I think it has something to do with how the picture is compiled. See:
http://www.flyingmag.com/article.asp...age_numb er=1

Since the radar sweeps take time (20 seconds for each 360 deg sweep) and
multiple are needed (14) to get a full vertical picture, it takes about 5
minutes for a complete volume scan.

Being a "system" involving many possible points of failure (not necessarily
catastrophic, sometimes just hiccups) a delay of 17 minutes seems to be
entirely possible albeit uncommon. The good thing is that it's kind enough
to show its age

Marco


"Dan Luke" wrote in message
...
http://tinyurl.com/2mz2y9

Upper right corner.

Note the age of the NEXRAD vs. the age of the XM lightning.


--
Dan
T-182T at BFM