Last question first - the baggage office should be open more or less until all flights for a day are done.
They will hold anything not picked up.
If possible see if you can same-day-change when you check in a the origin so that everything will go on the earlier flight. You may not be eligible for this if you aren't A-list or didn't buy WGA+ tickets, but if there is plenty of room they may go for it in anticipation of a storm.
Otherwise:
1) They won't want you to standby if you have checked luggage.
2) If they do allow it, you sign off that you'll be separated from your things and responsible to come get them at the airport.
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