After a good night’s sleep we can briefly review he overnight models and see where we stand with regard to the coastal event for November 27 – 28.
First stop is the 0z GFS. The 0z GFS continues to show a very wet system developing for much of the Deep south which reaches as far north as Washington, DC with the northern edge of the precipitation shield. But the model only takes the Low half way up the coast and slides the LOW off the Carolina Coast passing east of Cape Hatteras. When this sort of track actually occurs ….it’s never very good sign with respect to getting heavy precipitation into the big cities the northeast. The problem is of course that the GFS loves to do this with East Coast winter storms and many times it turns out to be completely wrong. This image shows the 0Z Thursday run of the GFS … and of course it is taking the system off the North Carolina Coast after bringing a very heavy rains too much of the Tennessee Valley and the southeastern states as well as Virginia and southern WVA.
If we take the model verbatim… there would be no reason to forecast any significant precipitation north of the MD /P A State line so areas such as Philly NJ NYC and New England would be dry. There could be significant snows over eastern KY the southern and eastern portions WVA the Blue ridge mountains & the Shenandoah Valley in western VA /sw VA and maybe into nw NC mtns.
This next image shows the low level cold air getting into the system on Thanksgiving morning which changes the rain over snow even into Central Virginia and eastern MD.
The 6Z GFS continues this trend without showing much of a change. As we can see here the 6z GFS continues to take this system off the Carolina Coast after dropping widespread heavy rains over much of the Deep south the TN Valley and into portions of VA …southern MD & DEL. On this image the thick blue line is the rain snow line. Notice here the even though the system stays to the south the leading edge of the cold air (thick blue line ) does NOT get past the I-95 corridor. The reason for this Hass to do with the upper air pattern which remains hostile for a East Coast snowstorm event.
This is why having a -NAO is important. This is why having a -AO is important. This is why having the cold air in place before the event begins is important. This is why having a 50/50 Low over southeastern Canada is important. It is these features which allow the cold air to get into the storm so that the precipitation falls as snow . And in this particular instance we don’t have any of that.
Interestingly the Canadian model agrees the GFS. This image shows the Canadian model which is slower than the European and closely matches the 0z and 6z GFS… with the Low over the eastern Carolinas and the closed UPPER Low over GA 7:00 PM on November 27. By Thursday morning the LOW is off the coast NC headed out to sea but we can clearly see that the cold air has rushed intoall of VA — even the coastal areas and this strongly implies the rain going over snow for several hours over portions of central VA and central MD. On the other hand this also would imply a Significant snowstorm for portions of Eastern Kentucky and Tennessee over the higher terrain as well as much of western and southwestern VA and eastern WVA.
Let’s take a look at the 0z Thurs European model (ECWMF). This image gives us the large scale view of the European. The map on the left hand side is valid for 7:00 PM Tuesday evening which is a bit faster than the other models. We can see the developing area of low pressure over central GA and the Arctic front racing the southward across the Great Lakes into the Ohio Valley and western New England. The map on the right hand side is for 7:00 PM Wednesday evening . The European model says the entire event is over and done with by that time and the arctic air is racing southward . The rain goes over snow fairly quickly the mountains of WVA western MD & western VA were several inches could accumulate and this continues up into much of central and eastern PA and NY State as well as the interior portions of New England.
Behind the Low the European model is showing that the heart of this Arctic air mass moves into the Northeastern U.S. on thanksgiving night with howling North winds and bitter cold temperatures. Right now the other models are not showing this sort of cold air invasion.
The 0z THURS EURO ENSEMBLE – clearly supports the operational run. It shows the area of low pressure Wednesday evening 7:00 PM over GA extending from AL GA FL SC all the way into New England and Maine along the old station are cold front . The model clearly shows the rain going over to snow in the mountains of eastern WVA far western VA central PA western & central MD eastern NY states and the western half of New England. In these areas the European ENSEMBLE implies at least a few inches of snow accumulating Wednesday afternoon and evening. The rain ends as snow over eastern KY western NC AND over central VA Eastern Maryland including Washington, DC and Baltimore as well as Philly NJ NYC and Eastern New England.
Finally if we take a look at the British model which only goes out to 6 days…. We can see that the model clearly shows a developing coastal low over GA / FL panhandle and the arctic front driving through the Great Lakes into the Ohio Valley. Clearly the southern LOW is going to come up the coast to some degree but how far north we cannot tell on this run iof the BR Model.
SUMMARY I reject the southern Low track/ scenario of the 0z and 6Z GFS that keeps most the precipitation out of the big cities in the northeast. Even if we were to accept the GFS scenario this would strongly implies significant snowstorm for the mountains of the Middle Atlantic states and rain for the Piedmont and the coastal areas. And this rain could end as snow as both the GFS and CMC models strongly support this idea.
However I think the European and the European ensemble is far more likely to be correct. I think the rain will break north eastward up the front pretty quickly laid on Tuesday and Tuesday night. And the arctic cold front will drive south and east. This looks a lot to me like a major Appalachian snowstorm from Western North Carolina all we into the western portions of New England. And it does look to be like the rain will and as snow for least a few hours over central portions of Northern North Carolina Virginia including Richmond Fredericksburg and Lynchburg the Washington, DC Baltimore area and even into Philly Northern NJ and NYC.
If one chooses to run with the European then we have to consider that the Thursday morning Thanksgiving will be an extremely cold morning with snow on the ground ove the mountains / interior and strong North winds coming straight out of Eastern Canada. Thanksgiving would be a brutally cold a and Friday morning could be extremely cold for all those twisted pervert black Friday shopping freaks.