Tkmcnam is rite. Turkey go in the Open areas during rain because they rely on their hearing and vision and when its raining, it messes with them in the wooded areas. So in open areas they can atleast see better. If its a light rain, they will gobble, but since its guna be 50 out, they may not gobble alot or they may wait till later in the afternoon to gobble. If its a hard rain and windy, in my experience, they go to cover, and in my area, they love to go down into small valleys that are somewhat more open but has alot of cover.
Hope i could help somewhat.
GOOD LUCK!
Go get'em!