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NOUS43 KLOT 222223
PNSLOT
ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-231030-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
523 PM CDT SAT AUG 22 2026 /623 PM EDT SAT AUG 22 2026/
..NWS DAMAGE SURVEY FOR 08/11/2026 DERECHO EVENT - UPDATE 3
UPDATE
ANALYSIS OF EXTREME WINDS THAT IMPACTED PORTIONS OF
LAKE AND PORTER COUNTIES IN NORTHWESTERN INDIANA WERE ADDED,
INFORMATION ABOUT ADDITIONAL TORNADOES WERE ADDED, AND MINOR
MODIFICATIONS WERE MADE TO METADATA ASSOCIATED WITH ALREADY-
CONFIRMED TORNADOES.
DURING THE EARLY MORNING HOURS ON TUESDAY, AUGUST 11TH,
THUNDERSTORMS ERUPTED ACROSS EASTERN IOWA AND ORGANIZED INTO AN
INTENSE LINE OF THUNDERSTORMS WHILE SWEEPING ACROSS NORTHERN
ILLINOIS AND NORTHWESTERN INDIANA. INITIALLY ISOLATED POCKETS OF
WIND DAMAGE ACROSS NORTH CENTRAL ILLINOIS QUICKLY BECAME
WIDESPREAD EAST OF INTERSTATE 39 AND ESPECIALLY ACROSS PORTIONS OF
COOK, WILL, KANKAKEE, LAKE, PORTER, NEWTON, AND JASPER COUNTIES
IN NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA. NUMEROUS
MEASURED WIND GUSTS OF 70 TO 90 MPH WERE RECORDED ACROSS THE
HARDEST-HIT AREAS, INCLUDING A 99 MPH WIND GUST MEASURED AT
GARY/CHICAGO INTERNATIONAL AIRPORT. PEAK WIND GUSTS WERE ESTIMATED
TO HAVE REACHED THE 100 TO 110 MPH RANGE ACROSS PORTIONS OF
NORTHERN LAKE AND PORTER COUNTIES IN NORTHWESTERN INDIANA WHERE
POCKETS OF EXTREME TREE DAMAGE WERE NOTED. IN ADDITION, AT LEAST
EIGHT TORNADOES OCCURRED WITH THE DERECHO INCLUDING ONE THAT WAS
RATED AN EF-2. OWING TO THE WIDESPREAD, CONTINUOUS, LONG- LIVED
NATURE, AND MAGNITUDE OF DAMAGING WINDS, THE INTENSE LINE OF
STORMS HAS BEEN CLASSIFIED AS A DERECHO.
INFORMATION ABOUT EACH TORNADO AS WELL AS CORRIDORS OF
PARTICULARLY INTENSE STRAIGHT-LINE WIND DAMAGE ARE PROVIDED BELOW.
OSWEGO
RATING: EF0
ESTIMATED PEAK WIND: 75 MPH
PATH LENGTH /STATUTE/: 5.40 MILES
PATH WIDTH /MAXIMUM/: 150 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:14 AM CDT
START LOCATION: 3 NE YORKVILLE / KENDALL COUNTY / IL
START LAT/LON: 41.6760 / -88.4008
END DATE: 08/11/2026
END TIME: 10:20 AM CDT
END LOCATION: 3 SSE OSWEGO / KENDALL COUNTY / IL
END LAT/LON: 41.6555 / -88.3078
SURVEY SUMMARY:
THE TORNADO BEGAN NEAR US ROUTE 34 AND AMERICAN WAY AND THEN
CROSSED THE FOX RIVER. IT CONTINUED IN A GENERALLY SOUTHEASTERLY
DIRECTION CAUSING INTERMITTENT TREE DAMAGE AS IT CROSSED THROUGH
SEVERAL SUBDIVISIONS IN THE VICINITY OF GROVE ROAD. THE TORNADO
APPEARED TO HAVE LIFTED NEAR DOUGLAS ROAD JUST SOUTH OF COLLINS
ROAD.
