Green Sky Chaser

10 May 2010 Chase Log

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Target Area: Blackwell, Oklahoma to Arkansas City, Kansas (Click on city names for Yahoo! maps links)

Chase Area: Blackwell/Nash/Tonkawa to Midwest City, Oklahoma

Observations: two tornadoes (at least one was multi-vortex), two funnel clouds, three wall clouds, one supercell, and lightning

Distance: 390 miles

Time: 8 hours, 40 minutes

Chase Team: Jeff Makowski, Esther White, and myself

SPC Convective Outlook: High Risk (Click to see SPC products, data, and storm reports)

Chase Setup: A shortwave trough was located over central Kansas / northern Oklahoma, with a surface low over southern Kansas. Warm front lifted through Oklahoma into central Kansas, while a tight dryline was located over west central Oklahoma by late afternoon. Dewpoints ahead of the dryline were in the upper 60s / near 70 oF. CAPE values of over 4000 J kg-1 and steep mid-level lapse rates ahead of the dryline in Oklahoma. With southeasterly surface winds and west-southwesterly winds aloft, wind shear was high and helicity values were over 500 m2 s-2. Storms expected to quickly become supercellular and tornadic, from central Oklahoma up into northeastern Oklahoma and southeastern Kansas.

Blog Entries:

Chase #5 (before)

Chase #5 Evaluation (after)

Monday's Oklahoma Tornado Outbreak (after)


Chase Log: Although parameters looked sufficient for supercells from north Texas into Kansas, we opted to go up to the Blackwell, Oklahoma area as it looked like the best lift and wind shear would be there. In the days leading up to the event, the models disagreed on where the dryline would be located; anywhere from the Texas Panhandle to central Oklahoma. On the morning of the event, the dryline was farther west than expected, west of I-35.

We got to Blackwell at about 12:30 pm, and stopped for lunch at Braum's. After lunch, we sat in a Comfort Inn parking lot and noted the Storm Prediction Center had just issued a PDS (Particularly Dangerous Situation) Tornado Watch, with the risk for every type of severe weather, including significant severe weather, high. This watch box extended from south central Kansas through Oklahoma to the Red River. A few cells started to go up to our west, along the dryline, and we headed off to Medford on Highway 11.

While we were in Medford, I got a call from KSBI (the Oklahoma City station I was attempting to stream for), who asked me to go after the biggest cell forming south of Woodward.

As the storms were moving at about 60 mph, we didn't have far to go west on Highway 11 before we intercepted the supercell. At the intersection of Highway 11 and Highway 132, we drove south on Highway 132, passing several storm chasers going the other way. Just before we arrived at Nash, we realized the storm was going to pass to our north, so we turned around and headed back north.

Once again at the intersection of 11 and 132, we drove just north of the intersection and stopped, as we watched a wall cloud form. As it started to rain, and the wall cloud and hail core was headed directly for us, we drove just south of the intersection again and stopped on a dirt road, facing west.

We saw another rapidly-rotating wall cloud form, and the inflow winds picked up. I tried getting some video of the mesocyclone, but my tripod blew over in the winds. A smooth, skinny funnel cloud appeared, and before we knew it there was a debris cloud on the ground, probably within a mile of our location. A second funnel cloud appeared around this time, and seemed to snake around the first one. As the tornado was rapidly coming towards us, we quickly turned around, drove back to Highway 132, and drove about a mile south on the highway. The tornado quickly dissipated, but I made my first NWS report at this time, calling in the tornado at 3:33 pm.

As soon as the angry-looking mesocyclone crossed the road, we drove back north again and got off on another dirt road just south of the 11 and 132 intersection, facing east. We saw some damage from the first tornado, including downed power poles less than 100 yards from our previous location. While stopped on this dirt road, we saw another tornado briefly touch down, this time a definite multi-vortex tornado. Several funnels appeared to snake around in the wide debris cloud (neither of the tornadoes had full condensation funnels). This tornado was on the ground around 3:40 pm.

We continued to drive east on the dirt road, but quickly lost the storm. We saw some more damage when we headed north again, back towards Highway 11, including more downed power poles, sheets of metal, and downed tree branches. At one point I almost ran into a large cylinder (appeared to be possibly a water tank), blocking the entire right side of the road on a narrow bridge. I slammed on the brakes as the cylinder started to roll towards the left side of the road, and I backed up a bit. The cylinder oscillated from one side of the road to the other, and I waited until it was at the farthest side of the right side of the road, before I accelerated past it, on the left side of the road.

We drove back east on Highway 11 to I-35, at which time another large, tornado-warned supercell was about to cross the freeway to our south. About to head out after it, the news station asked me to drive south instead, and head back towards the Oklahoma City metro area as they were starting to get pounded by supercells, large hail, and tornadoes.

There isn't too much to say about the rest of the chase; we made it back to the metro area at the time a large supercell had just moved off to the northeast, and we were asked to follow it eastward on I-40. However, I-40 was blocked (due to debris) just east of Midwest City, so we got off the freeway and drove east on SE 29th Street. Traffic was stop and go on this road, though, and eventually we ran across another road block at 29th Street and Luther Road.

Surrounded by multiple supercells, and hearing reports of a tornado in Norman, we bit the bullet and opted to go back home (drove north on Luther Road to Highway 62, then west to I-35).

We did have a lot of trouble streaming for KSBI, but not for lack of trying...cell phone data service (AT&T) wasn't too fast in northern Oklahoma or east of Oklahoma City, and I soon plan to invest in a cell phone signal amplifier. It was a crazy, hectic day, and storms were moving so fast, they were hard to keep up with anyway.

Regarding the tornado in Norman, it hit the southeast side of the city and severely damaged some houses and boats near Lake Thunderbird. The National Weather Service has some information on the outbreak at this website.


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