Alert archive / Illinois / Tornado Warnings in 2020

Tornado Warning 21, NWS Chicago, IL

August 10, 20204 counties in Illinois

NWS Chicago, IL issued this tornado warning at Aug 10, 2020, 3:11 PM CDT for 4 counties in Illinois. It was in force for 34 min. 15 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: Aug 10, 2020, 3:11 PM CDT (20:11 UTC)
Expired: Aug 10, 2020, 3:45 PM CDT
In force: 34 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties DeKalb County, IL, Kane County, IL, Kendall County, IL, LaSalle County, IL

The radar

The Chicago radar (KLOT), 38 km from the middle of the area, began a volume at 20:10 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
Aug 10, 3:12 PM CDT	TORNADO	3 Ssw Virgil, IL	DRONE FOOTAGE REVEALS A NARROW SWATH OF CORN LIKELY AROUND 40 YARDS ACROSS FLATTENED IN A CONVERGENT PATTERN. IN ADDITION, DAMAGE TO A BARN WAS NOTED, WITH A NEAR COMPLETE REMOVAL OF THE ROOF. THIS DAMAGE IS CONSISTENT WITH A TORNADO WITH WINDS OF EF-1 INTENSI
Aug 10, 3:14 PM CDT	TSTM WND GST 57	2 Ese Somonauk, IL	PRIVATE WEATHER STATION OBSERVED 57 MPH WIND GUST NEAR LAKE HOLIDAY. WIND GUSTS OVER 50 MPH FOR AT LEAST 15 MINUTES.
Aug 10, 3:14 PM CDT	TSTM WND GST 65	3 Sse Plano, IL	PRIVATE WEATHER STATION RECORDED 65 MPH WIND GUST.
Aug 10, 3:15 PM CDT	TSTM WND DMG	3 E Kaneville, IL	8 INCH DIAMETER TREE SNAPPED NEAR IL-47 AND NOTTINGHAM. RELAYED VIA NWS CHAT, TIME ESTIMATED BY RADAR.
Aug 10, 3:15 PM CDT	TSTM WND DMG	3 Ese Maple Park, IL	4 INCH DIAMETER BRANCH DOWNED AND DAMAGE TO TRAFFIC SIGNALS AT IL-38 AND MEREDITH ROAD. TIME ESTIMATED BY RADAR.
Aug 10, 3:15 PM CDT	TSTM WND DMG	Somonauk, IL	TRAINED SPOTTER REPORTS WIDESPREAD TREE AND POWER LINE DAMAGE ACROSS SOMANAUK. TREES UP TO 4-6 DIAMETER SNAPPED AT THE BASE.
Aug 10, 3:15 PM CDT	TORNADO	5 W Plainfield, IL	AN EF-1 TORNADO WITH PEAK WINDS OF 105 MPH, PATH LENGTH OF 14.5 MILES, AND MAX WIDTH OF 250 YARDS STARTED ON THE SOUTH SIDE OF YORKVILLE DESTROYING A PERGOLA, TAKING SIDING OFF A HOUSE, AND THROWING A TREE ACROSS A ROAD. THE TORNADO THEN CONTINUED SOUTHEAST AN
Aug 10, 3:16 PM CDT	TSTM WND GST 62	1 Wnw Sugar Grove, IL	AURORA ASOS PEAK GUST.
Aug 10, 3:16 PM CDT	TSTM WND GST 62	2 W Sugar Grove, IL
Aug 10, 3:20 PM CDT	TSTM WND DMG	2 W Sugar Grove, IL	TREE DAMAGE BLOCKING FAYS LANE WEST OF SUGAR GROVE. TIME ESTIMATED BY RADAR.
Aug 10, 3:20 PM CDT	TSTM WND DMG	Aurora, IL	10 INCH DIAMETER TREE SNAPPED. TIME ESTIMATED BY RADAR.
Aug 10, 3:20 PM CDT	TSTM WND DMG	Yorkville, IL	SEVERAL TREES AND LARGE BRANCHES DOWN. TIME ESTIMATED BY RADAR.
Aug 10, 3:29 PM CDT	TSTM WND DMG	St. Charles, IL	14 INCH DIAMETER TREE SPLIT IN HALF. POWER LINES DOWNED. TIME ESTIMATED BY RADAR.
Aug 10, 3:30 PM CDT	TSTM WND DMG	4 Nw Plainfield, IL	DAMAGE TO SIDING OF A HOUSE. SMALL BRANCHES DOWNED IN THE VICINITY. TIME ESTIMATED BY RADAR.
Aug 10, 3:38 PM CDT	TSTM WND GST 62	1 Wsw Dupage Airport, IL	DUPAGE ASOS PEAK GUST.

