Joint Session J2.4 The Greensburg, KS Tornado

Monday, 25 June 2007: 11:45 AM
Summit AB (The Yarrow Resort Hotel and Conference Center)
Daniel McCarthy, NOAA/NWS, SPC, Norman, OK

Presentation PDF (492.2 kB)

A wide, long-track tornado destroyed the town of Greensburg, KS the evening of 5 May 2007. The damage from this tornado was so severe it earned the rating of EF-5, a first in using the Enhanced Fujita Scale and the first tornado to earn a 5-rating in eight years.

Discrete supercells developed just east of the surface dryline over the northeast Texas panhandle into northwest Oklahoma very late in the afternoon on 5 May 2007. The flow was south-southwest to north-northeast in a highly sheared and very unstable environment. The wind field was highlighted by an 80 kt jet streak at 500 kPa over southeast Arizona and a southerly jet of 40-50 kt at 850 kPa from north central Texas into eastern Kansas. The exit region of the jet at 500 kPa moved into southwest Kansas at 0000 UTC on 6 May 2007 placing diffluent flow over south central Kansas with surface based CAPE greater then 2500 J/kg. Low level flow was southerly with deep layer shear of 65 kt. This was quite favorable for storms that moved northeast would 30 degrees of the mean flow enhancing storm relative helicity for tornadic storms.

Damage from the tornado was so severe that many of the 100 year old buildings on Main St. were destroyed. Much of the town's homes and structures west of Main St. were totally demolished. This paper will briefly review the synoptic conditions that were present the evening of 5 May 2007, and will also present the evidence that lead the team to rate the damage an EF-5.

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