High Plains Drifter

Last week (Friday 4/14) I chased an impressive high-based supercell thunderstorm in Northwest Oklahoma. This chase was one of those “high-risk, high-reward” type of chases in that it appeared to be a very marginal setup for supercells, and especially tornadoes. I was off work last Thursday and Friday and was watching the Friday setup with some interest along the dryline. What perked my interest in the setup for Friday was 1) a subtle triple point convergence of the dryline and a washed-out, weak front that had slowly pushed into far northwest OK… 2) long hodographs with 50-70kts of upper level winds… 3) intense afternoon heating into the lower-mid 90s to allow the cap to break. The NAM model was also showing a very small area of convective precip in about 3 or 4 consecutive runs, which was a pretty strong signal that initation may occur in far western/northwestern OK. I figured if initiation would indeed occur, it may just be one or two storms given the lack of an upper level system to enhance deep tropospheric lift. It would just be mainly boundary layer forcing. I also figured, from a photographic standpoint, that a supercell in this environment would be very photogenic. This was the forecast I posted in a storm chase discussion group the day before (Thursday 13th):

“There may be an opportunity for a picturesque storm in far northwest OK late tomorrow aftn/into the evening. It appears there will be weak to modest sfc convergence as this weak front/wind shift stalls out creating somewhat of a triple point with the downslope plume extending northeast from eastern New Mexico. The thermal nose of the NM downslope plume should be over the far northeastern TX Panhandle/far NW OK where highs should soar into the mid 90s once again. Model Tc of ~36C in this area so add in a little convergence to get things going, and there could be a storm. Deep layer shear looks pretty good with 270° flags down to about 8km AGL. If there is enough convergence to get a good mass of DMC going, there just might be a little high based low end supercell surprise. From a photography standpoint, I like these subtle looking possibilities… I’ll keep an eye out” -Mike U

On Friday, after I came home from running some errands around town, I pulled up a visible satellite image and radar and noticed storms already developing along the TX-OK border near the Canadian River…this was around 3pm. I was pretty much set to go, so after I saw this, I blasted south out of town. It’s about a 2-hr drive straight south to that area from Dodge City. I reached Laverne where I fueled up. In Laverne, there were two areas of towers going up…one to my immediate southeast and another area of more intense development of towers/weak storms to my distant south… probably near the Canadian River. I did not have radar data because Northwest OK is pretty much void of service for my Alltel aircard. This was not a problem, though, because my eyes are far better tools for me than radar. I continued south to the town of Arnett with this view to the southeast at pretty hard looking high-based towers and a weak storm underway. This whole area to my south and southeast now was becoming quite convective looking. It has been my experience that if there is a “towering Cu hot-spot” where towers would go up, anvil out and die… which repeats for 2 to 4 iterations in the same location…. that this indicates a very susceptible area for vigorous convective initiation in the not-too-distant future. This was occuring very near the Canadian River north of Roll, OK. I drove south to the Canadian River on Hwy 283 with this view looking east as I crossed the river. A mature updraft base was now underway and it appeared as if I was in pretty good shape for a nice storm.

I got south of this area when I reached Roll, which is where I continued east on Hwy 47 just south of the river. These photos (1 2) were looking northeast at the maturing updraft. I found a high spot overlooking the open prairie to the northeast with a dark updraft base just off to my northeast now. The storm was rapidly getting much better organized. With high temperature-dewpoint spreads (lower-mid 90s over mid 50s dewpoints)…downbursts would probably occur in the forward flank region of the storm. I continued driving east with the storm updraft becoming very well organized now (1 2 3). Continuing east, I was finally getting east of the updraft as I approached the town of Leedey. My first stopping point just east of Leedey offered this view to the northwest at a well-sculpted supercell updraft base! The precipitation core immediately downwind of the updraft base was becoming very intense. The beginnings of an impressive rain-foot, which denotes very strong surface winds from a downburst, were becoming apparent.

The visibility was just absolutely superb and there were no other storm chasers around. Not one — which is an incredible feat for being on a supercell thunderstorm in Oklahoma in April in this current era of storm chasing. Given the fact that tornadoes were NOT what I was after this day, I gave this one a more serious meteorological consideration than a majority of other storm chasers would. Watching this high-based storm with no other chasers around reminded me very much of my May 4, 2002 intercept of a gorgeous high-based supercell near Medicine Lodge, KS — another similar kind of setup with very subtle thermodynamics and kinematics, but enough to get one beautiful storm.

Back to the chase account… this storm offered some of my best rain foot photographs to date. When you drop a ton of water into a near-surface atmosphere with fairly low relative humidity, interesting things can happen. This is about as good as it gets for a supercell structure photographer! This was exceeding my expectations for the day for sure. Here’s a vertical compositon. Another wide angle shot of the supercell updraft, the forward flank precip core, and one of the most impressive rain-foots I have ever seen.

With the storm moving due east around 25 mph, I had to keep driving east to stay ahead. My next stopping point would be somewhere between Rhea and Burmah in southwestern Dewey County. This was the structure of the supercell from this location looking west-northwest. About 15 minutes later and about 7 miles farther east, I had this view (1 2). As I approached Hwy 183 near Putnam, the storm was beginning to shrivel up a little bit. This shot was looking west down Hwy 47. I expected this storm to diminish given the environment not supporting long-lived storms, although I didn’t expect it to meet its demise this soon. I continued east of the intersection of Hwy 183 about 4 miles and then optioned south to try and get better lighting looking more north at the storm instead of west-northwest into the sun (harsh contrast). Here’s one last vertical shot looking northwest in fairly harsh light with a young wheat field in the foreground.

I back-tracked west a bit on Hwy 47 to get a better lighting angle on the storm looking north. I wasn’t dissapointed… I had some great views of the waning storm with an impressive hail shaft overlooking green fields. More photographs from this same location: (1 2). I reached Hwy 283 again and tracked back north towards home. A rainbow offered a wonderful landscape photo opportunity. This is what was left of the storm looking off to the east from just south of Putnam. Here are a couple of shots with my 80-400mm zoom lens (@400mm) at the convection in the updraft (1 2).

I got back home in Dodge City around 11:30pm. This was one of the most satisfying solo chases in quite some time… in all facets from the forecast to the logistics of the chase, the location and beautiful scenery along the Canadian River valley to the incredibly photogenic storm structure itself. Chase days like these are hard to top. Onward!

Photo Gallery >>

http://www.underthemeso.com/gallery2/stormchase/chase06/2006apr14/

Mike Umscheid