April 2, 1999     WC/SW Oklahoma Tornadic Supercell

Today promised to be more like a May situation than early April. A cold front was
expected to drop south from Kansas by afternoon, and then become stationary
over W.Oklahoma and the Texas Panhandle. A mesolow( more common in the
late spring months) was expected to develop on the tail end of the stationary front
over the E. Texas Panhandle. This would create a large area of east winds to the
east of the mesolow and would provide favorable shear for supercells and yes
even isolated tornadoes over W and C Oklahoma. A moderate risk for severe storms was forecasted for this area by the Storm Prediction Center. We targeted
the I-40 corridor between Elk City and Oklahoma City as our chase zone. As with
most good ( and sometimes bad ) chase days, the cap was strong so instability
had time to build up during the peak heating hours. We were fairly confident that
today was going to be a late show- meaning more towards sunset - as the cap was going to suppress most of the supercell development. The cap was weaker
over N. Oklahoma; however, we did not want to chase cold front storms as they
are usually poor tornado producers. We were joined today by Dave Frost from
St.Louis Fox affiliate KTVI. He was shooting video for a storm chaser package for
the May sweeps. We left Tulsa by late morning and were followed by Kathryn
Ray who was also chasing today. She drove her car so that Dave could get some
action shots of Brian and I on the "hunt" for big supercells.

We headed down I-44/Turner Turnpike for Oklahoma City and were not in too big
of a hurry because of the cap. Further to our north, towering cu bubbled hard in
the Guthrie area as this was where the cap was weaker. We were a little worried
that this day was starting too early as it was just after noon when we approached
Oklahoma City, and storm towers were already up and getting organized. The
first storm actually developed on the northwest side of the Oklahoma City metro
near Piedmont and Cashion. We watched this storm grow very quickly as it raced
to the north-northeast. This was well ahead of the cold front so this storm was very
interesting to us. Radar continued to show that supercells were also going to town
over S.Kansas and N.Oklahoma. We stopped along I-40 to regroup our thoughts
on today's target area as things were already going at 1pm. We were intrigued
by the storm over Logan Co. as it was developing a weak hook echo to the north
of Guthrie . The storm was moving away from us at a good clip so we decided to
be patient and wait for the later show- it ended up being a very late show!!

The Logan Co. storm started to slow down and became more intense. Rotation
was now becoming very apparent on the Twin Lakes NEXRAD. The severe storm
was now becoming a supercell over N.Logan Co. and we were fairly sure that a
tornado warning was imminent. For a brief moment, we considered blasting to
the north and catching up with the storm as was looking more legitimate with each
radar update. Eventually, the severe t-storm warning was upgraded to a tornado
warning for N.Logan, NW Payne, and E. Noble Counties in NC Oklahoma. The
developing tornado was near Orlando (Logan Co.) moving n-ne at 35 mph. We
noticed that the cold front was on the move into N.Oklahoma so this was likely to
affect the Logan Co. supercell soon. This was reason enough for us to hold at our
spot on I-40 near El Reno. We watched the supercell to our distant northeast grow
into a massive structure with occasional overshooting domes.

For nearly 3 hours we waited and waited....and waited for some sign to tell us that
W.Oklahoma was going to explode. The cap limited our area significantly for any
sustained convective development. We watched every possible parameter for a
hint of later action. One interesting thing we noticed were the winds and the dew
points over the Texas Panhandle/South Plains. The dry line was surging to the
east and the winds were veering significantly at Lubbock and Childress. Deep Gulf moisture was pooling over SW Oklahoma and NW Texas ahead of the dry line. At the same time, the cold front was dropping rapidly into NW Oklahoma. This was going to create a squeeze play over W.Oklahoma between a bulging
dry line and a sagging cold front. Actually, we were glad to see the front getting closer to our target zone as the forecast models were showing that it would become stationary by early evening. This would result in the large scale area of east winds that we had forecasted earlier in the morning, and would also act to
cool the atmosphere enough for the cap to break. We just had to be patient for all
the chips to fall in place. We could see some vertical towers to our west so we
headed out on I-40 towards Clinton. We stopped there for a while and watched
satellite and radar closely.

