I wouldn't visit Washington, D.C. right now . . .

According to an article in the Washington Post (and reported elsewhere), the senior Taliban leader in Pakistan (Baitullah Mehsud) has threatened to "amaze the world" with an attack on Washington, D.C.

Below is a an analysis of the damage that would occur in the NCR (National Capital Region) from a 550 kiloton surface burst. As you can see, all of DC-proper would be annihilated, and significant damage would extend into NoVA and Maryland.

Remember that Hezbollah is utilizing our porous southern border with Mexico to infiltrate the United States, and that Mahmoud Ahmadinejad of Iran has selected Hezbollah to conduct terror operations against the U.S. if the U.S. were to strike Iranian nuclear facilities (see this report from Jihad Watch). Furthermore, Pakistan is a failing state armed with nuclear weapons.

Iran + Taliban + Hezbollah + Pakistani nukes = I wouldn't visit D.C.

On a brighter note, any nuclear weapon supplied by the Pakistanis (or stolen by the Taliban from Pakistan) would likely only have a yield of around 35 kilotons (more than double the yield of the bomb that destroyed Hiroshima, but less than double the yield of the bomb that destroyed Nagasaki). Both of those bombs were air bursts, which makes most efficient use of the destructive power of the burst. A surface detonation causes much of the energy of the bomb to be absorbed by the earth and immediately surrounding infrastructure.

So, if you live or work in D.C., you had better hope that the Administration's foolish quest* for the non-existant "moderate Taliban" pays off . . . if not, I'd find another place to be.
Source: Vulnerability of populations and the urban health care systems to nuclear weapon attack - examples from four American cities
William C. Bell and Cham E. Dallas
http://www.ij-healthgeographics.com/content/6/1/5

* even the Huffington Post agrees that the position of the Obama Administration on the transnational insurgency raging in Afghanistan and Pakistan is foolish.