24th Conference on Severe Local Storms


The Greensburg, KS tornadic storm: a storm of extremes

Leslie R. Lemon, CIMMS/Univ. of Oklahoma, Norman, OK; and M. Umschied

Late on May 4th and early on May 5th of 2007 a tornadic storm developed from a first echo in the Oklahoma panhandle and moved north northeast as it strengthened and became quite severe. The storm quickly developed very strong storm-relative inflow followed by three mesocyclones along its southern flank. As the storm continued moving northeast several remarkable storm structures developed including but not limited to a series of tornadoes, some of which were extremely large and were actually resolved by the WSR-88D of the Dodge City, KS National Weather Service Office about 34 miles away. One of the three extremely large tornadoes, the “Greensburg tornado” itself, was rated EF5 and was associated with a mean radar detectable velocity of 138 kts and a shear of 237kts or 121.9 m/s across a 2 km diameter. The second “extreme” vortex became so large (~ 7 km across) and so intense (mean tangential velocity of 106 kts) that its identity as either a “tornado” or “mesocyclone” is in question. An inverted cone of centrifuged hydrometeors became easily detectable and quite deep in association with these large, strong, tornadoes. It appears that an intense updraft of large proportions develops with these tornadoes and generated a large echo mass aloft surrounding the “vortex hole”. This BWER-like feature coincides with a nearby and more typical storm updraft associated BWER. The circulation around the storm became mesoscale and quite deep drawing in and merging with other storms in its environment. During the storms lifetime (nearly 8 hours) there are at least three periods when 3 tornadoes were underway simultaneously as resolved by the radar. The paper documents these and other characteristics of this truly remarkable storm.

extended abstract  Extended Abstract (2.2M)

wrf recording  Recorded presentation

Session 2, Geary, OK and Greensburg, KS storms
Monday, 27 October 2008, 10:30 AM-12:00 PM, North & Center Ballroom

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