4/7/98 Chase Summary by Don Lloyd


From: Don Lloyd (dlloyd@TCCCOM.NET):
Subject:      Illinois chase report
I didn't decide to chase until 8:30 after an analysis of 13Z surface data.
Moisture return was the main concern, but that analysis convinced me enough
moisture was advecting northward to push dewpoints to near 60F in southern
Illinois by late afternoon. My target was Vandalia based on my forecast
putting the low in southeast Iowa, a triple point near Springfield, with
a warm front stretching southeast, and the nose of a 500mb speed max
over Vandalia about 22Z.

As it turned out, the warm front pushed into northern Illinois moving the
axis of severe weather 60 miles north of my target. After a new surface
analysis at 19Z in Effingham, I drove to Springfield and to the first
storm of the afternoon. The sky just west was a mix of cumulus, ACCAS,
building ACs, with fairly young anvils in long thin plumes streaming east.
The storm southwest of Springfield (tornado warning about 4:20) looked
mushy at a distance but more impressive as I approached the southeast
flank, a tall crisp tower, a broken flanking line, and a flat rainfree
base typical of a classic supercell. I observed this storm for over an
hour but never saw a significant lowering or cloud base rotation through
several new backbuilding updrafts.

I drove east and south to intercept the next storm south as it moved east
of Taylorville. I reached the southwest flank and updraft base 2 miles
west of Moweaqua. A wide lowering was visible but rotation was difficult
to assess because of rain and 1" hail and numerous scud wannabes whipped
around by the wind. Regardless, with rain and hail wrapping around the
meso, it was starting to look like an HP storm. At this point, a local
sheriff reported a tornado touchdown at my location. I saw the sheriff
but I did not see a tornado...hmmm.

I followed the rear flank east, but was unable to lose the rain and hail
which was getting progressively larger...I started to worry about that
big windshield on my Voyager--I don't know what a new one costs and was
not ready to find out. So I backed out and cut north, thinking (I guess)
that I would see the next backbuilding updraft and could better plot a
chase route. And while the NWS was reporting all storm/meso movements to
the northeast, it was becoming obvious this storm was moving/propagating
due east. So I turned south and east several times trying to reposition
myself on the southwest flank of the storm. All I found was torrential
rain and large hail. And all this time, new tornado warnings are blaring
on the radio and there I was, lost in rear-flank hell....

I broke off the chase at dusk and pondered the lessons learned on the
long ride home. Chase distance: 927 miles.

Anyone have radar archived of that cell?

Don Lloyd
http://www.wx-fx.com


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