Blast Effects & Fallout
High-Altitude Detonations:
Generally, a high-altitude detonation of a nuclear device of 5MT or smaller would be devastating locally, but altitude is inversely proportionate to the level of fallout. The closer to the ground -AND/OR – the larger the device, the more fallout becomes an issue.
Ground Detonations
Because of the strict airspace defenses around the US, nuclear attacks on one or more US cities would likely be ground-based, with large devices hidden abord a ship or a truck. If China were to attack more than one target, the detonations would likely be timed to occur at the same time. A ground detonation of even a small 1KT device would produce a fallout pattern that would stretch for 30 miles or more with a 15mph wind. Larger devices would have far larger and more far-reaching effects.
Example: 5 Mt ground detonations in New York, Baltimore, and D.C., showing blast effects and likely fallout pattern:
Example: 5 Mt ground detonations in Washington D.C., showing blast effects and fallout pattern, with damage:
Wind Patterns
Winds in the N.E. United States vary, but are predominately out of the west. This is something of a saving grace, as most or all of the fallout from nuclear detonations would be carried toward the sea rather than inland toward more population centers. There are many people east of these targets, but far fewer than there are toward the west. This is not to downplay the fact that large amounts of deadly fallout would be directed into and perhaps over the Atlantic ocean, with awful consequences of some kind likely.
Though winds are usually from the west, it is not uncommon to have a northern wind that could blow deadly fallout toward the south, presenting a far deadlier event.
Check the current wind pattern on the Live Wind Map here.
One thing about these likely ground detonations is they reduce the range and scope of the EMP effects.
Air Burst
In the event of an air burst or high-altitude detonation, the fallout would likely present a far lesser problem, but the damage would be more widespread; especially the EMP effects, which could span hundreds or thousands of miles in diameter.
