Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 49, NWS Chicago, IL

July 28, 2021Cook County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 28, 2021, 4:50 AM CDT for Cook 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 28, 2021, 4:50 AM CDT (09:50 UTC)
Expired: Jul 28, 2021, 5:15 AM CDT
In force: 25 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Cook County, IL

The radar

The Chicago radar (KLOT), 53 km from the middle of the area, began a volume at 09:51 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
Jul 28, 5:03 AM CDT	TSTM WND DMG	Morton Grove, IL	DELAYED REPORT. MULTIPLE LARGE LIVE TREES DOWNED AROUND MORTON GROVE.

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 00:00Z, 9.8 hours before the alert went out and 219 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: 781 J/kg
Mixed-layer CIN: -301 J/kg
Mixed-layer LCL: 1487 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 47 m²/s²
0-3 km storm-relative helicity: 165 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

307 
WUUS53 KLOT 280950
SVRLOT
ILC031-281015-
/O.NEW.KLOT.SV.W.0049.210728T0950Z-210728T1015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville
450 AM CDT Wed Jul 28 2021

The National Weather Service in Chicago has issued a

* Severe Thunderstorm Warning for...
  Northeastern Cook County in northeastern Illinois...

* Until 515 AM CDT.

* At 450 AM CDT, a severe thunderstorm was located over Glenview,
  moving east at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Chicago, Arlington Heights, Evanston, Skokie, Des Plaines, Mount
  Prospect, Glenview, Buffalo Grove, Ohare Airport, Wheeling, Park
  Ridge, Northbrook, Elk Grove Village, Niles, West Town, Lake View,
  Irving Park, West Ridge, Lincoln Park and Chicago Loop.

Including the following interstates...
 I-90 between mile markers 73 and 84.
 I-94 between mile markers 26 and 50.
 I-294 between mile markers 26 and 50.

This includes...  Lincoln Park Zoo, Loyola University, Oakton
Community College, Northeastern Illinois University, Northwestern
University, Wrigley Field, and The Loop.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4211 8773 4208 8768 4206 8767 4203 8767
      4198 8765 4196 8763 4196 8764 4191 8762
      4190 8762 4189 8761 4188 8762 4195 8792
      4199 8792 4199 8797 4215 8796 4215 8776
TIME...MOT...LOC 0950Z 276DEG 27KT 4207 8784 

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

CMS

2 follow-up statements

069 
WWUS53 KLOT 281004
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
504 AM CDT Wed Jul 28 2021

ILC031-281015-
/O.CON.KLOT.SV.W.0049.000000T0000Z-210728T1015Z/
Cook IL-
504 AM CDT Wed Jul 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 AM CDT
FOR NORTHEASTERN COOK COUNTY...

At 502 AM CDT, a severe thunderstorm was located over Lincolnwood, or
over West Ridge, moving southeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Chicago, Evanston, Skokie, Des Plaines, Glenview, Ohare Airport, Park
Ridge, Northbrook, Niles, West Town, Lake View, Irving Park, West
Ridge, Lincoln Park, Chicago Loop, Austin, Wilmette, Franklin Park,
Norridge and Navy Pier.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4211 8773 4208 8768 4206 8767 4203 8767
      4198 8765 4196 8763 4196 8764 4191 8762
      4190 8762 4189 8761 4188 8762 4195 8792
      4201 8792 4215 8785 4215 8776
TIME...MOT...LOC 1002Z 298DEG 28KT 4200 8774 

HAIL...<.75IN
WIND...60MPH
 
OEMC zones...SEVERE THUNDERSTORM WARNING.  
1...2...3...4...5...and 6.
 
$$

CMS

214 
WWUS53 KLOT 281015
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
515 AM CDT Wed Jul 28 2021

ILC031-281025-
/O.EXP.KLOT.SV.W.0049.000000T0000Z-210728T1015Z/
Cook IL-
515 AM CDT Wed Jul 28 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN COOK COUNTY HAS
EXPIRED...
                
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 allowed to expire.  However gusty
winds and heavy rain are still possible with this thunderstorm.

LAT...LON 4211 8773 4208 8768 4206 8767 4203 8767
      4198 8765 4196 8763 4196 8764 4191 8762
      4190 8762 4189 8761 4188 8762 4195 8792
      4201 8792 4215 8785 4215 8776
TIME...MOT...LOC 1015Z 276DEG 27KT 4199 8764 

$$

CMS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 28, 3:35 AM CDT	Special Weather Statement	LOT	Boone, McHenry	25 min
Jul 28, 3:59 AM CDT	Special Weather Statement	LOT	McHenry	31 min
Jul 28, 4:30 AM CDT	Special Weather Statement	LOT	Will	45 min
Jul 28, 4:32 AM CDT	Special Weather Statement	LOT	Cook, Lake	43 min
Jul 28, 4:43 AM CDT	Special Marine Warning	LOT		77 min
Jul 28, 4:52 AM CDT	Special Weather Statement	LOT	DeKalb	38 min
Jul 28, 5:08 AM CDT	Special Weather Statement	LOT	Kankakee, Will	37 min
Jul 28, 5:27 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	34 min
Jul 28, 5:34 AM CDT	Special Weather Statement	LOT	Kendall	41 min
Jul 28, 6:11 AM CDT	Special Weather Statement	LOT	Will	34 min
Jul 28, 3:44 PM CDT	Beach Hazards Statement	LOT	Cook, Lake	51 hr
Jul 28, 3:44 PM CDT	Small Craft Advisory	LOT		51 hr

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.