4/15/98 Chase Summary by Mark Rhein


From: Mark Rhein (B40YOUNG@aol.com):

   My experience on April 15 was fairly uneventful.  I went down to just
north
of Bloomington at the intersection of 24 and 55 where I had a birds-eye view
of 
the mechanics setting up.  As I sat there I could see the dry punch expanding 
over my head with mid and lower cloud development to my north.  Only scattered
to
broken cu and a few towering cu were able to form from where I was and to the
south.  The towering cu were dissipating at their base whenever they would
reach any significant height.  At around 3pm we were in a tornado watch and I
heard from 
Spirros on WMAQ that the strongest cells were in northwest Illinois.  I
thought that
if I headed north to the southern edge of the activity as it came across that
I would be in good position.   As it turned out, there was a tornado warning
just north of
me in northwest La Salle county.  It wasn't much of an outbreak as that was
the last warning issued.   A cold front was pushing south as temps up toward
Rockford were
in the 40s now and winds were north and northeast up around Chicago.  The
activity seem to get wedged in north central Illinois and with activity
seemingly winding down now at around 7 to 8pm, I felt that the show was over.
I drove north through the rain
and found a cell producing 1/8 mile visibility in R+ in a very narrow band and
it was hardly moving.  Doppler later verified some over 2 inch rains there.  I
proceeded home just in time to mail my taxes which were in my back seat.

Some notes.. As I drove north on 55 toward the action, I kept an eye out west
thinking that there may be a cell to the south of the storms that were forming
along the warm front.  There was one cell that had an anvil, but it didn't
seem to be punching upward, rather it was leaning over quite a bit and rain
was falling from beneath the anvil..  It didn't look like something to chase.
I felt that I was in the best
place if something was going to develop.  I did see  the base of the
cumulonimbus that was causing the comotion with the tornado warning, but when
I saw it, it looked like a normal thunderstorm.  No rotation, the base hung
several hundred feet lower that anything near it, but I don't think that it
was a wall cloud.  Doppler may have 
seen a signiture for rotation in the cloud, but I couldn't make it out.  It
was a fair distance away as I didn't want to drive into its path before I knew
what it was.  Eventually I did core puch the cell as it was on my way home and
that's when I hit the big rain.  Again the base was lower than anything around
and it was very dark in comparison to anything in the vicinity.  Also the cell
had frequent lightning with it and 
there were strong surface winds blowing into it as I approached.  I think that
the strong low pressure in the area combined with the strong temperature
gradient explain the 25-30 mph sustained winds that I was experiencing.

I took pictures of what I saw but the camera has no zoom.

wmbd  could be picked up near bloomington.  they didn't have much to report
out there.   wjbc was dissapointing with little coverage but again, not much
was going on
at first.  the best coverage was Spirros on wmaq and a station near La Salle
Peru at 1220 am just one station from wjbc on the dial.  jbc is 1230 am.  1220
am was
very much on top of the watches/warning etc an even though they were covering
a local high school baseball game, kept interrupting with reports.

Mark Rhein


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