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Storm Chase: March 23, 2009

Overview: A long line of discrete storms developed along the dryline from OK through south KS. However, only a few of the cells became supercellular, with the only potentially tornadic storm being the one where we filmed the funnel cloud just south of Geuda Springs, KS. Storm motions were fast, given strong dynamic forcing in the upper-levels. Limiting factors were low instability and marginal dewpoints.
Double-click on the videos to view in full resolution.

Pre-chase map discussion

Part 1: Funnel cloud near
Geuda Springs, KS

Part 2: Tracking supercells
in KS and OK

Just one glance at the 12Z 3/23/09 NAM run of the 00Z 3/24/09 forecast hodograph for north central Oklahoma was enough to get the blood pumping...

The 12Z upper-air analyses showed the diffluent region of an approaching jet streak over New Mexico entering the Plains, together with nice veering winds with height and nice southeasterly surface winds ahead of the surface low. Since the surface low and the upper-level trough were almost vertically stacked, the system was not that progressive. However, due to the strong mean winds, storm motions were expected to be rather fast.

The 12Z Lamont, OK sounding showed a modest cap that did not pose too much of a hindrance given the nice upper-level forcing ahead of the trough. Hodographs and wind fields were already decent.

Our target area was north-central Oklahoma, ahead of the dryline just west of I-35. The southwestern portion of the Moderate Risk area of the latest SPC outlook was concident with our target area.

SRH maxima were observed just north of the dryline at 17Z, and shear vectors mostly perpedicular to the boundary hinted at the preference for discrete structures in the storms that would develop.

We had the pleasure of having two friends and meteorology students from Ohio University, Chip Redmond and Nick Brammer, join us for this chase. With Nick Engerer driving and myself navigating, the four of us comprised car #1. In addition, four other meteorology graduate students from the University of Oklahoma followed us in car #2: Nick Gasperoni (driver), Craig Schwartz, Nate Lehman, and Todd Kluber.

SPC issued a tornado watch at 1:05 pm CDT, around when a nice Cu field was developing ahead of the dryline in OK and southern KS.
The first line of discrete storms could be seen developing in the KVNX base reflectivity image at 2:35 pm CDT.

Favorable wind profiles at the surface in north central OK could be seen at 2:55 pm CDT per the Mesonet observations, and Nick commented on how he could feel the easterly component of the winds while he was driving north. However, with Tds in the 50s, moisture was less than ideal.

By 3:51 pm CDT, we were tracking our first updraft base to a developing supercell.

The storm approached and skirted Medford, OK at 4:00 pm CDT.

However, the best low-level SRV couplets did not appear until 4:50 pm CDT.

At 4:56 pm CDT, looking to the southwest, we could see a nicely developed meso in the updraft base.

And just two minutes later, on the northeast side of the meso, strong vertical motion translated into rapid rotation, and a broad funnel cloud dropped to near the ground. Because of the strong inflow winds all afternoon, there was already dust in the air, so we could not confirm whether or not there was a touchdown. We have also not seen any other chase photos or videos that can legitimately confirm a tornado touchdown. However, the rotation was very intense, and tornado reports from our location (just south of Geuda Springs, KS) were submitted by other spotters to SPC.

Later on, at 5:37 pm CDT, after passing Arkansas City, KS with tornado sirens blaring, we caught a glimpse of another rotating wall cloud and/or funnel to our southwest.

We followed this storm for a while until it began to occlude, at which point we turned our attention south to the line of discrete cells ahead of the dryline. The nice wind shear was evident in the tendency for all of the storms to remain discrete for hours, so we were convinced that "6 o'clock magic" would come in our favor. We intercepted two more supercells, the first of which weakened by the time it crossed into KS north of Osage County, OK. However, we made a last-minute decision to intercept the tornado warned storm north of Guthrie, OK.

As we approached, we were treated to a spectacular display of the back side of the supercell backlit by the crimson sunset.

Car #2 decided to abort the pursuit of the supercell and return to Norman, but Nick and I decided to take Chip and Nick Brammer to see a good supercell lightning show. Although it was quite a challenge, we finally got in front of the storm just after 8 pm CDT, where we could see the meso backlit by lightning.

We continued following the storm, but increasingly poor terrain and the proximity to Tulsa prevented us from proceeding. The storm did, in fact, weaken shortly after we left it. After a filling dinner at Denny's just south of OKC, we returned to Norman, just in time (11:20 pm CDT) to core punch (not on purpose) a supercell on I-35 within the city limits on our way back to the National Weather Center! However, we only observed small hail.