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524 NOUS43 KLOT 130047 PNSLOT ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002- 010-011-019-131300- Public Information Statement National Weather Service Chicago IL 747 PM CDT Wed Aug 12 2020 /847 PM EDT Wed Aug 12 2020/ ...NWS DAMAGE SURVEY FOR 08/10/2020 DERECHO AND TORNADO EVENT... .UPDATE... Through a combination of storm surveys, photos, video, and coordination with area EMAs, four additional tornado paths have been identified in association with the 08/10/2020 Derecho. These are: an EF-0 in Grant Park, and EF-0 in Park Forest, an EF-1 between Yorkville and Plainfield, and an EF-1 in Ottawa. This brings the total number of tornadoes in NWS Chicago's area of responsibility to 11 from the 8/10/2020 Derecho event. In addition, information about significant straight line winds in Forreston (NW Ogle County), Somonauk ((Dekalb and LaSalle Counties) and a corridor of enhanced straight line wind damage between Wheaton and Glen Ellyn (DuPage County) have been added. NWS Chicago continues to work with our local partners to diagnose potential additional areas of tornado damage. We hope to have this information finalized on Thursday. .OVERVIEW... A well-organized and long-lived thunderstorm complex produced widespread severe wind damage across northern Illinois and Indiana during the afternoon hours on Monday, August 10th. Associated straight line wind damage across NWS Chicago’s area of responsibility is consistent with 60 to 80 mph wind gusts, with pockets of enhanced winds likely in excess of 90 mph. Several tornadic circulations developed within the main line of thunderstorms, producing at least nine tornadoes across northern ILlinois. In addition, a lone supercell that was subsequently absorbed into the main line produced two tornadoes in and around the Rockford area, bringing the event total tornadoes to at least eleven. .FORRESTON AREA STRAIGHT LINE WINDS... Estimated peak wind: 100 mph Fatalities: 0 Injuries: 5 Start date: 08/10/2020 Start time: 2:15 PM CDT Start location: Forreston End date: 08/10/2020 End time: 2:30 PM CDT End location: Forreston Very strong straight line winds of 90 to 100 mph occurred in the town of Forreston in far northwestern Ogle County. Reports indicate that several mobile homes on the east side of the town were damaged or destroyed, and photos also revealed significant damage to a metal building near the BP gas station with associated debris all blown towards the northeast. Widespread tree damage also occurred. .SOUTHWEST ROCKFORD TORNADO... Rating: EF-0 Estimated peak wind: 75 mph Path length /Statute/: 1.5 miles Path width /Maximum/: 50 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 2:37 PM CDT Start location: 3 SW Rockford End date: 08/10/2020 End time: 2:38 PM CDT End location: 1.5 SW Rockford Survey Summary: A very brief tornado touched down near the intersection of Pierpont Ave and Montague Road and continued northeast into the southwest side of Rockford. The tornado ended near the intersection of Ferguson and Loomis streets. All damage was to trees along the tornado path. .ROCKFORD TO CALEDONIA TORNADO... Rating: EF-1 Estimated peak wind: 100 mph Path length /Statute/: 9.2 miles Path width /Maximum/: 300 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 2:47 PM CDT Start location: 3 NE Rockford End date: 08/10/2020 End time: 3:05 PM CDT End location: 1 SW Caledonia Survey Summary: This tornado was associated with the same supercell thunderstorm that produced an initial brief EF-0 tornado immediately southwest of Rockford, but it has been determined these exist as two separate tracks. This tornado developed as the main line of thunderstorm caught up, and eventually merged with, the parent supercell with this path starting near Guilford Road just north of Rockford College before heading northeast. Significant tree damage, consistent with EF-1 wind speeds, occurred in a localized area immediately east of Rock Valley College west of North Perryville Road. The tornado continued northeast, crossing I-90/39, producing sporadic damage before lifting near Caledonia Road. .OTTAWA