Tornadoes · United States · Illinois · 2010

EF1 tornado, Matteson to Park Forest, Illinois, June 23, 2010

Name: EF1 tornado, Matteson to Park Forest, Illinois, June 23, 2010
Start: 2010-06-23T23:26:00.000Z
End: 2010-06-23T23:28:00.000Z
Location: Matteson to Park Forest, Illinois

From Matteson to Park Forest, this EF1 tornado ran 2.4 miles across Cook County on June 23, 2010, touching down at 6:26 PM CDT and reaching 200 yards wide. It killed nobody, and did $100,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating: EF1
Date: June 23, 2010
Touchdown: 6:26 PM CDT (23:26 UTC)
Lifted: 6:28 PM CDT (23:28 UTC)
On the ground: 2 minutes
Path length: 2.4 miles (3.9 km)
Path width: 200 yards (183 m)
Deaths: 0
Injuries: 0
Property damage: $100,000
County: Cook County
Touchdown point: 41.505, -87.712
Lift-off point: 41.491, -87.669
Record number: 1006231726-01

What the Weather Service recorded

Severe thunderstorms moved across northern Illinois during the afternoon and evening hours of June 23rd producing widespread wind and tree damage as well as flash flooding.

There was an intense narrow path of damage starting just southeast of the intersection of Lincoln Highway and Governors Highway. The concentrated path went from near Memorial Park to the train platform at Main Street and Hickory. In this neighborhood many large limbs were down and some trees were uprooted. A garage was destroyed and the roof of the train platform was damaged. Winds through this area were likely 90 to 105 mph, which is EF1 on the enhanced Fujita Scale. The path of the damage was from northwest to southeast, but many of the trees were blown from southwest to northeast, across the damage path. This indicated there was likely rotation. Several residents reported seeing rotation or a funnel cloud in this area. Lighter damage continued southeast of the railroad tracks near Wildwood Park and east to the Norwood Plaza at Western and 26th Street. It appears that the tornado dissipated in the forest preserve near 26th Street.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

47 minutes of warning. NWS LOT issued a tornado warning for this county at 22:39 UTC, 47 minutes before the tornado touched down, in force until 23:45 UTC.

The county was under a tornado watch, issued at 19:12 UTC and running to 00:45 UTC.

Issued (UTC)	Expired	Product	Office
06:00 UTC	03:26 UTC	Flash Flood Watch	LOT
08:38 UTC	14:44 UTC	Severe Thunderstorm Watch	LOT
13:42 UTC	18:54 UTC	Flood Advisory	LOT
13:58 UTC	14:30 UTC	Severe Thunderstorm Warning	LOT
19:12 UTC	00:45 UTC	Tornado Watch	LOT
22:01 UTC	23:00 UTC	Severe Thunderstorm Warning	LOT
22:29 UTC	23:30 UTC	Severe Thunderstorm Warning	LOT
22:39 UTC	23:45 UTC	Tornado Warning	LOT
22:42 UTC	02:48 UTC	Flash Flood Warning	LOT
23:03 UTC	23:44 UTC	Tornado Warning	LOT
23:23 UTC	00:07 UTC	Severe Thunderstorm Warning	LOT
23:24 UTC	23:49 UTC	Tornado Warning	LOT
00:10 UTC	03:08 UTC	Flash Flood Warning	LOT
02:47 UTC	14:45 UTC	Flood Warning	LOT

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Moderate Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

What forecasters said that day

The local office's own words before the tornado touched down, 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 the tornado touched down at Jun 23, 5:06 PM CDT, 1 hour 20 minutes earlier.

Area forecast discussion, Jun 23, 5:06 PM CDT, 1 hour 20 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
506 PM CDT WED JUN 23 2010

.MESOSCALE DISCUSSION...
420 PM CDT

VISIBLE SATELLITE IMAGERY INDICATING THE CAP THAT HAD DEVELOPED
EARLIER IS RAPIDLY WEAKENING OR BEING OVERCOME BY THE WARMTH AT THE
SFC...NOTED IN THE INCREASING CUMULUS FIELD ACROSS NORTHERN IL. LLVL
FLOW HAS STRENGTHENED WITH MANY LOCATIONS AT 21Z INDICATING GUSTY
SFC WINDS BETWEEN 18-25KTS. MUCH OF THE REGION REMAINS VERY MOIST
WITH DEW PTS IN THE LOW/MID 70S ACROSS CENTRAL IL/IN. DEEP LAYER
MOISTURE FLUX CONVERGENCE IS NOTED FROM THE STORM PREDICTION CENTER
MESOANALYSIS PAGE ALONG THE BOUNDARY...WHICH IS CURRENTLY LOCATED
ACROSS CENTRAL KANSAS STRETCHING NORTHEAST THROUGH SOUTHERN
WISCONSIN.

