Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 77, NWS Quad Cities, IA

August 11, 2021Des Moines County, Lee County, Iowa; Hancock County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 11, 2021, 5:56 AM CDT for Des Moines County, Lee County, Iowa; Hancock County, Illinois. It was in force for 19 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 11, 2021, 5:56 AM CDT (10:56 UTC)
Expired: Aug 11, 2021, 6:15 AM CDT
In force: 19 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Des Moines County, IA, Lee County, IA, Hancock County, IL

The radar

The Quad Cities radar (KDVN), 136 km from the middle of the area, began a volume at 10:58 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.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 10.9 hours before the alert went out and 141 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: 856 J/kg
Mixed-layer CIN: -155 J/kg
Mixed-layer LCL: 940 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 77 m²/s²
0-3 km storm-relative helicity: 160 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -1.4

Open this sounding in Storm Lab

The text

As transmitted.

632 
WUUS53 KDVN 111056
SVRDVN
ILC067-IAC057-111-111130-
/O.NEW.KDVN.SV.W.0077.210811T1056Z-210811T1130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
556 AM CDT Wed Aug 11 2021

The National Weather Service in the Quad Cities has issued a

* Severe Thunderstorm Warning for...
  Northwestern Hancock County in west central Illinois...
  Southwestern Des Moines County in southeastern Iowa...
  Lee County in southeastern Iowa...

* Until 630 AM CDT.

* At 556 AM CDT, a severe thunderstorm was located near Donnellson,
  or 12 miles west of Nauvoo, moving east at 30 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* This severe thunderstorm will be near...
  Donnellson and New Boston around 605 AM CDT.
  Franklin around 610 AM CDT.
  Montrose around 615 AM CDT.

Other locations in the path of this severe thunderstorm include
Nauvoo, West Point, Fort Madison, Niota and Denmark.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
sturdy building.

&&

LAT...LON 4054 9162 4055 9165 4075 9166 4081 9121
      4054 9117 4052 9162
TIME...MOT...LOC 1056Z 250DEG 25KT 4060 9161 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

DC

2 follow-up statements

930 
WWUS53 KDVN 111105
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
605 AM CDT Wed Aug 11 2021

ILC067-IAC057-111-111130-
/O.CON.KDVN.SV.W.0077.000000T0000Z-210811T1130Z/
Hancock IL-Des Moines IA-Lee IA-
605 AM CDT Wed Aug 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 AM CDT
FOR NORTHWESTERN HANCOCK...SOUTHWESTERN DES MOINES AND NORTHERN LEE
COUNTIES...

At 605 AM CDT, a severe thunderstorm was located over Donnellson, or
9 miles northwest of Nauvoo, moving east at 30 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vehicles is expected.

This severe storm will be near...
  Nauvoo and Montrose around 615 AM CDT.

Other locations in the path of this severe thunderstorm include West
Point, Fort Madison, Denmark, Niota, Dallas City and Iowa Army
Ammunition Plant.

LAT...LON 4054 9162 4056 9163 4076 9158 4081 9121
      4054 9117 4052 9162
TIME...MOT...LOC 1105Z 250DEG 25KT 4062 9153 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

DC

403 
WWUS53 KDVN 111115
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
615 AM CDT Wed Aug 11 2021

IAC057-111-ILC067-111125-
/O.CAN.KDVN.SV.W.0077.000000T0000Z-210811T1130Z/
Hancock IL-Des Moines IA-Lee IA-
615 AM CDT Wed Aug 11 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN HANCOCK...
SOUTHWESTERN DES MOINES AND NORTHERN LEE COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.

LAT...LON 4054 9162 4056 9163 4076 9158 4081 9121
      4054 9117 4052 9162
TIME...MOT...LOC 1113Z 250DEG 25KT 4064 9144 

$$

DC

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 5:38 AM CDT	Special Weather Statement	DVN	Lee	37 min
Aug 11, 6:10 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Lee	20 min
Aug 11, 6:24 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines	22 min
Aug 11, 6:38 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Louisa	37 min
Aug 11, 6:59 AM CDT	Flash Flood Warning	DVN	Des Moines, Lee	3 hr
Aug 11, 7:04 AM CDT	Special Weather Statement	DVN	Muscatine	26 min
Aug 11, 8:16 AM CDT	High Wind Warning	DVN	Clinton, Des Moines, Louisa, Muscatine, Scott	104 min
Aug 11, 9:46 AM CDT	Areal Flood Warning	DVN	Des Moines, Lee	3 hr
Aug 11, 10:24 AM CDT	Special Weather Statement	DVN	Lee	21 min
Aug 11, 3:36 PM CDT	Special Weather Statement	DVN	Washington	24 min
Aug 11, 4:26 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque	49 min
Aug 11, 5:11 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jackson, Jones	49 min
Aug 11, 5:38 PM CDT	Tornado Warning	DVN	Dubuque	13 min
Aug 11, 6:24 AM CDT	Special Weather Statement	DVN	McDonough	36 min
Aug 11, 7:32 AM CDT	Special Weather Statement	DVN	Rock Island	28 min
Aug 11, 7:55 AM CDT	Special Weather Statement	DVN	Bureau, Henry, Whiteside	65 min
Aug 11, 8:07 AM CDT	Severe Thunderstorm Warning	DVN	Bureau, Henry, Rock Island, Whiteside	53 min
Aug 11, 8:33 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Bureau, Putnam, Whiteside	57 min
Aug 11, 9:59 AM CDT	Special Weather Statement	DVN	McDonough	31 min
Aug 11, 10:45 AM CDT	Special Weather Statement	DVN	Henderson, Warren	30 min
Aug 11, 10:57 AM CDT	Severe Thunderstorm Warning	DVN	Henderson, McDonough, Warren	33 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Severe Thunderstorm Warnings in Illinois, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.