Pattern Update First Week Of December...

We want to start this off by showing the EPO. There is no question that the EPO is negative and there is no question that the negative EPO has been responsible for the colder outlook on November. However..we have to duly note that while the EPO is negative ... this first week of December starting with today is going to average above normal temperature wise.. You can see this clearly when you look at Day 3 high temperatures along the east coast...

Temperatures into the 50s to near 60. As of writing this it is presently 52 degrees @ ABE ..53 @ PHL and 54 in Baltimore MD and 53 in NYC..  The point is that we still have the negative EPO in place but we are also going to be experiencing warmer then normal air temperatures. So this tells us that the negative EPO alone is not driving the weather pattern. 
Another certainty we know is that we are not getting any help from the Madden Julian Oscillation or the MJO..

We are presently in the COD or the Circle of death where the MJO has little influence on the weather pattern.
What we do see is that the ECM wants to bring the MJO out into phase 3.. and then phase 4 

Which would indicate a turn to milder weather in the longer range (talking around mid month)

Phase 3 and phase 4 are warmer phases of the MJO. However..we also know that these forecasts are not all that reliable either ..despite the ECM being one of the better performing weather models. However..it is what the model shows.

Even the GFS shows the MJO wanting to come out in phase 3.  So if this were to occur we would be looking at milder weather across the conus.
Still yet another certainty we know is that the PNA (refer to image at top) or image below is quite negative and forecasted to remain quite negative.

A negative PNA indicates two things. 

1. A negative PNA indicates a Southeast Ridge. And now we see the answer for the milder weather the next few days despite the - EPO.
This is shown quite well on the 12 Z ECM

2 . A negative PNA indicates troughing into the central and western part of the country. Again you can see this quite well on the ECM @ day 5.

You see in that image the Southeast ridge in place and you also see the troughing into the central and western US. 
AS LONG AS THE PNA IS NEGATIVE =A SOUTHEAST RIDGE over all will be involved. 

So essentially what you have is a battle between the - EPO which puts ridging into the Aleutian region and the - PNA which indicates a Southeast ridge.  
So what does that leave us with on the east coast? It really depends on what teleconnection is more dominant at the time (since right now there is no help from the MJO) ... It means we are going to have times of warmer weather and times of colder weather ..which is the reason why we have gone with essentially average temperatures for the winter. It sets up a gradient pattern and depending on what side of the gradient pattern one ends up on will determine what precipitation type one deals with in sensible weather.
Also with a Southeast ridge in place you run the risk of storm systems cutting to our west... we see this on the 12 Z ECM...

Just looking at that image we see the troughing into the central US and the west with the ridging into the east which is forcing the storm system to track to our west which leads to a event starting as frozen in PA but turning over to rain as the mid levels and upper levels warm up.

What about the AO and NAO? 

We know these images change with every 00z model run but presently the AO is positive ..however forecasted to go to neutral and then members become divided with some taking it negative and some taking it positive..

NAO is shown positive right now but expected to turn negative (east based) .. we really want a west based negative NAO to deliver the snow that so many people are looking for. 

So basically we can expect times of warmer weather (-PNA southeast ridge) and times of colder weather (when the negative EPO allows the colder air to bleed into the east ..aka behind cold fronts etc) .. Storms potentially tracking to the west of the region (aka Southeast ridge) starting as frozen but changing to rain ... with temperatures ending up average when all is  said and done. 

Now..there is a question mark to mid month because the ECM ensembles are showing the - EPO breaking down and switching to positive (and you can kind of see this happening in the first image where it is rising from its extremely negative state) and a GOA low taking shape. If this happens then with the - PNA being so negative it would flood the country with mild air from the PAC..

So essentially it is a wait and see to see how things shape up come mid month.