THE FOCUS FOR THE AFTERNOON CONVECTION DEVELOPMENT REMAINS WITH
DAMAGING WINDS...HOWEVER WITH LCL HEIGHTS BELOW 2KFT AGL AND
PROXIMITY OF NUMEROUS LLVL BOUNDARIES...HELICITY AND ROTATING
UPDRAFTS OR ISOLATED TORNADOES ARE STILL POSSIBLE. THE 0-6KM BULK
SHEAR VALUES REMAIN PEGGED BTWN 40-50KTS FROM LATEST RUC
ANALYSIS...WITH A FEW POCKETS OF 50-60KTS. 850MB WINDS FROM 20Z
CYCLE OF THE RUC CONTINUE TO INDICATE NEARLY 50KTS OF UNIDIRECTIONAL
WIND FROM SW TO NE. CONVECTION HAS BEGUN TO REALIZE THE DIMINISHING
CAP AND ABUNDANT ENERGY IN THE BOUNDARY LAYER...COUPLED WITH THE
DEEP LAYER SHEAR AND IMPRESSIVE WIND FIELDS BLO 500MB...THE CONCERN
IS ALSO FOR THE DEVELOPMENT OF FAST MOVING LINE OF CONVECTION OR
BOWS. IN ADDITION IT CAN/T BE RULED OUT FOR THE POTENTIAL OF A
DERECHO. DESPITE THE DEEP LAYER SHEAR AND POTENTIAL THAT UPDRAFTS
COULD BECOME SHEARED...THERE IS ALSO A THREAT FOR LARGE HAIL OF
GOLFBALLS OR LARGER.

THE FLOODING THREAT REMAINS VERY HIGH AS WELL WITH VERY MOIST OR
SATURATED SOILS FROM FREQUENT ROUNDS OF CONVECTION OVER THE PAST
SEVERAL DAYS...INCLUDING EARLIER TODAY. FLASH FLOOD GUIDANCE REMAINS
VERY LOW OR IN SOME LOCATIONS LESS THAN ONE HALF INCH...THUS ANY
PRECIPITATION COULD SPAWN LOCALIZED FLOODING. PWAT VALUES REMAIN
ELEVATED IN THE 2 TO 3 STD DEV ABOVE NORMAL OR NEARLY 2.00 INCHES.
BRIEF HEAVY DOWNPOURS ARE POSSIBLE FROM THE LATE AFTERNOON
CONVECTION FOR PORTIONS OF NORTHERN IL.

&&

.DISCUSSION...
227 PM CDT

MAIN FORECAST CONCERN IS ON SEVERE POTENTIAL LATE THIS AFTERNOON
INTO THIS EVENING. PLEASE REFER TO THE ABOVE MESOSCALE DISCUSSION
FOR MORE INFORMATION ON THE SEVERE POTENTIAL THIS AFTERNOON INTO
TONIGHT. GENERALLY QUIET WEATHER EXPECTED FOR THURSDAY AND MOST
OF FRIDAY...WITH FOCUS THEN SHIFTING TO ADDITIONAL CHANCES OF
SHOWERS AND THUNDERSTORMS FOR THE WEEKEND.

SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEAST PORTIONS OF FORECAST
AREA LATE THIS EVENING. UPPER LEVEL SHORT WAVE RESPONSIBLE FOR
ENHANCING CONVECTION THIS EVENING WILL ALSO BE TRACKING INTO THE
OHIO RIVER VALLEY AND NORTHEAST UNITED STATES ON THURSDAY WITH
FAIRLY STRONG MID LEVEL SUBSIDENCE BECOMING ESTABLISHED ACROSS THE
AREA. BY FRIDAY NIGHT...LOW LEVEL RIDGE AXIS WILL BE SHIFTING EAST
OF THE AREA SETTING UP SOUTHWEST LOW LEVEL WARM ADVECTION ONCE
AGAIN AND A POTENTIAL OF ELEVATED CONVECTION MAINLY ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA. NAM/GFS ARE IN GENERAL
AGREEMENT IN ANOTHER SHORT WAVE MOVING ACROSS THE NORTHERN GREAT
LAKES REGION THAT WILL ALLOW A WEST TO EAST BOUNDARY TO DROP
SOUTHWARD ACROSS THE GREAT LAKES REGION ON SATURDAY POSSIBLY
REACHING FAR SOUTHERN LAKE MICHIGAN BY SATURDAY NIGHT. VERY WARM
DAY IN STORE FOR SATURDAY AS FORECAST AREA REMAINS SOUTH OF THIS
BOUNDARY...AND 850 HPA TEMPS INCREASE INTO THE +20 TO +22 DEG
RANGE. HEAT INDICES LIKELY TO APPROACH 100 DEGREES ON SATURDAY DUE
TO THE COMBINATION OF DEW POINTS RISING BACK INTO THE LOWER 70S
AND HIGH TEMPERATURES FORECASTED IN THE LOWER TO MID 90S. A MORE
AMPLIFIED UPPER LEVEL TROUGH EXPECTED TO PROGRESS THROUGH
PROGRESSIVE NORTHERN TIER OF STATES FLOW PATTERN ON SUNDAY WITH
ANOTHER ASSOCIATED COLD FRONTAL PASSAGE EXPECTED ON SUNDAY.

