Here's the issue... Most people will flee the city creating a massive over crowding of the highways. I'd build up a larger reserve of ammo and food over the 2 week period. Then I'm staying put in the suburbs as long as I can. That is where the food and supplies will be. Plenty of rats, dogs, and corpses to eat. I'll surface 2 weeks after the attack to pick supplies off of the crashed vehicles on the highways.
After the cities are largly cleared out I'll start hording supplies. I will then venture out to the camps of survivors and sell/ exchange these supplies for men, gold, silver and other things I need. I will repeat thismultiple times until I am the wealthiest person in the post apocalypse world.
Rek & Fuj.... why not just take reffuge at THE FUCKING ARMY BASE.
Who else would be better supplied to cope with a disaster.