Chase Log: June 07th, 2007

Click on any of the SPC products below (Convective Outlooks, Watches, or MCDs) to see the SPC's "Severe Thunderstorm Events" page pertaining to this event.

MAP

Total Distance: 100 miles
Target Area: OKC to TUL
Chase Area: BUST
Maximum SPC Risk category: Moderate
Watches:
Mesoscale Discussions (MCDs):

Well, we were supposed to have the radar back by noon this day, but we were lucky enough to be given another day with the radar. With deep Gulf moisture in place (70-74F tds) east of a dryline that stretched from near Kansas City, KS, to Wichita Falls, TX. Though shear profiles weren't quite as strong as the previous day's, 0-3km SRH of 250-300 m2/s2 would work with >4000 j/kg MLCAPE and 40-50k5 0-6km shear to produce a risk of supercells and significant tornadoes. Several high-resolution WRFs initiated precipitation in the area between OKC and TUL. Game on.

Well, not really. Despite a strong dryline, convection had trouble developing. We sat in Chandler for several hours awaiting initiation, but that never happened in central OK. A few cells did develop N and NW of Tulsa, as well as N of Wichita Falls, TX, but they were surprising insignificant.

So, why did the event bust? Honestly, I'm not sure. The cap was forecast to be weaker than the day before, and the 00z OUN sounding indicated negligible capping, with extreme instability and respectable low-level shear. A few TCUs did try to develop into Cbs across the area, but none lasted more than 20-30 minutes. The only thing I can come up with is that surface parcels weren't able to stay in the convergence zone long enough to develop a sustained updraft. Now, I know there have been plenty of days on which updrafts developed on an updraft and quickly moved off the dryline as they further developed. What was different in this case I don't know. Perhaps the depth of convergence was not great enough, but the moisture depth was quite significant, so low-level mixing off the updraft should not have been prohibitive.

I should have guessed that the event would bust... We haven't had a significant tornado event in the state of Oklahoma in several years, so surely we should have guessed that Oklahoma, yet again, was not going to produce for us. A terribly uneventful end of a marginal 30 day period.