Alert archive / Illinois / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 13, NWS Chicago, IL

May 4, 2012Grundy County, LaSalle County, Livingston County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at May 4, 2012, 12:34 AM CDT for Grundy County, LaSalle County, Livingston County, Illinois. It was in force for 71 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: May 4, 2012, 12:34 AM CDT (05:34 UTC)
Expired: May 4, 2012, 1:45 AM CDT
In force: 71 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Grundy County, IL, LaSalle County, IL, Livingston County, IL

The radar

The Chicago radar (KLOT), 95 km from the middle of the area, began a volume at 05:35 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 4, 12:58 AM CDT	TSTM WND DMG	Long Point, IL	MULTIPLE UTILITY POLES AND WIRES DOWNED ALONG WITH A FEW TREES BLOWN DOWN IN THE AREA. TIME ESTIMATED BASED ON RADAR.
May 4, 1:07 AM CDT	TSTM WND DMG	Cornell, IL	SCATTERED WIND DAMAGE IN THE AREA...INCLUDING A FEW TREES AND UTILITY POLES DOWNED. TIME ESTIMATED BASED ON RADAR.
May 4, 1:15 AM CDT	TSTM WND DMG	Pontiac, IL	SCATTERED WIND DAMAGE...INCLUDING A FEW TREES AND MULTIPLE UTILITY POLES DOWNED. TIME ESTIMATED BASED ON RADAR AND PONTIAC AIRPORT OBSERVATION.
May 4, 1:15 AM CDT	TSTM WND GST 52	Pontiac, IL
May 4, 1:15 AM CDT	TSTM WND GST 64	Pontiac, IL

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 3, 11:34 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 5.6 hours before the alert went out and 88 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: 1905 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 1071 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 12 m²/s²
0-3 km storm-relative helicity: 96 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

404 
WUUS53 KLOT 040534
SVRLOT
ILC063-099-105-040645-
/O.NEW.KLOT.SV.W.0013.120504T0534Z-120504T0645Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1234 AM CDT FRI MAY 4 2012

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN GRUNDY COUNTY IN NORTHEAST ILLINOIS...
  SOUTHERN LA SALLE COUNTY IN NORTH CENTRAL ILLINOIS...
  LIVINGSTON COUNTY IN CENTRAL ILLINOIS...

* UNTIL 145 AM CDT

* AT 1229 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
  LOCATED ALONG A LINE EXTENDING FROM MC NABB TO VARNA TO METAMORA TO
  PEORIA...AND MOVING EAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  TONICA AROUND 1240 AM CDT.
  STREATOR AROUND 100 AM CDT.
  FLANAGAN AROUND 105 AM CDT.
  PONTIAC AROUND 120 AM CDT.
  ODELL AROUND 125 AM CDT.
  FAIRBURY AROUND 130 AM CDT.
  FORREST AROUND 140 AM CDT.


LAT...LON 4062 8858 4075 8859 4075 8894 4092 8894
      4093 8905 4110 8905 4111 8917 4136 8917
      4135 8890 4117 8834 4075 8838 4062 8845
TIME...MOT...LOC 0534Z 291DEG 36KT 4116 8921 4099 8922
          4077 8934 4075 8954
WIND...HAIL 60MPH 1.00IN

$$

IZZI

4 follow-up statements

614 
WWUS53 KLOT 040551
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 AM CDT FRI MAY 4 2012

ILC063-099-105-040645-
/O.CON.KLOT.SV.W.0013.000000T0000Z-120504T0645Z/
LA SALLE IL-LIVINGSTON IL-GRUNDY IL-
1251 AM CDT FRI MAY 4 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHWESTERN
GRUNDY...LIVINGSTON AND SOUTHERN LA SALLE COUNTIES UNTIL 145 AM
CDT...

AT 1249 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM NAPLATE TO STREATOR TO MINONK TO
5 MILES SOUTHEAST OF WASHBURN...MOVING SOUTHEAST AT 35 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  FLANAGAN AROUND 105 AM CDT.
  PONTIAC AROUND 120 AM CDT.
  ODELL AROUND 125 AM CDT.
  DWIGHT AROUND 135 AM CDT.
  FAIRBURY AROUND 140 AM CDT.
  FORREST AROUND 145 AM CDT.


LAT...LON 4062 8858 4075 8859 4075 8894 4092 8894
      4093 8905 4110 8905 4111 8917 4136 8917
      4135 8890 4117 8834 4075 8838 4062 8845
TIME...MOT...LOC 0552Z 295DEG 30KT 4127 8886 4110 8887
          4088 8899 4086 8919
WIND...HAIL 60MPH 1.00IN

$$

IZZI

478 
WWUS53 KLOT 040611
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
111 AM CDT FRI MAY 4 2012

ILC063-099-105-040645-
/O.CON.KLOT.SV.W.0013.000000T0000Z-120504T0645Z/
LA SALLE IL-LIVINGSTON IL-GRUNDY IL-
111 AM CDT FRI MAY 4 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHWESTERN
GRUNDY...LIVINGSTON AND SOUTHEASTERN LA SALLE COUNTIES UNTIL 145 AM
CDT...

