News Chopper 9 Pilot Johnny Rowlands live streamed tornadogenesis southwest of Sedalia, MO on May 20, 2010 at approximately 6:45 p.m. http://www.kmbc.com/video/23626976/
Discussion: A surface area of low pressure was passing near Kansas City, MO and an H7 upper level low was positioned just northwest of the surface low. A cold front trailed back into southeastern Kansas and northeastern OK from the surface low with a boundary draped along and just south of the the I-70 corridor.
A bit of sunshine this afternoon allowed temperatures to reach the upper 60's to lower 70's and dewpoints were in the low to mid 60's. In addition, surface and upper level shear was maximized near the low pressure centers.
As thunderstorms formed, they encountered the boundary and storm relative helicities were enhanced allowing the atmosphere to reach the correct parameters for tornadic thunderstorms. Once the thunderstorms crossed the boundary, they weakened considerably, thus eliminating the tornado threat.
In addition to the parameters already mentioned, cold air aloft at the 500mb level, crossed over the Johnson and Pettis County areas near the time of peak afternoon heating. 500mb temps were on the order of -13C to -14C. This has similar characteristics to a CC500L tornado event, but I am not versed well enough in this phenomenon to accurately discuss it. Jon Davies has a great paper, which I continue to read over and over, at this link for review: http://www.jondavies.net/DaviesWAF_coldcoretors_dec06.pdf.
SPC MesoAnalysis indicated 500 J/kg of CAPE and SRH 0-1 and 0-3 in the 150-200 m^2/s^2 range in the area of the tornadoes this afternoon. The 0Z/21 SPC Mesoanalysis references are below:
Shawna Davies: Excellent post, Corey! I believe you've got the cc down pat! Kudos!!
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