As per usual there is a lot of confusion, excitement, anticipation, even hype perhaps about the potential snowstorm next week along the East Coast.

The uncertainty will remain up until Monday of next week AFTER the system and it’s energy crosses the Rockies and Plains, a key area in which we’ll be able to gage both how the system is developing, how far south and how the trough is reacting out ahead.

Let me breakdown key aspects which will make or break this.

Despite Blocking, There Is Enough Movement!

I made mention of this yesterday. Despite all the blocking between Nunuvut (btw, the low here this morning of -61F was coldest since March 95′) and Greenland, there is still movement in the flow underneath (very important), in other words the trough that’s deepening and diving down the East Coast right now, will not anchor. The block does’nt extend far enough south in the Atlantic to hold this but more slows it’s eastward progression as well as the system crossing the Lower 48 through the weekend.

The ‘slowing’ down of the upper disturbance is in many ways crucial and it will allow the eastern trough to move and weaken east which could open the door for a northward lift in energy rather than diving straight into the Carolinas and out to sea. The slowdown also would allow for ‘cylogenesis’ along the coast. Where that would occur exactly would also be key as to impacts onshore.

Current Northeast System An Important Player

Now, let’s not also forget the importance of the storm that’s currently still over New England. (Also: did you see snow rates Thursday night over Maine? Caribou picked up 3-6″ in 2 hours). It is this storm, seen by the ECMWF to EXIT and slide far enough east, quick enough.. that colder, drier air feeds south into the Northeast. A surface high would build and thus set the stage for the eastward sliding system.

Here’s the latest GFS 500mb charts. This chart is good because at 500mb, this shows you where the energy is in the upper levels and how it’s moving.

The GFS btw is less reliable, kicks the energy east too fast. The ECMWF is almost always the superior model and even with this, it’s looking more likely.

Anyway, here is the situation at 24 hours according to the GFS.

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48 hrs

 

Notice GFS kicking east the trough as well as the system over New England, this would bode well for a Mid-Atlantic snowstorm as all this is seen to be getting out of the way but slowing the system back over the PNW down.

90 hrs

By 90 it’s crossing the Plains, this will bring a decent snowstorm to the Northern Plains btw!

114 hrs

By 114 it is a strong system cutting SE, but with the GFS model, I think it has the trough too strong and so it’s taking the system too far south and therefore would exit out to sea, not hook.

How about the ECMWF?

114 hrs

Notice the ECMWF has the ebrgy both further north and spread out, this further north track means it’s closer to the connection with the cold coming into the Northeast from Canada and also can ‘bundle’ more once it reaches the coast.

Below is the 144 hr and you can see the ‘bombing’ out off the Virginia Capes. Also note the feed of upper energy coming down from Canada. That’s your cold air diving south and with the bombing out off the coast, the moisture will get driven back onshore and into that cold air.

Position of the low also would mean the Mid-Atlantic gets hammered, perhaps shutdown with a foot of snow across the Richmond-DC-Baltimore corridor, perhaps 2-3ft in the West Virginia mountains. Snow would also hit the Philly to Boston corridor too but the focus would be on the snow starved Mid-Atlantic.

More tomorrow on the weekend cold for South and Florida!

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