Let's think about this.

If the original finish time was April, but has been brought forward to Jan, what forecast would become more accurate the closer we get to that date?

Certainly not a comet or asteroid, as trajectories would be well established - certainly without a three month margin of error. Anything which was due to impact soon after the 20th of January would now be visible - fact.

Sun activity cannot be forecast so accurately in advance either. Neither can seismic activity.

So let's assume that it's not a huge disaster that'll wipe everyone out apart from those underground; let's assume it's a hiding place.

So what's the most likely scenario? Total global economic collapse & war. The dollar is screwed. The Euro is screwed. The Asian tiger economies are built on sand. The Middle East looks as if it could kick off big style.