Well folks we have been talking about this upcoming event a little more then a week now and we have taken some hard criticism in the world of weather around the internet from those who simply refused to look at and understand the guidance. The sad part about it is that some of this criticism came from those who are Pro Mets.
So lets get right down to it shall we? We are going to take a look at the guidance operational and the guidance ensembles…This is being written before the 18 Z GFS arrives so that will not be included in this update .
Lets look at the teleconnections first .
The above teleconnections are the AO/NAO/PNA. As the charts show the AO is on the downward trend..the NAO is also on the downward trend and the PNA is on the rising trend. When ever you see this combination it becomes supportive of a East Coast Storm.
The Arctic Oscillation going on the downslope is suggestive of colder air pulling into the system.
The rising PNA is suggestive of a trough along the east coast and a ridge out west.
The NAO declining is also supportive of a trough with colder weather in the east.
Factor into this the EPO or Eastern pacific Oscillation ..
And you have teleconnections that are very supportive of a developing storm system and a mechanism of release for colder air into the central and eastern part of the Conus.
So we see that the teleconnections are supportive of a storm but what about the guidance.
The GFS started showing this storm system several days out as being a potential threat for rain changing to snow but then yesterday at 00z the model actually was the model to show the system going south and east. Today at 12 Z the model has started coming back to the NW ..actually this trend started just 6 hrs. after the 00z run with the 6 Z run.
So you can see here that we really are not looking at anything all that impressive on the 12 Z GFS. However..if you turn to the ensemble means you are looking at a totally different story..
The next model we want to look at is the 12 Z NAM. This model quite shockingly has actually been pretty consistent and this is what it looked like at 12 Z
Here on the NAM we are looking at a solution very similar to the GFS ensemble means from 12 Z which means that this can simply not be discarded..
To furthermore show the consistency of the NAM is the 18 Z which shows the following:
There is no question that the NAM is consistent and showing a fairly intense system across the area which is very similar to majority of the 12 Z GFS members of the ensemble means.
Next up is the GGEM..Now with the GGEM it is important to keep in mind that prior to today at 12 Z the model was never even showing the storm system…
So this is a big improvement for the model in general and it is still catching up to the rest of the guidance.
Next is the UKMET which last night was the precursor to showing that the ECM was going to finally begin to get a better grasp on this system and it showed a low pressure system going off the coast around Ocean City Md and then moving up and along the coast and the 12 Z keeps that same theme going..
Now last but not least is the ECM or the European Computer Model guidance.
As stated above the ECM has been having a difficult time with this storm system and finally as of last night it started to come around to showing a solution very similar to ALL the old GFS runs prior to the 00z GFS last night and here is what we see at 12 Z today..
And then the ECM ensemble means for 72 hours which is further NW then the operational which is not a surprise with all the above already mentioned..
So there is no denying that the guidance and the ensemble means are beginning to converge onto a solution of a storm moving up along the eastern Seaboard.
The teleconnections support it..the guidance shows it.
Putting this all together as far as what we are expecting with looking over the data and the guidance above.
We are anticipating a cold front to move thru the area around 7 AM or 12 Z Wednesday morning. This is going to set up the stage for a wave of low pressure to develop along the front and move to a position near or along the coast of Cape Hatteras.
This low pressure will take on a negative tilt and begin to move up the eastern Seaboard. We are anticipating a storm to be about 5-75 miles off the coast.
With the + AMO that is in place and the warmer then normal waters this storm should follow along the western side of the warm gulf stream. What this means is that this storm has the “potential” to deepen pretty decently from around 1008 mbs to about 990-996 mbs as it moves NE along the coast.
The cold air behind the cold front will be moving into the region as the storm starts to move towards the region. All areas will begin as rain..very similar to the October 29th storm and then transition to a wet snow. especially inland. Along the coast it may take some time for the air to cool off more but even these areas we anticipate will change over to snow with the potential of 1-3 inches.
The map below is actually based on a blend of the NAM/GFS/ECM/UKMET. We have taken into consideration that the ECM tends to be a little to warm at the surface along with the UKMET and are using more of a GFS/NAM blend with the temperatures.
If you are along the coast ..there is the potential that this may end up being to low if the cold air moves in quicker then anticipated.
If some of the latest runs end up coming to fruition such as the 18 Z NAM these totals will be too low. So this is something to keep an eye on.
Another concern is because the snow will be wet..even though there is less leaves on the trees we could be looking at tree branches down. This again will be something we have to keep an eye on!
Stay tuned for more information thru the next 48 hrs.!
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