The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or 
The 0z SUN ECMWF and 0z GGEM have a s/w digging into the 4-corners region on D7 which would only be allowed to lift northward to a point after coming out into the plains previous to getting forced eastward since the 50-50 low is present, and in near textbook position held in by the strong block.
Remember the position and intensity of the 50-50 low, PV and Positive height anomaly associated w/ a -NAO are what determine whether or not an east coast snow event would occur.
0z GGEM has a similar idea, and takes the NAO to the depths of the tank w/ strong 50/50 low ensuring that the northward progression of the s/w would be stopped and it would get forced westward abruptly.
there is a s/w on the tail of the system (which you can see coming into the PAC NW at 216 hrs) as it digs into the 4-corners region--a KICKER, so I doubt it would be able to cutoff. In other words the system has to come out.
Notice also the model is building a strong OMEGA ridge/block over Greenland w/ strong 50-50 low as the s/w is tilting negative and lifting Northward. In a sense this seems similar to what we will be going through this coming wee in the plains but w/ a twist, we wont have the 50-50 low or block in place for the event this week, for the system were discussing now, there WILL BE. Having it makes a world of difference.
A -NAO can come in three flavors WRT to the location of the Positive height anomaly at h500. It can be as far east as england, or as far west a QUEBEC and BI while still qualifying.
By D10 the GGEM phases the s/w w/ an appendage associated w/ the 50-50 low/vortex near NF. Not exactly sure I buy how it’s doing it, but we have several days to watch this.
My guess is that this would be a Miller B event w/ one center running into the OV or eastern low lakes and a center jumping to the MA coast. The where and the when details can be dealt with at a later time assuming this idea holds.
Im tripping the alarm folks. You’re officially forewarned!! LOL
BUT PLEASE DON’T ASK ME HOW MUCH FOR PHILLY. It’s impossible to tell anything specific from 10 days out other than to simply suggest the potential is there (which IT IS IMO). The synoptic pattern favors it; there is support from two very reliable models and now is a matter of watching and waiting.
Also a note about the pattern. The PV over SW Siberia moves eastward toward the Aleutian Islands where it becomes a new Aleutian low by 216 hrs. This could help to pump the PNA ridge and set-up a highly amplified pattern over NA to end the month and start DEC.
Furthermore, the GGEM suggests the block over Greenland will continue to retrograde westward over Labrador, the Davis Strait into QUEBEC/BI by D10.
Well 1963 looks pretty appetizing now? Huh?
