 |
The WSR-88D calculates atmospheric motion
based on cloud and precipitation movements. It senses motion
directed toward and away from the radar, i.e., only motion parallel to a
radar beam (radial velocity).
Two types of velocity data are available: 1) base velocity which shows
movement with respect to the stationary ground and 2) storm-relative velocity map (SRM) data.
For more information, consult "Overview
of the WSR-88D Radar System." At left is a low-level base
velocity image on May 14, 1995. Green (red) represents radial winds directed
toward (away from) the radar located at the small while hole at Ft. Knox in
northern Hardin County. An arcing outflow boundary/gust front is evident
from central Meade through western Hardin to northern Grayson Counties. The
feature is associated with damaging straight-line winds associated with an
intense bow echo. However, since actual winds are directed from northwest to
southeast across southern Breckinridge and western Hardin Counties, i.e.,
nearly perpendicular to the radar beam, the radar "thinks" winds
are near zero in
this area. Nevertheless, the pattern displayed here, in addition to
reflectivity data (not shown) suggested damaging winds along the entire
boundary. |
