Chase Log: October 26th, 2006
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.
Total Distance: 323 miles
Target Area: Blackwell to Ponca City, OK
Chase Area: Near Arkansas City, KS
Maximum SPC Risk category: Slight
Watches:
Tornado Watch 839
Mesoscale Discussions (MCDs): 2157, 2158, 2159, and 2160
A nice, compact, powerful bowling-bowl type of upper low was forecast to approach the southern plains. Early model runs indicated that it was pass through Oklahoma during the overnight hours, minimizing any local severe threat and pushing the main threat into the southern Mississippi River valley. As the time neared, models slowed down the progress of the storm system, enough so to get me excited to chase again. Shear would be very strong (00z OUN sounding verified nearly 80kts 0-6km shear!), but marginal moisture and relatively weak lapse rates would limit instability. By mid-morning on the day of the chase, a wind shift made its way a couple of counties to the east of I35, which dropped dewpoints and made the worry about limited instability even more of a worry. Gabe and I briefly discussed a possible cold-core play in southwestern Kansas, but we liked the shear profiles along the warm front near the Oklahoma / Kansas border enough to stick with warm-sector activity.
Gabe Garfield, Dan Dawson, Rebekah Lebar, Heather ?, and I headed to play the warm front near the OK/KS border this afternoon. By mid-afternoon, a nice wall of TCU was bubbling just north of the border along a front that was one of the most evident that I've ever seen (marked change in visibility in a very short distance, solid line of soft, low Cu, etc.). We watched Tcu bubble up and down for a couple of hours, with marginal CAPE one of the most inhibiting 'ingredients'. By late afternoon, however, a more substantial updraft developed right on the front along the Osage Co / Cowley Co border. The base was smooth, and the rotation at cloud-base, while organized only for short intervals, was relatively impressive (very turbulent). A glance at radar indicated substantial development of this cell, as well as one to our north. We followed this cell northeastward for a little bit before it went linear. A supercell with nice hook and mesocyclone developed north of the cell we were on, but waning daylight led us to call off the chase. We headed back through Arkansas City, at which time a "just-in-case" look at ICT 88D indicated a classic supercell near Wellington. Ah ha! Nice hook, good reflectivity structure (e.g. strong reflectivity gradient along updraft-downdraft interface, etc), and a moderate mesocyclone -- all what we were hoping for earlier in the day. We followed this storm through Oxford, after which time we gave up as it was apparent the storm wouldn't become surface-based with temperatures in the low-mid 60s.
Overall, another marginal chase. Though my expectations were relatively low given the marginal dewpoints that resulted from a dry intrusion in the morning, I would consider this chase largely a bust. At least there was convection, and the motion at cloud base and nearby was pretty spectacular. The low-level clouds streaming into the updrafts were moving at a speed that I don't see very often, which made things interesting at least. The cold-core play ended up paying off for those who chased that area, with SPC storm reports indicating nearly 20 tornadoes. Cold-core strikes again! The dryline / cold front failed to initiate any convection in Oklahoma.