NORMAN TOWNSHIP
RATING: EF0
ESTIMATED PEAK WIND: 80 MPH
PATH LENGTH /STATUTE/: 1.63 MILES
PATH WIDTH /MAXIMUM/: 250 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:20 AM CDT
START LOCATION: 2.1 NE LANGHAM / GRUNDY COUNTY / IL
START LAT/LON: 41.3114 / -88.5057
END DATE: 08/11/2026
END TIME: 10:22 AM CDT
END LOCATION: 2.1 N WAUPONSEE / GRUNDY COUNTY / IL
END LAT/LON: 41.3044 / -88.4758
SURVEY SUMMARY:
THE TORNADO BEGAN NORTHWEST OF THE INTERSECTION OF DUPONT AND
VERONA ROADS IN NORMAN TOWNSHIP INITIALLY PRODUCING A NARROW
CONVERGENT PATH OF DAMAGE TROUGH A CORN FIELD. THE TORNADO THEN
REMOVED A PORTION OF A ROOF ON A BARN, PUSHED A GRAIN BIN OFF ITS
FOUNDATION, AND DOWNED MULTIPLE TREES AT A PROPERTY ON DUPONT
ROAD. THE TORNADO THEN DAMAGED SEVERAL MORE TREES NEAR THE
INTERSECTION OF DUPONT ROAD AND GORHAM ROAD BEFORE DISSIPATING.
MORRIS
RATING: EF0
ESTIMATED PEAK WIND: 80 MPH
PATH LENGTH /STATUTE/: 2.18 MILES
PATH WIDTH /MAXIMUM/: 150 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:23 AM CDT
START LOCATION: 2.6 N MORRIS/ GRUNDY COUNTY / IL
START LAT/LON: 41.4004 / -88.4213
END DATE: 08/11/2026
END TIME: 10:25 AM CDT
END LOCATION: 2.5 NE MORRIS / GRUNDY COUNTY / IL
END LAT/LON: 41.3850 / -88.3847
SURVEY SUMMARY:
THE TORNADO APPEARED TO BEGIN NEAR THE INTERSECTION OF STATE ROUTE
47 AND GRANVILLE ROAD, INITIALLY DAMAGING CROPS IN THE FIELDS TO
THE SOUTHEAST OF THE INTERSECTION. EYEWITNESSES REPORTED SEEING
THE TORNADO TRACK ACROSS INTERSTATE 80 BEFORE IMPACTING A TRAILER
RETAILER ALONG US ROUTE 6. NUMEROUS TRAILERS WERE TOSSED OR ROLLED
AND SECTIONS OF ROOFING MATERIAL WERE PEELED OFF AT THE MAIN
OFFICE BUILDING. IN ADDITION, A SEMI-TRUCK WAS BLOWN ONTO A DITCH
ALONG ROUTE 6 AND POWER LINES WERE DOWNED AT THE RETAILER.
FURTHER TO THE SOUTHEAST, DAMAGE TO SEVERAL TREES WERE NOTED NEAR
THE GRUNDY COUNTY ROD AND GUN CLUB WHERE THE TORNADO APPEARED TO
END.
WILMINGTON
RATING: EF1
ESTIMATED PEAK WIND: 90 MPH
PATH LENGTH /STATUTE/: 1.52 MILES
PATH WIDTH /MAXIMUM/: 150 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:37 AM CDT
START LOCATION: 1 NNE WILMINGTON / WILL COUNTY / IL
START LAT/LON: 41.3064 / -88.1558
END DATE: 08/11/2026
END TIME: 10:39 AM CDT
END LOCATION: 1 ENE WILMINGTON / WILL COUNTY / IL
END LAT/LON: 41.3003 / -88.1309
SURVEY SUMMARY:
THE TORNADO STARTED NEAR W BALTIMORE STREET AND N 1ST STREET
WHERE IT REMOVED PART OF THE ROOF OF AN AUTOMOTIVE REPAIR SHOP AND
TOSSED IT INTO THE SIDE OF AN ADJACENT STRIP MALL. DAMAGE IN THIS
AREA WAS CONSISTENT WITH PEAK WINDS NEAR 90 MPH. THE TORNADO THEN
CROSSED THE KANKAKEE RIVER AND SUBSEQUENTLY TRACKED ACROSS THE
OAKWOOD CEMETERY WHERE IT CAUSED SUBSTANTIAL TREE DAMAGE, AGAIN
CONSISTENT WITH WINDS NEAR 90 MPH. THE TORNADO THEN TRACKED EAST
ALONG RIDGE STREET BEFORE LIFTING NEAR THE FORKED CREEK PRESERVE.
