Severe Weather of August 23, 2007

Severe weather reports from August 23

Severe weather reports from Illinois for Thursday, August 23, 2007 (click image to enlarge)

National severe weather reports

National reports of severe weather for Thursday, August 23, 2007 (click image for specific details)

Quick Links:
Event Overview, Galesburg Survey, Other Knox County Storms,
Radar & Weather Images, Damage Pictures, Local Storm Reports

Event overview:

Strong to severe thunderstorms moved out of southeast Iowa during the midday hours of August 23.  They intensified and raced northeast across northern Illinois, causing significant damage across portions of Warren and Knox Counties, as well as the Chicago metropolitan area.  This particular page will focus on the Knox County portion of the storms.

Surveys conducted by the Lincoln NWS office, as well as the Knox County EMA, confirmed that widespread damage across the city of Galesburg was caused by wind gusts in the 70 to 80 mph range.  These wind estimates continued for several miles past Galesburg, to the Wataga and Victoria areas.  Within the city of Galesburg, enhanced damage was caused by a fast-moving microburst, which produced estimated wind speeds of around 100 mph.

Galesburg Information:

Radar loop of storm moving across Knox County (1.3 MB)

The area of widespread wind damage was caused by an intensifying area of thunderstorms, which moved into west central Knox County shortly after 1 pm.  These storms were moving from southwest to northeast, at 55-60 mph.

The area of damage was about 8 miles wide.  A wind gust of 74 mph was reported at the Galesburg Municipal Airport at 1:09 pm, before the automated weather station failed.  Damage began in the city of Galesburg around 1:10 pm, and continued within the city limits for approximately 5 minutes.  There were more than 500 trees either damaged or destroyed.  Falling trees or large tree limbs resulted in significant damage to dozens of buildings and vehicles.  Numerous buildings sustained damage to roofing and chimneys, as well as minor damage to siding and broken windows.  About 20 power poles were snapped, and numerous power lines were brought down.  At least two semi-trailers were blown over on U.S. Highway 34 west of Galesburg, and on I-74 just east of Galesburg.

Map of worst damage in GalesburgAn area of enhanced wind damage was found within the city as well.  This area was about 1/2 mile wide, and 2 miles long.  It began close to the intersection of Knox and Pine Streets, and continued to the northeast, crossing the intersections of Grand Avenue and Oak Street, Farnham and East Main Street, and extending to Illini Drive and the Soangetaha Country Club east of I-74.  Significant damage to trees, fences, garages and a business occurred around 1:15 pm.  Several homes sustained roof and siding damage, primarily from debris and falling tree limbs.

The storm injured 7 people in Galesburg, with cuts and broken bones.  Another 22 people sustained minor injuries during the cleanup effort.  More than 10,000 customers in the city were without power.

Information for Knoxville, Wataga, and Victoria:

The city of Knoxville, about 4 miles southeast of Galesburg, also sustained widespread wind damage, shortly after 1:15 pm.  Wind speeds were estimated to be 60-80 mph.  Extensive damage was done to trees and power lines.  Roofs and autos were damaged, mainly from falling trees and limbs.

Wataga, 4 miles northeast of Galesburg, was affected by the high winds around 1:20 pm.  Winds estimated at 60-80 m ph also produced damage to trees, and downed power lines.

The town of Victoria, 15 miles east-northeast of Galesburg, also sustained 60-80 mph wind gusts.  The damaging wind struck around 1:25 pm, downing trees and power lines.  A man was killed in rural Victoria after a falling tree struck him.

Numerous farm fields sustained damage in northern Knox County, due to the high winds.  Corn stalks and soybean plants were flattened as a result.

Radar and Weather Images (click images to enlarge):