Along the Oklahoma/Texas Panhandle border, the dry line had mixed out to the
east and numerous towering cumulus clouds were bubbling all along the sharp
boundary. Three areas were beginning to look interesting. The Abilene/Seymour
Texas area looked like it was going to pop at any moment. The other 2 areas that
looked good for rapid storm development was over the SE Texas Panhandle,
where a swirl on radar was forming, and over the Amarillo area that was already
behind the frontal boundary. As expected, the cold front sagged all the way down
to I-40 before hanging up. Meanwhile the winds at Childress backed significantly
and the dew point jumped 10 degrees in an hour!! The mesolow was starting to
crank!! Further south, dry line storms popped in the extreme heating/instability
between Lubbock and Abilene. These storms rapidly became severe with large
hail and weak/moderate rotation. It was gut check time!! Peak heating changed
the whole picture for our outlook.

We were prepared for a night chase as sunset was closing in on our chase day.
Radar was indicating that an isolated storm was forming on the dry line near the
border town of Texola( 65 miles to our west). This storm struggled at first, but it
broke through the cap with violence and started to become established. Almost
instantly, the Storm Prediction Center issued a tornado watch for W.Oklahoma
and the extreme E. Texas Panhandle. We got into high gear and blasted west at
warp speed to reach the developing storm. This storm was developing in the
right place- right at the intersection of the stationary boundary and the dry line,
and northeast of the developing mesolow. We fairly sure that this storm was the
"big daddy" we were waiting for!! A severe t-storm warning was issued for the
W. Beckham Co. for hail up to golfball sized. Not bad for a storm in it's first few
minutes of development. We could see the vertical storm tower to our west about
40 miles. More impressive was the thick diffluent anvil that was mushrooming out
very quickly. This indicated good venting of the storm which in turn would allow
for an intense updraft. The chase was on!! We just hoped we did not waste too
much time playing the waiting game.

Our attention was focused on this growing supercell that was moving towards
the town of Mayfield OK. At this point we probably should have also continued to
watch satellite and radar as well. Yet another supercell "hyper" exploded over
the town of Wellington right on the mesolow. We were more or less oblivious to
this "grand pappy" supercell that almost immediately had strong rotation. Back to
our storm... the supercell was becoming larger with time and was starting to rotate
as it moved northeast up the boundary. Hail up to baseball sized was now being
reported to the northwest of Sayre (Beckham Co.) and we were closing in from the east on I-40. We were at the Canute exit when the severe t-storm warning was
upgraded to a tornado warning for N. Beckham and S. Roger Mills Counties. The
developing tornado was located near the town of Berlin moving northeast at 35
mph. We were still 20 miles away, but we could see great inflow bands jutting
into the updraft/tower due west of us and west of Elk City. We closed in on the storm quickly as a powerful RFD punched into the storm. To the distant west, we
noticed a low hanging wall cloud and scud tags, but no funnel. Actually, the
first circulation had blasted out and we were watching the formation of a new
circulation on the tail end of the gust front. This was almost text book stuff now!!

The northern circulation was completely wrapped up in rain/hail, but the new
southern circulation was well separated from the core. Our winds were becoming
more easterly as the stationary front was now south of I-40 a few miles. We exited
off I-40 on to the business loop for Elk City. The new circulation was just to the northwest of town and the setting sun provided great contrast with the dark base
of the new updraft region. Rotation was still quite broad but the overall width of
the bowl shaped wall cloud started to slowly decrease. The wall cloud now was
starting to tighten up and the winds were increasing too as the inflow became
more concentrated. We pulled over at the Elk City airport to setup for video and
photos. We were almost sure this one was going to do it !! The winds were due
east and gusting to 35-45 mph. The strong RFD started to punch in from the west
as the wall cloud drifted to the northeast. Deep striation bands were now showing
incredible mid level rotation, while just above the surface, very long inflow bands
knifed into the barrel shaped updraft. Most of the cloud to ground lightning was
focused to the northeast of the wall cloud. We remained at the airport for nearly a
half hour watching this wall cloud organize and then get undercut by cold air from
the large core's outflow. The gust front eventually cut off the inflow to the supercell
and it slowly started to weaken. The core remained quite healthy though so we
followed the storm east.

