NWS Louisville Doppler Radar Composite Reflectivity

Storm System to Move Across the Ohio Valley to the Mid-Atlantic and Northeast

Isolated severe thunderstorms will be possible on Veterans Day across parts of the lower Ohio and western Tennessee Valleys. A developing storm will bring rain and gusty winds to the Mid-Atlantic and Northeast on Thursday, with the first accumulating snow likely in the higher elevations of the central Appalachians and interior Northeast. Read More >

NWS Doppler Radar (WSR-88D) Example Products

While base reflectivity data shows the location and intensity of precipitation at one radar elevation angle (i.e., one plane or "cut" through the atmosphere), "composite reflectivity" (CR) shows the location and highest reflectivity values from all elevation angles (as many as 14 per volume scan) employed by the Doppler radar. In other words, CR is useful to determine the maximum reflectivity value within a thunderstorm without regard to the maximum's vertical location. It also can help identify elevated or suspended high reflectivity cores when used in conjunction with low-level base reflectivity. Large elevated cores can be associated with subsequent hail or strong winds at the surface after the core descends.

In this image, numerous thunderstorms were present on March 2, 2012 over central Kentucky. Red and pink colors represent high CR values within these storms, with the highest values in blue and gray shades within the storms near the center and lower left parts of the image.