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People in central Illinois observed a strange phenomenon February 11 and 12, 2003.
Log-shaped "snowballs" showed up on lawns, fields, and other open areas.
This is a phenomenon referred to as "snow rollers". These are
formed under specific weather conditions:
The ground surface must have an icy, crusty snow, on which
falling snow cannot stick.
About an inch or so of loose, wet snow must accumulate.
Gusty and strong winds are needed to scoop out chunks of snow.
Snowfall of 1 to 4 inches occurred
across central Illinois the morning of February 11. That evening,
as a strong cold front pushed through the area, wind gusts of 40 to 60
mph were noted in many areas.
Once the initial "seed" of the roller
is started, it begins to roll. It collects additional snow from
the ground as it rolls along, leaving trails behind it. The
appearance is similar to building snowmen, except the snowball is more
log-shaped rather than spherical, and many times they are hollow.
They can be as small as a golf ball, or as large as a 30 gallon drum,
but typically they are about 10 to 12 inches in diameter.
Several photographs have been provided
of these snow rollers:
This snow roller picture was taken by NWS observer Paul White
near Petersburg.
The ruler indicates this snow roller was nearly
11 inches thick.
Another snow roller near Petersburg. The scale
indicates that this roller
weighed nearly 5 pounds.
These snow rollers were photographed at the Lincoln Christian College, by NWS
personnel in Lincoln. Tracks that the rollers took can be seen trailing
behind.
(The snow rollers generally moved in an eastward direction.)
Another image from the Lincoln Christian College. Several dozen of these snow
rollers were visible along Highway 10.
These snow rollers were photographed at Scully Park in Lincoln.
NWS employee Chris Geelhart took this picture in Sherman.
NWS observer Paul Hadfield sent this picture from near Forsyth.
NWS employee Dan Kelly photographed these snow rollers in
rural Macon County.
Another view of snow rollers in Macon County.
Karen Thompson photographed these snow rollers near Buffalo.
Another picture of snow rollers near Buffalo.
Photo taken by Karen Thompson of Snow Rollers in Buffalo.
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