I wouldn't make or cancel plans based on what the weather people predict will happen. This season, especially, they've been wrong, often wildly wrong, far more than they've been right. They need to get their head out of their... uh... out of their computers
and learn the art of weather prediction.
I cannot count the number of times this season where The Admiral and I cancelled plans to sail or race because of wind or weather predictions and it turned out we missed beautiful sailing weather.
As for What To Do if a storm came along while you were in a big raft-off... I have no experience in this, but here's what I think I'd do: I think I'd get out of the raft-off, get well up-wind of it, throw out the hook with at least
10:1 scope (that's 100' of rode in 10' of water), and ride it out. This a$$
umes you have proper ground tackle for your boat, properly rigged, know how to set it, and the anchor is one inclined to hold well in whatever the bottom is.
Also, on our bow-rider: I'd secure the bow canvas and put up the convertable top, even if the latter would only partially shield the cockpit.
Then I'd light a cigarette (if I still could), sit back, cross my fingers and pray