April 24, 2007

Statistics:

Initial Target: Enid, OK
Departure: Bolingbrook, IL 8:00 pm CDT April 23
Arrival: Bolingbrook, IL 2:00 pm CDT April 25
Intercepts: Nickerson, KS
Tornadoes: 1
Hail: Non-Severe (pea sized)
Wind: Non-Severe (not measured)
Features: Multiple Vortex Tornado, Funnels, Inflow Bands, Outflow Boundary
Miles: 1913

Summary:

Highly anticipated Southern Plains setup.  Originally targeted dryline in OK for early initiation.  Early initiation was linear squall, so hung around Enid, OK waiting for the dryline to fire later as 500 mb jet arrived.  OK remained quiet so blasted north to Kansas.  Intercepted Tail-End-Charlie on line of dryline cells just after it went supercellular near Nickerson, KS.  Noted multiple funnels and associated ground circulations from one or more weak, multiple vortex tornadoes.  Pursued beautiful supercell structure until storm gusted out.  Arrived home the next afternoon after being slowed by a flat tire near Tuscola, IL.

Crew and Equipment:

Chase team included Andrew Pritchard and Chad Cowan.  Equipment consisted of a TH-F6A Tribander, and GPS/Cell Phone equipped laptop.  Photography and video by Skip Talbot.

Video:

Nickerson Supercell and Tornado (18MB WMV)

Details:

This setup was initially overshadowed by Saturday's dryline setup (April 21), which resembled March 28.  However, when SPC issued a day 3 moderate risk (a rare event) for this setup, it caught everyone's attention who wasn't watching the models.  Expecting a large tornado outbreak, the setup of the year, and possibly several years, I took the day off work and made plans to team up with Andrew Pritchard for a marathon run to Oklahoma.
I got an email the week before from Chad Cowan, whom I had never met, saying he recently moved to Chicago from Kansas and was wondering if I wanted to team up for chasing.  I spent Saturday in Wisconsin, gearing up for a run to South Dakota to chase April 21 by the triple point.  The RUC ruined the forecast the morning of so I didn't go.  I also made plans to chase Iowa on Sunday, but that also fell through, so I was itching to get out there.  I replied to Chad's email on Sunday night saying I was making a run to Oklahoma and he was welcome to come.  Andrew, Chad, and I were able to get everything squared away in time for a Monday night departure.  I met Chad at Union Station in downtown Chicago and he commuted back with me to Bolingbrook, where the chase officially began.  We picked up Andrew at about 10pm and were Oklahoma bound.

A funny story en route to Andrew's:  Entering Champaign County, I passed a well known speed trap doing 73 in a 65, which I assumed was fairly safe.  Flashing red and blues appeared behind me.  At first I thought there was another car between me and the patrol car, but I looked carefully and only saw one pair of headlights, the flashing lights above, and the cruiser's spotlight shining ahead.  I signaled and pulled off the road.  Chad woke up and asked what's wrong and I told him I got pulled over.  I prepared my insurance card and driver's license and waited for the officer to show.  A minute or two later he strolls up to our van.  "How you gentlemen doing?" he asked.  "Good," I replied.  "Yeah, I pulled them over, not you guys."  I look behind and sure enough, there was another car between the cruiser and my van.  "You guys weren't driving fast at all, have a nice night."  I felt like a goof.

There appeared to be such a broad area of favorable parameters that we had trouble narrowing down a target.  We opted for north central Oklahoma.  There was a razor sharp dryline, backed surface winds, and the exit region of a 90 knot 500 mb jet streak forecasted.  Sure that SPC was upgrading to high risk on the Day 1, I imagined tornadic supercells all along the dryline from Kansas to Texas.

We were in Oklahoma by about 5 am after taking turns sleeping in the back.  We decided that Enid would be a good place to wait for initiation based on the RUC's position of the dryline.  Andrew and I had never been to Oklahoma, and Chad had never chased Oklahoma, so we were excited.  We arrived at Enid at 10am and had breakfast at the IHOP.  Then we relocated to a Holiday Inn Express were we spent the bulk of the day waiting and waiting some more.

 

Cells fired in southwest Oklahoma early, and this was the reason we were in Enid so early.  The RUC indicated early initiation while the the WRF showed initiation at around 0z.  Despite the inconsistency, both models showed little cap, so we made sure we were there early.  A line quickly developed from southwest OK up to just east of us.  It was very linear in nature with little break between cells.  We let it slide east without flinching.  Some weak looking mammatus on the back end looking east from Enid:
The 500 mb jet hadn't arrived yet and the dryline was supposed to reorganize and stall at our current location.  So we held fast and waited for new initiation on the dryline.  Cumulus started to blow in later that afternoon which got our hopes up.

A Louisiana chaser pulled in next to us for about 20 minutes to check data and then abruptly left.  Chad: "Do we follow?"  Andrew: "We do not."  Classic Twister quote.

