Alert archive / Illinois / Tornado Warnings in 2011

Tornado Warning 6, NWS Chicago, IL

May 12, 2011McHenry County, Illinois

NWS Chicago, IL issued this tornado warning at May 12, 2011, 5:25 PM CDT for McHenry County, Illinois. It was in force for 20 min. 2 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, 5:25 PM CDT (22:25 UTC)
Expired: May 12, 2011, 5:45 PM CDT
In force: 20 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon

County McHenry County, IL

The radar

The Milwaukee radar (KMKX), 61 km from the middle of the area, began a volume at 22:26 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, 5:26 PM CDT	HAIL 0.25	Hebron, IL	GREENWOOD AND RT 173. HORIZONTAL RAIN AS WELL
May 12, 5:35 PM CDT	TSTM WND DMG	Richmond, IL	TWO 10 INCH DIAMETER TREES BLOCKING BROADWAY STREET...1/2 MILES FROM KEYSTONE ROAD.

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, 10.4 hours before the alert went out and 202 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.

908 
WFUS53 KLOT 122225
TORLOT
ILC111-122245-
/O.NEW.KLOT.TO.W.0006.110512T2225Z-110512T2245Z/

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

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

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

* UNTIL 545 PM CDT

* AT 519 PM...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...AND      
  MOVING NORTHEAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  RICHMOND AND 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 4245 8820 4235 8839 4242 8850 4250 8842
      4250 8820
TIME...MOT...LOC 2224Z 226DEG 21KT 4244 8834

$$

MERZLOCK

2 follow-up statements

065 
WWUS53 KLOT 122238
SVSLOT

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

ILC111-122245-
/O.CON.KLOT.TO.W.0006.000000T0000Z-110512T2245Z/
MCHENRY IL-
538 PM CDT THU MAY 12 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHEASTERN MCHENRY
COUNTY UNTIL 545 PM CDT...

AT 530 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED NEAR RICHMOND...MOVING NORTHEAST AT 25 MPH.  THIS 
STORM WILL BE MOVING INTO KENOSHA COUNTY WISCONSIN BY 545 PM CDT. 

LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF EXTREME NORTHEASTERN MCHENRY COUNTY.

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 4245 8820 4235 8839 4242 8850 4250 8842
      4250 8820
TIME...MOT...LOC 2237Z 226DEG 21KT 4249 8826

$$

MERZLOCK

735 
WWUS53 KLOT 122245
SVSLOT

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

ILC111-122255-
/O.EXP.KLOT.TO.W.0006.000000T0000Z-110512T2245Z/
MCHENRY IL-
545 PM CDT THU MAY 12 2011

...THE TORNADO WARNING FOR NORTHEASTERN MCHENRY COUNTY HAS EXPIRED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED 
AREA.

LAT...LON 4245 8820 4235 8839 4242 8850 4250 8842
      4250 8820
TIME...MOT...LOC 2238Z 226DEG 21KT 4250 8826

$$

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, 4:58 PM CDT	Tornado Warning	LOT	McHenry	32 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.