Early Season Snow Setting Up for Parts of Region.

It's hard to believe that we were basking in the 70's just a few days ago with the pattern that has taken shape since and certainly with what we've got coming our way later this week.

Now our focus shifts ahead towards a rather complex scenario shaping up for the end of the workweek with a storm that is expected to develop across the Ohio River Valley before tracking quickly northeast.

Phasing Jet Streams

What makes this scenario especially difficult to forecast is because it involves "phasing" between the two branches of the jet stream.

We are tracking a pair of upper level systems, one across Western Canada and the other over the Baja of California. These two disturbances located in those fast moving winds aloft are expected to merge together late Thursday and into Friday over the Northeast.

The exact timing and placement of these two upper features will have a huge impact on what happens at the surface. With that being said, most models now agree on a general theme, see Euro below for reference, one that will track and then deepen a surface low pressure system from somewhere near the ohio River Valley before transistioning to a coastal storm on Friday.

Critical Temperatures

As is so often the case with early season snow storms, both surface temperatures and road temperatures will have a significant impact on how much accumulating actually occurs.

Current data suggests, GFS for reference below, shows temps falling below freezing by early evening on Thursday for Rochster and the Finger Lakes, and data supports temps will only plummet from there Thursday night well down into the 20's. This, of course, is plenty cold to support accumulations even on roads if precip is heavy enough.

How much snow?

With us being about 72 hours out, it is still a little too early to start throwing out snowfall projections. However, to give you an idea of the spread, I'm sharing the latest Euro (12z) and Nam (18z) below.

So what do I think?

Obviously, there are some BIG differences here. While I would favor the Euro in it's ability at this range over the NAM, many of the models, including the Euro have been trending north with the track of this storm increasing the odds of some accumulations for Western New York. However, the main action should remain on the backside of the Coastal Low as it forms into an early season Nor'easter with the potential for very heavy snowfall into Eastern New York and Northern New England.