Where Are We Heading?

We are not going to start this off with a look at where we have been because unless you been dwelling in a cave ..You know where we have been with the warmer then normal November pattern.

So we are going to take a look at where we expect the pattern to be headed and the reason WHY we expect the pattern to be headed the direction that it is..

We all have noticed that the operational models are bouncing back and forth between colder and warmer etc. And it can be quite frustrating if you are looking to the operational guidance to figure out what is going on..

First, whenever a pattern change is imminent this is usually what happens with operational models. So..when you see inconsistency in the operational runs…you turn to the ensemble means of those models.. So that is what we are going to do. We are going to take a look at the ensemble means of the GFS/ ECM/GGEM and see if they agree on the pattern we are heading into..

We are going to take a look at about a week from now.. (even though the pattern change has already started in the step down thought process)…

GGEM

So above is the 12 Z GGEM means & you can see they start at 156 hrs. and 240 hrs. is the last one I show. This is because this takes you ten days out which anything beyond that really becomes a crapshoot..

The light blue shaded colors is the start of below freezing weather at the 850 mb level and majority of the time you can count on that leading to colder temperatures at the surface. You want the levels above you cold.. in order for that air to be at the surface.

Ok, ok that is only one model so lets go look at the ECM..

Ok so now we look at the ECM ensemble means starting with 168 hrs. out and ending with 240 hours out and they look very similar to the GGEM ensemble means. So it looks like the GGEM/ECM means are in relatively good agreement.

Now this is pretty important for two reasons:

#1. The GGEM means are normally the warmest running model means.

#2 The ECM is the most accurate ensemble means because of its superior resolution.

So lets look at the GFS ensemble means..

Now we see the GFS means at 156 hrs. out and then 240 hours out! So now it appears that the GFS/GGEM/ECM ensemble means are all in agreement on a turn to a colder gradient pattern starting next week and lasting thru the next few days. Remember we are only going to 240 hours.

Now you may be asking what a gradient pattern looks like so this map below is going to show an example:

Now keep in mind that this gradient can be pushed north or south..this is JUST an example of what to expect…. If you are on the north side of the gradient you are looking at more cold and snow and if you are on the south side you are looking at milder temps with rain and if you are in between the two it is usually referred to the “Battle zone!”

Now..people all around the internet are confused about where this cold air is coming from when the AO looks like this:

Now this is from something Steve D (Pro Met)  wrote back in 2008-09 and is in reference to the EPO or the Eastern pacific Oscillation..

“

. When the EPO index falls into the negative, a trough is the result over the eastern United States”

Alright so lets look at the EPO …

Interesting the ECM ensembles and the GFS 18 Z are both indeed showing a negative EPO. So THIS is how you get cold air into the region without a negative NAO or – AO..

Now lets take this a step further and just show you the power of the negative EPO and there are some out there that do NOT understand this power and when I talk about Jan 1994 they say..

“but…but…the AO was negative and it aided the – EPO…”

Lets see if this is true…

Locate 1994 on the chart above and when you do you see that the answer is NOPE,,,we had a positive AO.

Now in case some do not remember what that looked like for Jan 1994…

That was with a SEVERELY positive NAO and a positive AO in combination with a negative EPO resulted in.

And that my friends is the power of a negative EPO!