CONDITIONS SHOULD DRY OUT ONCE AGAIN LATE SUNDAY AS THIS FRONT
MOVES THROUGH SETTING UP A FAIRLY QUIET BEGINNING TO NEXT WORK
WEEK. HAVE KEPT REMAINDER OF FORECAST DRY AT THIS TIME WITH RISING
UPPER HEIGHTS THROUGH THIS PERIOD AS AMPLIFIED UPPER RIDGE ACROSS
WESTERN CONUS SLOWLY SHIFTS EASTWARD. HAVE NOT MADE MANY CHANGES
TO DAY 6/7 PERIOD AT THIS TIME WITH DIMINISHING CONFIDENCE IN THE
HANDLING OF UPPER LOW DROPPING SOUTHWARD ACROSS EASTERN CANADA.
12Z ECMWF IS MORE AGGRESSIVE IN DROPPING THIS LOW SOUTHWARD INTO
EASTERN GREAT LAKES REGION BY MID WEEK. NOT MUCH CONFIDENCE IN
THIS ECMWF SOLUTION...AND HAVE SIDED WITH MORE OF A OPERATIONAL
GFS/NCEP ENSEMBLE MEAN IDEA OF A FURTHER NORTH POSITIONING OF THIS
UPPER LOW. GREATER POTENTIAL OF RETURN OF HUMID AND HOT CONDITIONS
EXPECTED FOR BEYOND DAY 7 PERIOD AS UPPER RIDGE SHOULD EVENTUALLY
SHIFT EASTWARD OVER GREAT LAKES REGION.

MARSILI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

PRIMARY CONCERN REMAINS CONVECTION THROUGH EARLY/MID EVENING. CMS

//DISCUSSION...UPDATED 22Z...

CLUSTERS OF THUNDERSTORMS CONTINUE TO DEVELOP FROM NORTHWEST IL
SOUTHWEST INTO NORTHERN MISSOURI. NEW THUNDERSTORMS DEVELOPING
FURTHER EAST AND IMPACTING DPA/ORD. HAVE HIT THE TEMPOS HARDER
WITH GUSTS TO 45 KTS...POSSIBLY LOCALLY HIGHER. WILL WATCH TRENDS
AND AMEND AS NEEDED. BACK EDGE OF ACTIVITY SHOULD BE PASSING EAST
OF ORD/MDW BY 01Z OR SO. CMS

PREVIOUS DISCUSSION FROM 18Z...

ATMOSPHERE IN STATE OF FLUX ATTM AS COOL/STABLE BOUNDARY LAYER AIR
LEFT IN WAKE OF EARLIER CONVECTIVE COMPLEX IS IN THE PROCESS OF
RECOVERING. CURRENT VIS SATLT IMAGERY SHOWS RESIDUAL CONVECTIVE
DEBRIS DISSIPATING RAPIDLY AND SWLY LOW LVL FLOW INCRG IN RESPONSE
TO RAPID PRESSURE FALLS NOW OCCURRING FROM ERN IA-NWRN IL. THIS IS
ALLOWING QUICK RETURN OF DEEP TROPICAL AIR AHEAD OF APCHG COLD
FRONT. LATEST SPC MESO ANALYSES SHOW AIR OVER CNTRL/ERN IA...NRN
MO AND FAR W CNTRL IL DESTABILIZING RAPIDLY WITH SFC DEW POINTS
NEAR 80 DEG POOLING OVER SERN IA. IN ADDITION...WATER VAPOR IMAGERY
SUGGESTS SIGNIFICANT SUBSIDENCE AND DRYING IS OCCURRING BHD FRONT
FROM WRN MN-NW IA/ERN NEB. GUSTY NW WINDS IN THIS AREA SUPPORT
THIS AS WELL. THIS MEANS THAT IN ADDITION TO GROWING
INSTABILITY...ATMOSPHERE FROM UPR MS VALLEY THROUGH THE SRN GRTLKS
REGION IS BECOMING QUITE DYNAMIC.

