Alert archive / Illinois / Tornado Warnings in 2019

Tornado Warning 15, NWS Chicago, IL

September 11, 2019Cook County, Lake County, McHenry County, Illinois

NWS Chicago, IL issued this tornado warning at Sep 11, 2019, 6:53 PM CDT for Cook County, Lake County, McHenry County, Illinois. It was in force for 52 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Sep 11, 2019, 6:53 PM CDT (23:53 UTC)
Expired: Sep 11, 2019, 7:45 PM CDT
In force: 52 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Cook County, IL, Lake County, IL, McHenry County, IL

The radar

The Chicago radar (KLOT), 66 km from the middle of the area, began a volume at 23:54 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.

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.9 hours before the alert went out and 217 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: 1145 J/kg
Mixed-layer CIN: -72 J/kg
Mixed-layer LCL: 1188 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 47 m²/s²
0-3 km storm-relative helicity: 26 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this tornado warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this tornado warning went out at Sep 11, 6:50 PM CDT, 3 minutes earlier.

Area forecast discussion, Sep 11, 6:50 PM CDT, 3 minutes before

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Hazardous weather outlook, Sep 11, 3:37 PM CDT, 3 hours 16 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
337 PM CDT Wed Sep 11 2019

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
122045-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-Cook-
La Salle-Kendall-Grundy-Will-Kankakee-Livingston-Iroquois-Ford-
Lake IN-Porter-Newton-Jasper-Benton-
337 PM CDT Wed Sep 11 2019 /437 PM EDT Wed Sep 11 2019/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited hail risk...up to 1 inches in diameter.
     Limited damaging wind risk...up to 60 mph.
  Limited Flooding Risk.
  Limited Excessive heat Risk.

DISCUSSION...

  There is a chance of thunderstorms across the entire outlook
  area through tonight, but the stronger, more organized storms
  should be north of I-80. The most likely timing for stronger
  storms will be this evening into early tonight. If storms do
  indeed occur, there is a very limited chance of an isolated
  severe thunderstorm or two. In addition, any storms that
  occur could produce torrential rainfall.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday...
  Elevated Severe Thunderstorm Risk.
  Limited Flooding Risk.
  Limited Excessive Heat Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.
Tuesday...
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters are not expected to be needed do to the limited nature
  of any severe risk.

GENERAL STORM MOTION OF THE DAY:

  Moving toward to the east at 25 to 30 mph.

LMZ740>745-122045-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
337 PM CDT Wed Sep 11 2019

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited hail risk...up to up to 1 inch in diameter.
     Limited thunderstorm wind gust risk...up to 50 knots.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday...
  Elevated Thunderstorm Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.

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In the hours before

Special weather statement, Sep 11, 6:34 PM CDT, 19 minutes before

Special Weather Statement
National Weather Service Chicago/Romeoville
634 PM CDT Wed Sep 11 2019

ILZ005-006-120030-
Lake IL-McHenry IL-
634 PM CDT Wed Sep 11 2019

...SIGNIFICANT WEATHER ADVISORY FOR LAKE AND EASTERN MCHENRY COUNTIES
UNTIL 730 PM CDT...

At 634 PM CDT, Doppler radar was tracking a strong thunderstorm over
Island Lake, moving east at 25 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Waukegan, Buffalo Grove, North Chicago, Gurnee, Mundelein, Algonquin,
Highland Park, McHenry, Vernon Hills, Woodstock, Grayslake,
Libertyville, Lake Zurich, Lake Forest, Round Lake, Deerfield, Beach
Park, Wauconda, Fox Lake and Lake Villa.

This includes...  College of Lake County, Great Lakes Naval Training
Center, IL Beach State Park, Lake County IL Fairgrounds, Lake Forest
College, Mchenry County College, Moraine Hills State Park, and Six
Flags Great America.

LAT...LON 4239 8781 4238 8781 4236 8782 4237 8782
      4233 8783 4233 8782 4231 8782 4230 8783
      4229 8783 4223 8781 4217 8777 4217 8840
      4242 8839 4243 8780
TIME...MOT...LOC 2334Z 269DEG 22KT 4229 8820

RODRIGUEZ

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 11, 6:34 PM CDT	Special Weather Statement	LOT	Lake	56 min

Nearby

Tornado Warnings in Illinois, 2019 Every tornado warning in 2019 Tornadoes in 2019

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.