I have attached four spectrum of Uranus 1999, 2000, 2001 and 2006. All four 
spectras line up together and you can see if there is any difference. 

    In 1999, Uranus was facing us between equatorial and polar regions. In 
2006, of course we are facing more equatorial. I don't see any real difference 
in the spectrum. This shows that Uranus is basically the same as far as the 
atmospheric concern. The methane absorption bands are strong and it is quite 
clear. If there is an outbreak and it goes above the methane atmosphere, the 
absorption bands would be lighter and weaker...Also, it pops in and out during the 
rotation period if it occurs in one area.
 I strongly believe this is the best way to find out what's going on in Uranus' atmosphere.

[Frank J Melillo  Holtsville NY U.S.A]