I've never used in-aircraft Nexrad. But the Nexrad images displayed on the
web by the National Weather Service has two modes, Precipitation and Clear
Air. When there isn't significant precip they use Clear Air mode that is
much more sensitive and will displays colors without any precip. Don't know
if that applies to the in-aircraft version.

"Wyatt Emmerich" wrote in message
...
Flying back from Atlanta to Jackson, my Echo Flight finally received its
downloaded Nexrad data. It showed me flying right in the middle of a big
blotch of red. I look outside the window. I'm in light 40 F light drizzle
with ceilings of about 6000 above a broken 2000 layer. I turn on the
Bendix/King RDR 2000 on-board radar. It shows nothing. Nothing on the
stormscope.

Why the huge contrast between the on-board and the Nexrad return? Perhaps
the Nexrad was picking up water far above me, while the on-board was
looking
ahead (I was at 5,000.)