Below is a link to the page for information on and to install the NASA World Wind program (version 1.4.0).http://worldwind.arc.nasa.gov/download.html
Not sure how many people know about this program, and there is a lot more you can do with it beyond what I will mention, but...
You can use the program to get a general map overview. But, if you have .kml files (or .gpx files that you can convert to .kml) you can use the program to view current cloud cover and, by scrolling/zooming in with the mouse, current snowpack thru a route you may be planning on doing soon. Just go to File/Import KML/KMZ file ..., load your file, then zoom in to view the current conditions.
I know there are many times that people will want to know if a route is going to be doable, and with this program, you can at least see if you have a 'clear' route or will have to be trudging thru snow fields. Now, for river crossings, there is another site to check those potential issues. But, thought this might be a nice additional tool for folks to use.
Myself, I'm using it to monitor the situation/conditons thru late Spring/early Summer for the Sierras, Central Oregon, Idaho and the San Juan region of Colorado. Hoping to do a 6 to 7 week trip from around the end of May to the beginning of July. What I do depends on the conditions. I know the options, and this will help me plan a route.
Check it out.