Replying to GoPro Time Lapse Question

Hey guys,

i searched for some info on here but coulden't find anything so dont hate on repost. anyway so in toronto its supposed to snow like crazy tomorrow so im thinking about doing a time lapse of all the snow piling up. but i have a few questions.

my first question is what time interval should i film the time lapse at? i believe it can be set at every 2, 5, 10, 30 and 60 seconds. it is supposed to snow around 5cm an hour tomorrow, so how long should i keep the time lapse going? should the 2.5 hours the battery can last for be enough? I have an 8GB card for it and also have an extra battery. so i can just pop that in if needed.

thanks!