|Friday, 30 July 2010 23:56|
Total Distance: 390 miles
Finally, a more classic dryline setup presented itself, as deep moisture surged northward ahead of a strong shortwave entering the southern plains. As this ocurred, a dryline was progged to setup across the central OK/TX panhandles, south and southeast of a surface low in southeastern Colorado. For the first time this year, models were forecasting strong instability to develop in southwestern Oklahoma (~3000 j/kg CAPE) as dewpoints were progged to be in the 64-69F range (in the end, we saw 59-62F, again a huge model overforecast of dewpoints, as we've seen a few times already this year). While cirrus was an initial concern in the days leading up to the event, a look at the morning visible satellite showed that it would be a problem.
Ugh, another frustrating day (to go with Thursday). I headed out with a crew of folks (including Jana Lesak, Gabe Garfield, Phil Hurlbut, Justin Walker, etc), originally aiming somewhere between Elk City and Shamrock, not necessarily because we thought that area was the best, but because it kept our north and south options open. By the time we made it to Clinton, we looked at some data, and opted to slide south towards Altus. We noted a subtle boundary that was located very near the Red River (pretty well forecast by the NAM and RUC, actually). With the best CAPE to the south, we figured that may be our best option. Most of the chase days this spring so far have been a little CAPE deficient, so we were happy to see >2500 j/kg CAPE. We sat in Altus for a while, as TCu bubbled around. We eventually opted to head for the storm leaving Collingsworth county, TX.
When we got to the storm, it looked quite high based, and there was massive amts of precip to the west and southwest of the area of weak rotation. The storm was spitting out lots of scud from the FFD, and some of it was being reingested it appeared. The storm did have a very nice green/cyan colored appearance though. Looking at surface obs, I was extremely concerned by the low RH / high dewpoint deficits (see my failure reason below). Regardless, we followed this storm until it was south of Clinton... It had one more run at an RFD occlussion, but that too was very wet. By the time it was into Was$$$a county (6:15ish), it was looking progressively more outflow-dominant, with a shelfy appearance. I did see that SRV imagery indicated some rotation in the forward-flank, and this was confirmed visually. However, there was no doubt that the storm was lining out.
I've chased 3 times in 4 days, and struck out all three times. Thurs and today were HP sups, none of which were really that impressive. The rotation on today's supercell was largely pretty weak, and the structure was far from breath-taking. The storm did take two good runs at producing something, but the RFD was hugely precip-filled and quite cool.