We are going to start this off with taking a look at the first 8 days of January 2012. As you can see there has not been much change from November 11 and December 11. The region is still running above normal temperature wise. It is important to keep this in the back of your mind as we move forward in this update.
However..indications are that another shot of arctic air is going to make its way into the region. Models agree on this…lets look..
So yes without a doubt the guidance is suggesting that another shot of arctic air is going to invade the region. However..the question becomes whether or not this arctic air is going to be sustained…or if it is going to continue to be a transient pattern where shots of colder air come into the region followed by warmer air or moderation?
So the first thing that we are going to look at is the Madden Julian Oscillation to get the background of what is happening..
What we are looking at now is the GFS ensemble means MJO and the ECM MJO. And as you can tell the GFS takes the MJO into phase 7 and 8… this would be an excellent pattern for snow and cold lovers in the east..
You can see both of these translate into a colder pattern in the east with a trough to the east and a ridge to the west which would give plenty of opportunity for snowfall across the east.
However..on the other side of the spectrum is the ECM which keeps the MJO in the Circle of Death and then brings it out into phases 3-5.
As you can see these would not be favorable phases for the east coast and would indicate warmer then normal anomalies.
So what we have here is a classic model battle when looking at the Madden Julian Oscillation. So now we will look at the teleconnections from the GFS and the ECM to see what we can glimmer from them..
Now as we look at the above we see that the GFS is showing :
1. A positive WPO turning strongly negative (keep this in mind)
2. A strongly negative Arctic Oscillation (supporting cold pattern)
3. Positive EPO to negative to Positive (supporting warm to cold to warm)
4. Positive NAO to negative back to positive…(supporting warm to cold to milder)
5. A PNA that is mainly positive (trough in the east) but at times negative (ridge in east or more zonal flow)
Now lets look at the ECM teleconnections:
Well from looking at the above teleconnections on the ECM @ 12 Z we see the following:
1. NAO ..mainly positive with brief – east based NAO
2. AO is mainly positive with a brief flirt in the negative territory..
3. EPO going from positive to negative but mainly negative..
4. PNA going from positive to negative and quite strong negative
5. WPO going from positive to off the charts negative!
So as you can see the teleconnections differ as well on the guidance and I think that can be contributed to the evolution on the Madden Julian Oscillation chart above. Now lets go back to that:
Look at the one that is for the GFES and notice the green line. That is the NVEP GFS ..do you see how it showed it going into the COD and then kind of making a due north turn and heading into phase 7? Now look at the red line and look for the #8..that is where the MJO is as of Jan 8th and you notice two things:
A. Its on the INSIDE of the circle not like on the outside as the GFES means shows and:
B. It never made that due N turn into phase 7 so the NCEP GFES is already in error with the MJO.
Now…lets go back to the guidance and see what is happening on the ECM as of 12 Z..
Now this here is the ECM 850 mb anomaly temperature departures and as you can see they are indicating warmer departures moving into the central part of the USA and heading towards the east…
This here is a look at HPC and the positive departures for day 6 and day 7. Looks quite familiar to the ECM up above one could say…
So..in summary so far we have a classic model battle between the GFS & the ECM…Remember the beginning of this update the departure map for the first 7 days of January? Remember how it has been warmer then normal…Well..if one were to follow and believe the GFS we should have been colder then normal… but the reality is we have been warmer then normal.
So why the difference between the models? DT talked about what could go wrong in a post a few days ago and the next two images are from wxrisk.com Dave Tolleris..
Remember above both the ECM and GFS are showing a fairly strong – WPO but the ECM is the strongest by far.. this is what this would look like:
And you can see this “gradient” pattern setting up on the ECM today at 12 Z
Notice the ECM has +12C 850 temps in Kansas with -24C temps at 850 touching the border of the US at 192 hours? This is what you call a gradient pattern. It represents a difference in thermal or temperature profile over a short distance..
If the ECM has the correct idea then we will look like this:
This would be due to the – WPO which both the ECM and GFS are showing. IF IF the NAO goes negative like the GFS is suggesting and the AO then the colder air would be more along the east coast..
If the ECM ideal is correct with a strong negative PNA and – WPO and positive AO and mainly positive NAO then the above image would be how things would play out.
So in summary ..we here at Real Wx Services do not like the GFS and how it tanks the AO and the NAO. We feel the ECM has a better grip on the weather pattern…
One fly in the ointment is the stratospheric warming. If this begins to down well and we can obtain blocking over the Davis straights then this to would cause the above to end up falling by the wayside…
However..all a strat warming down welling implies is that the NAO would go negative and the AO would go negative –it does not guarantee colder air into the east but somewhere in the USA. If the EPO is negative and the WPO is negative as strongly as suggested this could still cause the above image (WPO classic pattern) to occur…
So we are anticipating arctic air to invade the region in about 3-5 days ..but we are anticipating it to be transient in nature with the potential of warming up (moderation in temps) again before cooling down.
Latest ECM weeklies which have been verifying well also support this discussion…
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