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
Aug 10, 11:26 AM CDT	Severe Thunderstorm Watch PDS	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 8.2 hours before the alert went out and 163 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: 1683 J/kg
Mixed-layer CIN: -223 J/kg
Mixed-layer LCL: 894 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 80 m²/s²
0-3 km storm-relative helicity: 96 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

167 
WFUS53 KLOT 102011
TORLOT
ILC037-089-093-099-102045-
/O.NEW.KLOT.TO.W.0021.200810T2011Z-200810T2045Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Chicago/Romeoville
311 PM CDT Mon Aug 10 2020

The National Weather Service in Chicago has issued a

* Tornado Warning for...
  Kendall County in northeastern Illinois...
  Northeastern La Salle County in north central Illinois...
  Southeastern De Kalb County in north central Illinois...
  Kane County in northeastern Illinois...

* Until 345 PM CDT.
    
* At 310 PM CDT, severe thunderstorms capable of producing tornadoes 
  were located along a line extending from Maple Park to near 
  Hinckley to near Sandwich to Lake Holiday to near Sheridan, moving 
  east at 60 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* These dangerous storms will be near...
  Plano and Lily Lake around 315 PM CDT.
  Yorkville, Campton Hills, Sugar Grove and Elburn around 320 PM 
  CDT.
  Aurora, St. Charles, Oswego, Geneva, Montgomery, North Aurora, 
  Boulder Hill and Valley View around 325 PM CDT.
  Bartlett, West Chicago, Batavia, Minooka and Wayne around 330 PM 
  CDT.
  Joliet and Plainfield around 335 PM CDT.

Other locations impacted by these tornadic storms include Kaneville,
Plattville, Norway, Virgil, Lisbon, Bristol, Millbrook, Millington,
Little Rock and Big Rock.

This includes...  Sandwich Fairgrounds, Aurora University, Fermilab,
IL Math and Science Academy, Kane County Cougars Ballpark, and
Waubonsee Community College.
 
Including the following interstates...
 I-80 between mile markers 120 and 122.
 I-88 between mile markers 97 and 120.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4146 8825 4146 8859 4145 8860 4145 8870
      4162 8869 4171 8870 4179 8866 4198 8868
      4199 8826
TIME...MOT...LOC 2010Z 271DEG 51KT 4191 8862 4180 8861 4172 8865 4162
8864 4152 8865

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

Carlaw

3 follow-up statements

696 
WWUS53 KLOT 102021 RRA
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
321 PM CDT Mon Aug 10 2020

ILC037-099-102031-
/O.CAN.KLOT.TO.W.0021.000000T0000Z-200810T2045Z/
La Salle IL-De Kalb IL-
321 PM CDT Mon Aug 10 2020

...THE TORNADO WARNING FOR NORTHEASTERN LA SALLE AND SOUTHEASTERN DE
KALB COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 700 PM CDT for
northeastern Illinois.

LAT...LON 4146 8825 4146 8859 4198 8860 4199 8826
TIME...MOT...LOC 2021Z 268DEG 53KT 4191 8842 4177 8844 4170 8847 4158
8842

$$

ILC089-093-102045-
/O.CON.KLOT.TO.W.0021.000000T0000Z-200810T2045Z/
Kendall IL-Kane IL-
321 PM CDT Mon Aug 10 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 345 PM CDT FOR KENDALL
AND SOUTHERN KANE COUNTIES...
        
At 321 PM CDT, tornado producing storms were located along a line
extending from near Elburn to Sugar Grove to near Yorkville to 8
miles southeast of Plano, moving east at 60 mph.

HAZARD...Damaging tornado.

SOURCE...Radar confirmed tornado near Lisbon. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These tornadic storms will be near...
  Aurora, St. Charles, Oswego, Geneva, Montgomery, Boulder Hill and 
  Valley View around 325 PM CDT.
  Bartlett, West Chicago, Batavia, South Elgin, North Aurora and 
  Wayne around 330 PM CDT.
  Plainfield around 335 PM CDT.

