| April 15 April 15 Continued
As we approached the small town of
Lonedell (10 miles southeast of St.Clair),
we started to observe long inflow bands stretched out east/west and aligned
with the outflow boundary. The storm was headed right along that boundary!!
Amateur radio spotters were reporting a rotating wall cloud and very large
hail about 5 miles w-sw of St.Clair moving east- right for us. At 4:25 pm , large
hail (dime to quarter sized) fell as we passed through Lonedell. Hail size
steadily increased as we approached the Meramec River bridge on Highway
30/47. Soon after crossing the bridge and just 3 miles southeast of St.Clair, we
caught a brief glimpse of the wall cloud (with pendant funnel) but were now
driving into golfball and occasional baseball sized hail. We were forced to
turn around or pay the consequences!!
After our hasty retreat, we heard a
report of softball sized hail on the west and
southwest sides of St.Clair. The very large circulation passed just south of the
city of St.Clair and a prominent wall cloud could now be observed to our west.
We found a hill with a less obstructed view to the west and southwest where we
could video this large wall cloud. Frequent cloud to ground lightning strikes
arced to the ground around us as the wall cloud took on the pre-tornado look
complete with wrapping rain curtains. Our ears started to pop and that usually
means to watch out!! We watched violent rotation with this wall cloud but the
circulation could never work its way to the ground before gusting out. Large
hail was ejected far ahead of the hail core and some reports were now coming
out of Jefferson Co to our east. After viewing the demise of this wall cloud, we
figured out that the low level jet was not strong enough to balance the strong
winds aloft. This coupled with a large hail core was causing the storm to gust
out severely-the warm air inflow wedge collapsed. No tornado !! We did get
blasted with 70 mph+ winds from the west as the gusted out circulation passed
to our north. We quickly departed the Lonedell area through the windy wooded
areas near DeSoto Mo. We tried to intercept the storm several times before it
crossed the Mississippi River, but the uncooperative roads limited our success.
We crossed into Illinois via the J.B. bridge on I-255 and headed into Monroe
county and south on rt 3. The supercell did produce a brief tornado near the
town of Red Bud which was 25 miles to our s-se. The storm continued to track
to the east at 30 mph. This storm by now has had a tornado warning posted
on it for the past 3 hours and we were not going to let this one get away from
us!! We planned on an intercept of this storm in N.Randolph county. The time
was 5:50pm and we were passing through the town of Waterloo. A tornado
warning was re-issued for N.Randolph county at this time. We finally caught
up to the storm near the town of Baldwin (Randolph Co.). The storm recently
gusted out but was starting to re-organize. We stopped on rt 154 about 2 miles
west of Baldwin to watch rotation increase with the storm. The chaotic storm
motions soon revealed a newly formed wall cloud at 6:14 pm to our nw. We
watched this wall cloud rotate strongly for a few minutes and then it gusted out!!
We headed east toward Coulterville and then ne to the town of Oakdale. The
storm was now a very large HP supercell which was tracking east-northeast
in Washington Co.. A new tornado warning was issued for Washington Co.
and the tornado was to track towards the town of Nashville. The inflow was
increasing quickly with sustained se winds at 40 mph at our location near
Oakdale. We decided to head on to Nashville as the core was approaching
rapidly!! On the way to Nashville, we were once again blasted by intense
RFD winds, only this time they were stronger. Tree damage and power line
flashes were observed as the RFD gust front blasted in south of Nashville at
7:10 pm.
Once again we were playing catch up with this storm. We encountered a
wide swath of tree damage and snapped power poles at 7:22 pm east of
Nashville about 4 miles on rt 15. The circulation was well to our northeast
near Richview and tornado reports started flowing in as the storm moved
into Marion and Jefferson counties. Apparently, the storm had finally reached
a stronger low-level jet to sustain vigorous rotation and tornadoes. Darkness
was now upon us so we called it a day and headed back to St. Louis. Quite
a few tornadoes touched down after dark over SC Illinois that evening. The
strongest was a F-2 in the town of Flora at 8:45 pm.
Special thanks to the NWS St.Louis for their assistance !!
Although no tornadoes were seen, valuable experience was gained today
regarding the importance of the low-level jet to strong tornado development-
a common trend in the 1998 tornado season!!
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