The overnight model runs are still in a big disagreement on the 19th storm. The GFS has made steps towards a very interesting solution while the European model continues to stay well offshore and the Canadian is throwing out another very interesting solution.
The new GFS places more emphasis on the 50/50 low and as a result slows down the pattern. Verbatim this is not far from a big snow storm in the Middle Atlantic and Northeast. The pattern slow sdown with a more amplified northern stream interacting with southern stream energy. Downstream heights are rising in response to the amplified pattern and favorable duration of gulf stream convection. Why this system does not form close to the coast on the model is beyond me but somehow the GFS keeps it out to sea!
Hard to see on the map above but I drew in where I would put that sfc low based off upper levels. It would be very close to the NC/VA border right offshore. The upper levels support it and the Gulf Stream supports it also. Another red flag here on this model is it is in a similar spot to the previous 12z run which is much faster with trough.
Comparing the GFS to the Euro the first thing that stands out is the lack of ridging in the Western US. This flat solution leads to a lead southern stream s/w rounding the northern stream increasing curvature and as a result a low over Middle Atlantic that pushes ne.
Way too warm for snow because this is a pure southern stream disturbance. The interaction seen on the GFS does not happen until hr 144 that is well to the NE:
This is a very bad run on the European and the ensembles disagree:
The CMC is not that different from the GFS aloft and shows a strengthening low that leads to a rain to significant snow for PHL on north. This model has been crazy the past few runs so not putting much thought into it right now.
Why the amplified solution?
The reason I am not liking a lot of these runs is the lack of ridging out west. My reasoning can be seen on current IR imagery and the signs of a MJO phase 1.
Phase 1 MJO is highlighted in certain areas of enhanced convection. The bonus part here which is kinda inhibiting a stronger signal (besides convection south of Sri Lanka) is the convection SW of HI which extends to the favorable phase 1 Mexico. The convection near the dateline here is going to pump up the heights along the western US. This would favor a setup closer to the GFS which could make things interesting if the model places the sfc features correctly.
Phase 1 MJO composite:
Notice the higher height anomalies over the Western US. This fits the overall tropical forcing perfectly.
Remember that Christmas gift that is in the wake of the December 19th storm...here is some eye candy from the European Ensembles!
The pattern is favorable through Christmas so this could be one of the few gifts we get!
The PNA is forecast to push up to near neutral briefly, before dropping back down to negative, so there won't be much ridging out west, but we can still get a coastal storm or two, they just won't originate in the deep south.