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 
5-10" (10" MAXIMUM...there will be no accumulations over that). Cape may NJ to Warrenton VA on the southern side...then Warrenton VA to Harrisburg PA (making up th western extent of the 5-10" area). the northern extent will be bounded by a line from harrisburg PA to Bridgeport CT.
Coastal sections are the MOST LIKELY TO SEE THE HIGHEST ACCUMULATIONS.
the system will not be strong or able to come up the coast because of the following things:
1) INTENSE (486DM) and strongly dislocated PV Near newfoundland. this causes the jet to strengthen underneath it which will not allow for the s/w to dig. IF the s/w was further north and closer to the PV it would simply be sheared apart.
We can pick this out VERY well on the 18z 1/12 run of the GFS valid 06z 1/15:
Notice the strong PV depressed across southeast canada with the lowest height center (486DM) centered near Newfoundland. this is an EXTREMELY displaced position for the PV speaking from a climatology standpoint. the s/w to the south of the PV is our system in question.
2) while the s/w should be far enough south to avoid getting ripped up by the strong jet...it still will not be able to dig and WILL NOT close off at H5.
3) this will be a VERY FAST moving system...and moisture starved at least initially. what QPF is cranked out is largely the result of the dynamics associated with the system as compared to significant amounts of moisture. this is common for clippers and other similar Arctic waves.
I DO NOT believe the set-up is correct for a major east coast snowstorm. but this is a relatively strong clipper and it will be able to throw back some atlantic moisture helping to increase QPFs as it bombs out off the east coast thurday.
Phasing between the s/w in question and another associted with the PV lobe digging into the great lakes region will occur offshore... and too late to make any kind of difference. also even as phasing takes place...the s/w will be drawn into the PV forming a HUGE ocean low.
78hr GFS (off the 18z run) Valid 00z 1/16:
the GFS is implying that the PV splits into two sections and takes on a dipole structure at 78hrs with one center just west of newfoundland and the other (developing in the western portion of the lobe) over maine. this will be accompanied by a shot of BRUTALLY COLD air into the northeast on FRI:
78hr GFS (off the 18z run --- 850 heights...temps and winds) Valid 00z 1/16:
the GFS at 78hrs has the -30C isotherm at 850 all the way down to the SOUTHERN NEW ENGLAND COAST !!!! meanwhile the other second section of the PV dipole is located over Maine!!
problems loom this weekend as well with regard to the STJ feature and why this COULD become a BIG TICKET ITEM for the northeast and mid-latlantic **** IF **** and thats a BIG BIG IF everything comes together correctly. it will largely depend on how much the PJ relaxes as the PV is getting out of SE canada and how quickly the STJ energy gets kicked out. IF the PJ relaxes enough to allow the s/w this weekend to dig and the STJ energy is kicked out AHEAD of the northern branch feature....you folks in the mid atlantic...and northeast...LOOK OUT.
the -SOI implies that the pattern should be more progressive by this time...which is why that energy cant stay back that far for too long. and if we assume that the EC the past few runs has been slipping into its usual funk (with regard to its handling of the STJ ---- one of its only major biases) things COULD be getting very interesting up and down theeast coast this weekend.
a one-two punch of wintery wx?? its possible. but lets take this one event at a time.
