Just looked through old Screamscope reports.
Here's some info on the recent talk of a snow effect on FJ..
"It looks like there will be a special 'snow' effect put into use within the Wizarding World of Harry Potter. This news bit, sent to us by 'Allen W.'
was first discovered as a posting to the Zigmont Magic F/X website (link removed by request of Zigmont), but was later removed. In the various descriptions of snow effects there was a section labeled Universal Studios Theme Park which mentioned installing custom snow machines in December 2009 for the theme park, possibly for use in a 'Coefficient of Friction Test for Harry Potter’s the Dark Arts Classroom.'"
--- Update ---