High Plains Drifter

The long-lived, significant tornadic supercell of 31 May 2010 will go down as probably my most thoroughly and successfully documented significant tornadic supercell in my 13 years of storm chasing.  There were three distinct phases of this storm chase, and as such, I will document this account and share my images in 3 parts.  The first phase (Part 1 of 3) was the time frame from roughly 2:45pm to 4:30pm which included a 20-minute tornado southwest of Pritchett, Colorado.  The second phase was a long period from 4:30pm to about 7:00pm when the supercell was non-tornadic but still cycled through several significant occlusions, one of which was very close to being tornadic (Part 2 of 3).  Lastly, the Campo, Colorado significant tornado, the hallmark moment of this supercell, will be documented in Part 3 along with the post-tornado sunset structure as the storm rolled southeast into the Oklahoma Panhandle northeast of Boise City.

Part 2 of 3. 4:30 to 6:55pm CDT (Non-tornadic phase)

(times CDT unless otherwise noted.  numbers in brackets refer to the image number in the embedded image album at the end of this post)

After the south of Pritchett tornado dissipated, the supercell entered a non-tornadic phase, which lasted from roughly 4:30pm until about 7:00pm.  After photographing the tornado, I drove east about a mile and a half then south two miles photographing the storm structure at various points along the way through 4:50pm.  The storm appeared to be taking on a high-precipitation supercell structure with a large mass of precipitation descending from near the main updraft area looking off to the west [1,2,3,4].  I was expecting the storm to approach my location… but it simply wasn’t doing so.  It was moving straight south.  So instead of just sitting there waiting for the storm to approach, I decided to head west again and then drift south.  I sat for awhile at a county road intersection as lightning activity was increasing abruptly.  I set up the tripod with the D200 in hopes of capturing a cloud-to-ground (CG) flash with the storm structure to my west northwest.  I didn’t capture any CG’s, so then I went south.  There is one county road that goes into the far western Oklahoma Panhandle to Black Mesa Park, and I was seriously considering taking this road considering the storm motion straight south… so I made my way south and west through 5:15pm, stopping along County Road 13 about 5 miles north of the Oklahoma border.

I photographed some of the high-based storm structure from here [5] and then drifted back to the north to the road intersection with County Road G where I met up with a group of Canadian storm chasers.  We sat here at this road intersection for a good 10 to 15 minutes or so [6,7,8].  It was at this time that the storm appeared to be making more of a southeast track instead of the due south track it had been taking.  The decision now was to head east back to highway 287 at Campo.  I was in no hurry, though, since the storm was still just crawling at around 5 mph.  At around 5:45 to 5:50pm or so, a high-based rear-flank downdraft clear slot was developing to the north [9].  I drove about three miles east or so and stopped to photograph a new wall cloud to my north-northwest.  This wall cloud in the RFD occlusion was classic [10], and I was preparing for another tornado, setting the tripod up with my D200 zoomed in to about 70mm for some up-close images [11,12].  Right at about 6:00pm, a laminar funnel developed within the tightening wall cloud [14,15,16], making up the tornado cyclone scale rotation.

It came very close to producing a tornado here, and it is quite possible there could have been unseen ground-based rotation beneath the laminar funnel.  I could never confirm a tornado, nor did any other chaser that I know of.  About three or four minutes later, this laminar funnel became a little more stretched out and diagonally oriented [19] as it began to dissipate.  The whole wall cloud area then became wrapped up in rain around 6:10pm [20,21], and I continued east toward Campo.  There were quite a few people from town, including local spotters, watching the storm from the west edge of town on County Road J.

At 6:20pm, I reached Hwy 287/385 and headed south from Campo about 3 miles before stopping along another county road adjacent the highway.  I met up with the College of Dupage group at this location and photographed the structure with some wildflowers to the northwest [23,24,25].  I photographed from this location for about 10 or so minutes before continuing on.  At this point, I was quite content with the chase and decided not to get too cocky in positioning.  It was all about finding the right light at this point since the sun was getting lower.  I didn’t want to shoot into the light to the west.  I took a county road (County Road C) east about a mile or so and found a high spot to shoot from.  There was a fairly well-developed high-based “swirl” marking the new mesocyclone to my northwest [26,27,28].  I sat here for about 10 minutes as well watching this feature approach.  Time was about 6:45 to 6:55pm or so.

With the light pretty harsh to the west, I got tired of shooting to the northwest, so I went back west to Highway 287/385 then south about 1/2 of a mile or so before stopping again along the shoulder of the highway.  Again, up to this point, the chase day was going perfectly, and I was very content with what I have seen up to this point.  Little did I know what I was about to photograph from this very location.  Details of this… the so-called “Campo Tornado”… in Part 3!