Monday, May 23, 2011

EF1 Tornado Near Polo

9:30pm Update: Another one near Stillman Valley.
Stillman Valley, IL

TORNADO CONFIRMED - MAXIMUM RATING EF1: 90-110 MPH
PATH WIDTH: 50 TO 100 YARDS
PATH LENGTH: 1/2 MILE
LOCATION 2.9 MILES NORTH OF STILLMAN VALLEY TO 3.1 MILES NNE OF STILLMAN VALLEY

A brief tornado took out a dual wood truss electrical transmission line tower, tore off the gable and part of the roof of a house, peeled sofit and shingles from a couple other houses, and knocked down trees and limbs. Truck trailers were also overturned.

8pm Update: Another tornado confirmed in Stateline
** CONFIRMED EF1 TORNADO **

MAXIMUM RATING: EF1
PATH LENGTH: 17 MILES
PATH WIDTH: 200 YARDS
LOCATION: 2 MILES EAST-SOUTHEAST OF FORRESTON TO 1 MILE SOUTH
OF WINNEBAGO, IL
TIME: 6:25 TO 6:45 PM CDT (PRELIMINARY)




Polo, IL

TORNADO CONFIRMED - MAXIMUM RATING: EF1 (86-110 MPH WINDS)
PATH LENGTH: 1 1/2 MI
PATH WIDTH: 200 YARDS
LOCATION: 1 MILE SOUTHEAST OF POLO, IL
TIME: TBD

The tornado touched down just south of incorporated Polo, just south of the intersection of Union Road and Judson Rd. A power pole was blown leaning over the road. At this point the tornado was rated EF1 with winds estimated at 85 mph.

The tornado widened slightly as it progressed to the east along Judson road, and uprooted a 20 inch diameter fir tree. At this point the tornado was still at EF1 strength, and there were branches down. The tornado then moved east and its width widened to 200 yards. There was roof damage to sheet metal roofing on 4 buildings and a wood outbuilding that was left leaning over by the tornado. In this area several 2X4’s were speared into the ground from different directions and insulation was plastered on the east and northeast face of buildings.

Another property just to the northeast of this point experienced six 16 inch diameter Norway Spruce trees snapped off, and a new wood power pole was snapped in half. It was here where the tornado reached its maximum intensity with winds at 100 mph. The tornado continued to the east maintaining its intensity (EF1 strength) another ¼ mile to the east where a grain bin was ripped off its foundation and a portion of the roof blown off to the north up against a fence. After this the winds weakened as the tornado lifted. A couple of additional grain bins were blown over, small branches snapped off, and shingles blown off roofs. Winds were estimated at 70-80 mph. Tornado lifted at 10506 Judson Road at Dailey Rd.


Rockford, IL
STRAIGHT LINE WIND DAMAGE CONFIRMED - MAXIMUM WIND RATING: 90-100 MPH WINDS DAMAGE WIDTH: 5 MILES
LOCATION: WEST AND NORTHWEST ROCKFORD, ROSCOE, AND ADJACENT WINNEGAGO CO
TIME: 6:49 PM TO 7:09 PM CDT

A fairly wide swath (up to 5 miles wide) of sporadic wind damage was observed across the west and northwest sides of Rockford and adjacent parts of rural Winnebago County. Preliminary survey results indicate this damage was due to straight line winds. However additional surveying continues and this information is preliminary only. Damage was somewhat more concentrated around the Roscoe Fire Station, where a large garage door was blown in, and around the Kennedy middle school which had part of a roof blown off.

Debris all across this area were observed to have been blown from southwest to northeast. Other than to the fire station and middle school, no structural damage was observed except where trees fell on houses. Winds were estimated to have been 50 to 70 mph across the wide swath of damage area, with a few concentrated areas of winds as high as 90-100 mph, equivalent to EF1 strength.

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