Other locations impacted by these tornadic storms include Kaneville,
Plattville, Virgil, Lisbon, Bristol, Millbrook, Little Rock and Big
Rock.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. TAKE COVER NOW! Move to a
basement or an interior room on the lowest floor of a sturdy
building. Avoid windows. If you are outdoors, in a mobile home, or in
a vehicle, move to the closest substantial shelter and protect
yourself from flying debris.

&&

LAT...LON 4146 8825 4146 8859 4198 8860 4199 8826
TIME...MOT...LOC 2021Z 268DEG 53KT 4191 8842 4177 8844 4170 8847 4158
8842

TORNADO...OBSERVED
HAIL...<.75IN

$$

Carlaw

057 
WWUS53 KLOT 102030
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
330 PM CDT Mon Aug 10 2020

ILC089-093-102045-
/O.CON.KLOT.TO.W.0021.000000T0000Z-200810T2045Z/
Kendall IL-Kane IL-
330 PM CDT Mon Aug 10 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 345 PM CDT FOR EASTERN
KENDALL AND SOUTHEASTERN KANE COUNTIES...
    
At 329 PM CDT, severe thunderstorms capable of producing tornadoes
were located along a line extending from Geneva to Montgomery to near
Plainfield, moving east at 60 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These dangerous storms will be near...
  Joliet around 335 PM CDT.

Other locations impacted by these tornadic storms include Plattville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4148 8825 4154 8840 4199 8838 4199 8826
TIME...MOT...LOC 2029Z 270DEG 53KT 4188 8830 4173 8831 4158 8829 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

Carlaw

787 
WWUS53 KLOT 102044
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
344 PM CDT Mon Aug 10 2020

ILC089-093-102053-
/O.EXP.KLOT.TO.W.0021.000000T0000Z-200810T2045Z/
Kendall IL-Kane IL-
344 PM CDT Mon Aug 10 2020

...THE TORNADO WARNING FOR EASTERN KENDALL AND SOUTHEASTERN KANE
COUNTIES WILL EXPIRE AT 345 PM CDT...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 700 PM CDT for
northeastern Illinois.

LAT...LON 4148 8825 4154 8840 4199 8838 4199 8826
TIME...MOT...LOC 2043Z 271DEG 51KT 4188 8806 4173 8807 4158 8805 

$$

Carlaw

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 7:07 PM CDT	Special Weather Statement	LOT	Lake	53 min
Aug 10, 1:41 PM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle, Winnebago	94 min
Aug 10, 1:57 PM CDT	Special Marine Warning	LOT		3 hr
Aug 10, 2:03 PM CDT	Beach Hazards Statement	LOT	Cook	23 hr
Aug 10, 2:03 PM CDT	Severe Thunderstorm Warning	LOT	Boone, DeKalb, LaSalle	87 min
Aug 10, 2:24 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Kane, Kendall, McHenry	96 min
Aug 10, 2:43 PM CDT	Tornado Warning	LOT	Boone, Winnebago	62 min
Aug 10, 2:47 PM CDT	Severe Thunderstorm Warning	LOT	Livingston	58 min
Aug 10, 2:55 PM CDT	Tornado Warning	LOT	Boone	34 min
Aug 10, 2:56 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Kankakee, Lake, Will	49 min
Aug 10, 3:21 PM CDT	Areal Flood Advisory	LOT	Boone, Winnebago	3 hr
Aug 10, 3:25 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	65 min
Aug 10, 3:26 PM CDT	Tornado Warning	LOT	DuPage, Will	34 min
Aug 10, 3:31 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee	89 min
Aug 10, 3:32 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Kankakee, Lake, Will	43 min
Aug 10, 3:43 PM CDT	Tornado Warning	LOT	Cook, DuPage	26 min
Aug 10, 3:44 PM CDT	Tornado Warning	LOT	Lake, McHenry	47 min
Aug 10, 4:23 PM CDT	High Wind Warning	LOT	Boone, Cook, DeKalb, DuPage, Grundy, Kane and 10 more	90 min
Aug 10, 4:53 PM CDT	Special Marine Warning	LOT		85 min
Aug 10, 6:08 PM CDT	Small Craft Advisory	LOT		10 hr

Nearby

Tornado Warnings in Illinois, 2020 Every tornado warning in 2020 Tornadoes in 2020

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.