National Weather Service United States Department of Commerce

Heavy Rainfall Moves into the Mid-Atlantic and Northeast

A slow moving cold front will gradually progress through the Mid-Atlantic and Northeast through Friday with possible severe weather and heavy rainfall which may bring flash flooding. The trailing end of the cold front will bring daily rounds of strong thunderstorms capable of producing locally heavy downpours over South Florida. Read More >

Slide 9

Reflectivity Image from the Twin Lakes (KTLX) WSR-88D National Weather Service Doppler radar at 7:28 PM CDT on May 3, 1999.

These images explicitly show the grave danger posed by flying debris in a tornado passing through an urban area, particularly a tornado of this intensity. The image on the left is the reflectivity image from the Twin Lakes (KTLX) WSR-88D National Weather Service Doppler radar at 7:28 PM CDT on 3 May. The highest reflectivity values, in white, are in the ‘ball’ at the tip of the hook echo, which is the location of the tornado. The reason for this is that large and numerous pieces of debris make for very good reflectors of radar energy (the radar ‘sees’ anything that will scatter radar energy - and that is NOT limited to precipitation particles!).

The two images on the right are image captures from a video taken by KFOR-TV (Oklahoma City Channel 4) at roughly the same time as the radar image. These pictures clearly show the large amount of debris within the circulation of this tornado as it destroyed numerous housing subdivisions near the highway. When violent tornadoes hit a large number of structures, this amout of debris is typical; even small objects become dangerous missiles. It's not the wind that causes casualties, it's what's *in* the wind. This was the situation facing the people underneath the Shields Boulevard overpass bridge.

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