NightCrawler,
It occurred to me this morning that the Hellas basin might completely clear of cloud and frost when it's Summer in the southern hemisphere of Mars. I checked some Hubble images, and found that this is indeed the case. So we both get to learn something by you asking your question, and perhaps other who read this will too, so thanks for asking! Here's a link to an image showing this:
http://hubblesite.org/gallery/album/pr2007045e/