be near...
  Amana around 610 PM CDT. 
  Oxford around 620 PM CDT. 
  Coralville, North Liberty, Tiffin, Swisher and Shueyville around 
  630 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Middle
Amana, Iowa City Municipal Airport, South Amana, Homestead, West
Amana, Sugar Bottom Camp Ground, Cou Falls, Johnson County
Fairgrounds, Upper South Amana and Cosgrove.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 219 and 245.
 Interstate 380 between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4186 9170 4186 9154 4162 9150 4162 9202
      4180 9205
TIME...MOT...LOC 2251Z 253DEG 14KT 4173 9194 

TORNADO...OBSERVED
HAIL...<.75IN

$$

NICHOLS

4 follow-up statements

527 
WWUS53 KDVN 112257
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
557 PM CDT TUE JUL 11 2017

IAC095-103-112330-
/O.CON.KDVN.TO.W.0047.000000T0000Z-170711T2330Z/
Johnson IA-Iowa IA-
557 PM CDT TUE JUL 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN JOHNSON AND NORTHEASTERN IOWA COUNTIES...
    
At 556 PM CDT, a confirmed tornado was located 3 miles northeast of 
near Conroy, or 7 miles southeast of Marengo, and is moving 
northeast at 15 MPH.

HAZARD...Damaging tornado. 

SOURCE...Law enforcement confirmed tornado. 

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 tornado will be near...
  Amana around 610 PM CDT. 
  Oxford around 620 PM CDT. 
  Coralville, North Liberty, Tiffin, Swisher and Shueyville around 
  630 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Middle
Amana, Iowa City Municipal Airport, South Amana, Homestead, West
Amana, Sugar Bottom Camp Ground, Cou Falls, Johnson County
Fairgrounds, Upper South Amana and Cosgrove.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 219 and 245.
 Interstate 380 between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4186 9170 4186 9154 4162 9150 4162 9202
      4180 9205
TIME...MOT...LOC 2256Z 253DEG 14KT 4175 9193 

TORNADO...OBSERVED
HAIL...<.75IN

$$

NICHOLS

916 
WWUS53 KDVN 112310
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
610 PM CDT TUE JUL 11 2017

IAC095-112319-
/O.CAN.KDVN.TO.W.0047.000000T0000Z-170711T2330Z/
Iowa IA-
610 PM CDT TUE JUL 11 2017

...THE TORNADO WARNING FOR NORTHEASTERN IOWA COUNTY IS CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

LAT...LON 4183 9183 4186 9170 4186 9155 4183 9154
      4173 9152 4166 9182 4169 9183
TIME...MOT...LOC 2309Z 245DEG 18KT 4178 9182 

$$

IAC103-112330-
/O.CON.KDVN.TO.W.0047.000000T0000Z-170711T2330Z/
Johnson IA-
610 PM CDT TUE JUL 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN JOHNSON COUNTY...
    
At 609 PM CDT, a confirmed tornado was located near Amana, or 12 
miles east of Marengo, moving northeast at 20 mph.

HAZARD...Damaging tornado. 

SOURCE...Law enforcement confirmed tornado. 

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 tornado will be near...
  Coralville, North Liberty, Tiffin, Swisher, Shueyville and Lake 
  Macbride State Park around 630 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Twin
View Heights, Sandy Beach Camp Ground, F.W. Kent  Park, Sugar Bottom
Camp Ground and Cou Falls.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 230 and 237.
 Interstate 380 between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4183 9183 4186 9170 4186 9155 4183 9154
      4173 9152 4166 9182 4169 9183
TIME...MOT...LOC 2309Z 245DEG 18KT 4178 9182 

TORNADO...OBSERVED
HAIL...<.75IN

$$

NICHOLS

002 
WWUS53 KDVN 112323
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
623 PM CDT TUE JUL 11 2017

IAC103-112330-
/O.CON.KDVN.TO.W.0047.000000T0000Z-170711T2330Z/
Johnson IA-
623 PM CDT TUE JUL 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN JOHNSON COUNTY...
    
At 622 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Swisher, or 12 miles south of Cedar Rapids, moving 
east at 15 mph.  The tornado has lifted but a circulation remains 
capable of producing a tornado.

HAZARD...Tornado. 

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
northwestern Johnson County, including the following locations: Twin
View Heights, Sandy Beach Camp Ground, F.W. Kent  Park, Sugar Bottom
Camp Ground and Cou Falls.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 230 and 237.
 Interstate 380 between mile markers 1 and 11.

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 4183 9183 4186 9170 4186 9155 4183 9154
      4173 9152 4166 9182 4169 9183
TIME...MOT...LOC 2322Z 252DEG 14KT 4180 9175 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

NICHOLS

015 
WWUS53 KDVN 112327
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
627 PM CDT TUE JUL 11 2017

IAC103-112337-
/O.EXP.KDVN.TO.W.0047.000000T0000Z-170711T2330Z/
Johnson IA-
627 PM CDT TUE JUL 11 2017

...THE TORNADO WARNING FOR NORTHWESTERN JOHNSON COUNTY WILL EXPIRE AT
630 PM CDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

A neew circulation is developing south of this system.

LAT...LON 4183 9183 4186 9170 4186 9155 4183 9154
      4173 9152 4166 9182 4169 9183
TIME...MOT...LOC 2327Z 253DEG 14KT 4180 9173 

$$

NICHOLS

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 10, 7:41 PM CDT	Tornado Warning	DVN	Lee	34 min
Jul 10, 8:17 PM CDT	Special Weather Statement	DVN	Lee	58 min
Jul 11, 5:27 AM CDT	Special Weather Statement	DVN	Iowa, Johnson, Keokuk, Washington	48 min
Jul 11, 5:40 AM CDT	Severe Thunderstorm Warning	DVN	Henry, Iowa, Jefferson, Johnson, Keokuk, Washington	50 min
Jul 11, 6:26 AM CDT	Special Weather Statement	DVN	Des Moines, Henry, Lee, Louisa	49 min
Jul 11, 7:10 AM CDT	Special Weather Statement	DVN	Des Moines, Lee	50 min
Jul 11, 11:25 AM CDT	Heat Advisory	DVN	Des Moines, Henry, Jefferson, Keokuk, Lee, Louisa and 2 more	9 hr
Jul 11, 5:31 PM CDT	Special Weather Statement	DVN	Johnson	44 min
Jul 11, 6:40 PM CDT	Special Weather Statement	DVN	Johnson	65 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.