"John Smith" wrote in message
...
What are the weather overlay capabilities of these units? Can you
overlay
a radar map on top of your airspace map? Across a route you are
navigating?

Think of the presentation you see when you go to aviationweather.gov.
That is pretty much what you get on the 496.

It does look something like that, but there is a difference that most people
don't know about that makes a huge difference.

XM has their own very powerful weather processor rather than use the NWS's
processing functions. What this means is they are taking the raw scan data
and developing their own composite. The NWS waits until all scans are
finished and then they process all of them at once. The result is the
weather 'jumps' every few minutes when the update is performed and the new
composite is developed. XM processes each scan as it comes in and updates
accordingly. The result is a much faster update.