Green Sky Chaser

13 May 2009 Chase Log

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VIDEO (opens to YouTube)


Target Area: Ponca City, Oklahoma (Click on city names for Yahoo! maps links)

Chase Area: Ponca City/Tonkawa to Chickasha/Anadarko, Oklahoma

Observations: two tornadoes, two wall clouds, three supercells, and lightning

Distance: 300 miles

Time: 9 hours

Chase Team: Dean Narramore, Rob Lee, Rob Warren, Esther White, and myself

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

Chase Setup: Vigorous trough in the Northern Plains and a strong polar jet max in place. Cold front extending from surface low in the east Texas Panhandle up through northwest Oklahoma, southeast Kansas, northwest Missouri, and up to another surface low in central Iowa. A moist, unstable airmass, with dewpoints in the upper 60s and CAPE values of 3000 to 4000 J kg-1, expected to provide a rich environment for storms forming along the front. Although sufficient for perhaps some weak, isolated tornadoes, the wind shear in Oklahoma looked more favorable for hail formation than tornado formation.


Chase Log: Although it was a moderate risk day, this was one of the most reluctant storm chases I ever went on - I had just moved into my new apartment that morning, my parents were coming into town the next day for graduation, and the day only looked marginal for tornadoes. However, I am grateful to Dean for persuading me to go, as it turned out to be one of my favorite chase days.

At first we headed up to Ponca City, where we hung out for a little while until a beautiful storm formed nearby. Driving through Tonkawa, we saw a small rotating cloud, on the underside of the supercell, that we jokingly called a wall cloud as Dean continued his tradition of saying, as he did with just about every storm, "it's lowering; I think it's a lowering!" We thought the cloud looked too small to be a wall cloud, but before we knew it, the tornado sirens were going off. A funnel cloud appeared below the wall cloud, but it was about as wide as the small wall cloud. We certainly didn't expect to see what we saw next - the moment we drove out of Tonkawa and away from the trees and buildings, we saw a beautiful cone tornado on the ground! The rapid formation of the wall cloud and tornado was astonishing. Mesmerized, we stopped to watch the tornado dance around and move a little closer to us before getting wrapped up in the rain.

We chased the storm for a little while after this, but didn't see any more signs of another tornado. Happy with our catch for the day, we turned back towards Norman. On our way back, we noticed other supercells were forming all along the cold front and there was a beastly one southwest of Norman. Although it was near sunset, we were not quite ready to give up for the day, so decided to drive past Norman and straight down towards Chickasha in the hopes of seeing another tornado lit up by lightning.

Sure enough, as we approached the supercell, we saw a lot of amazing lightning. Listening to the radio, we heard Mike Morgan (Oklahoma City TV weatherman) start shouting that there was debris in the air and a possible tornado near Anadarko. Still driving towards Anadarko from Chickasha, we decided we had better stop as it was dark and we didn't want to drive into a possible tornado.

It was very windy when we stopped, and we watched the lightning light up an interesting-looking wall cloud nearby. We then started to see a large amount of power flashes, both bright green and orange. Esther thought she saw something suspicious-looking under the wall cloud, and the rest of us also saw what appeared to be a stovepipe tornado lit up several times by the power flashes and lightning. Wondering if what we had seen was just our eyes playing tricks on us in the dark, we eventually lost the possible tornado and drove a little farther up the road to watch more lightning. At this point we heard that the tornado sirens were going off in Norman for the second time that night.

No sooner did we get back to Norman than the tornado sirens went off again, for the third time. This time the supercell was east of Norman, though (the sirens had just been set off for all of Cleveland County).

The next day, when Dean and Esther came over to get copies of my chase photos and videos, we reviewed my video of the Anadarko storm. The tornado was confirmed this day as an EF2. We slowly reviewed the video, stopping it at every power flash or lightning stroke. Several of the enhanced contrast video stills confirmed our suspicions - a stovepipe-shaped cloud in the right location at the right time, right where the power flashes were occurring.


PHOTOS

VIDEO (opens to YouTube)