Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 74, NWS Quad Cities, IA

August 10, 2021Stephenson County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 10, 2021, 5:49 PM CDT for Stephenson County, Illinois. It was in force for 41 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: Aug 10, 2021, 5:49 PM CDT (22:49 UTC)
Expired: Aug 10, 2021, 6:30 PM CDT
In force: 41 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

County Stephenson County, IL

The radar

The Milwaukee radar (KMKX), 106 km from the middle of the area, began a volume at 22:52 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 10, 5:58 PM CDT	TSTM WND DMG	Freeport, IL	TREE DOWN NEAR THE INTERSECTION OF IL 26 AND STEPHENSON ST. PICTURE FROM SOCIAL MEDIA.

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 10, 3:47 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 10.8 hours before the alert went out and 114 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: 3755 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 819 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

076 
WUUS53 KDVN 102249
SVRDVN
ILC177-102330-
/O.NEW.KDVN.SV.W.0074.210810T2249Z-210810T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
549 PM CDT Tue Aug 10 2021

The National Weather Service in the Quad Cities has issued a

* Severe Thunderstorm Warning for...
  Stephenson County in northwestern Illinois...

* Until 630 PM CDT.

* At 549 PM CDT, a severe thunderstorm was located near Pearl City,
  or near Freeport, moving east at 35 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Freeport and Cedarville around 600 PM CDT.

Other locations in the path of this severe thunderstorm include
Dakota, German Valley, Rock City and Ridott.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4250 8940 4220 8940 4220 8976 4251 8989
TIME...MOT...LOC 2249Z 264DEG 31KT 4228 8977 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.88 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Speck

1 follow-up statement

455 
WWUS53 KDVN 102328
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
628 PM CDT Tue Aug 10 2021

ILC177-102338-
/O.EXP.KDVN.SV.W.0074.000000T0000Z-210810T2330Z/
Stephenson IL-
628 PM CDT Tue Aug 10 2021

...THE SEVERE THUNDERSTORM WARNING FOR STEPHENSON COUNTY WILL EXPIRE
AT 630 PM CDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
northwestern Illinois.

LAT...LON 4250 8940 4220 8940 4220 8976 4251 8989
TIME...MOT...LOC 2328Z 264DEG 31KT 4231 8933 

$$

Speck

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 7:12 PM CDT	Tornado Warning Tornado observed	DVN	Bureau	48 min
Aug 9, 7:30 PM CDT	Tornado Warning Tornado observed	DVN	Bureau	45 min
Aug 9, 8:02 PM CDT	Flash Flood Warning	DVN	Bureau	2 hr
Aug 9, 8:16 PM CDT	Severe Thunderstorm Warning	DVN	Bureau, Putnam	29 min
Aug 9, 9:39 PM CDT	Special Weather Statement	DVN	Henry	36 min
Aug 9, 9:54 PM CDT	Special Weather Statement	DVN	Henry	51 min
Aug 9, 10:44 PM CDT	Special Weather Statement	DVN	Mercer	31 min
Aug 10, 2:28 PM CDT	Heat Advisory	DVN	Bureau, Carroll, Hancock, Henderson, Henry, Jo Daviess and 7 more	29 hr
Aug 10, 4:04 PM CDT	Severe Thunderstorm Warning	DVN	Jo Daviess	56 min
Aug 10, 5:00 PM CDT	Severe Thunderstorm Warning	DVN	Carroll, Jo Daviess, Whiteside	45 min
Aug 10, 5:24 PM CDT	Severe Thunderstorm Warning	DVN	Carroll, Jo Daviess, Stephenson, Whiteside	51 min
Aug 10, 5:47 PM CDT	Special Weather Statement	DVN	Bureau	13 min
Aug 10, 5:47 PM CDT	Special Weather Statement	DVN	Bureau	13 min
Aug 10, 6:16 PM CDT	Severe Thunderstorm Warning	DVN	Stephenson	13 min
Aug 10, 6:50 PM CDT	Severe Thunderstorm Warning	DVN	Bureau	25 min
Aug 10, 6:53 PM CDT	Special Weather Statement	DVN	Mercer, Warren	37 min

Nearby

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.