Noon weather map This is the noon weather map for northern and central Illinois and adjacent areas.  The shading indicates the Convective Available Potential Energy (CAPE).  The highest values are indicated by the yellow, orange and red shades, of approximately 2500 J/kg or above.  Lifted index values are shown by the orange dashed lines.  Across Galesburg and vicinity, temperatures were in the mid to upper 80s with dewpoints in the mid 70's.  Significantly cooler conditions were noted further northwest, with temperatures around 70 degrees northwest of the Quad Cities.
Radar image at 12:43 pm The Lincoln radar image from 12:43 pm shows the thunderstorms well west of Galesburg, in Henderson County.
Radar image from 12:53 pm By 12:54 pm, the storms were beginning to move into Kirkwood, in western Warren County.  Damage surveys conducted by the Quad Cities NWS indicate that winds of 100 mph were produced by these storms.
Radar image from 1:05 pm The radar image from 1:05 pm showed the storms were approaching the Warren/Knox county line.
Radar image from 1:10 pm The 1:10 pm radar image showed the leading edge of the storms coming into Galesburg.  The Galesburg airport reported a 74 mph wind gust at 1:09 pm.
Radar image from 1:15 pm At 1:15 pm, damage was beginning to occur in Knoxville, southeast of Galesburg. 
Radar image from 1:31 pm The radar image from 1:31 pm showed the thunderstorms beginning to take more of a "bow" shape, as indicated by the bulge in the echoes across southwest Stark and northwest Peoria counties.
Radar image from 1:42 pm This image from 1:42 pm showed the line of thunderstorms mainly out of Knox County.  The storms travelled approximately 60 miles over the course of an hour (first image in this sequence to last image).

 

Pictures (click images to enlarge):

Extensive tree damage in eastern part of Galesburg
Galesburg

This car was extensively damaged by falling trees.
Galesburg

Tree tops sheared off by high winds
Galesburg

Extensive damage to trees, shed and garage
Galesburg

NWS and EMA personnel survey the damage
Galesburg

This large tree was split into several pieces
Galesburg

 

 

Specific storm reports:

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LINCOLN IL
1003 PM CDT THU AUG 23 2007

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

0105 PM     TSTM WND DMG     1 W GALESBURG           40.95N 90.40W
08/23/2007                   KNOX               IL   EMERGENCY MNGR

            LARGE HIGH VOLTAGE TRANSMISSION LINES BLOWN DOWN...PART
            OF A ROOF OF A COMERCIAL BUILDING BLOWN OFF...AND A SEMI
            BLOWN OVER ON US ROUTE 34.

0109 PM     TSTM WND GST     GALESBURG               40.95N 90.38W
08/23/2007  M74.00 MPH       KNOX               IL   AWOS

            REPORTED AT THE GALESBURG AWOS...RELAYED FROM SPC

0110 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   EMERGENCY MNGR

            POWER POLES DOWN AT RT 41 AND MONMOUTH AVE IN
            GALESBURG...AND RIDING LAWNMOWERS BLOWN INTO THE STREET.
            REPORT FROM KNOX COUNTY EM

0112 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   TRAINED SPOTTER

            3 TO 4 INCH DIAMETER TREE LIMBS DOWN AT SANDBURG MALL IN
            GALESBURG. TIME ESTIMATED...REPORT OCCURRED BETWEEN 107
            AND 117PM. ESTIMATED 60-70MPH WINDS

0115 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   CO-OP OBSERVER

            ESTIMATED 100MPH WIND GUST. TREES DOWN AND POWER OUTAGES
            IN GALESBURG. REPORT FROM NEAR US ROUTE 34 AND SEMINARY
            ROAD

0115 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   CO-OP OBSERVER

            SEVERAL TRAILERS DAMAGED...STORE SIGN BLOWN OVER...TIME
            ESTIMATED BETWEEN 110 PM AND 120 PM.

0115 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   TRAINED SPOTTER

            LARGE OAK TREES UPROOTED...TREES DOWN ON GARAGES AND
            HOUSES OFF OF FREEMONT STREET. EXTENSIVE DAMAGE ON THE
            NORTHEAST SIDE OF GALESBURG

0115 PM     TSTM WND DMG     GALESBURG               40.95N 90.38W
08/23/2007                   KNOX               IL   PUBLIC

            NUMEROUS TREES UP TO 1 FOOT DIAMETER AND POWER LINES DOWN
            ON HARRISON ST...ROCK ISLAND AVE...LANE ST AND MOISIER ST
            ON THE NORTHEAST SIDE OF GALESBURG.

