Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 7, NWS Chicago, IL

June 12, 20214 counties in Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jun 12, 2021, 2:55 PM CDT for 4 counties in Illinois. It was in force for 65 min. 5 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: Jun 12, 2021, 2:55 PM CDT (19:55 UTC)
Expired: Jun 12, 2021, 4:00 PM CDT
In force: 65 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

Counties DuPage County, IL, Kane County, IL, Kendall County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 25 km from the middle of the area, began a volume at 19:57 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
Jun 12, 3:00 PM CDT	HAIL 0.5	Batavia, IL	LARGEST HAILSTONES HALF AN INCH IN DIAMETER.
Jun 12, 3:36 PM CDT	HAIL 0.5	3 Nw Montgomery, IL	HALF-INCH HAIL REPORT FROM MPING.
Jun 12, 3:38 PM CDT	HAIL 1	3 Sw North Aurora, IL	NICKEL TO QUARTER SIZE HAIL.
Jun 12, 3:40 PM CDT	HAIL 0.75	3 Wnw Aurora, IL
Jun 12, 3:41 PM CDT	HAIL 0.5	3 Se Sugar Grove, IL

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 7.9 hours before the alert went out and 185 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: 897 J/kg
Mixed-layer CIN: -111 J/kg
Mixed-layer LCL: 1584 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 29 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

895 
WUUS53 KLOT 121955
SVRLOT
ILC043-089-093-197-122100-
/O.NEW.KLOT.SV.W.0007.210612T1955Z-210612T2100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville
255 PM CDT Sat Jun 12 2021

The National Weather Service in Chicago has issued a

* Severe Thunderstorm Warning for...
  Northeastern Kendall County in northeastern Illinois...
  Northwestern Will County in northeastern Illinois...
  Southeastern Kane County in northeastern Illinois...
  Southwestern DuPage County in northeastern Illinois...

* Until 400 PM CDT.

* At 255 PM CDT, a severe thunderstorm was located over Batavia,
  moving southeast at 15 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Aurora, Naperville, Bolingbrook, Wheaton, Romeoville, Plainfield,
  St. Charles, Woodridge, Oswego, West Chicago, Batavia, Geneva,
  Yorkville, Lisle, Montgomery, North Aurora, Warrenville, Winfield,
  Sugar Grove and Boulder Hill.

Including the following interstates...
 I-55 between mile markers 266 and 269.
 I-88 between mile markers 113 and 128.
 I-355 near mile marker 11, and between mile markers 13 and 14.

This includes...  Aurora University, Benedictine University,
Fermilab, IL Math and Science Academy, Kane County Cougars Ballpark,
and North Central College.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4188 8843 4193 8823 4173 8803 4168 8803
      4164 8839
TIME...MOT...LOC 1955Z 334DEG 15KT 4184 8830 

HAIL...0.88IN
WIND...60MPH
 
$$

Borchardt

3 follow-up statements

951 
WWUS53 KLOT 122014
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
314 PM CDT Sat Jun 12 2021

ILC043-089-093-197-122100-
/O.CON.KLOT.SV.W.0007.000000T0000Z-210612T2100Z/
Kendall IL-Will IL-Kane IL-DuPage IL-
314 PM CDT Sat Jun 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR NORTHEASTERN KENDALL...NORTHWESTERN WILL...SOUTHEASTERN KANE AND
SOUTHWESTERN DUPAGE COUNTIES...

At 314 PM CDT, a severe thunderstorm was located over Aurora, moving
southeast at 15 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Aurora, Naperville, Bolingbrook, Romeoville, Plainfield, Woodridge,
Oswego, West Chicago, Batavia, Yorkville, Lisle, Montgomery, North
Aurora, Warrenville, Sugar Grove and Boulder Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4184 8842 4188 8820 4173 8803 4168 8803
      4164 8839
TIME...MOT...LOC 2014Z 334DEG 15KT 4178 8826 

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

Borchardt

604 
WWUS53 KLOT 122032
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
332 PM CDT Sat Jun 12 2021

ILC043-089-093-197-122100-
/O.CON.KLOT.SV.W.0007.000000T0000Z-210612T2100Z/
Kendall IL-Will IL-Kane IL-DuPage IL-
332 PM CDT Sat Jun 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR NORTHEASTERN KENDALL...NORTHWESTERN WILL...SOUTHEASTERN KANE AND
SOUTHWESTERN DUPAGE COUNTIES...

At 332 PM CDT, a severe thunderstorm was located over Montgomery, or
near Aurora, moving southeast at 15 mph.

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

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Aurora, Naperville, Bolingbrook, Romeoville, Plainfield, Woodridge,
Oswego, West Chicago, Batavia, Yorkville, Lisle, Montgomery, North
Aurora, Warrenville, Sugar Grove and Boulder Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4184 8842 4188 8820 4173 8803 4168 8803
      4164 8839
TIME...MOT...LOC 2032Z 322DEG 12KT 4176 8838 

HAIL...1.00IN
WIND...60MPH
 
$$

Borchardt

250 
WWUS53 KLOT 122051
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
351 PM CDT Sat Jun 12 2021

ILC043-089-093-197-122101-
/O.EXP.KLOT.SV.W.0007.000000T0000Z-210612T2100Z/
Kendall IL-Will IL-Kane IL-DuPage IL-
351 PM CDT Sat Jun 12 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN KENDALL...
NORTHWESTERN WILL...SOUTHEASTERN KANE AND SOUTHWESTERN DUPAGE
COUNTIES WILL EXPIRE AT 400 PM CDT...
                
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 will be allowed to expire.  However gusty
winds and heavy rain are still possible with this thunderstorm.

LAT...LON 4184 8842 4188 8820 4173 8803 4168 8803
      4164 8839
TIME...MOT...LOC 2051Z 334DEG 15KT 4170 8834 

$$

Borchardt

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 12, 1:23 PM CDT	Special Weather Statement	LOT	Cook, DeKalb, DuPage, Grundy, Kane, Kankakee and 5 more	112 min
Jun 12, 1:52 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	68 min
Jun 12, 2:26 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	41 min
Jun 12, 2:37 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage	3 hr
Jun 12, 3:26 PM CDT	Severe Thunderstorm Warning	LOT	Kane, Kendall, Will	47 min
Jun 12, 4:13 PM CDT	Special Weather Statement	LOT	Kankakee	62 min
Jun 12, 5:04 PM CDT	Special Weather Statement	LOT	Ford, Iroquois	71 min
Jun 12, 5:11 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Livingston	64 min
Jun 12, 5:30 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	45 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.