MOKENA - TINLEY PARK
RATING: EF1
ESTIMATED PEAK WIND: 95 MPH
PATH LENGTH /STATUTE/: 7.57 MILES
PATH WIDTH /MAXIMUM/: 200 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:39 AM CDT
START LOCATION: 2 NNE NEW LENOX / WILL COUNTY / IL
START LAT/LON: 41.5487 / -87.9589
END DATE: 08/11/2026
END TIME: 10:46 AM CDT
END LOCATION: 1 NW FRANKFORT SQUARE / WILL COUNTY / IL
END LAT/LON: 41.5336 / -87.8167
SURVEY SUMMARY:
THE TORNADO BEGAN NEAR W MAPLE AND BLODGETT ROADS AND THEN
CROSSED I-80 NEAR MILE MARKER 141. THE TORNADO CONTINUED IN A
SOUTHEASTERLY DIRECTION, CAUSING MAINLY MINOR TREE DAMAGE AS IT
ROUGHLY PARALLELED W REGAN ROAD AND 195TH STREET. THE TORNADO
REACHED ITS PEAK INTENSITY IN A SUBDIVISION NEAR ST. MARY'S
CATHOLIC CHURCH WHERE SEVERAL RESIDENCES SUSTAINED SHINGLE AND
SOFFIT DAMAGE AND LARGE HARDWOOD TREES WERE SNAPPED, CONSISTENT
WITH PEAK WINDS OF 85 TO 95 MPH. THE TORNADO THEN CONTINUED EAST
ROUGHLY ALONG 195TH STREET BEFORE LIFTING JUST NORTH OF THE HILDA
WALKER INTERMEDIATE SCHOOL.
ORLAND PARK TO HAMMOND
RATING: EF1
ESTIMATED PEAK WIND: 105 MPH
PATH LENGTH /STATUTE/: 22.50 MILES
PATH WIDTH /MAXIMUM/: 300 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:41 AM CDT
START LOCATION: 3 NNW MOKENA / COOK COUNTY / IL
START LAT/LON: 41.5738 / -87.9057
END DATE: 08/11/2026
END TIME: 11:00 AM CDT
END LOCATION: 2 N MUNSTER / LAKE COUNTY / IN
END LAT/LON: 41.5776 / -87.5002
SURVEY SUMMARY:
THE TORNADO BEGAN JUST EAST OF THE WILL COOK COUNTY LINE IN THE
BROOK HILL SUBDIVISION AND MOVED RAPIDLY EAST AND SOUTHEASTWARD
ACROSS SOUTHERN PORTIONS OF ORLAND PARK AND TINLEY PARK RESULTING
IN CONSIDERABLE DAMAGE TO TREES AND POWER LINES. SOME STRUCTURAL
DAMAGE TO SEVERAL BUILDINGS WAS NOTED ALONG 183RD ST IN TINLEY
PARK. THE TORNADO THEN CROSSED INTERSTATES 80 AND 57 BEFORE
MOVING ACROSS COUNTRY CLUB HILLS AND FLOSSMOOR AND GLENWOOD WHERE
THE MOST SUBSTANTIAL TREE DAMAGE WAS NOTED WITH NUMEROUS LARGE
TREES SNAPPED OR UPROOTED ALONG THE PATH. SOME TREES FELL INTO
BUILDINGS AND ONTO CARS CAUSING SIGNIFICANT DAMAGE. THE TORNADO
CROSSED THE BISHOP FORD EXPRESSWAY AND MOVED ACROSS LANSING WHERE
IT CONTINUED TO PRODUCE CONSIDERABLE TREE DAMAGE. THE TORNADO
CROSSED THE STATE LINE JUST NORTH OF RIDGE RD AND CONTINUED TO
PRODUCE CONSIDERABLE TREE DAMAGE INTO MUNSTER BEFORE TURNING
NORTH AND DISSIPATING SHORTLY AFTER CROSSING I-80 JUST EAST OF
CALUMET AVE.
