Roanoke F4 Tornado of
July 13, 2004
Plant before the tornado (undated photo)
F4 Tornado striking Parsons
Manufacturing Plant (courtesy of Scott Smith)
Track of tornado, from
north of Metamora to south of Roanoke
Remains of Parsons
Manufacturing Plant, taken July 15 (courtesy of Woodford County ESDA)
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Radar Images, Photos
Violent Tornadoes (F4 or F5)
across Illinois since 1950
Parsons Plant Gallery of F4 Roanoke Tornado & Damage
Rebuilt April 2005
Summary of Event:
Supercell thunderstorms tracked across northern and
central Illinois the afternoon and evening of July 13. A violent
tornado tracked for 9.6 miles across Woodford County, with the tornado
reaching F4 intensity along a 1-mile stretch between Metamora and Roanoke.
Damage surveys were completed by National Weather
Service and Woodford County ESDA personnel on July 14 and 15.
Specific details on the tornado's track follows.
The tornado touched down approximately 1.8 miles
north of Metamora, a few hundred yards southeast of the intersection of
Illinois Route 89 and county road 1600N. The tornado was initially
of F0 (40-72 mph) strength. It moved southeast, and strengthened to
F2 intensity (113-157 mph) near the time it reached county road 1300E.
It then began a temporary eastward movement for about a half mile, before
curving southeast again. It crossed Route 116 just west of the Route
117 junction, and was at F3 strength (158-206 mph) at this point.
The tornado increased to F4 intensity
(approximately 210-240 mph) as it crossed Route 117,
demolishing the Parsons Manufacturing Plant at this intersection.
Approximately 140 people were in the plant at the time, but all made it to
storm shelters in time (approximately 3-5 minutes before the tornado
arrived). Steel beams and metal siding from the plant were found
approximately 3/4 mile east in a farm field.
From the plant, the tornado continued east, just
south of Routes 116/117, affecting 4 farmsteads
approximately 1/2 to 1 mile east of the plant. Two of the farmsteads
closest to the plant (about 1/2 to 3/4 mile east) had the 2-story houses
completely blown away, with only debris remaining in the basements and
nearby property. The other two farmsteads had significant damage to
the 2-story houses, with outbuildings demolished. The center of the
tornado's track was about 100 yards south of the farmsteads on the south
side of the highway.
From the plant to the farmsteads, the storm was F4
intensity. The average width of the tornado during this time was 400
yards, and was close to 1/4 mile wide at times.
At this point, the tornado began to travel in a more
east-southeast direction, and caused significant damage to a barn near the intersection
of county roads 1300N and 1700E. It caused significant damage at a
farmstead at the southeast corner of 1300N and 1800E. The tornado crossed 1300N shortly
afterward, and lifted around 2:57 pm about 2.5 miles southeast of Roanoke,
at county road 1900E.
The tornado was on the ground for approximately 23
explanation of the Supercell in Illinois on 7/13/04
Weather and Radar Images:
||This is the upper-air sounding taken at
Lincoln at 7 am (12Z) July 13. The air is already quite
unstable, with a lifted index of -11.
||A special upper-air sounding was taken that
day. The 1 pm (18Z) sounding showed CAPE values were over 6400
J/kg, the lifted index had decreased to -14.7, and wind shear in the
lower levels of the atmosphere were increasing.
||This is a surface weather plot of Illinois
from 7 am. CAPE values are overlaid and shaded. Dewpoint
values in the lower 70s were common over the area.
||The surface plot at 11 am indicated dewpoint
values rising across the southwest half of the state, and were close
to 80 degrees. The CAPE values consequently rose, and were
over 4500 J/kg in the white areas on the map.
||By 2 pm, the oppressive heat and humidity had
spread east to the I-57 corridor. CAPE values well over 6000
J/kg were common, and heat index values were in the 105 to 110
||This is a 4-panel visible satellite image of
the supercell storms that moved across Illinois. Starting
clockwise from the upper left panel, image times were 11:01 am, 1:15
pm, 3:15 pm, and 5:02 pm. Roanoke is located at the green X
labeled "Home" in the image.
||This is the 0.5 degree reflectivity image
from the Lincoln Doppler radar at 2:01 pm. The Roanoke storm
will quickly evolve from the shower located just east of Spring Bay.
The site of the Parsons plant in this and subsequent images is
indicated by the blue X labeled "Home".
||By 2:11 pm, the storm begins to grow as it
approaches a separate strong thunderstorm located across north
central Woodford County.
||At 2:16 pm, moderate to heavy rain is
occurring at the Parsons plant, with the most intense part of the
storm still to the northeast, approaching Benson.
||The 0.5 degree Storm Relative Motion (SRM)
image taken at the same time does not show evidence of a circulation
from the southwest part of the storm. (The radar site is
located about 45 miles south of the "Home" location on the image.)
||The image from 2:21 pm shows the storms
beginning to merge, with the western storm starting to become the
more dominant storm.
||The SRM image at 2:21 pm shows the beginnings
of a circulation between Chillicothe and Metamora.
||At 2:26 pm, the heart of the storm is moving
through Roanoke. Note the appendage extending northwest to
between Chillicothe and Metamora.
||The SRM image at 2:26 pm is beginning to show
an intensifying circulation in the previously mentioned appendage.
A Tornado Vortex Signature (TVS) is indicated by the radar, as the
purple triangle in the image.
||The 2:31 pm radar image showed the Parsons
plant beginning to see the rain taper off. However, the
appendage on the northwest part of the storm is becoming more
concentrated, with a definite hook-shape indicated (at the purple
triangle labeled "S1" in the picture).
||The 0.5 degree SRM image at 2:31 pm shows the
mesocyclone significantly more intense than 5 minutes ago.
Later storm damage surveys indicate that a tornado has touched down
around this time.
||At 2:36 pm, the hook echo is quickly
approaching the Parsons plant from the northwest.
||About a mile or so to the west of the plant,
the SRM images at 2:36 pm continue to show the tornado's
intensification. The bright-green and bright-red squares next
to each other indicate what radar operators call "gate-to-gate
shear", with winds in excess of 50 knots (58 mph) in opposite
directions next to each other.
||At 2:41 pm, the Parsons plant is being
demolished by the tornado (location indicated by the white circle).
The increase in reflectivity strength (red shades in the hook echo)
may be due to debris being drawn upward, enhancing the radar beam's
||The SRM image at 2:41 pm shows the
gate-to-gate shear couplet over the plant site.
||At 2:46 pm, the tornado is moving
east-southeast from the plant, with the appendage/hook still visible
on the west edge of the storm.
||The gate-to-gate shear couplet is now located
between the Parsons plant and the town of Roanoke.
||The 2:51 pm radar image shows the appendage
feature now over the town of Roanoke...
||and the SRM image shows the circulation
moving just south of town. However, the shear is not quite as
strong as earlier.
||At 2:56 pm, the appendage is no longer
readily visible, as the storm pulls away from the Roanoke area.
||The SRM image still shows a very broad
circulation across central Woodford County, but no longer indicates
a potential tornado.