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