We have made some changes to the map that we had issued earlier in reference to this system. Before we get to the details of the map we want show what the guidance is actually showing..
Pretty much since the beginning of tracking this storm system we have been using the following model as the tool to compare the rest of the guidance to.
For those that do not understand this tool it is pretty simple. This model, the NOGAPS is the most progressive model..so if you see this model closer to the coast and the rest of the guidance is to the east of it..this means the rest of the guidance is to far east! Why? The answer is relatively simple as well..because a more progressive biased model should be WELL off the coast.. So that will be the first model that we look at..
As you can see this is clearly just right off the east coast and the message it delivers is that after starting off as rain the 850s crash and the surface temps lower and the precipitation changes to snow in interior locations .
This model from the start has ALWAYS been more west then the rest of the guidance so this was a sign to Real Wx Services that this was going to become a pretty amped up storm system.
Now lets look at the rest of the guidance and we will see that they have indeed come more west. At one point and time the GFS was showing the possibility of snow in the I 95 region but as you will see it has corrected its ways..
As the images above show the storm is indeed further NW and more amplified.
GGEM is also showing the same type of scenario though this model does have a warm bias and is probably one of the reasons that the 850 line is further to the west compared to the rest of the guidance. However the moral of the story is the same as the rest of the guidance in showing an impressive storm system.
You can see on the UKMET above that the same story exists on this model and it too is showing an impressive storm along the eastern seaboard and west.
The only model that is left to show is the ECM and even though the model is initially warm and it has itself come further west (again no surprise) it crashes the 850s and the surface temps become supportive of an interior snow event..
So what do these models all have in common?
1. They have all trended west. It became clear yesterday that with this system there was going to be no east trend. This time period we are in is different from last year where we seen this happen. At the present time we do not have any blocking occurring so there is essentially nothing to slow this system down.
2. They are all suggesting that we would have an interior coast snow storm after some initial rainfall..
So what exactly are we thinking with the updated thoughts?
The cold front still looks like it is scheduled to come thru the region around 12 Z or 7 AM Wednesday morning. This cold front looks to stall just off the coast.. Low pressure will develop along this front around the time of the passage of the cold front and then this low pressure will move ENE to a position over East Central VA by 7 PM Wednesday. And then will continue to move ENE off the coast around the Chesapeake Bay area to the Delmarva intensifying as it moves NE to a position along the east coast of Maine by 12 Z Thursday!.
Rainfall will move into the region first. Once the cold front passes the upper levels will begin to fall and as the precipitation falls which will be heavy at times this will begin to pull the colder air from above down to the surface. Rain will change to snow and we expect that to be later in the evening Wednesday after 10 PM across the eastern region of PA. The snow may fall heavy at times once the change over occurs because all the guidance is indicating deformation banding setting up across the region.
So with that in mind here is the updated map for this storm system..
As far as the I-95 region we do still anticipate that they have the potential to end as some light snow but because of the further west track the potential is not as great as it was 24 hrs. ago so there is lower totals then the previous map.
We still urge caution for the locations that do switch over to snow as it will be a heavy wet snow. This could cause tree branches to come down across those regions…
Stay tuned for more information should it become necessary!
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