MONEE TO CROWN POINT
RATING: EF2
ESTIMATED PEAK WIND: 115 MPH
PATH LENGTH /STATUTE/: 25.75 MILES
PATH WIDTH /MAXIMUM/: 500 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:43 AM CDT
START LOCATION: 5 SSW FRANKFORT / WILL COUNTY / IL
START LAT/LON: 41.4289 / -87.8842
END DATE: 08/11/2026
END TIME: 11:02 AM CDT
END LOCATION: 2 WNW CROWN POINT / LAKE COUNTY / IN
END LAT/LON: 41.4373 / -87.3916
SURVEY SUMMARY:
THE TORNADO BEGAN NEAR S. LA GRANGE ROAD/US HIGHWAY 45 THREE
QUARTERS OF A MILE SOUTH OF W DRALLE ROAD. IT INITIALLY PROGRESSED
IN A GENERALLY EASTERLY DIRECTION CAUSING SPORADIC TREE DAMAGE AS
IT ROUGHLY PARALLELED W MONEE MANHATTAN ROAD. DAMAGE IN THIS AREA
WAS CONSISTENT WITH EF-0 WINDS OF 60 TO 80 MPH. THE TORNADO THEN
CROSSED INTERSTATE 57 AND DAMAGED EXTERIOR DOORS AND ROOFS AT
SEVERAL INDUSTRIAL BUILDINGS ON THE NORTH SIDE OF MONEE BEFORE
MOVING ACROSS UNIVERSITY PARK AND INTO CRETE WITH CONTINUED TREE
DAMAGE. THE SEVERITY OF TREE DAMAGE INCREASED AS THE TORNADO
PROGRESSED INTO NORTHWESTERN INDIANA. THE TORNADO REACHED ITS PEAK
INTENSITY IN ST. JOHN IN A LOCALIZED AREA IN A SUBDIVISION OFF OF
BLAINE STREET ON THE EASTERN EDGE OF ST. JOHN. HERE, A SINGLE
RESIDENCE AT THE CORNER OF DEWEY PLACE AND 96TH PLACE LOST OF MOST
OF ITS ROOF AND SOUTH AND WESTERN WALLS, CONSISTENT WITH PEAK
WINDS AROUND 115 MPH. TORNADO DAMAGE BECAME INCREASINGLY
INTERSPERSED WITH STRAIGHT-LINE THUNDERSTORM WIND DAMAGE AS THE
TORNADO ENTERED CROWN POINT NEAR CLARK ROAD, AND LIKELY DISSIPATED
IN THIS AREA.
GLENWOOD TO LANSING
RATING: EF1
ESTIMATED PEAK WIND: 110 MPH
PATH LENGTH /STATUTE/: 3.33 MILES
PATH WIDTH /MAXIMUM/: 300 YARDS
FATALITIES: 0
INJURIES: 0
START DATE: 08/11/2026
START TIME: 10:55 AM CDT
START LOCATION: 1 E HOMEWOOD / COOK COUNTY / IL
START LAT/LON: 41.5539 / -87.6407
END DATE: 08/11/2026
END TIME: 10:58 AM CDT
END LOCATION: 2 W LANSING / COOK COUNTY / IL
END LAT/LON: 41.5669 / -87.5827
SURVEY SUMMARY:
THE TORNADO BEGAN WEST OF HALSTED BETWEEN 183RD AND 187TH,
CROSSING HALSTED AND CAUSING STRUCTURAL DAMAGE TO A STRIP MALL
AND SEVERAL BUILDINGS IN AN APARTMENT COMPLEX. THE TORNADO THEN
AFFECTED A NEIGHBORHOOD EAST OF THE STRIP MALL, CAUSING
SUBSTANTIAL TREE DAMAGE AS WELL AS SOME ROOF DAMAGE TO A HANDFUL
OF HOMES. THE TORNADO UPROOTED AND SNAPPED NUMEROUS TREES ACROSS
A CEMETERY OFF OF GLENWOOD THORNTON RD BEFORE CONTINUING EAST
THROUGH THE THORNTON-LANSING ROAD NATURE PRESERVE. THE TORNADO
DISSIPATED JUST EAST OF 394 SOUTH OF THORNTON-LANSING RD.
WARRENVILLE-LISLE STRAIGHT-LINE WINDS
ESTIMATED PEAK WIND: 80 MPH
FATALITIES: 0
INJURIES: 0
A CORRIDOR OF DESTRUCTIVE WINDS IMPACTED WARRENVILLE AND A
PORTION OF LISLE DURING THE DERECHO ON AUGUST 11. EXTENSIVE TREE
DAMAGE OCCURRED IN BLACKWELL FOREST PRESERVE, HERRICK LAKE FOREST
PRESERVE, AND DANADA FOREST PRESERVE WITH SNAPPED AND UPROOTED
TREES. IN ADDITION, EXTENSIVE TREE DAMAGE OCCURRED THROUGHOUT
WARRENVILLE AND ON THE NORTH SIDE OF LISLE INCLUDING THE SNAPPING
AND UPROOTING OF TREES RANGING IN SIZE FROM 1 TO 3 FEET IN
DIAMETER. SEVERAL TREES FELL ON HOMES CAUSING STRUCTURE DAMAGE, AS
WELL. BASED ON VIDEO FOOTAGE AND WITNESS REPORTS, THE DAMAGE WAS
MOST LIKELY CAUSED BY STRAIGHT LINE WINDS IN EXCESS OF 80 MPH ON
THE SOUTHERN SIDE OF A RADAR-INDICATED ROTATION PATH.
.LAKE AND PORTER COUNTIES STRAIGHT-LINE WINDS..