The tornado warnings continued with the storm into Custer Co. as there was still
a major circulation near Butler. The only problem was that it was becoming dark and the circulation was embedded in the huge core. We pulled over and stopped/ regrouped at the Foss exit on I-40. We pulled up some radar images and about had a coronary!! The supercell coming out of Harmon Co. was spinning like a top. We were all kind of mad because we did not pay enough attention to radar earlier.
the radar loop showed that it without a doubt exploded right on the mesolow!! A
major circulation was moving across N. Harmon Co. into W.Greer Co.. We also
somewhat busted because we had turned down weather radio. When we turned
the volume up, live brodcasts/updates were being aired regarding this supercell.
Tornado warnings were now posted for N. Greer and S. Beckham Counties. The
storm relative velocities were nearly maxing out as it was crossing into Greer Co..
We plotted up an intercept point near Retrop and we blasted south on OK-44 from
I-40.

We could see intense in cloud / frequent cloud to ground lightning as we made
our way south towards Sentinel. The live broadcast/update indicated that there
was a confirmed tornado on the ground near Willow moving northeast at 35 mph.
The sun had set an hour ago, so the best we could hope for was illumination of
the tornado by lightning. As we approached Sentinel, the winds were roaring
from the east and inflow bands were screaming to the west towards the supercell.
We reached OK-55 in Sentinel which would take us right to the tornado. A new
tornado warning was issued for NW Kiowa and W.Washita Counties and was now
extended for NE Greer and SE Beckham Counties. The tornado was confirmed and doing damage just to the north of Willow. The towns of Retrop and Carter
were urged to take cover. To our west, the isolated supercell was spinning like
mad. The updraft tower was about as vertical and striated as any that Brian or I
have seen before. The flying saucer updraft was ringed with helical bands that
resembled more of saturn like image than what could be found on earth. These
rings started just above the wall cloud and extended all the way to anvil level.
The moon helped illuminate these rings with an eerie glow!!

We passed through rain curtains and incredible cloud to ground lightning as
we headed west on OK-55. A tornado was reported by storm chasers near the
town of Moravia (a good 3 Stooges town name) moving northeast for Retrop. We
were concerned about huge hail as we closed in on Retrop. Dave was amazed at
how something so compact could be so violent!! As intense as the rotation was,
we were really fearing the wrath of softballs. When we rolled through town, rain
curtains swirled and were racing to the northwest. This indicated to us that the
main circulation was still several miles southwest of Retrop. We cautiously drove
through Retrop and eye balled covered areas just in case the cantaloupes and
softballs started to fall!!

The lightning showed us the amazing storm tower structure, and as we reached
the intersection of OK 55 and OK-6, we could now see a very low bowl hanging down to the 3 miles west-southwest of the intersection. The rain curtains moved
away and we could now see the base with something black (a tornado of course)
hanging down under the smooth bowl shaped wall cloud. The tornado was still
on the ground!! We decided to get a little more to the south away from the core
that was not too far to our north. The storm was very compact but intensely rotating
as it slowly moved to our northwest. We all grabbed our video cameras and setup
tripods to get some great night tornado video. The rings around the updraft were
so well formed that we could actually look straight up and see the stars between
the smooth updraft wall and the laminar rings!! What a sight with the full moon!!
The tornado due west of Retrop more or less anchored and occluded over the
next 5 minutes. Meanwhile in textbook cyclic fashion, a new tornado developed
to the southeast of the original tornado. The inflow increased to 50 mph from the
east as the new tornado strengthened. Other small appendages also dangled
from the wall cloud. Lightning provided us a great show and helped to light up
both tornadoes!! We watched the tornado for about 10 minutes before the rain
curtains obscured our view. We headed back east to Sentinel and then north. The
storm turned due north and paralleled OK-44 about 5-8 miles west of the road.
We lost sight of the updraft so the chase was more or less over at this point. To
our northwest, the supercell continued with a strong circulation as it crossed I-40
between Canute and Elk City. Kathryn had a close call with the large hail core as the circulation crossed not more than a mile in front of her on I-40. Fortunately she
was able to seek refuge under an overpass to avoid the hail. We decided to call
it a night and prepared for the drive back to Tulsa.

After witnessing one of the more stunning supercell structures of our chase career,
we reviewed the video and did capture images of the dual tornadoes. The first
tornado (which was occluding) was the larger of the 2 tornadoes. The tornado
was about 200 yards wide and appeared to anchor west of Retrop about 5 miles.
The second tornado was smaller, but had a slow drift to the north as the overall
storm motion had shifted more to a northerly direction. Unfortunately we were not
able to get any still photography of this incredible supercell. We believe that it
would have been award winning if had been seen and photographed during the
daylight hours!!