Seasons, Island Living, and terrible snow storms in Sulani

The only way it can snow in Sulani without a weather machine is when it's mysterious weather. But then the snow shouldn't stick.
But since you use MCCC, you can use the cheats module on the mailbox to change the weather. Maybe that's how you got it to snow? You can set the desired weather and the amount of time that weather lasts. I haven't tested it extensively, but I do suspect that that weather carries over to all worlds. But you can also use it to turn the weather back to sunny cool, or warm if you prefer.