Alert archive / Iowa / Tornado Warnings in 2018

Tornado Warning 22, NWS Quad Cities, IA

August 28, 2018Iowa County, Johnson County, Iowa

NWS Quad Cities, IA issued this tornado warning at Aug 28, 2018, 6:02 PM CDT for Iowa County, Johnson County, Iowa. It was in force for 28 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: Aug 28, 2018, 6:02 PM CDT (23:02 UTC)
Expired: Aug 28, 2018, 6:30 PM CDT
In force: 28 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Iowa County, IA, Johnson County, IA

The radar

The Quad Cities radar (KDVN), 92 km from the middle of the area, began a volume at 23:05 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
Aug 28, 6:15 PM CDT	TSTM WND DMG	1 Se North Liberty, IA	24 INCH DIAMETER TREE DOWN IN FRONT YARD. TIME ESTIMATED BASED ON RADAR
Aug 28, 6:15 PM CDT	TSTM WND GST 82	2 W University Heights, IA	WIND GUST MEASURED AT JOHNSON COUNTY EMA. TIME ESTIMATED BASED ON RADAR.
Aug 28, 6:22 PM CDT	TSTM WND DMG	Iowa City, IA	POWER LINES AND TREE BRANCHES DOWN IN TOWN AND SOUTH OF TOWN.
Aug 28, 6:28 PM CDT	TSTM WND GST 83	Iowa City Arpt, IA	ASOS STATION IOW, IOWA CITY ARPT.
Aug 28, 6:30 PM CDT	TSTM WND DMG	2 Se Iowa City, IA	8 TO 12 INCH DIAMETER HARDWOOD TREE UPROOTED - WINDS WERE MEASURED AT 70 MPH BEFORE THE POWER FAILED. THEY WERE LIKELY HIGHER.
Aug 28, 6:30 PM CDT	TSTM WND GST 70	2 Se Iowa City, IA	WINDS MEASURED AT 70 MPH BEFORE THE POWER WENT OUT. THEY WERE LIKELY HIGHER.

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
Aug 28, 5:06 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.0 hours before the alert went out and 98 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: 955 J/kg
Mixed-layer CIN: -230 J/kg
Mixed-layer LCL: 1046 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 360 m²/s²
0-3 km storm-relative helicity: 487 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

As transmitted.

151 
WFUS53 KDVN 282302
TORDVN
IAC095-103-282330-
/O.NEW.KDVN.TO.W.0022.180828T2302Z-180828T2330Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Quad Cities IA/IL
602 PM CDT TUE AUG 28 2018

The National Weather Service in the Quad Cities has issued a

* Tornado Warning for...
  Central Johnson County in east central Iowa...
  East central Iowa County in east central Iowa...

* Until 630 PM CDT.
    
* At 602 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Oxford, or 13 miles west of Iowa City, moving east
  at 55 mph.

  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 dangerous storm will be near...
  Coralville and Tiffin around 610 PM CDT.
  North Liberty, University Heights, Hills and Oakdale around 615 PM 
  CDT.
  Iowa City around 620 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Newport, Elmira, Iowa City Municipal Airport, Frytown, Morse,
Windham, Johnson County Fairgrounds, West Overlook, University Of
Iowa and Oasis.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 226 and 253.
 Interstate 380 between mile markers 1 and 2.

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.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4169 9191 4176 9137 4160 9137 4155 9185
TIME...MOT...LOC 2302Z 258DEG 49KT 4165 9179 

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

$$

McClure

2 follow-up statements

960 
WWUS53 KDVN 282306
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
606 PM CDT TUE AUG 28 2018

IAC095-282316-
/O.CAN.KDVN.TO.W.0022.000000T0000Z-180828T2330Z/
Iowa IA-
606 PM CDT TUE AUG 28 2018

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

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
east central Iowa.

LAT...LON 4170 9183 4176 9137 4160 9137 4155 9182
TIME...MOT...LOC 2306Z 258DEG 49KT 4166 9171 

$$

IAC103-282330-
/O.CON.KDVN.TO.W.0022.000000T0000Z-180828T2330Z/
Johnson IA-
606 PM CDT TUE AUG 28 2018

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR CENTRAL
JOHNSON COUNTY...
    
At 606 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Tiffin, or 9 miles west of Iowa City, moving east at
55 mph.

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 dangerous storm will be near...
  Coralville around 610 PM CDT.
  North Liberty, University Heights, Hills and Oakdale around 615 PM 
  CDT.
  Iowa City around 620 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Newport, Iowa City Municipal Airport, Frytown, Windham, Johnson
County Fairgrounds, Oasis, Cosgrove, Elmira, Morse and West Overlook.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 230 and 253.
 Interstate 380 between mile markers 1 and 2.

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.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4170 9183 4176 9137 4160 9137 4155 9182
TIME...MOT...LOC 2306Z 258DEG 49KT 4166 9171 

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

$$

McClure

655 
WWUS53 KDVN 282319
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
619 PM CDT TUE AUG 28 2018

IAC103-282330-
/O.CON.KDVN.TO.W.0022.000000T0000Z-180828T2330Z/
Johnson IA-
619 PM CDT TUE AUG 28 2018

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR EAST
CENTRAL JOHNSON COUNTY...
    
At 619 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Iowa City, moving northeast at 50 mph.

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
east central Johnson County, including the following locations...
Newport, Elmira, Iowa City Municipal Airport, Morse, Johnson County
Fairgrounds, West Overlook, University Of Iowa, Oasis, Sharon Center
and Coralville Lake Dam Complex.

This includes the following highways...
 Interstate 80 in Iowa between mile markers 236 and 253.
 Interstate 380 between mile markers 1 and 2.

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.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4176 9137 4160 9137 4156 9169 4172 9170
TIME...MOT...LOC 2319Z 245DEG 42KT 4171 9149 

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

$$

McClure

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 28, 9:08 AM CDT	Flash Flood Watch	DVN	Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines and 15 more	20 hr
Aug 28, 2:16 PM CDT	Special Weather Statement	DVN	Scott	59 min
Aug 28, 5:14 PM CDT	Severe Thunderstorm Warning	DVN	Iowa, Johnson, Keokuk, Washington	61 min
Aug 28, 5:22 PM CDT	Special Weather Statement	DVN	Benton	53 min
Aug 28, 5:40 PM CDT	Tornado Warning	DVN	Iowa	35 min
Aug 28, 5:51 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Jefferson, Keokuk, Van Buren, Washington	39 min
Aug 28, 5:59 PM CDT	Severe Thunderstorm Warning	DVN	Cedar, Johnson, Louisa, Muscatine, Washington	61 min
Aug 28, 6:18 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Louisa, Washington	42 min
Aug 28, 6:24 PM CDT	Special Weather Statement	DVN	Jones, Linn	36 min
Aug 28, 6:37 PM CDT	Severe Thunderstorm Warning	DVN	Cedar, Clinton, Jackson, Johnson, Jones, Linn	38 min
Aug 28, 6:41 PM CDT	Severe Thunderstorm Warning	DVN	Cedar, Clinton, Muscatine, Scott	64 min

Nearby

Tornado Warnings in Iowa, 2018 Every tornado warning in 2018 Tornadoes in 2018

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.