From: Andrew Johnson
Date: 2010-05-10 13:30:17
t the bottom of the page, weather.unisys.com/r… there is this text: This is a composite plot of the radar summary, echo tops, storm movement, TVS and MESO signatures and watch boxes. The radar summary is color coded by precip type. Greens, yellows and reds are rain. Pinks are mixed precipitation (freezing rain, sleet). Blues are snow. NOTE: Radar data is susceptible to a phenomena called anomalous propagation. This generally happens at night and appears as a area of 20 dBZ echos (darkest green) which is centered around each radar site and expands with time. To try and reduce the problem, low echo values near the radar sites have been removed. So the rings seem to be the result of excluded data – caused by “anomalous propagation” – not really sure what they’re saying… but perhaps the process they are using on the data covers up things like this (from 2007, Texas) www.youtube.com/watc…
