In reply to Mike Peacock:
Another one for Siabod/Ddear ddu. Winds are forecast 30-40mph westerlies on Saturday.
You might be able to avoid some of that by doing Tryfan Little and North gullies rather than the North ridge, but you would still be very exposed on the summit and any reasonable descent, and with poor visibility and rain / snow forecast I wouldn't recommend it.
Ddear ddu allows you to avoid steep drops and choose how much scrambling you do, gives the option of reversing at any point and has a nice gentle descent as long as you can navigate from the summit onto the descent path to Plas y Brenin. (Water levels should have dropped by then, but be aware that the river crossing at Plas y Brenin could be flooded if heavy rain persists!)