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June 19
June
19, 1998 SW Missouri Severe Weather
I was not expecting to
chase today, but I got a bit of a surprise by evening. I was returning to Tulsa from
St.Louis on I-44. When I reached the town of Lebanon Mo on I-44, I started to notice that
the skies were darkening to my west. Much to my surprise, a tornado watch had just been
issued for much of SW/C. Missouri into
the late evening hours. I knew of the warm front which stretched out across the
area, but I was not aware of the extreme warm air advection pattern which was
quickly developing in and around the Springfield Mo area. By the time I reached
the town of Marshfield (Webster Co.), the NWS had just issued a tornado warning
for Polk and N.Greene counties. A developing tornado was reported in extreme
NW Greene Co. near the town of Walnut Grove. The circulation was expected to
track northeast into S.Polk Co. and was heading directly towards my location. I
knew that other storms were also rapidly developing around the Springfield area,
so I knew my window of opportunity would be short to intercept this storm. The
other storms would soon compete for the rich supply of moisture pooled along
the warm front, reducing the tornado potential of the Polk Co. storm.
I headed into the
Springfield area and quickly got to my road option north U.S. 65
towards the town of Buffalo. A tornado warning was soon extended into S.Dallas
Co., so I knew the storm was at least still holding it's own. Spotters reported a
funnel cloud in S.Polk Co. heading northeast at 35mph. I was not too impressed
with the storm's structure which I could see to my west-northwest. The storm most
certainly had the typical warm frontal look to it. The storm had some evidence of
inflow bands, but the overall appearance was gundgy at best. Spotters continued
to report rotation with the storm as it was approaching the Polk/Dallas Co. line. I
was closing in on the storm at this time, but I still was not able to discern any of
the rotation which was reported. A few small appendages extended from cloud
base from time to time, but nothing sustained could ever develop. I followed the
storm into Webster Co., but the storm started to weaken some as it raced into the
heavily forested areas north of Marshfield. Other severe storms also developed
that evening, but I decided to end my chase and head back to Tulsa. I needed
to prepare for the next day's severe storms which were expected in N. Kansas
and S. Nebraska.
June 20
June
20, 1998 NE Kansas Severe Weather
Today was definitely a
chase day. Much of NC and NE Kansas, and SE Nebraska
was outlooked for a moderate risk of severe storms/supercells. A surface low was
expected to intensify west of Topeka Ks by evening. An upper level disturbance
was also forecast to approach N.Kansas by early evening. The cap was expected
to hold firm over S and C Kansas through the evening hours allowing unimpeded
inflow to supercells which were forecasted to develop over S.Nebraska. By late
afternoon, storms rapidly developed over SE Nebraska and started to work into
the NC and NE sections of Kansas. A tornado watch was quickly posted for these
areas as a line of tornadic supercells started to back-build into N.Kansas. I was in
the Topeka area when the watch was issued, and was in prime location to chase
the supercells. I headed north from Topeka on U.S. 75 to intercept the tornadic
storms which were moving into Marshall and Nemaha counties in N. Kansas. I
could see the distant storm towers to my northwest, and the diffluent anvils which
were fanning out to the east-southeast.
I wasted no time in
reaching the storms in Marshall and Nemaha counties. Radar
showed 3 distinct supercells crossing into Kansas at 5:45pm. All 3 supercells
had circulations, but the strongest rotation was indicated near the town of Axtell
Ks in Nemaha Co. I was near the town of Fairview at the time the tornado warning
was posted for Marshall, Nemaha, and N. Pottawatomie counties. The supercells
were 20-25 miles to my west and northwest, and appeared to be back-building
as they slowly headed e-se. Radar continued to indicate circulation approaching
the town of Seneca, but a new and stronger circulation was indicated southeast
of Frankfort. The storms were indicating very large hail at this time. The 2 cells to
northeast of Seneca indicated that they had gusted out on radar, as a pronounced
outflow boundary pushed out southeastward from the storms. The supercells near
Seneca and Frankfort looked well structured on radar, and had strong circulations
on radar. I wanted to avoid the gust front which was pushing south toward my
location east of Seneca. A tornado warning was re-issued for SE Marshall, SW Nemaha, and
NW Pottawatomie counties. Two separate circulations were now reported with the new
warning. One circulation was nw of Seneca, while a much
stronger circulation was reported just west of Lillis in SE Marshall Co. This is the
circulation which interested me the most. The location of the storm was very near
the intersection of the dry line and an outflow boundary produced by the storm
nw of Seneca. I quickly worked my way southwest towards this area.
I found a good spot to
pull over and watch the updraft area approach me from
the west-northwest. I was in SW Nemaha Co. and the circulation was just crossing
into Nemaha Co.. I setup my digital camera on tripod and shot video of the storm
which was slowly heading in my direction. Radar indicated a well pronounced
hook echo just to my northwest, and lightning continued to increase dramatically
to the immediate north and northeast of the storm. At 6:15 pm, strong rotation was
noticed on the south-southeast section of the storm. The front flank downdraft
started to spread east towards me, while at the same time a strong RFD punched
into the sw section of the storm. The circulation tightened up to my immediate
west or 6 miles west of Corning. I watched the storm continue to rotate but it was
starting to show signs of intense outflow. The gust front quickly passed me, but
it 's passing revealed a tightly constricted wall cloud about 2 miles to my west.
The wall cloud looked very much occluded, but it transitioned to a distinct funnel
appearance at 7:15pm. The outflow quickly undercut the storm completely, and
the funnel quickly started to diminish. I believe that if the outflow had not been so
strong with the storms to it's northeast, this storm would have had a much better
chance to maintain a strong circulation. I decided to check out other storms which
were back-building down the line, but they too also quickly gusted out. Later, I
watched an impressive lightning show near Emporia as the storms rapidly back-
built into C.Kansas after dark. This was my last chase of the spring/early summer
season. A strong and extremely hot surface ridge dominated the Central/Southern
Plains for much of the summer into early fall. Near drought conditions set in as
extended periods of 100 degree heat and no rainfall were common from Texas to
Nebraska.
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