0117 PM     TSTM WND DMG     KNOXVILLE               40.91N 90.29W
08/23/2007                   KNOX               IL   CO-OP OBSERVER

            ESTIMATED WINDS OF 60 TO 80 MPH...TREES AND POWERLINES
            DOWN. EXTENSIVE DAMAGE THROUGHOUT KNOXVILLE

0120 PM     TSTM WND DMG     VICTORIA                41.03N 90.10W
08/23/2007                   KNOX               IL   EMERGENCY MNGR

            *** 1 FATAL *** PART OF A TREE WAS BLOWN DOWN AND FELL ON
            A MAN WALKING UP THE SHORE OF A SMALL LAKE NEAR THE TOWN
            OF VICTORIA. REPORTED BY KNOX COUNTY ESDA. WIDESPREAD
            WIND DAMAGE OCCURRED ACROSS ALL OF KNOX COUNTY...WITH THE
            MOST EXTENSIVE DAMAGE IN GALESBURG...WATAGA...AND
            VICTORIA. AT LEAST 8000 PEOPLE WERE WITHOUT POWER AT THIS
            TIME IN THE COUNTY.

0145 PM     TSTM WND DMG     TOULON                  41.09N 89.86W
08/23/2007                   STARK              IL   LAW ENFORCEMENT

            SEVERAL REPORTS OF TREES AND POWERLINES DOWN THROUGHOUT
            STARK COUNTY. REPORT FROM STARK COUNTY SHERIFF

0150 PM     TSTM WND DMG     PRINCEVILLE             40.93N 89.76W
08/23/2007                   PEORIA             IL   EMERGENCY MNGR

            3 INCH DIAMETER LIVE TREE LIMBS DOWN ON THE WEST SIDE OF
            PRINCEVILLE...FROM PEORIA COUNTY EMERGENCY MANAGER

0150 PM     TSTM WND DMG     TOULON                  41.09N 89.86W
08/23/2007                   STARK              IL   EMERGENCY MNGR

            WINDOWS BLOWN OUT IN A CHURCH IN TOULON

0215 PM     TSTM WND DMG     HENRY                   41.11N 89.36W
08/23/2007                   MARSHALL           IL   MESONET

            TREES BLOWN DOWN AND LIMBS DOWN. FROM SWOP OBSERVER.

0215 PM     TSTM WND DMG     LACON                   41.02N 89.41W
08/23/2007                   MARSHALL           IL   LAW ENFORCEMENT

            TREES AND POWERLINES DOWN ACROSS MARSHALL COUNTY

0236 PM     TSTM WND DMG     5 NE SPRING BAY         40.87N 89.46W
08/23/2007                   WOODFORD           IL   EMERGENCY MNGR

            TREE BLOWN ON ROUTE 26 AND LOON CREEK ROAD NORTH OF
            SPRING BAY

0635 PM     HAIL             BRADFORD                41.18N 89.66W
08/23/2007  M0.75 INCH       STARK              IL   CO-OP OBSERVER

0645 PM     TSTM WND DMG     BRADFORD                41.18N 89.66W
08/23/2007                   STARK              IL   CO-OP OBSERVER

            LARGE TREE BRANCHES DOWN.

0714 PM     TSTM WND DMG     HENRY                   41.11N 89.36W
08/23/2007                   MARSHALL           IL   EMERGENCY MNGR

            LIMBS BLOWN DOWN ON POWER LINES. FROM COUNTY ESDA.

0715 PM     TSTM WND DMG     HENRY                   41.11N 89.36W
08/23/2007                   MARSHALL           IL   MESONET

            POWER LINES DOWN. FROM HENRY CITY ESDA SWOP OBSERVER.

0730 PM     TSTM WND GST     2 SW TOULON             41.07N 89.89W
08/23/2007  M61 MPH          STARK              IL   CO-OP OBSERVER

            TIME ESTIMATED. OBSERVER REPORTED SEVERAL TREES DOWN AND
            NUMEROUS CORN STALKS BLOWN DOWN. REPORT FROM COOP
            OBSERVER

0740 PM     TSTM WND DMG     CAMP GROVE              41.08N 89.63W
08/23/2007                   MARSHALL           IL   EMERGENCY MNGR

            LIMBS DOWN. FROM COUNTY ESDA.

0820 PM     HAIL             HENRY                   41.11N 89.36W
08/23/2007  M1.00 INCH       MARSHALL           IL   MESONET

0827 PM     HEAVY RAIN       HENRY                   41.11N 89.36W
08/23/2007  M2.24 INCH       MARSHALL           IL   MESONET

            2.24 INCHES OF RAIN SINCE THIS AFTERNOON. FROM SWOP
            OBSERVER.



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