TO SUMMARIZE ALL THIS...WX TO REMAIN QUIET THOUGH ABOUT 19Z...AS
AIR MASS CONTINUES TO RECOVER FROM EARLIER STORMS. BEGINNING
AROUND 20Z TS ARE EXPECTED TO ERUPT AHD OF ADVANCING COLD
FRONT...FROM NRN IL SWWD INTO MO. THESE STORMS SHOULD THEN RAPIDLY
BECOME SVR AFT 20Z...AND FORM INTO A SQLN FROM NR GYY-PNT-PIA BY
23Z.

STORMS TO ACCELERATE EWD OUT OF AREA ERLY THIS EVENING BHD BOWING
SQLN. BY 06Z...AREA TO BE OVERSPREAD BY MODEST NWLY WINDS AND ASSD
DRYING/STABILIZATION. THIS WILL BE THE BEGINNING OF AN EXTENDED
PERIOD OF VFR CONDITIONS WITH NIL WX.

MERZLOCK

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

HIGH CONFIDENCE ON CONVECTION/TIMING THRU EARLY EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 06Z FRIDAY-12Z TUESDAY...UPDATED 18Z...

THURSDAY NIGHT...VFR.
FRIDAY...VFR.
SATURDAY...CHC TS...OTRW VFR.
SUNDAY...CHC TS...OTRW VFR.
MONDAY...VFR.
TUESDAY...VFR.

MERZLOCK

&&

.MARINE...
259 PM CDT

TROUGH OF LOW PRESSURE CURRENTLY STRETCHING FROM SOUTHERN QUEBEC
SOUTH THROUGH WISCONSIN...AND DOWN INTO NW MISSOURI...CONTINUES TO
SHIFT EAST. THIS TROUGH WILL MOVE THROUGH AND GRADUALLY BEYOND THE
LAKES LATER TONIGHT AND INTO TOMORROW. RAPID PRESSURE FALLS HAVE
KEPT WINDS UP AND AROUND SMALL CRAFT LEVELS FOR THE NEAR SHORE...AND
OCCASIONALLY GUSTING INTO THE 30 KT RANGE ACROSS THE SOUTHERN OPEN
LAKE. EXPECT THESE WINDS TO CONTINUE THROUGH THE EVENING HOURS
BEFORE VEERING AROUND TO THE NORTHWEST AS A COLD FRONT SWEEPS
THROUGH THE LAKE. OPTED TO KEEP THE SMALL CRAFT ADVISORY GOING THE
MORNING HOURS...AS A FAIR AMOUNT OF SUBSIDENCE SETTLES IN AND
THINK THE WINDS WILL REMAIN GUSTY THROUGH THE EARLY MORNING HOURS.
HIGH PRESSURE WILL THEN SETTLE IN ACROSS THE LAKES...REACHING THE
CENTRAL LAKES BY THURSDAY. AS HIGH PRESSURE SITS OVERHEAD...EXPECT
RELATIVELY LIGHT FLOW BEFORE THE HIGH SLIDES OFF TO THE EAST
FRIDAY AND SOUTHERLY WINDS ARRIVE BACK INTO THE AREA.

SHEA

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLASH FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
     ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 1 AM THURSDAY.

IN...FLASH FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 1
     AM THURSDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY.

&&

Hazardous weather outlook, Jun 23, 4:45 PM CDT, 1 hour 41 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
445 PM CDT WED JUN 23 2010

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
242145-
WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE-
DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-
IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON-
445 PM CDT WED JUN 23 2010 /545 PM EDT WED JUN 23 2010/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME COULD PRODUCE:

  DAMAGING WINDS IN EXCESS OF 80 MPH.
  HAIL TO THE SIZE OF GOLF BALLS.
  ISOLATED TORNADOES.
  HEAVY RAINFALL...WITH LOCALIZED FLASH FLOODING.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS...SOME SEVERE...HAVE BEGUN TO MOVE INTO NORTH
  CENTRAL ILLINOIS LATE THIS AFTERNOON...AND ARE EXPECTED TO MOVE
  INTO THE CHICAGO METRO AREA SOUTHWEST TO LIVINGSTON AND LA SALLE
  COUNTY BETWEEN 5 PM AND 8 PM...THEN INTO NORTHWEST INDIANA AND
  EAST CENTRAL ILLINOIS INCLUDING IROQUOIS COUNTY BETWEEN 6 PM AND
  9 PM CDT.