Mesoanalysis showed the 500 streak and instability much further south, prompting a high risk in TX, and OK stabilizing.  Our target was looking bleak.  We ate at Chilli's before we noticed towers going up on the dryline in Kansas.  We packed up and made for 35, blasting into Kansas.  The cells were more than a hundred miles away and storm motions were against us.  I estimated a two hour ETA for our intercept, which put us in at 7:30 pm.  Chad was driving, and risked a speeding ticket for our intercept.  Traffic was surprisingly light around Wichita.
We exited just before highway 56, dodging McPherson, and blasted east to intercept the line of storms on the dryline.  One cell was tornado warned with funnel clouds being reported.  It lost its warning as we approached, and it was still north of us, so we wound up intercepting a rather linear looking part of the line.  The base coming into view near Little River:
We were watching Tail-End-Charlie, but it had a very weak appearance on radar.  However, just as we got on the line it blossomed into a beautiful supercell and went tornado warned.  Andrew and I both shouted, "LOOK AT THAT!" when the radar updated, causing Chad, still driving, to jump in his seat. "WHERE? WHERE?" thinking we had spotted something under the base coming into view.  I plotted a route south to intercept but the gremlins struck.  "Where is our turn?" Andrew asked a few times.  "Its still coming," I said each time.  But our GPS had locked up and we passed the turn.  We stopped under the gust front of this linear part of the line.  I rebooted the computer and we grabbed a few stills.  A few chasers passed us, hauling down to Tail-End-Charlie.
We found a paved road south and took while I finished setting up the laptop.  We passed an updraft base as we booked south and were able to snag a picture of it.  It was probably the southern end of this elongated cell that we shot in the above photo.
Tail-End-Charlie came into view.  The sight was immediately impressive.  A beautiful LP-esque supercell, with a funnel already dangling from the base.  Andrew noted ground contact upon our first sighting.  My ninth tornado and sixth of the season was already underway and putting on a show as we arrived.  We found an excellent viewing location north of Nickerson and setup our tripods for stills and video.
A close up of the funnel pictured above:

 

Nickerson Supercell and Tornado (18MB WMV)
We watched the funnel come and go.  The storm moving directly toward us, the entire thing slowly rotating.  Two inflow bands extended north and east out of the storm.
A needle funnel formed for a moment under the base and I was only able to grab it on video:
A bowl shaped funnel remained for awhile afterwards.  Sporadic dust swirls were forming underneath it.  The best debris cloud of the day developed with multiple vortices evident:
We had one more good ground circulation before the storm seemed to go quiet.  The base was starting to bow out like a horseshoe as an RFD punched through.  Note the well defined rain foot to the right.  This storm was absolutely gorgeous!

We stayed in our spot, allowing the storm to pass directly overhead.  The clear slot came pretty close and I thought we would get blasted by the RFD.  As the storm passed overhead we noted strong rotation.  Its an unsettling, vulnerable feeling to be staring directly up at a rotating base.

We went east and north to keep ahead of the storm, pausing for pictures as the setting sun created some interesting lighting.  A local in a pickup truck and stopped and asked where a safe spot would be.  We told him he was safe if  he stayed put and then we left to keep up with the storm.
We came to our north road option and saw the Doppler On Wheels go by, a first for me!  I snagged a picture as it lumbered past followed by a parade of chasers, joining on the back end to keep up with the storm.
Ahead of the storm again we pulled onto a gravel road to watch.  The storm was gusting out now, the base fanning out to form an outflow boundary.  The dieing storm still had great structure.
Looking back east, the last of the sunlight was painting a pretty, pastel picture in the clear air ahead of the storm.
Looking north at the gust front and increasingly large precip core
Chad silhouetted by twilight, shooting the outflow boundary.
Although a dieing storm, the outflow boundary passed overhead with dramatic motion and contrast.  We left it here, heading north for 70 to start our long trek home.  The precip core flanked us and we got into some pea sized hail before breaking back onto into the clear on 70.

We had dinner late at a Denny's in Junction City.  A woman burst through the bathroom door, holding a pregnancy tester, "This thing can't be right!"  Chad's reaction: "You guys had enough of Kansas yet?"

 

We almost made it home without incident but the Mudpuppy blew a tire near Tuscola, IL, 20 miles from Pritchard's house.  We couldn't get two lug nuts off and stripped them in the process.  We had to get the van towed to a service shop in Arcola where they replaced the lug nuts and put the spare on.  The incident slowed us down about three hours, but would have taken longer if Chad hadn't saved the day with his AAA card.

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Conclusion:

I broke a few of personal records on this chase.  At 1913 miles it was the furthest I have traveled in one chase, beating March 28 of this year.  It was also the furthest difference between my initial target and intercept at 182 miles.  This was my first Oklahoma chase even though we wound intercepting in Kansas.  We came very close to busting on this chase as our initial target never verified, and we had to race a great distance to catch storms with motions opposite our travel direction.  It all paid off though and I witnessed some of the best supercell structure that I had ever seen and another tornado.  We made it to the storm of the day, with only cold core activity over CO, and isolated tornadoes embedded in the line from OK to TX.  The high risk region of the later outlooks busted almost completely.

Despite there being multiple funnels and ground circulations associated with the Nickerson supercell, I decided to count the event as one tornado.  There was only one mesocyclone, it was not cyclical, and the funnels and circulations were too brief to distinguish as separate tornadic events.  I don't doubt that there were separate parent storm circulations producing debris clouds, but these weak, multiple vortex tornadoes are too intermittent to accurately count.

 

Radar Analysis with GPS Overlay:

KICT Animated GIF (3.5MB) Individual PNG Frames

 

Lessons Learned:

  • Watch other target areas as the day progresses instead of focusing on the initial target