Snowy Weekend Ahead?

If you read through Tuesday's post (and actually Wednesday's below as well) you'll see that I was keeping my eyes on a potential storm system expected to pass near the region Saturday night and Sunday. There's been signals in the upper air and surface patterns for a period of at least some light snow Saturday night and Sunday morning for the last several days. But there's also been hints for something more meaningful should a slightly different jet stream configuration evolve.

The key to the situation lies in the interaction between the upper level energy driving the arctic front to the coast and moisture riding northward up the eastern seaboard on the quasi-frontal boundary left behind from Friday's storm system. The questions are: can the upper level trough digging through the east amplify just enough to drag that all important temperature gradient closer to the coast and subsequently allow a coastal storm to rapidly deepen and pass close to the region? Or will it remain flatter and force any wave of low pressure riding northward from the Carolinas to head more east than north?

A look at the models: The global forecast system has maintained a low track further east than the remainder of the global computer guidance, as has its package of ensemble members. Should the GFS verify, we'd see a light 1 to 2 inch snowfall Saturday night. The European model began a push westward early in the week and was followed by the Canadian model, each bringing a stronger shot of precipitation - though recent trends in each have been a bit more easterly once again, with the latest 00z CMC providing little if any precipitation.

Now, the most aggressive model solution continues to be the NAM, which favors a deeper storm system closer to the coast. The NAM cranked out .5" of melted liquid equivalent precipitation in its 00z run, and now has .8" at Chatham in its 06z run. Either of those two situations would be a much snowier scenario here on the Cape. If you used a basic 10:1 snow ratio, that would be a 5 to 8 inch snowfall. The mean of the SREF ensembles, derived from the NAM, are less agressive, however, and only show a low probability of 4" or greater snows.

So anyway...for now, taking the consensus, the idea is for a quick hitting light snowfall Saturday night (2 to 3 inches?) into Sunday morning. But we have several more model cycles to go...

What's certain is whatever snow is on the ground Sunday morning will turn dry and powdery and will be whipped around in arctic cold Sunday night into Monday. Get ready for some VERY cold weather and strong winds.