Chase Log: March 04th, 2004

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: 300 miles
Target Area: Duncan, OK
Chase Area: Waurika to Ardmore, OK
Maximum SPC Risk category: High
Watches: PDS Tornado Watches 22, 23, and 24, Tornado Watch 25, Severe Watches 20 and 21
Mesoscale Discussions (MCDs): 157, 160, 161, 162, 164, 166, 167, 168, 169, 170, and 171

Models were having a difficult time with this system for several days leading up to this event. From earlier in the week, it was looking as if Wednesday would be the good severe weather day for the southern plains. However, the models slowed down the arrival of the main upper low with each run. By Wednesday night (the 3rd), it was quite obvious that a very strong upper low would kick out of the southwest US and induce rapid cyclogenesis in western TX by early on the 4th. The wind field was forecast to be very strong, with 500mb winds over 100kts across TX and into OK. The low was actually kicking out of northern Mexico, which left the mid-upper flow across the southern plains quite backed. However, a very warm and moist airmass (dewpoints in the mid to upper 60s) was advancing across northern TX and into OK ahead of the forming surface low. Shear was not going to be a problem; rather, limited instability was expected to be the main hindrance in what would otherwise be a significant severe weather outbreak...

Advancing to the morning of the 4th... We were targeting northern TX, on hopes that the unexpected clearing that was taking place ahead of the advanced pacific front / dryline would allow temperatures and resulting instability to increase. We left Norman at about 10:30p, after waiting for the upgraded SPC Day One convective outlook. It was becoming more and more evident that a signficant tornado outbreak and severe wind event may unfold, as local NWS offices stressed the very real risk of long-track, significant tornadoes. We headed out towards Ardmore, where we stopped to assess the situation. I was having significant problems with my mobile internet, which prevented me from using it. Therefore, all we really had to go on was NOAA Weather Radio and a few calls to some friends back in Norman for some nowcasting assistance.

Out for ADM, we headed west on Hwy 70. I was quite concerned about becoming involved with the developing squall line to the west. Reviewing the situation in my head, I knew there was very little chance of getting tornadoes out of the linearly-organized convection. Therefore, I was putting all my hope in the chance that a couple isolated, discrete supercells would form out ahead of the line. As we neared Waurika, the bow echo passed us. The maximum gust we recorded was near 50 mph. To make a long story short, we wandered around trying to catch back up to the edge of the bow, which was advancing northeastward at 60-70mph, in an attemp to get ahead of it and into any pre-frontal supercells. As it turned out, prefrontal activity was very limited, and the activity that there was was short-lived as it was quickly overrun by the squal line.

All in all, this was a nice first chase to test out my new equipment for the year. It was very frustrating that, despite the unforecast cloud breaks, instability still remained very limited. If this had not been the case, a major tornado outbreak would likely have occurred, considering the 50+kt 0-1km shear, +600 m2/s2 0-3km helicity, etc. As is common with these late winter / early spring storms, the kinematics were too strong and the thermodynamics too weak. The convection quickly formed into a linear MCS, with very little prefrontal activity. The relatively low visibility, along with the very fast storm motion, made chasing what convection there was rather difficult. Oh well, it was still exciting to get out for the first time this year, and it was still exciting to be in such a 'high-risk' situation...