  DISCUSSION:

  THE ATMOSPHERE CONTINUES TO DESTABILIZE AHEAD OF A COLD FRONT
  MOVING THROUGH THE REGION THIS EVENING. THUNDERSTORMS HAVE
  ALREADY DEVELOPED OVER PARTS OF IOWA AND ARE MOVING INTO NORTH
  CENTRAL ILLINOIS AT THIS HOUR. SEVERE WINDS...LARGE HAIL AND
  FUNNEL CLOUDS HAVE ALREADY BEEN REPORTED FROM THESE STORMS AS
  THEY MOVED ACROSS EASTERN IOWA...AND THE THREAT OF SEVERE
  WEATHER WILL PERSIST AS THEY CONTINUE TO MOVE ACROSS NORTHERN
  ILLINOIS AND NORTHWESTERN INDIANA.

  WINDS ALOFT ARE UNSEASONABLY STRONG...WHICH GIVEN THE
  INCREASINGLY UNSTABLE AIR MASS IS RESULTING IN AN EXTREMELY
  VOLATILE AND POTENTIALLY DANGEROUS SITUATION. INITIALLY THE
  THREAT WITH THE THUNDERSTORMS WILL BE VERY LARGE HAIL...LOCALLY
  DAMAGING WINDS...ALONG WITH SOME POTENTIAL FOR TORNADOES. AS
  THE STORMS MOVE EAST INTO EASTERN ILLINOIS AND NORTHWEST INDIANA
  IT APPEARS QUITE POSSIBLE THAT THEY WILL EVOLVE INTO A FAST
  MOVING LINE WITH THE POTENTIAL INCREASING FOR WIDESPREAD
  DAMAGING WINDS...SOME POSSIBLY QUITE SIGNIFICANT WITH GUSTS IN
  EXCESS OF 80 MPH.

  IN ADDITION TO SEVERE WEATHER...THE VERY WARM AND MOIST
  CONDITIONS WILL RESULT IN THESE STORMS PRODUCING LOCALLY HEAVY
  RAINFALL. THIS COULD LEAD TO FLOODING...AS THE GROUND REMAINS
  WET FROM REPEATED PERIODS OF HEAVY RAINFALL OVER THE PAST
  SEVERAL DAYS.

  HEAT INDEX VALUES MAY APPROACH 100 DEGREES LATE THIS AFTERNOON
  MAINLY SOUTH OF INTERSTATE 80.

  PORTIONS OF THE ILLINOIS RIVER...AND SUGAR CREEK...WILL REMAIN
  IN FLOOD.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

  THERE IS A CHANCE OF THUNDERSTORMS SATURDAY THROUGH SUNDAY
  NIGHT.

  HOT AND HUMID WEATHER MAY PRODUCE HEAT INDEX VALUES NEAR 100
  DEGREES SATURDAY AND SUNDAY.

.SPOTTER INFORMATION STATEMENT...

  SPOTTERS WILL BE NEEDED LATER THIS AFTERNOON AND EVENING.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ740>745-242145-
WINTHROP HARBOR TO WILMETTE HARBOR-
WILMETTE HARBOR TO NORTHERLY ISLAND-
NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY-
GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-
445 PM CDT WED JUN 23 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS NEARSHORE
WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT.

SEVERE THUNDERSTORMS ARE LIKELY LATE THIS AFTERNOON INTO THIS
EVENING. THESE STORMS MAY PRODUCE WINDS IN EXCESS OF 60 KNOTS AND
CLOUD TO WATER LIGHTNING.

HAZARDOUS WINDS FOR SMALL CRAFT ARE LIKELY THROUGH TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

THERE IS A CHANCE OF THUNDERSTORMS SATURDAY THROUGH SUNDAY NIGHT.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-242145-
LAKE MICHIGAN FROM MICHIGAN CITY IN TO ST. JOSEPH MI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM SEUL CHOIX POINT TO ROCK ISLAND PASSAGE 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN SOUTH OF A LINE FROM SEUL CHOIX POINT TO THE
MACKINAC BRIDGE AND NORTH OF A LINE FROM CHARLEVOIX MI TO SOUTH
FOX ISLAND 5 NM OFFSHORE-
LAKE MICHIGAN FROM CHARLEVOIX TO POINT BETSIE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM POINT BETSIE TO MANISTEE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM ROCK ISLAND PASSAGE TO STURGEON BAY WI-
LAKE MICHIGAN FROM STURGEON BAY TO TWO RIVERS WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM TOW RIVERS TO SHEBOYGAN WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM SHEBOYGAN TO PORT WASHINGTON WI 5 NM OFFSHORE
TO MID LAKE-
LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM NORTH POINT LIGHT TO WIND POINT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WIND POINT WI TO WINTHROP HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WINTHROP HARBOR TO WILMETTE HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WILMETTE HARBOR IL TO MICHIGAN CITY IN 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM PENTWATER TO MANISTEE MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM WHITEHALL TO PENTWATER MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM GRAND HAVEN TO WHITEHALL MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM HOLLAND TO GRAND HAVEN MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM SOUTH HAVEN TO HOLLAND MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM ST. JOSEPH TO SOUTH HAVEN MI 5 NM OFFSHORE TO
MID LAKE-
445 PM CDT WED JUN 23 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT.

SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND THIS
EVENING. STORMS MAY PRODUCE WIND GUSTS IN EXCESS OF 50 KNOTS AND
CLOUD TO WATER LIGHTNING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

THERE IS A CHANCE OF THUNDERSTORMS FROM FRIDAY NIGHT THROUGH
SUNDAY NIGHT.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

BMD

In the hours before

Local storm report, Jun 23, 6:10 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
610 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0545 PM     TSTM WND DMG     PLANO                   41.66N 88.53W
06/23/2010                   KENDALL            IL   EMERGENCY MNGR

            2 LARGE TREES DOWN ON KELLER ST. TREES DOWN ON RIVER RD.
            60MPH WINDS RECORDED. LARGE TREES ON POWER LINES.

0545 PM     TSTM WND DMG     OSWEGO                  41.70N 88.33W
06/23/2010                   KENDALL            IL   EMERGENCY MNGR

            SEMI BLOWN OVER ON RT. 34.

0545 PM     TSTM WND DMG     3 E SANDWICH            41.65N 88.57W
06/23/2010                   KENDALL            IL   AIRPLANE PILOT

            POWER LINES AND POWER POLES DOWN AT SANDY BLUFF AND
            GRISWOLD.

&&

ALYZA

Local storm report, Jun 23, 6:16 PM CDT, 10 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
616 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 PM     FUNNEL CLOUD     DOWNERS GROVE           41.80N 88.02W
06/23/2010                   DUPAGE             IL   NWS EMPLOYEE

            JUST S OF RT. 56 ABND MAIN REPORTED BY OFF-DUTY NWS
            EMPLOYEE.

&&

ALYZA

Local storm report, Jun 23, 6:18 PM CDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
618 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0605 PM     TSTM WND DMG     WENONA                  41.05N 89.05W
06/23/2010                   LA SALLE           IL   TRAINED SPOTTER

            SEMI BLOWN OVER ON I-39.

&&

ALYZA

Local storm report, Jun 23, 6:19 PM CDT, 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
619 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0552 PM     TSTM WND GST     YORKVILLE               41.64N 88.45W
06/23/2010  M78 MPH          KENDALL            IL   TRAINED SPOTTER

            4 MILES S OF RT. 30 ON ORCHARD RD.

&&

ALYZA

Local storm report, Jun 23, 6:21 PM CDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
621 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0617 PM     TSTM WND GST     MIDWAY AIRPORT          41.78N 87.75W
06/23/2010  M64 MPH          COOK               IL   ASOS

            MEASURED GUST TO 64 MPH AT MIDWAY AIRPORT.

&&

Local storm report, Jun 23, 6:23 PM CDT, 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
623 PM CDT WED JUN 23 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0610 PM     TSTM WND GST     JOLIET                  41.53N 88.12W
06/23/2010  E70 MPH          WILL               IL   TRAINED SPOTTER

            NUMEROUS LIMBS DOWN.

&&

ALYZA

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Lincoln, IL (KILX), 12:00Z

11.4 hours before the tornado, 168 km from the path. June 23, 2010.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.

Mixed-layer CAPE: 1735 J/kg
Mixed-layer CIN: -84 J/kg
Surface CAPE: 1098 J/kg
Mixed-layer LCL: 1302 m above ground
0-6 km bulk shear: 30 kt
0-1 km bulk shear: 23 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.1
0-3 km lapse rate: 4.4 K/km

Open this sounding in Storm Lab

Lincoln, IL (KILX), 00:00Z

0.6 hours after it, 168 km from the path. June 24, 2010.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

Mixed-layer CAPE: 2418 J/kg
Mixed-layer CIN: -7 J/kg
Surface CAPE: 3762 J/kg
Mixed-layer LCL: 1278 m above ground
0-6 km bulk shear: 38 kt
0-1 km bulk shear: 27 kt
0-1 km storm-relative helicity: 163 m²/s²
0-3 km storm-relative helicity: 258 m²/s²
Significant tornado parameter: 1.6
Supercell composite: 14.3
0-3 km lapse rate: 6.8 K/km

