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June 14
June
14, 1998 WC Illinois Severe Weather
An unusually deep surface
low for June (29.20") was located over NW Missouri
during the morning hours. A strong dry line extended southeast from the surface
low from southwest of Kirksville to east of Columbia to near the Rolla area in
C.Missouri. The dry line was expected to shift east to the Missouri/Illinois border
by evening. During the early morning hours, warm air advection phased in with
a strong mid-level shortwave. The result was a raging squall line which bowed
out in response to the strong mid-level wind max which streaked into EC Missouri
and into C.Illinois. Extreme wind gusts of over 100 mph were reported north and
northwest of St.Louis , and widespread wind damage was reported throughout
this area. The early morning squall line created a pronounced outflow boundary
over Central/Eastern Missouri and into C. Illinois. The boundary remained nearly
stationary throughout the day, and extended from the Jefferson City Mo area to
just north of St. Louis to north of Vandalia Il. Another strong mid-level shortwave
was forecasted to pivot northeast across EC/NE Missouri and WC/SW Illinois by
evening. The lobe of energy was expected to become negatively tilted with time,
so a large amount of mid-level drying would spread across E. Missouri and WC
Illinois . Significant mid-level cooling would also steepen lapse rates in the area.
The stage was set for a significant severe storm outbreak including tornadoes by
afternoon. The Storm Prediction Center outlooked Central and Eastern Missouri
and West Central and Southern Illinois accordingly with a high risk. Supercells
and strong tornadoes were highlighted in the discussion.
Now it was time to figure
out an exact target spot to chase today. After reviewing
weather data and satellite loops, the most unstable air was setting up over SE Mo
and S Illinois. Afternoon CAPEs were expected to be well over 4000 j-kg allowing
for explosive storm development when the mid-level shortwave approached. I
was in contact with Brian Stertz during the morning, and initially we targeted the
area just east/southeast of St. Louis for the hot-spot target area. Brian and his
chase partner Tom Zeitinger were returning from a weekend trip to Peoria. We
planned to meet on the Illinois side of the St.Louis Metro so we could avoid any
local traffic tie-ups. I started out from Columbia Mo around 10:30am, and the dry
line was already mixing out just east of Columbia. I figured the show was going
to be closer to St.Louis so I headed east on I-70. Brian called and said he was
already approaching the Springfield Il area on I-55, and that the airmass in this
area looked severely worked over/rain-cooled. He and Tom continued on to the
meeting spot we set up near Belleville Il on I-64. As I headed east on I-70, I was
able to see towers bubbling on both the dry line to my north , and along the out-
flow boundary to my immediate south. This concerned me since it was still quite
early for things to start cooking. For the next hour, storms quickly fired down the
dry line from Kirksville southward to northeast of Columbia. I watched radar very
closely as I headed towards St.Louis and the designated meeting spot. I could
see a small but growing storm to my distant north. Radar indicated the small but
highly sheared storm was near Mexico Mo and was tracking to the northeast. A
few minutes later, the Storm Prediction Center posted a tornado watch for NE Mo
and S.Ia. The storms were already severe around Kirksville, and a few looked
interesting/possibly tornadic on radar.
By the time I reached the
northwest suburbs of St.Louis, the small storm which I
noticed earlier, was now producing confirmed tornadoes over Audrain and Pike
counties in NE Mo. Since the day was still quite young, I decided to continue on
to the meeting spot to hook up with Brian and Tom. Brian called me and said he
had talked to the NWS, and they indicated that we might want to consider going
after the storm which was approaching Bowling Green. The storm was very much
dry line structured- small but certainly rotating!! I finally reached the rest stop and
met Brian and Tom. A new tornado watch was also issued for E.Missouri and W.
Illinois when I pulled up. Brian had plotted the nw-se oriented tornado watch box
and was also monitoring amateur radio to track the storms. Radar continued to
indicate rotation of varying intensities with the storm over Pike Co. Now it was
time to make the chase decision! Since the cap was increasing over SE Missouri
and S. Illinois, we decided to head for the storm which was located just northeast
of Bowling Green Mo.
We quickly plotted up the
storm's projected track, and estimated an intercept
point near the town of Carlinville Il (Macoupin Co.). Unfortunately, it would take
close to an hour before we could reach the storm. We headed north on I-255
to I-55/70, but soon encountered a construction related traffic jam on I-55 near
Collinsville. The highway was reduced to a single lane, so you can imagine the
traffic jam!! We finally broke free from the traffic at 3:50 pm, but lost valuable time
(20 minutes more specifically) to reach our target area. Once we got free of the
nasty traffic on I-55, Brian and Tom followed me as we picked up the pace, and
were northbound and down! The tornadic supercell which we were planning to
intercept was approaching the Mississippi River near the town of Louisiana Mo.
A tornado warning was issued for N.Calhoun and Greene counties in WC Illinois.
The projected path of the tornadic circulation was towards the town of Belleview,
and the storm motion was slowing slightly (25 mph as opposed to 35 mph over
Pike Co.). The slower motion was hopefully going to allow us to gain back some
of the lost time!!
We passed through the
town of Staunton (remember that town name for later) on
the way to Carlinville. It was now looking like we would have to head further west
from Carlinville. We could see a new storm erupting to our northwest, and to the
west of Carlinville. Since the storm was so close, we decided to watch this storm
for further intensification. The storm rapidly became severe over W.Macoupin Co.,
and quarter sized hail was reported west of Carlinville near Palmyra Il. A severe
t-storm warning was quickly issued as the storm continued to increase. We were
approaching Carlinville when the warning was posted at 4:45pm. A strong mid-
level dry punch was blasting into the area at this time. A large majority of clouds
quickly vaporized, including the storm we were now upon. Almost as quick as the
storm developed, the storm dissipated and the core diminished. We tracked the
storm just to make sure it did not re-intensify again. Unfortunately, the eventually
withered away into a weak virga shower by 5pm. The cap was working in!! The
tornadic storm to our northwest about 30 miles continued to rotate, but the storm
abruptly started to move rapidly n-ne. No way we could catch this one!!
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