ESTIMATED PEAK WIND: 110 MPH
FATALITIES: 1
INJURIES: 0
WIDESPREAD AND DESTRUCTIVE STRAIGHT LINE WINDS IMPACTED THE
NORTHERN PORTIONS OF LAKE AND PORTER COUNTIES IN NORTHWESTERN
INDIANA PRIMARILY ALONG THE INTERSTATE 80 AND 94 CORRIDORS.
WIDESPREAD DAMAGE TO THE POWER INFRASTRUCTURE RESULTED IN
UNUSUALLY LONG POWER OUTAGES (WHICH ARE ONGOING IN SOME LOCATIONS
AS OF THE ISSUANCE OF THIS PRODUCT), AND NUMEROUS ROADS BECAME
IMPASSABLE DUE TO DENSE CONCENTRATIONS OF TREE DAMAGE. DAMAGE
ACROSS THE AREA WAS BLOWN PRIMARILY TOWARD THE EAST SOUTHEAST
CONSISTENT WITH STRAIGHT LINE WINDS AND RADAR DATA DURING THE
EVENT.
IN GARY, WIDESPREAD TREE DAMAGE OCCURRED INCLUDING UPROOTING AND
SNAPPING OF LARGE TREES NEAR THEIR BASE. SEVERAL HIGH TENSION
POWER TRUSSES WERE DOWNED NEAR THE INTERSECTION OF INTERSTATES 65
AND 90, AND AN UNHOUSED WOMAN LOST HER LIFE AFTER BEING STRUCK BY
DEBRIS NEAR THE INTERSECTION OF CLAY STREET AND E DUNES HIGHWAY.
A WIND GUST OF 99 MPH WAS MEASURED AT THE TOP OF THE FAA TOWER AT
GARY AIRPORT, AND SEVERAL AIRPORT HANGAR BUILDINGS WERE DAMAGED.
IN HOBART AND LAKE STATION, WIDESPREAD DAMAGE TO TREES AND WOODEN
POWER POLES OCCURRED. SEVERAL TREES FELL ONTO AND CAUSED DAMAGE
TO STRUCTURES, AND NUMEROUS TREES WERE SNAPPED MIDWAY UP THEIR
TRUNK.
THE INTENSITY OF THE STRAIGHT LINE WINDS APPEARED TO PEAK IN
PORTAGE AND OGDEN DUNES. SEVERAL CONCENTRATED AREAS OF EXTREME
TREE DAMAGE OCCURRED INCLUDING DENSE GROUPINGS OF TREES THAT WERE
UPROOTED, SNAPPED, OR LOST A MAJORITY OF THEIR LIMBS. SEVERAL
FORESTED AREAS EXPERIENCED GREATER THAN 80 PERCENT LOSS OF THE
TREE CANOPY, INCLUDING JUST SOUTH OF INTERSTATE 94 WEST OF MARINE
DRIVE, NEAR AND SOUTH OF US HIGHWAY 20 NEAR CRISMAN ROAD, AND ON
EITHER SIDE OF OLD PORTER ROAD NEAR TONIA STREET. TREES FELL ON
STRUCTURES AND CAMPERS CAUSING STRUCTURAL DAMAGE, AND A HOTEL NEAR
THE INTERSECTION OF US HIGHWAY 20 AND CRISMAN ROAD SUSTAINED ROOF
DAMAGE. POWER POLES WERE SNAPPED ON A WIDESPREAD BASIS, AND THE
COVER OF A STEEL COIL CONTAINER CAR WAS THROWN A STATIONARY TRAIN
BETWEEN INTERSTATE 94 AND LAKE MICHIGAN.
AFTER CONSULTATION WITH A PANEL OF EXPERTS ON WIND DAMAGE AS WELL
AS WITH KNOWLEDGE OF THE MEASURED 99 MPH WIND GUST IN GARY, PEAK
WIND GUSTS ACROSS NORTHERN PORTIONS OF LAKE AND PORTER COUNTIES
LIKELY RANGED FROM 100 TO 110 MPH. THANK YOU TO THOSE WHO AIDED
IN OUR ASSESSMENT OF THE WIND DAMAGE AND ESTIMATION OF THE PEAK
WIND GUSTS.
EF SCALE: THE ENHANCED FUJITA SCALE CLASSIFIES TORNADOES INTO THE
FOLLOWING CATEGORIES:
EF0.....65 TO 85 MPH
EF1.....86 TO 110 MPH
EF2.....111 TO 135 MPH
EF3.....136 TO 165 MPH
EF4.....166 TO 200 MPH
EF5.....>200 MPH
NOTE:
THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO
CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN NWS
STORM DATA.
NWS CHICAGO
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