TORNADO... Rating: EF-1 Estimated peak wind: 100 mph Path length /Statute/: 0.75 miles Path width /Maximum/: 150 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 2:59 PM CDT Start location: Ottawa End date: 08/10/2020 End time: 3:01 PM CDT End location: Ottawa The tornado started south of Marquette street west of Michigan street and progressed eastward. The tornado impacted several businesses ripping off well-anchored roofing material and snapping a power pole at its base. It was here that the max intensity of the tornado was reached with peak winds of around 100 mph. The tornado then continued eastward ripping shingles off roofs of buildings and houses just west of Route 23 and shredding trees. The tornado is believed to have lifted in an inaccessible forested area east of the Fox river. Eye witnesses indicated the tornado may have had multiple vortices with clear rising and rotating motion of debris. .SOMONAUK STRAIGHT LINE WINDS... Estimated peak wind: 90 mph Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 2:59 PM CDT Start location: Somonauk End date: 08/10/2020 End time: 3:01 PM CDT End location: Somonauk Widespread tree damage with a few trees snapped very near their base were observed throughout Somonauk and surrounding areas. Seven large and new utility poles were also snapped about 10 feet up from thier base about three miles north of Somonauk on Somonauk Road. The damage was consistent with straight line winds up to 90 mph. .SOUTHEAST MARENGO TORNADO... Rating: EF-1 Estimated peak wind: 95 mph Path length /Statute/: 5.7 miles Path width /Maximum/: 200 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:05 PM CDT Start location: 5 SW Marengo End date: 08/10/2020 End time: 3:11 PM CDT End location: 3 SW Marengo Survey Summary: This EF-1 tornado started on Harmony Road immediately southwest of I-90 near the McHenry/DeKalb County line. Tree damage consistent with winds around 95 mph occurred immediately northeast of I-90. The tornado heavily damaged a single family home near Maple Street before heading northeast and lifting near Coral and Dunham Roads. .YORKVILLE TO SOUTH PLAINFIELD TORNADO... Rating: EF-1 Estimated peak wind: 105 mph Path length /Statute/: 14.5 miles Path width /Maximum/: 250 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:15 PM CDT Start location: 4 S Yorkville End date: 08/10/2020 End time: 3:30 PM CDT End location: 4 S Plainfield The tornado started on the far south side of Yorkville near Walsh Drive where a pergola was destroyed, siding was ripped off a house, and parts of a fence and a tree were thrown over a roadway. Eyewitnesses accounts indicate the debris was lifted and twirled, consistent with a tornado. The tornado then progressed east- southeastward producing damage to trees along State Route 126 toward Schlapp Road. The most significant damage was found east of Schlapp Road along Wheeler road where trees were mangled, a farm building was destroyed with debris deposited in a nearby field, and a large grain bin was bent inward. Wood panels were thrown into the ground leaving scour marks in the grass. Six power poles were snapped along Ridge road, and a 1000-1500 lb auger was moved about 50 feet. This is where the tornado likely reached peak intensity with winds near 105 mph. The tornado continued southeast into neighborhoods south of Renwick road producing mainly tree damage, and ended just before I-55. A swath of damaging winds consistent with speeds of 70 to 80 mph continued into Crest Hill based on prolific tree damage. .WHEATON TORNADO.... Rating: EF-1 Estimated peak wind: 90 mph Path length /Statute/: 0.3 miles Path width /Maximum/: 200 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:35 PM CDT Start location: .25 NE Wheaton End date: 08/10/2020 End time: 3:36 PM CDT End location: 0.5 NE Wheaton Survey Summary: A very brief tornado touched down near the intersection of Seminary Avenue and Scott Street before moving northeast where it knocked a roughly 50 foot steeple around to the north side of the College Church in Wheaton. The tornado then produced minor tree damage before lifting near College Avenue