luuna31 - 3:14 pm on Aug 22, 2012 (gmt 0)

If your impressions are going down, means your website is showing up less as a search result in Google/Yahoo/Bing/etc. This really just means that there haven't been many searches relevant to your website recently -- could this be explained by seasonality? Might be a silly question, but when the migration was done, did you update your Webmaster Tools account as well?