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  • Author or Editor: Gary K. Schmocker x
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Bartlett C. Hagemeyer
and
Gary K. Schmocker

Abstract

Climatological analyses indicate that strong morning tornadoes in the dry season, and weak afternoon tornadoes in the wet season, are significant forecast problems in east-central Florida. To address this issue, an analysis of upper-air soundings for Tampa Bay, West Palm Beach, and Cape Canaveral, Florida, released within ±2 hours of tornado touchdowns in the County Warning Area (CWA) of future National Weather Service (NWS) Weather Forecast Office (WFO), Melbourne, Florida, was completed. Mean dry- and wet-season tornado-proximity soundings to 200 mb were produced, and selected mean diagnostic parameters and variance statistics computed.

Both dry- and wet-season tornado environments were associated with deep moist layers overlain by dry air, but no capping inversions. Dry-season cases were characterized by lower-tropospheric o w values well above normal, very low Convective Available Potential Energy (CAPE) and Bulk Richardson Number (BRN), strong speed and directional shear at low levels, a strong midlevel dry intrusion, and a maximum wind at 200 mb. The thermodynamic environment of the wet-season cases under westerly flow was close to mean seasonal values, but U increased steadily above 650 mb to a mean westerly maximum wind at 275 mb. These middle and upper-level winds, greatly exceeding mean seasonal values, allow thunderstorms developing along low-level convergent boundaries to be organized and sustained by the production of strong, persistent, tilted updrafts and continued low-level inflow of high o w air.

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Theodore W. Funk
,
Kevin E. Darmofal
,
Joseph D. Kirkpatrick
,
Van L. DeWald
,
Ron W. Przybylinski
,
Gary K. Schmocker
, and
Yeong-Jer Lin

Abstract

A long-lived highly organized squall line moved rapidly across the middle Mississippi and Ohio Valleys on 15 April 1994 within a moderately unstable, strongly sheared environment. Over Kentucky and southern Indiana, the line contained several bowing segments (bow echoes) that resulted in widespread wind damage, numerous shear vortices/rotational circulations, and several tornadoes that produced F0–F2 damage. In this study, the Louisville–Fort Knox WSR-88D is used to present a thorough discussion of a particularly long-tracked bowing line segment over central Kentucky that exhibited a very complex and detailed evolution, more so than any other segment throughout the life span of the squall line. Specifically, this segment produced abundant straight-line wind damage; cyclic, multiple core cyclonic circulations, some of which met mesocyclone criteria; several tornadoes; and embedded high precipitation supercell-like structure that evolved into a rotating comma head–comma tail pattern. The bowing segment also is examined for the presence of bookend vortices aloft and midaltitude radial convergence. In addition, the structure of other bowing segments and their attendant circulations within the squall line are discussed and compared with existing documentation. Radar sampling issues and ramifications of the squall line’s complicated structure on the warning process of future similar severe weather events are touched upon as well.

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