AT 108 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 7 MILES EAST OF GRAND RIDGE TO 9
MILES SOUTHEAST OF STREATOR TO FLANAGAN TO EL PASO...MOVING SOUTHEAST
AT 35 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  PONTIAC AROUND 120 AM CDT.
  ODELL AROUND 125 AM CDT.
  DWIGHT AROUND 135 AM CDT.
  FAIRBURY AROUND 140 AM CDT.
  FORREST AROUND 145 AM CDT.


LAT...LON 4062 8858 4075 8859 4075 8894 4092 8894
      4093 8905 4101 8899 4110 8897 4135 8900
      4135 8890 4117 8834 4075 8838 4062 8845
TIME...MOT...LOC 0611Z 295DEG 30KT 4120 8867 4103 8868
          4081 8880 4079 8900
WIND...HAIL 60MPH 1.00IN

$$

IZZI

385 
WWUS53 KLOT 040627
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
127 AM CDT FRI MAY 4 2012

ILC063-099-105-040645-
/O.CON.KLOT.SV.W.0013.000000T0000Z-120504T0645Z/
LA SALLE IL-LIVINGSTON IL-GRUNDY IL-
127 AM CDT FRI MAY 4 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHWESTERN
GRUNDY...LIVINGSTON AND SOUTHEASTERN LA SALLE COUNTIES UNTIL 145 AM
CDT...

AT 126 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 8 MILES WEST OF DWIGHT TO 8 MILES
SOUTH OF ODELL TO CHENOA...MOVING SOUTHEAST AT 35 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  FAIRBURY AROUND 135 AM CDT.
  DWIGHT AROUND 140 AM CDT.
  FORREST AROUND 145 AM CDT.


LAT...LON 4062 8858 4075 8859 4075 8894 4089 8888
      4095 8880 4108 8876 4128 8875 4127 8865
      4117 8834 4075 8838 4062 8845
TIME...MOT...LOC 0628Z 295DEG 30KT 4113 8855 4088 8846
          4073 8865
WIND...HAIL 60MPH 1.00IN

$$

IZZI

961 
WWUS53 KLOT 040645
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
145 AM CDT FRI MAY 4 2012

ILC063-099-105-040655-
/O.EXP.KLOT.SV.W.0013.000000T0000Z-120504T0645Z/
LA SALLE IL-LIVINGSTON IL-GRUNDY IL-
145 AM CDT FRI MAY 4 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN GRUNDY...
LIVINGSTON AND SOUTHEASTERN LA SALLE COUNTIES HAS EXPIRED...

HOWEVER...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR FAR 
EASTERN LIVINGSTON COUNTY.

THE LINE OF STORMS WHICH PROMPTED THE WARNING HAVE MOVED OUT OF THE
WARNED AREA...HOWEVER GUSTY WINDS AND HEAVY RAIN ARE STILL POSSIBLE
WITH THESE THUNDERSTORMS.

LAT...LON 4062 8858 4075 8859 4075 8894 4089 8888
      4095 8880 4108 8876 4128 8875 4127 8865
      4117 8834 4075 8838 4062 8845
TIME...MOT...LOC 0627Z 295DEG 30KT 4113 8856 4088 8847
          4073 8866

$$

IZZI

The office that day

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

Issued	Product	Office	Counties	Lasted
May 3, 7:08 PM CDT	Severe Thunderstorm Warning	LOT	Cook	67 min
May 3, 7:23 PM CDT	Flash Flood Warning	LOT	Cook, DuPage	4 hr
May 3, 8:00 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	75 min
May 3, 8:07 PM CDT	Severe Thunderstorm Warning	LOT	LaSalle, Livingston	68 min
May 3, 8:12 PM CDT	Special Marine Warning	LOT		2 hr
May 3, 8:43 PM CDT	Flash Flood Watch	LOT	DuPage, Grundy, Kankakee, Kendall, LaSalle, Livingston	7 hr
May 3, 9:19 PM CDT	Special Marine Warning	LOT		116 min
May 3, 9:29 PM CDT	Special Weather Statement	LOT	Will	31 min
May 3, 9:50 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Will	55 min
May 3, 10:10 PM CDT	Flash Flood Warning	LOT	Cook	5 hr
May 3, 10:47 PM CDT	Special Weather Statement	LOT	Cook	28 min
May 4, 12:46 AM CDT	Flash Flood Warning	LOT	LaSalle, Livingston	6 hr
May 4, 1:26 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Grundy, Iroquois, Kankakee, Livingston	63 min
May 4, 3:07 AM CDT	Marine Dense Fog Advisory	LOT		18 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2012 Every severe thunderstorm warning in 2012

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.