Open this sounding in Storm Lab

The surface observations

Chicago/Lansing (IGQ), 14 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
21:41 UTC	87.8	71.6	230° 10 kt	18	1010.8
22:01 UTC	87.8	71.6	230° 12 kt	21	1010.5
22:21 UTC	86	71.6	220° 10 kt	14	1010.2	VCTS
22:41 UTC	86	71.6	220° 8 kt		1009.8	VCTS
23:05 UTC	84.2	73.4	210° 8 kt		1009.5
23:25 UTC	84.2	73.4	220° 3 kt		1010.5	VCTS
00:00 UTC	69.8	66.2	260° 4 kt		1014.2	+TSRA
00:01 UTC	69.8	66.2	250° 4 kt		1014.2	+TSRA
00:23 UTC	69.8	66.2	230° 11 kt	17	1011.2	-TSRA
00:41 UTC	69.8	66.2	200° 8 kt		1011.2	-TSRA
01:01 UTC	69.8	66.2	220° 8 kt	18	1012.9	RA
01:23 UTC	69.8	66.2	160° 8 kt		1011.9	TSRA

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Chicago radar (KLOT), 35 km away, was scanning. The volume nearest the touchdown began at 23:25 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)	Report	Where	County	Remark
22:15 UTC	HAIL 0.25	Wheaton	Dupage, IL
22:30 UTC	FUNNEL CLOUD	Downers Grove	Dupage, IL	JUST S OF RT. 56 ABND MAIN REPORTED BY OFF-DUTY NWS EMPLOYEE.
22:35 UTC	TSTM WND DMG	7 Se Lakewood Shores	Kankakee, IL	2 POWER POLES BENT OVER ON WARNER BRIDGE ROAD ON THE KANKAKEE/WILL COUNTY BORDER.
22:35 UTC	FLOOD	Downers Grove	Dupage, IL	6 INCHES OF STANDING WATER.
22:35 UTC	HAIL 0.88	3 Nne Downers Grove	Dupage, IL	I-88 AT MILE MARKER 135.25.
22:38 UTC	HAIL 0.25	Westmont	Dupage, IL	N SIDE OF WESTMONT.
22:40 UTC	TSTM WND GST 65	2 Nnw Lynwood	Cook, IL	CORN STALKS BENT TO 45 DEGREE ANGLE
22:40 UTC	HAIL 0.88	Oak Brook	Dupage, IL	ACCOMPANIED BY HEAVY RAIN AND PONDING ON ROAD.
22:45 UTC	FUNNEL CLOUD	Montgomery	Kane, IL	SIGHTED IN MONTGOMERY BY SPOTTER.
22:45 UTC	TSTM WND DMG	Oak Brook	Dupage, IL	MEDIA REPORTS OF DAMAGE ON 22ND STREET IN OAKBROOK INCLUDE ROOF OFF BUILDING...POWER POLES AND STREET LIGHTS DOWN...AND LARGE TREE DOWN BLOCKING 22ND STREET.
22:45 UTC	TSTM WND DMG	Oswego	Kendall, IL	SEMI BLOWN OVER ON RT. 34.
22:47 UTC	TSTM WND DMG	Montgomery	Kane, IL	POWERLINES DOWN.
22:50 UTC	TSTM WND DMG	8 W Joliet	Kendall, IL	TOP OF TREE SNAPPED...4 INCHES IN DIAMETER AT TOWNSEND AND COUNTY LINE RD.
22:50 UTC	TSTM WND DMG	Naperville	Dupage, IL	LARGE TREES DOWN...POWER LINES DOWN...AND ROOF DAMAGE...MAINLY S OF 75TH ST. TIME ESTIMATED.
22:53 UTC	TSTM WND GST 70	5 E Yorkville	Kendall, IL	3 INCH DIAMETER BRANCH DOWN. VISIBILITY OF 200 YARDS IN RAIN.
22:55 UTC	HAIL 1	1 N La Grange	Cook, IL
22:56 UTC	TSTM WND GST 60	Oswego	Kendall, IL
22:57 UTC	TSTM WND DMG	Chicago	Cook, IL	ROOF DAMAGE AND TREES DOWN AT 27TH AND KEDZIE. TIME RADAR EST.
22:57 UTC	TSTM WND DMG	Crest Hill	Will, IL	TREES UPROOTED...GUTTERS OFF HOMES...SHINGLES OFF ROOFS...AND POWER LINES DOWN AT PLAINFIELD AND WEBB ST. TIME EST. BY RADAR.
22:58 UTC	TSTM WND GST 62	Plainfield	Will, IL	MEASURED GUST AT RT. 59 AND 135TH ST.
23:00 UTC	TSTM WND DMG	Joliet	Will, IL	CONSIDERABLE TREE DAMAGE AT MIDHURST AND EDGERTON WITH ONE 12 INCH DIAMETER TREE SNAPPED OFF.
