There is really nothing complicated about it at all. Either the storm comes upthe coast this weekend or it doesn't. Now that tells you a lot.Here's what it will take to make the storm to track up the East Coast. Thenorthern part of the jet stream must curl back toward the southwest forcing theupper-level winds to become more southerly along the East Coast. If thathappens, the mid-Atlantic region would be staring down the barrel of a majorsnow event.

The other scenario, which seems somewhat more likely, is that the storm comesnorthward to a point then is redirected out to sea. This would happen if thenorthern and southern branches of the jet stream stay out of sync.

Much more on this threat to follow. Stay with us.

Story By AccuWeather.com Senior Meteorologist John Kocet.