During the late afternoon and early evening of May 20, 1998, a bow echo raced across north-central and east-central Kentucky. No tornadoes were reported with this severe thunderstorm complex. However, numerous wind gusts of at least 60 mph did occur producing power outages, knocking down many trees and power lines, and damaging some roofs and barns.
|Base reflectivity data at the lowest radar elevation (radar located in the upper left part of the image) showed an arced/bowed out line of multicell thunderstorms (bow echo) across north-central KY. Heaviest rainfall was occurring in the red colors, although this does not necessarily correspond to the location of strongest surface winds, which were occurring within the bow apex along the leading edge of the storms (on the gust front).|
|Corresponding storm-relative velocity (SRM) data where red (green) represent radial winds directed away (toward) the radar located in the upper left part of the image. An arc/bow of red color is shown in the image center with areas of green ahead of the red zone. The gust front/leading edge of damaging winds was located along the leading edge of the red zone. The green areas ahead of this zone represented converging flow into the line of storms. Just behind the red zone are pockets of green (in the image center). This green area next to red zone just ahead of it represented low-level divergence associated with rain and winds spreading out behind the leading line of intense storms.|
|Fifteen minutes later, the bow echo continued eastward. Heaviest rainfall was occurring in the red colors, although little or no hail was reported. However, the strongest surface wind damage was occurring along the entire length of the bow apex (across extreme northeast Nelson, Washington, and Marion counties). The northern end of the bow echo (the "comma head") in this case represented a broad area of cyclonic circulation, but not associated with a mesocyclone or tornado.|
|Corresponding storm-relative velocity data showed a continued arced/bowed out gust front along the leading edge of the red zone of colors. The gust front was very definitive, meaning that surface winds would increase quite dramatically and abruptly shift to west as the gust front moved through. Notice that the gust front is located on the leading edge of the squall line with the heaviest rain occurring after the gust front passes. The brightest red colors across Marion and Washington counties represented the strongest rear-to-front flow associated with the most bulged out reflectivity pattern and the most severe wind damage.|