Severe thunderstorms moved across parts of southern Wisconsin and
northern Illinois Tuesday evening, producing hail up to three inches in
diameter in some locations, damaging many cars and buildings.
Thunderstorms were quick to develop over Wisconsin late Tuesday
afternoon ahead of a cold front, producing hail north of Milwaukee and
over far southwest Wisconsin. One particular supercell thunderstorm
continued to strengthen as it moved into southern Green County before
dipping south into Jo Daviess and Stephenson counties. There, golf ball
sized hail was reported in Orangeville, as well as a few miles south of
Monroe. That storm continued to grow as it moved east, prompting
severe thunderstorm warnings further east over Winnebago County. As the
storm moved across northern Stephenson County it began to show signs of
rotation in the mid-levels. The tornado threat with this particular
storm, in this environment, was low but such a strong updraft continued
to promote the development of large and damaging hail.
Golf ball to tennis ball sized hail reports continued to come in from
near Durand and Davis/Lake Summerset in northwest Winnebago County. As
the storm continued to move southeast, another storm developed north of
Winnebago and produced golf ball sized hail that covered the ground in
Winnebago. Pea to dime sized hail, even moth-ball sized hail, was
reported north of Rockford while the strongest part of the storm moved
through New Milford. The storm continued to travel to the southeast
into northern DeKalb County before moving out of the viewing area a
little after 9pm. A few additional showers and storms developed, with
one storm producing quarter sized hail in Sycamore a little after 9pm.
To understand why these storms produced such large hail we need to
understand how the storm developed itself. All thunderstorms have
updrafts and downdrafts. The updraft provides the warm, moist air to
fuel the storm while the downdraft is the wind, rain and hail that falls
from the storm. Temperatures Tuesday afternoon warmed close to 80
degrees across northern Illinois and southern Wisconsin, building quite a
bit of instability in the atmosphere. But that energy was 'capped' by
warmer air aloft. Think of our
 |
| Clayton Warren New Milford |
|
atmosphere as a pot of boiling water
with a lid on it. The water doesn't boil as much when the lid is on,
but once you remove the lid the water begins to boil rapidly. The same
idea applies to our atmosphere. As the cold front moved in from the
northwest, it helped 'remove' the lid allowing storms to quickly form.
We didn't have all the right ingredients in place for tornado producing
thunderstorms, but with the intense rising air through the atmosphere
there was rotation present in the mid-levels of the thunderstorm
allowing large hail production.
 |
| Steven Dittmar Winnebago |
|
Rising water droplets inside the storm will freeze and collide with
other water droplets, ice crystals and hail stones. When the hail stone
becomes too heavy for the updraft to hold, the hail stone will fall to
the ground. The stronger the updraft, the larger the hail stone is
likely to grow. As it remains suspended within the thunderstorm it will
continue to collide with other hail stones. This is why large hail
stones are rarely ever smooth and have more of a rough look to the outer
edges, and sometimes will look like it has layers.
The storms Tuesday evening were definitely intense and damaging but
thankfully skies will remain much more quiet during the overnight.
No comments:
Post a Comment