|Friday, 30 July 2010 23:56|
Total Distance: 420 miles
I sat with Gabe, Dan, and a few other chaser-friends in Ardmore for several hours this afternoon, waiting for one of the TCu along the dryline to take hold. I became quite discouraged by 6pm, after having watched TCu after TCu lose the battle of initiation. We meandered southward a little based on satellite observations of persist "clumping" of TCu just across the Red River in northern Texas, before heading eastward to catch up with a shower that had developed southeast of Ardmore. It appeared as though a new cell developed to this cell's southwest, so we dropped southward to get into better position to watch this new cell. A bad road option near Coleman (red dirt+rain=bad) resulted in us having to drop southward to Kenefic and Caddo; in hindsight, we should have gone north to Wapanucka instead (as Amos and Eric did).
As we emerged out of the precip north of Kenefic, the structure of the storm improved rapidly, and we sat near Caddo for ~10 minutes admiring this structure when the tornado warning was issued. The position given in the warning text indicated that the meso would pass south of Atoka, which meant that we either had to wait for the meso to pass over Hwy69/75 or head eastward and try to checker-board our way north. The roads between Caddo and Lane (near Bentley) weren't too bad, as they were at least gravel-covered in most spots. Regardless, visibility was extremely limited owing to large trees lining many of the hilly roads. Lightning, fortunately, was frequent enough to at least give us hope that we'd be able to see something under the base if there was something to see. Through this time, we saw at least a couple of very nice wall-clouds, and one or two possible funnels.
We encountered some downed trees 4-5mi south of Lane, presumably from RFD winds (since the roads were relatively dry and the center of rotation given in an SVS, IIRC, was very near Lane). My cell phone is broken, so I didn't have any NWSFOs phone numbers (and didn't have data either). Most of the downed branches were small, but there were a few 6-8" branches down, and even a few trees downed. At any rate, we made it to Lane, at which time we decided to head southeastward on Hwy 3 towards Antlers. Despite looking as though we'd be able to catch back up with it, we were never able to get within 10-15 miles of the mesocyclone. We called off the chase just east of Rattan, after which time we went back to Sonic in Antlers, where we ran into Erik and Amos.
All in all, a decent chase for this time of year. Shear was obviously very strong, and I had high suspicions that it may have been too strong for the convection that tried to develop on the dryline. I was very surprised to see the strong convection that developed east of the dryline, near Paris, TX, and Durant, OK, by late afternoon. Looking at the 0z OUN and FWD soundings, however, I'm not as surprised. The moisture at OUN is knee-deep, while CAPE on the FWD sounding is as marginal as one could expect to see on a warm-sector chase day. This agrees quite well with our observations of the pulse-like nature to the TCu on the dryline. I told Dan that I guessed the FWD sounding would have <800 j/kg sbCAPE, which ends up being a pretty good guess (sounding on CoD indicates 600 j/kg sbCAPE). Adjusting for higher Tds to the east/northeast does bring the CAPE into levels slightly more typical of severe weather events in the Plains (albeit still in the low range).