Chase DetailsAugust 12, 2006 (eastern South Dakota)
Chase Type: Tornado
Chasers: Reed Timmer
Location: South Dakota
Distance: 1800 miles
Tornadoes: 0
Hurricanes: 0
Max Wind Speed: 50 mph
Summary
Saturday, August 12, 2006 had very high expectations in eastern South Dakota for supercells and even strong tornadoes, given the incredible low-level shear and extreme instability forecast by the RUC and WRF models. Both models predicted dewpoints in the mid-70s, temperatures soaring through the mid-90s, CAPE values of at least 4000 J/kg, and neglible CIN by peak heating across east SD and southeast ND, thus surface-based convective initiation was not expected to be a problem. An unseasonably strong short wave forecast to traverse the area Saturday afternoon further enhanced our expectations for explosive supercell development over the target area.
We departed Norman, OK Friday afternoon, and stayed the night in Souix City, IA, planning to wake up early to analyze the morning model output. We became very excited when we analyzed the 12z RUC model forecast, which predicted a ridiculously strong low-level jet of 45 knots+ by 00z Sunday, and even greater instability than the WRF forecast. We thought that tornadic supercells were a given if the RUC verified. The low-level shear and instability was maximized between Pierre and Aberdeen, SD, so we began to head northwest towards this area. As we were driving, we began to notice a thick deck of mid- and high-level clouds engulf the entire western sky. This clould deck destroyed our chances for surface-based convection and supercells Saturday afternoon, because it held the high temperatures down and prevented the cap from being broken.
Therefore, we were forced to settle for elevated, outflow dominant storms after our 20 hours driving in eastern SD. Still though, the shelf clouds produced the severe storms Saturday were spectacular, and I experienced one of the best lightning shows I have ever seen. The cloud-to-ground (CG) lightning was so frequent that it felt very unsafe to be outside of the vehicle.
We departed Norman, OK Friday afternoon, and stayed the night in Souix City, IA, planning to wake up early to analyze the morning model output. We became very excited when we analyzed the 12z RUC model forecast, which predicted a ridiculously strong low-level jet of 45 knots+ by 00z Sunday, and even greater instability than the WRF forecast. We thought that tornadic supercells were a given if the RUC verified. The low-level shear and instability was maximized between Pierre and Aberdeen, SD, so we began to head northwest towards this area. As we were driving, we began to notice a thick deck of mid- and high-level clouds engulf the entire western sky. This clould deck destroyed our chances for surface-based convection and supercells Saturday afternoon, because it held the high temperatures down and prevented the cap from being broken.
Therefore, we were forced to settle for elevated, outflow dominant storms after our 20 hours driving in eastern SD. Still though, the shelf clouds produced the severe storms Saturday were spectacular, and I experienced one of the best lightning shows I have ever seen. The cloud-to-ground (CG) lightning was so frequent that it felt very unsafe to be outside of the vehicle.
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