Alert archive / Illinois / Tornado Warnings in 2011

Tornado Warning 5, NWS Chicago, IL

May 12, 2011McHenry County, Illinois

NWS Chicago, IL issued this tornado warning at May 12, 2011, 4:58 PM CDT for McHenry County, Illinois. It was in force for 32 min. 4 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: May 12, 2011, 4:58 PM CDT (21:58 UTC)
Expired: May 12, 2011, 5:30 PM CDT
In force: 32 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon

County McHenry County, IL

The radar

The Milwaukee radar (KMKX), 65 km from the middle of the area, began a volume at 21:58 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
May 12, 5:06 PM CDT	HAIL 1	Woodstock, IL	INTERSECTION OF NELSON AND HEARTLAND
May 12, 5:15 PM CDT	TSTM WND DMG	Hebron, IL	HORIZONTAL RAIN AND SMALL TREE BRANCHES DOWN.
May 12, 5:20 PM CDT	TSTM WND DMG	Hebron, IL	SCHOOL ZONE SIGN DOWN BY THUNDERSTORM WINDS. PRICE RD AND RT 47
May 12, 5:26 PM CDT	HAIL 0.25	Hebron, IL	GREENWOOD AND RT 173. HORIZONTAL RAIN AS WELL

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 12:00Z, 10.0 hours before the alert went out and 187 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: 698 J/kg
Mixed-layer CIN: -97 J/kg
Mixed-layer LCL: 1070 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 9 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

359 
WFUS53 KLOT 122158
TORLOT
ILC111-122230-
/O.NEW.KLOT.TO.W.0005.110512T2158Z-110512T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
458 PM CDT THU MAY 12 2011

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  MCHENRY COUNTY...

* UNTIL 530 PM CDT

* AT 455 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS STORM WAS 
  LOCATED 2 MILES NORTHWEST OF MARENGO...MOVING NORTHEAST AT 20 MPH.

  IN ADDITION...A TRAINED SPOTTER REPORTED A FUNNEL CLOUD IN         
  ASSOCIATION WITH THIS STORM. 

* LOCATIONS IMPACTED INCLUDE...
  MARENGO...WOODSTOCK...AND WONDER LAKE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4250 8840 4233 8822 4217 8870 4233 8870
      4250 8849
TIME...MOT...LOC 2155Z 234DEG 15KT 4226 8862

$$

MERZLOCK

2 follow-up statements

767 
WWUS53 KLOT 122211
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
511 PM CDT THU MAY 12 2011

ILC111-122230-
/O.CON.KLOT.TO.W.0005.000000T0000Z-110512T2230Z/
MCHENRY IL-
511 PM CDT THU MAY 12 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR MCHENRY COUNTY UNTIL 530
PM CDT...

AT 506 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 5 MILES NORTHWEST OF WOODSTOCK...MOVING NORTHEAST 
AT 25 MPH.  

AT 505 PM CDT ONE INCH DIAMETER HAIL WAS REPORTED TO BE COVERING THE 
GROUND AT NELSON AND HEARTLAND ROADS JUST NORTH OF WOODSTOCK.  

LOCATIONS IMPACTED INCLUDE...
  WOODSTOCK...WONDER LAKE...BULL VALLEY...HEBRON AND RICHMOND. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4250 8840 4233 8822 4217 8870 4233 8870
      4250 8849
TIME...MOT...LOC 2206Z 234DEG 15KT 4229 8857

$$

MERZLOCK

946 
WWUS53 KLOT 122222
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
522 PM CDT THU MAY 12 2011

ILC111-122230-
/O.CON.KLOT.TO.W.0005.000000T0000Z-110512T2230Z/
MCHENRY IL-
522 PM CDT THU MAY 12 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR MCHENRY COUNTY UNTIL 530
PM CDT...

AT 518 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 4 MILES WEST NORTHWEST OF WONDER LAKE...MOVING 
NORTHEAST AT 25 MPH.

LOCATIONS IMPACTED INCLUDE...
  WONDER LAKE...RICHMOND...SPRING GROVE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4250 8840 4233 8822 4217 8870 4233 8870
      4250 8849
TIME...MOT...LOC 2220Z 234DEG 15KT 4232 8851

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
May 11, 7:04 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Will	56 min
May 11, 7:37 PM CDT	Special Marine Warning	LOT		83 min
May 11, 7:57 PM CDT	Severe Thunderstorm Warning	LOT	Cook	19 min
May 11, 8:57 PM CDT	Special Marine Warning	LOT		32 min
May 12, 3:20 AM CDT	Special Weather Statement	LOT	Kane	30 min
May 12, 3:29 AM CDT	Marine Dense Fog Advisory	LOT		36 hr
May 12, 3:34 AM CDT	Special Weather Statement	LOT	DuPage	56 min
May 12, 3:58 AM CDT	Special Weather Statement	LOT	Lake	32 min
May 12, 9:11 AM CDT	River Flood Advisory	LOT	Kane, Kendall	12 hr
May 12, 5:25 PM CDT	Tornado Warning	LOT	McHenry	20 min

Nearby

Tornado Warnings in Illinois, 2011 Every tornado warning in 2011 Tornadoes in 2011

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.