MODEL SCOREBOARD:

NAM- 3-6" band from MD into PHL SE into all of S Jersey into N DE

GFS- 3-6" for Northern VA-DC-SE PA-PHL-Trenton-Northern DE...Coastal areas and southern two thirds of DE have temp issues that will lower snowfall.

GGEM- 3-6" DC-PHL-Trenton on east.

UKMET- 3-6" makes it up to NYC and down through DC.  Shows closer to 6" for Philly on east.

EURO- 1-2" for many

Another discussion thread on 00z's

00z Model Thread

 NAM

The model is quicker with the kicker s/w and this prevents the main system from slowing down.  By not slowing down the NAM has a harder time getting things together and cuts back on convection across the Southeast.  Verbatim this upper level set up is not the real destroyer for a more significant snow in the area and slightly farther north.  It is the lack of convection that gets going across the Gulf Stream and Southeast.  So a slight tweak in this model brings back bigger numbers and slighlty farther north.

We can assume that this profile is similar for many in that heavier snow band.  The profile above shows 2 great things for snow lovers.  The sounding shows roughly 75mb thick dendritic snow growth zone coinciding with some instability.  This should lead to the potential for 1"hr rates in this heavier band.  This will help the stick factor.  

GFS

Dark blue is 3-4"....lighter blue is 4-5". 

The kicker s/w is not as amped. This does not impact our system for a little while longer giving it room to slow down.  This means a few things:

1) Slightly longer duration of the event

2) This leaves the door wide open for a trend higher in QPF and slightly higher qpf

The image above shows very strong diffluence right over MD into C PA. This is a great sign for favorable precip growth and intensity.  The GFS backs down from the 18z GFS, but it is a great step in the right direction if you want a bigger snow storm.  The first global model of the night is not impressed with kicker s/w which is a great thing!

GFS leaves the door open for surprise start:

The model does not show any precip or anything much for portions of SE PA into NJ.  As I mentioned above the upper levels are extremely favorable for precip growth into this region.  Also in this region is the potential for slantwise convection.  Weak conditional stability extends into the 650-500mb layer.  The strong mid level forcing extends into the area mentioned above with this slantwise instability possible.  The layer is saturated in addition with a reduction in absolute vorticity showing up in the model.   Slantwise convection takes longer to develop than upright convection, but the GFS leaves this door open for the onset of this event.  Something to watch closely.  

UKMET

Shows a nice hit in the previous frame for DC and Northern VA.  But this system really gets going as it departs and drops 10-15mm from SE PA/Much of NJ/LI.  That is a 0.40-0.60" approximate liquid equivalent.  The frame before gave a little bit more which could lead to a few amounts exceeding 6" across Philly on east.  

GGEM

EURO

Summary

The global models may have different solutions with the Euro not being impressive and the GFS/UKMET/GGEM all agreeing on a 3-6" event.  But more importantly is that all models slowed down this system tonight.  This is good for two reasons if you like snow:

1) It comes in later and possibly stays around longer during the nighttime hours.  This will allow more sticking and lessen the worries of a warm ground.

2) It gives the system more room to impress and come a little bit north.  As I pointed out on the GFS, there is room for this to increase qpf in a realistic manner.  The more time we allow this low to strengthen the more it can impress especially with the convection over the Southeast.  

A lot to look forward to in the 12z runs!