8/16/97 IL Chase by Doug Sefried


                                                        
8/16/97 chase report by Doug Sefried

Although the threat for tornadoes and severe weather was not
as likely then the previous SPC outlook(moderate risk downgraded
to slight) due to weaker wind fields, this was still a great 
chase.

                                                    THE SET UP

A surface trough/outflow boundry was ahead of the main cold 
front and was sitting over northwest Illinois and east 
central Iowa.  Temps were in the upper 80's and low 90's 
across the area. Dewpoints were pooling to the low 80's 
with an extremly unstable airmass(CAPE 4000-6000 and 
LI's to -14).  A 40 knot jet streak was forecast to move 
into the area late in the afternoon.  Mark Sefried and I 
left Peoria at 2:45 and headed west then north on interstate 
74 . At 3pm Peoria was reporting 92 degrees , dewpoint 77, 
and a south wind at 10.  Moline had a temp of 88 and a 
dewpoint of 79.  We were getting hungry around 3:30 so we 
decieded to stop in Andover in westren Henry county for some 
food. We left Andover at 4:15 with towers trying to form to 
our north but they were being cut off.  Then at  4:20 the CAP 
was broken and the storms exploded very rapidly of to the 
north and northwest and ten minutes later one storm had an
anvil already!  At 4:55 a severe thunderstorm watch is issued 
for NW IL and easten Iowa. We are north of Cambridge heading 
north on IL 78 at 5pm.

                                                    Storm #1 

We reached Hooppole at 5:48. The storm is looking very 
impressive with a back building anvil and impressive new 
towers on its west side. At 5:58 we are in Prophetstown in 
southren Whiteside county. A Tornado warning is issued with 
a rotating wall cloud west of Morrison (about 8 miles NW). The 
Rock River was a problem though, should we cross knowing that 
we my get trapped on the west side or head NE along its east 
side? The storms seemed to be moving slow so we decided to 
cross. Then Mark said "What is that!?". I had lost my right 
contact earlier and the sun was glaring so I couldn't see it.  
He said it was the wall cloud. We were just south of Lyndon 
and the town/trees blocked the view. He headed on 78 west 
of town so we could see northwest again.  There it was
was about 6 miles northwest of us.  It spun of several 
funnels and spotters near Morrison also reported funnels. 
You could see the whole meso. We decieded to  a little 
west then north to get a closer look. It was quite a site 
and the updraft was very strong with some rotation. I 
thought it was going to go but then the whole thing quickly 
fell apart in two minutes. The time was 6:36.  We chased a 
few more miles east but then gave up..for there were more 
storms moving in from the west.
 
                                               Storm # 2

With Storm # 2 building in form the west I deceided to 
take country roads instead if interstate 88.  What a 
bad decision. The winding, unmarked, gravel roads gave 
us headaches as we wasted time trying to figure out were 
the heck we were. We finally made it to Fenton at 6:54 
with a new Tornado warning issued for Whiteside county.  
We then crossed 88 and took a road that ran SW along it. 
A Tornado warning was issued for Rock Island county at 
7:11. We could see the new wall cloud to the storm that 
was now Northwest of us and was turning right but moving 
very slowly. This was actually a new storm (I think) so 
lets call it #3.  

                                                     Storm #3

Anyway the wall cloud was spinning off small funnels as 
we heading east just west of Erie. Then the Rock River 
problem came into play again. There was a road the went 
south-east and crossed the river and there was a road 
went north-east along the west side of it that took 
you back to Lyndon.  I wanted to take the road that 
ran SE but the road structure is very poor and we 
got lost even with detailed street maps.  We spent 
5-6 minutes in the town (with the wall cloud heading 
for us) I said we better just head back to Lyndon for 
safety reasons. This was around 7:30. Then spotters 
reported a wall cloud with funnels near Morrison
form storm #2, we tried to catch up with it but we 
couldn't.  Then the Tornado warning was extended 
with a tornado detected by radar 15 miles SW of Sterling 
(Storm #3) . We were now north of Lyndon so we turned
around and headed back south as it was getting dark.  
At 7:56 a tornado was reported 2 miles south of Prophetstown 
(form the earlier Erie wallcloud) As we headed south on 78 
from Lyndon we could see a new storm with overshooting tops 
WSW of us (storm 4) and a new tornado warning was issued for 
Rock Island county at 7:50, I may have been able to see the 
lowering form storm 4 but being 15-20 miles east it was hard 
to tell. Spotters were reporting a rainwraped wall cloud 
with funnels in storm #3. We arrived south of Prohetstown 
around 8:05 and storm #3 was now just of to the south-east 
as we headed south on 78. We could see a possible rainwrapped 
cone shaped funnel form the wall cloud as what little light 
was left was reflecting of it.  We then t it was now dark 
so we headed back home south on 78.  A tornado warning was 
issued for Muscatine county in Iowa from a nice looking 
storm to the SW.
                                  
                                                   Storm #4

As we headed home south on 78 a tornado warning was issued 
for Henry county at 8:23 for a possible tornado 4 miles 
west of Galva.  Spotters reported a rotating wall cloud 
just west of Galva at 8:40.  At 9:04 we reached Kewanee 
with street flooding in the city. Then as we continued 
south we could turn west on 91 towards Galva or continue 
south on 78.  We tried to go west but we ran into heavy 
rain and some hail and since it was now dark it was too 
dangerous to chase, we headed south on 78.  We got south 
of the storms and we entered Peoria county. The storms 
were in a line now (that when I checked the radar stretched 
form New York to Kansas!!)

           We arrived back in Kickapoo around 10. There we 
several reports on Tornadoes across northren Peoria county 
by the public. We had a great view form the backyard 
looking north..just funny looking rain shafts.  Last time 
I checked the only confirmed reports of tornado touchdowns 
were in Iowa.  I give this chase an "B+", no confirmed
touchdowns but plenty of excitment and a good lightning show. 


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