23:00 UTC	TSTM WND DMG	Woodridge	Dupage, IL	AT ILRT 53 AND 83RD ST, SPOTTER REPORT OF FALLEN LARGE TREE BRANCHES, SOME MEASURING SEVEN INCHES IN DIAMETER. ALSO REPORTED A METAL CHIMNEY HAVING BEEN SEPERATED FROM A TWO STORY APARTMENT BUILDING.
23:00 UTC	FLOOD	North Riverside	Cook, IL	9 INCHES OF STANDING WATER MEASURED ON IL. 171 BETWEEN 22ND/CERMAK AND 26TH ST.
23:00 UTC	FLASH FLOOD	North Riverside	Cook, IL	IL-171 BETWEEN 22ND AND 26TH STREETS. 9 INCHES OF STANDING WATER.
23:00 UTC	TSTM WND GST 60	North Riverside	Cook, IL	TIME ESTIMATED. POWER IS OUT.
23:01 UTC	HEAVY RAIN 1.35	1 Sse Evanston	Cook, IL	1.35 INCHES IN 23 MINUTES.
23:02 UTC	TSTM WND DMG	Crest Hill	Will, IL	EXTENSIVE TREE DAMAGE NEAR LARKIN AND ROUTE 30.
23:02 UTC	TSTM WND DMG	Joliet	Will, IL	EXTENSIVE TREE DAMAGE NORTH OF GLENWOOD AND SOUTH OF BLACK ROAD.
23:02 UTC	TSTM WND GST 70	Joliet	Will, IL	GUTTERS FROM HOUSES AND TREE LIMBS BLOWN DOWN.
23:03 UTC	FUNNEL CLOUD	Oak Lawn	Cook, IL	95TH AND RICHLAND.
23:10 UTC	FUNNEL CLOUD	Darien	Dupage, IL	87TH AND LAMONT MOVING NORTHEAST.
23:10 UTC	FLOOD	Downers Grove	Dupage, IL	1.60 INCHES OF RAIN IN 45 MINUTES. STREETS FLOODED.
23:10 UTC	TSTM WND GST 70	Joliet	Will, IL	NUMEROUS LIMBS DOWN.
23:13 UTC	TSTM WND DMG	Naperville	Dupage, IL	SHINGLES BLOWN OFF ROOFS AND TREES DOWN NEAR 87TH AND WASHINGTON.
23:15 UTC	TSTM WND DMG	Naperville	Dupage, IL	TREES BLOWN DOWN NEAR 87TH AND NAPER BLVD.
23:15 UTC	FLOOD	New Lenox	Will, IL	6 INCHES OF WATER ON THE ROADS.
23:15 UTC	TSTM WND GST 62	New Lenox	Will, IL	SMALL TREES DOWN THROUGH OUT NEW LENOX
23:17 UTC	FLOOD	Bolingbrook	Will, IL	6 INCHES OF WATER ON ROAD AT WEBER AND RODEO DR. ALSO 6 INCHES OF WATER ON ROAD AT BRIARCLIFF AND LILY CACHE.
23:17 UTC	TSTM WND GST 64	Midway Airport	Cook, IL	MEASURED GUST TO 64 MPH AT MIDWAY AIRPORT.
23:17 UTC	NON-TSTM WND GST 80	Joliet	Will, IL	TRAINED SPOTTER REPORTS ESTIMATED 70 TO 80 MPH WINDS ON INTERSTATE 80 ONE MILE EAST OF INTERSTATE 55.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the track Every 2010 tornado in Illinois Every tornado in Illinois since 1950 Warnings in force in Illinois now The forecast where you are

The other tornadoes of June 23, 2010

11 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Damage
June 23	2:18 AM CDT	EF1	Bremer, IA	0.3	35	$10,000
June 23	3:22 AM CDT	EF0	Crawford, WI	3.9	25	$5,000
June 23	8:59 PM EDT	EF1	Elkhart, IN	11.8	50	$300,000
June 23	9:09 PM EDT	EF1	Elkhart, IN	1.0	50	$500,000
June 23	9:14 PM EDT	EF1	Kosciusko, IN	4.8	150	$300,000
June 23	9:15 PM EDT	EF1	Elkhart, IN	3.5	100	$50,000
June 23	9:16 PM EDT	EF0	Elkhart, IN	0.5	25	$10,000
June 23	9:17 PM EDT	EF0	Elkhart, IN	1.9	50	$75,000
June 23	9:50 PM EDT	EF0	Van Wert, OH	0.9	50
June 23	9:52 PM EDT	EF0	Washtenaw, MI	3.7	75	$75,000
June 23	10:06 PM EDT	EF1	Monroe, MI	11.5	100	$100,000

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.