All the internet & weather fanatics are watching the time frame essentially from December 5 thru about the 10th for the possibility of a winter storm.
For those that have been following my posts in my forum…which the link (banner) can be found on the right hand side of the blog…you may have noticed that I have been talking about the different model solutions and how from my perspective ..I simply can not just ignore the GFS model in the fact that it has been consistently not showing a storm for the December 5th-6th time frame.
Meanwhile.. the ECM up until tonight had been showing a system that would effect portions of the Mid Atlantic into portions of the NE with a snow event albeit light for the most part. While on some model runs it would also show a second storm system..much bigger and more potent effecting mainly the southern Mid Atlantic and deep south regions.
So recently ..the GFS was not showing a system on the 5th and it also was not showing a system in the aforementioned dates above for the latter part..occasionally a run would show a storm but just as soon as it did that ..6 hrs later ..poof gone.
A very challenging forecast lies ahead and I am going to attempt to explain the reasons why.
Lets look at the modeling tonight between the two main models..
First up is the GFS..or the American Model.
Now this is quite the change from earlier runs of the GFS. However, the reason that this happened on the GFS is because of what is happening at hour 180
So the GFS is initially weaker with the S/W that everyone was watching for the 5th to 6th time period..and the block is stronger. What happens is as the block lifts North..there is a Polar S/W that is diving into the trough…which causes the system to explode and under go rapid cyclogenesis.
This then creates so much blocking that the entire rest of the GFS run is extremely cold.
So lets look at the ECM and see what this model does..
After showing a system on its 12 Z run which delivered a snow event to parts of the Mid Atlantic into the NE..tonights run has a weaker S/W (trend towards the GFS) which just fades away by 144 hrs. However..it starts to build a storm in the SW around 156 hrs out . Massive blocking on the ECM..so much blocking that it actually tries to connect with the Ridging out west..
You can see the blocking above..that it appeared it may get cut off but by 174-180 hrs its starting to eject from the TX area . By 198 its south of Mobile, Lousianna ..however..before this point it had already closed off. Very close to phasing ..however..its not able to make the turn and heads off Hatteras and then ENE from there. This provides a snow storm across the deep south into the SE places like GA, Alabama, LA, TX etc
As you can see the two solutions are pretty similar in there depiction and the result of what is going to happen with this system is going to highly depend on the positioning of the blocking and the timing of the S/W’s involved.. If the block is not as strong then this system would be able to make the turn and if the GFS is correct (which keep in mind the ECM trended towards it with the Dec 5th now non event) ..and this storm undergoes Rapid Cyclogenesis…further NORTH..we could be indeed talking about a blockbuster event!
Stay tuned for further updates on this challenging time period!
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