Long Range Thoughts

Lets take a look at where we have been so far for the month of March

For the most part the month of March has been seasonal to above normal in the Northeast with the exception of SW PA and SE NJ and then the southeast. 

Now this is important as we try and figure out where we are headed for the future weather wise. If you look at the above chart you will see that the AO has been negative and still is negative but as the temperature departure map shows we have still been seasonal to above seasonal values. Normally when you have a - AO this allows a discharge of colder air into the USA but as we have pointed out in times past you can not figure out WHERE this discharge of cold air will end up just by looking at the AO. You have to look at other teleconnections..

The NAO was negative but recently has risen to the neutral value but it is shown to go back negative before once again rising towards neutral or positive. So you can see why the temperatures in the southeast were below normal due to the NAO being negative it allowed the discharge of colder air into the southeast. 

Factor in the PNA and you can see that it was quite positive ..so the - AO - NAO and positive PNA allowed the colder air to discharge into the southeast part of the USA. 
However, and this is important you notice that the PNA has since gone negative.. so when the PNA declined ..and the NAO rose to neutral ..despite the AO remaining negative ..temperatures were well above normal.. and you can see this in the last 7 day departures..

There is still one more teleconnection we have to look at and that is the MJO

You can see the the MJO was in phase 7 and if you look below you can also see why the southeast was cooler 

However now the MJO is back into phase 6 and this shows you once again why the temperatures have become warmer. 
So when we go back and look at the teleconnections they pretty much show why what has occurred has occurred. Now when we look into the future we see the NAO going negative , the AO going extremely negative (both these signals indicate a discharge of colder air into the USA but remember now we are in the month of March and the averages are now higher then they were in say December and Jan ) but we still need to go back and look at the PNA and this is expected for the time being to stay negative and actually get more negative. So what this implies is that the discharge of colder air will be more central and west based then east based as long as the MJO is in phase 6. 
Forecasts are showing the MJO to go thru phase 7 again so when this occurs temperatures once again would become colder then normal with the other teleconnections already in place..but as long as the PNA remains negative the brunt of the coldest would be central and west based. If the PNA were to go positive with the AO so negative and the NAO going negative this would once again put a trough over the eastern part of the country.
Keep in mind that colder then normal does not necessarily mean temperatures supportive of snowfall if and when the PNA goes positive.  Normal high temperature at ABE for example is 48 degrees...all it would imply is temperatures below normal which could mean the upper 30s or lower and mid 40s.
Also keep in mind that when the MJO is in phase 6 this also involves the southeast ridge and gives a much more likely hood of storms cutting to the west of the region which is what we see on the model guidance for around the 18th to the 20th. When a storm system cuts west of the region it allows for warm air advections and mid levels to warm and while it may initially start off as frozen likely hood with a western track is for the system to change over to a cold rainfall.