Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 59, NWS Quad Cities, IA

July 15, 2021Stephenson County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Jul 15, 2021, 12:05 AM CDT for Stephenson County, Illinois. It was in force for 25 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 15, 2021, 12:05 AM CDT (05:05 UTC)
Expired
Jul 15, 2021, 12:30 AM CDT
In force
25 min
Issued by
NWS Quad Cities, IA
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Stephenson County, IL

The radar

The Milwaukee radar (KMKX), 107 km from the middle of the area, began a volume at 05:04 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

TimeReportWhereRemark
Jul 15, 12:15 AM CDTTSTM WND DMG1 Sse Freeport, ILAT LEAST ONE TREE REPORTED TO BE BLOWN DOWN IN FREEPORT.

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 00:00Z, 5.1 hours before the alert went out and 112 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-pSkew-T log-p diagram, Davenport, at 00:00Z on 2021-07-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2569 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 00:00Z on 2021-07-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 253 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2569 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
832 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
253 m²/s²
0-3 km storm-relative helicity
346 m²/s²
Significant tornado parameter
3.2
Supercell composite
23.4

Open this sounding in Storm Lab

The text

As transmitted.

477 
WUUS53 KDVN 150505
SVRDVN
ILC177-150530-
/O.NEW.KDVN.SV.W.0059.210715T0505Z-210715T0530Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
1205 AM CDT Thu Jul 15 2021

The National Weather Service in the Quad Cities has issued a

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

* Until 1230 AM CDT.

* At 1205 AM CDT, a severe thunderstorm was located over Freeport,
  moving east at 50 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* This severe thunderstorm will be near...
  Dakota and German Valley around 1215 AM CDT.
  Rock City and Ridott around 1220 AM CDT.
  Davis around 1225 AM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4247 8940 4220 8940 4220 8978 4241 8981
TIME...MOT...LOC 0505Z 258DEG 42KT 4229 8968 

HAIL...<.75IN
WIND...60MPH
 
$$

Gibbs
1 follow-up statement
943 
WWUS53 KDVN 150519
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
1219 AM CDT Thu Jul 15 2021

ILC177-150530-
/O.CON.KDVN.SV.W.0059.000000T0000Z-210715T0530Z/
Stephenson IL-
1219 AM CDT Thu Jul 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM CDT
FOR EASTERN STEPHENSON COUNTY...

At 1218 AM CDT, a severe thunderstorm was located over Ridott, or 8
miles east of Freeport, moving east at 50 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

This severe thunderstorm will remain over mainly rural areas of
eastern Stephenson County, including the following locations...
Scioto Mills, Red Oak, Winneshiek, Dakota Dornink Airport, Damascus,
Albertus Airport, Stephenson  County Fairgrounds, Afolkey and Lake
Summerset.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4247 8940 4220 8940 4220 8969 4242 8972
TIME...MOT...LOC 0518Z 258DEG 42KT 4232 8947 

HAIL...<.75IN
WIND...60MPH
 
$$

Gibbs

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 14, 11:10 PM CDTSevere Thunderstorm WarningDVNCarroll, Jo Daviess50 min
Jul 14, 11:41 PM CDTSevere Thunderstorm WarningDVNCarroll, Jo Daviess, Stephenson34 min
Jul 15, 12:07 AM CDTSevere Thunderstorm WarningDVNCarroll, Whiteside23 min
Jul 15, 1:01 AM CDTSpecial Weather StatementDVNRock Island89 min
Jul 15, 1:51 PM CDTSpecial Weather StatementDVNMcDonough39 min
Jul 15, 2:31 PM CDTSpecial Weather StatementDVNMcDonough29 min
Jul 15, 5:23 PM CDTSpecial Weather StatementDVNWhiteside37 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2021Every 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.