Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 73, NWS Quad Cities, IA

August 10, 20214 counties in Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 10, 2021, 5:24 PM CDT for 4 counties in Illinois. It was in force for 51 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: Aug 10, 2021, 5:24 PM CDT (22:24 UTC)
Expired: Aug 10, 2021, 6:15 PM CDT
In force: 51 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

Counties Carroll County, IL, Jo Daviess County, IL, Stephenson County, IL, Whiteside County, IL

The radar

The Quad Cities radar (KDVN), 88 km from the middle of the area, began a volume at 22:25 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, 5:34 PM CDT	TSTM WND GST 51	3 N Stockton, IL	VERY HEAVY RAIN ALSO.
Aug 10, 5:35 PM CDT	TSTM WND GST 60	Milledgeville, IL	ESTIMATED 55 TO 60 MPH GUST.
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, 10.4 hours before the alert went out and 82 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.

456 
WUUS53 KDVN 102224
SVRDVN
ILC015-085-177-195-102315-
/O.NEW.KDVN.SV.W.0073.210810T2224Z-210810T2315Z/

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

The National Weather Service in the Quad Cities has issued a

* Severe Thunderstorm Warning for...
  Eastern Whiteside County in northwestern Illinois...
  Jo Daviess County in northwestern Illinois...
  Carroll County in northwestern Illinois...
  Stephenson County in northwestern Illinois...

* Until 615 PM CDT.

* At 524 PM CDT, severe thunderstorms were located along a line
  extending from near Council Hill to Mount Carroll to near Tampico,
  moving northeast at 40 mph.

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

  SOURCE...Radar indicated.

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

* Severe thunderstorms will be near...
  Rock Falls, Chadwick and Deer Grove around 530 PM CDT.
  Lanark around 540 PM CDT.

Other locations in the path of these severe thunderstorms include
Pearl City, Shannon, Apple River, Warren, Freeport and German Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4220 8947 4220 8969 4193 8969 4193 8963
      4162 8963 4159 8983 4251 9040 4251 8964
TIME...MOT...LOC 2224Z 243DEG 34KT 4245 9035 4209 9001 4165 8973 

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

$$

Speck

1 follow-up statement

223 
WWUS53 KDVN 102302
SVSDVN

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

ILC015-085-177-195-102315-
/O.CON.KDVN.SV.W.0073.000000T0000Z-210810T2315Z/
Whiteside IL-Jo Daviess IL-Carroll IL-Stephenson IL-
602 PM CDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM CDT
FOR EASTERN WHITESIDE...EASTERN JO DAVIESS...CARROLL AND STEPHENSON
COUNTIES...

At 602 PM CDT, severe thunderstorms were located along a line
extending from 7 miles southwest of Argyle to near Freeport to near
Franklin Grove, moving northeast at 40 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
  German Valley.

LAT...LON 4220 8947 4220 8969 4193 8969 4193 8963
      4162 8963 4159 8983 4183 8998 4250 9003
      4251 8964
TIME...MOT...LOC 2302Z 243DEG 34KT 4260 8994 4224 8960 4180 8932 

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

$$

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, 5:47 PM CDT	Special Weather Statement	DVN	Bureau	13 min
Aug 10, 5:47 PM CDT	Special Weather Statement	DVN	Bureau	13 min
Aug 10, 5:49 PM CDT	Severe Thunderstorm Warning	DVN	Stephenson	41 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.