If the rapture truly fulfills a Jewish Feast, Pentecost would be my second guess.  (Feast of Trumpets would be my first guess.)  I'd even accept "no man knows the day nor the hour" (out-of-the-blue imminency.)
 
In case it's to be on Pentecost this year, it's good to keep in mind that the Biblical Hebrew way of figuring out when that will be is different than what some may assume.
 
This data is from Hebrew-Christian sources:
 
"Pentecost always occurs on a Sunday 50 days after the Feast of Hebrew Firstfruits.
 
"Feast of Firstfruits is always on the Sunday after the Passover."
 
(Source : antipas.net/pentecost.htm)
 
"A false Pentecost is Sunday, May 11, 2008, 28 days before true Pentecost.
True Pentecost begins June 7, 2008, at sundown."
 
 
Can any of you with a Hebrew-Christian knowledge verify this?
 
Gloria McCrea