and Howard Street. .WHEATON TO GLEN ELLYN STRAIGHT LINE WINDS... Estimated peak wind: 90 mph Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:36 PM CDT Start location: 1 ENE Wheaton End date: 08/10/2020 End time: 3:38 PM CDT End location: 1 NE Glen Ellyn After a very brief break in damage after the Wheaton tornado lifted, a corridor of enhanced straight line winds developed at the southern flank of a circulation. Damage to trees and utility poles were noted, with the peak of the damage corridor occurring east of North Main Street and towards Lake Ellyn Park. Damage in this region is consistent with wind speeds of up to 90 mph. .LOMBARD/VILLA PARK TORNADO.... Rating: EF-1 Estimated peak wind: 95 mph Path length /Statute/: 2.1 miles Path width /Maximum/: 200 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:39 PM CDT Start location: 1 NE Lombard End date: 08/10/2020 End time: 3:42 PM CDT End location: 1 NW Villa Park Survey Summary: The same storm which produced the brief Wheaton tornado produced another region of tornado damage immediately east of I-355 just east of Lilacia Park. This tornado also continued in a northeasterly direction, uprooting trees--some snapped at the trunk--as well as causing some house damage including a few with substantial roof damage. The worst damage occurred near and around the Lombard Common just south of St. Charles Road. Damage eased considerably on the north side of the circulation, with a more gradual drop off in damage to its south. The tornado lifted just northeast of the Jefferson Middle School. .PARK FOREST TORNADO... Rating: EF-0 Estimated peak wind: 85 mph Path length /Statute/: 2 miles Path width /Maximum/: 350 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:57 PM CDT Start location: 1.5 SW Park Forest End date: 08/10/2020 End time: 4:59 PM CDT End location: 0.5 ESE Park Forest A brief tornado touched down very close to the Cook/Will county line near Shabbona Drive. It racked northeast where it produced a localized area of fairly widespread tree damage consistent with high-end EF-0 wind speeds. The worst damage was confined to a small area near Marquette and Somonauk Parks, although very little structural damage was noted in this area. The tornado lifted over Schuberts Woods Forest Preserve. Sporadic straight-line wind damage continued east towards State Street east of South Chicago Heights. .ROGERS PARK (CHICAGO) TORNADO.... Rating: EF-1 Estimated peak wind: 110 mph Path length /Statute/: 3.2 miles Path width /Maximum/: 300 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 3:59 PM CDT Start location: Near Lincolnwood End date: 08/10/2020 End time: 4:04 PM CDT End location: Jarvis and Fargo Beaches Survey Summary: This tornado initially touched down south of the intersection of Crawford and Touhy avenues in the suburb of Lincolnwood. It then continued moving just north of due east before moving offshore near the Jarvis and Fargo Beaches. The most intense damage, consistent with that of a high-end EF-1 tornado, occurred within approximately one mile of the lakefront, as well as near and within Phillip Rogers Park. .GRANT PARK TORNADO... Rating: EF-0 Estimated peak wind: 80 mph Path length /Statute/: 1.5 miles Path width /Maximum/: 250 yards Fatalities: 0 Injuries: 0 Start date: 08/10/2020 Start time: 4:04 PM CDT Start location: 1 NE Grant Park End date: 08/10/2020 End time: 4:06 PM CDT End location: Grant Park An EF-0 tornado touched down just northwest of Grant Park along N 11000 E Road and traveled southeast through Grant Park. Considerable tree damage was found along the path. The tornado ended near Lake Metonga. EF Scale: The Enhanced Fujita Scale Classifies Tornadoes into the following categories. EF0...Weak......65 to 85 mph EF1...Weak......86 to 110 mph EF2...Strong....111 to 135 mph EF3...Strong....136 to 165 mph EF4...Violent...166 To 200 mph EF5...Violent...>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. We thank local academic and emergency management partners for their help in surveying the damage from the 8/10/2020 derecho event. $$ Bardou/Borchardt/Carlaw/Castro/Izzi/Lenning/Lincoln/Sirvatka