Posted for Tom Hall <tkhall@highland.net>:

 MessageSomething's amiss with your GPS or your looping. I have found it to be
extremely accurate. I have been using for 2 years also. A storm showing no
movement or change in 45 minutes would be very unusual. The WxWorx system
doesn't use base reflectivity and this may cause an exaggeration of some
precip at different altitudes. (see flying mag this issue).
 
 NB. I would be VERY hesitant to pick my way thru any embedded storms. Level
1-3 with no significant convective activity might be OK, but the downloaded WX
data is for strategic use, i.e planning and avoidance of general areas of CB.
Tactical use is very hazardous. The data maybe 10 minutes old and, with
rapidly developing convective activity, this is too old. Best to be able to
see the storms with your Mark 12 eyeballs if wx is serious. We have lost 3
Lancairs in the last year to CB activity. Time to learn from that. Use the
nexrad cautiously and wisely. Don't rely on ATC and don't take a vector or a
path that you don't like. Remember, you are the PIC. You fly the plane. If ATC
wants you to go where it doesn't look safe, then just say "unable". If all
else fails, tell them that you can hold or circle until other options are
available.
 
 Check your WXWorxs. Call tech support. They are very willing to help.