NWS Louisville - Bow Echo Velocity Data

Heavy Rainfall and Flooding Threats in the Midwest and Ohio Valley; Heat Continues in the Plains and Southeast

An active pattern will continue to bring heavy to excessive rainfall and flash flooding threats to the Midwest and Ohio Valley over the next couple of days. Dangerous heat continues across the central/southern Plains and Southeast U.S. into next week. There is potential for record-tying/breaking temperatures with many areas forecast to see their hottest temperatures so far this year. Read More >

NWS Doppler Radar (WSR-88D) Example Products

NWS Doppler Radar calculates atmospheric motion based on cloud and precipitation movements. Using the "Doppler effect," it senses targets moving toward and away from the radar parallel to radar beams (radial velocity). It cannot sense motion directed perpendicular to a beam since there is no phase shift in the Doppler effect for such movement. Two types of velocity are available: 1) base velocity which shows movement with respect to the ground (estimated actual environmental wind), and 2) storm-relative velocity map (SRM), which shows movement relative to a moving target, e.g., wind a thunderstorm "feels" as it moves through its environment.

Above is base velocity data over Crawford County in southern Indiana on August 13, 2011 (west of Louisville). The blue line is the Ohio River. Green colors are winds directed toward the radar site at Ft. Knox, KY (black circle at lower right). The light blue color within the bright green and white colors in Crawford County represent estimated winds of 60-70 kts only a couple thousand feet off the ground. These intense winds are associated with a bow echo in reflectivity data, and where strong winds and/or wind damage would be located. As the winds moved east, wind damage occurred along its path in Crawford and Harrison counties in southern Indiana, then across Jefferson County (and Louisville), Kentucky where Bowman Field Airport (LOU) reported a 69 mph wind gust. More information on this August 13, 2011 event, including damage photos and radar imagery is available on our Science and Tech site.

Heavy Rainfall and Flooding Threats in the Midwest and Ohio Valley; Heat Continues in the Plains and Southeast

NWS Louisville - Bow Echo Velocity Data - Southern Indiana

NWS Doppler Radar (WSR-88D) Example Products