Fellas, here's a page with a nuclear weapons effects simulator, which enables you to plot multiple detonations in a target area. Some weapons are historically added (Trinity, Hiroshima, Ivy Mike, Tsar Bomba, the Davy Crockett, and so on), but you can enter the yield and the target city, and adjust ground zero as needed.
http://nuclearsecrecy.com/nukemap/
Enjoy slagging cities, people. I did this morning (L.A., SF, NYC, and a few others).