Good news = Wet / cloudy weather can help you to slip in close to roosted birds. It gives you more time and quiet walking.
Bad news = Wet / cloudy turkeys tend to be tight jawed on the roost and late in flying down.
For lack of a better plan, I would suggest moving in close to a known roosting area before dawn. Try to place yourself between the birds and the nearest open field. The more I hunt, the less I call on the limb. Let them come down before you start talking to them. If you are lucky, they'll swing by to pick up another hen on their way to the fields. If that fails, plan B would be to move to the field edge, stake a decoy and call intermitantly.
Two of my kills this season were cloudy day turkeys. They both to fell to plan B as described above. Good luck.