Absolutely pull all of your cash out of the bank. The worst that can happen is that you have paper money to barter with (if you don't have time to convert it to silver). I advise that you use the cash you have to stock up on ammo. Ammo will be the most widely accepted currency in case of a blackout, or EMP event. The silver that you manage to stack up only after you have at least 6 months of food, water and ammo taken care of will create generational wealth in the years to come. Silver and Gold are not something that you want to be bartering with for food!