Real Wx Services is continuing to carry the level 1 Alert to be on guard for the potential of a significant East Coast storm in the time frame of the 19th to the 21st of December.
Models continue to converge on a solution with the GGEM being the furthest to the east and considered an outlier. GFS model over the past 8 runs has shown a major east coast snowstorm 5 times.
The ECM while still missing the northern areas of the mid atlantic has actually come back some to the SW from its 00z run last night.
The UKMET is still showing a coastal solution which retrogrades into the Northeast essentially. For the purpose of this discussion we are going to look at the time frame of 120 hrs with the exception of showing the 18 Z GFS @ 114 which equates to the same time frame.
As you can see the 18 Z GFS is the furthest to the west with the ECM the furthest to the east and the UKMET in the middle of the solution spectrum.
What becomes interesting however is when one looks at the 12 Z ECM ensemble means and compares it to the 18 Z 114 hr GFS image.
GFS is still slightly west of the ECM at that position but not by all that much and its interesting that the ECM ensemble means are actually more west or south west and closer to the coast then the ECM operational.
As we mentioned in previous updates we have a negative NAO and a negative AO and Greenland blocking with it retrograding. The question really comes down to does the energies involved in this system phase & if so what actually phases & when? Is it the Polar Vortex that will drop down into the backside of the trough and phase this causing it to go negative tilt or is it a S/W that comes thru Montana that drops into the backside of the trough that causes it to go negative tilt?
If there is no phase then of course we will have a S/W coming out of the Southwest that would slide off the Southeast coast and pass harmlessly out to sea.
Even though we lack the positive PNA the –NAO and the –AO would argue for a deeper trough along the east coast despite that PNA lacking. In addition almost every piece of guidance is indicating the trough going negative tilt and this usually would indicate a stronger low closer to the coast.
With the GFS being the most consistent model run to run and the GFS means coming west (exception 18 Z was SOUTH AND EAST) and the GGEM being an outlier to its ensembles and the ECM operational trending more west..and the means arguably supportive of an east coast snowfall.. At this point and time more consideration is being given towards a UKMET/GFS /ECM ensemble blend.
The outcome of this will be dependent on whether this phases or not and how it phases. The ECM phases in the operational but a dollar to late…The GFS is a partial phase but it phases and amplifies via that S/W coming thru Montana instead of the Polar Vortex.
So while there are still questions to be answered and might take till 48 hrs and under for the answer…we have made two different images or maps.
First image is a storm tracking scenario showing two tracks. One favorable for areas further north and one not favorable.
In the second image which will be below..it is a impact scenario map based on track # 1 in the image above.
If track # 2 begins to become the more likely of the tracks then the area in white would be the area that is impacted the most from this system.
So questions still need to be answered but that is where we see things standing at this point and time.
Stay tuned for further updates!
No comments:
Post a Comment