WRAL WeatherCenter Blog

Is there any chance your Doppler radar has a hard time picking up drizzly rain? I rode my bike this morning from south Durham (near Southpoint Mall/I-40) to Duke, from 9:45-10:30am, and it was a steady misting drizzle the whole way. I checked your radar map before I left, and also when I got to campus, and there doesn't appear to be any sign of rain! I was pretty darn wet though!

Posted April 27, 2008

MIKE MOSS SAYS:        Ron,     It isn't uncommon for any weather radar to fail to show much of an indication that drizzle may be occuring. The very tiny drop sizes involved lead to low radar reflectivity, and in addition drizzle often develops within a fairly startified, shallow layer not very far above the ground. The combination can lead to what appears to be a "dry" radar image, when in fact it is rather misty at the ground. Radars can be "tuned" a bit so as to be more indicative of drizzle, but there are some trade-offs involved that would lead to more ground clutter, more echoes from virga (precipitation aloft that doesn't reach the ground) and other drawbacks in terms of the main function of the radar in showing areas of light, moderate and heavy rain.


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