Pattern Changing or Pattern Delayed?

Lets look at the teleconnections to see if we can get an answer to the question of this post.

The above is the Current MJO phase which shows in phase 6. This makes sense with the weather pattern we are currently observing when you look at the 500 mb composite for phase 6..

Ideally for the Month of November you want to see the MJO reach into phases 1-2. Looking at the MJO forecasts:

The NCEP ensemble MJO shows just this happening. However..

The ECM MJO forecast shows that the latest MJO pulse is going to collapse into the COD or what we like to refer to as the circle of death.

If the MJO has legs and can make it into Phase 1 then the composite would look like this:

On this image you would see strong positive heights in SE Canada into Greenland and then back into Scandinavia..That would then to develop the –NAO.

And this is what is shown when it comes to the NAO

Now…another important aspect is the Arctic Oscillation and the guidance is divided on this issue..

The above is the ECM operational guidance and from the operational all systems are a go for the colder weather with the negative AO

On the other hand is the GFS..

So you can see the GFS is on opposite camps where it only takes it slightly negative before raising it highly positive. So we have divided camps..

So we turn to the ensembles for the AO..

GFS after a positive spike takes it negative and then spikes positive and then goes back essentially to neutral or either side of positive /negative..

ECM shows us in the ensemble means that we are mainly looking at slightly negative then around neutral.

So the ensemble means are closer in agreement then the operational runs are.

Now lets look at the AO from the ensemble means spread ..

Perhaps this explains why we are seeing the back and forth..roughly half of the members are keeping the AO positive, while the other half are tanking the AO. As we get closer to the 20th this should begin to iron itself out.

Finally we come to the real problem and that is the PNA.

The PNA is negative and strongly so. Now again however the guidance is not in agreement as the GFS starts to take this back up towards neutral at the end of its run..

So what does all this imply? With a negative NAO building and a negative AO building this is going to cause the air into Canada to become extremely cold and allow the snowpack in Canada to increase. THIS is what you WANT to see happen in order to see the winter in the Mid Atlantic into the Northeast be colder and snowier then normal. And you see this in the temperatures for ex: at 240 hrs. on the GFS

So the cold air builds across Canada and then with the NAO going negative and the AO going negative you will start to get some CROSS POLAR air and then this will start to discharge south into the USA. However, because of the PNA being so negative this discharge of cold air will head into the Western Part of the USA and slowly bleed to the south and to the east.

So essentially the Negative PNA is what is slowing things down and until that PNA breaks (the ridging in the north pacific) we will be in more of a step down kind of process with the pattern.