BLOG SONG: "Uptown Funk" by Mark Ronson ft. Bruno Mars
INTRODUCTION:
ANALYSIS:
12z EURO OPERATIONAL:
Believe it or not, the weak storm system we are expected to get rain from on Saturday plays a role in how the larger storm comes together Tuesday of next week. If the Saturday storm intensifies off our coast, it will buckle the flow a bit and help slow everything down. Since we are currently in a progressive pattern, this would actually be a big factor in the evolution of the storm next week. If you take a look at the GFS H5 maps (not pictured), you will notice it has Saturday's storm much weaker and exiting off the coast much faster than the EURO and CMC.
Notice the ridge spike in the western U.S. (+PNA) with a northern stream s/w diving down along its eastern flank. Thanks to the Saturday storm acting as a traffic block, the northern stream is able to catch up with the southern s/w and develop a potent storm.
Fast forward to Tuesday afternoon on the EURO and you can see H5 has closed off over the northeast and a sub 990 mb storm is currently bringing rain, snow, and wind to the area. Notice the leftover strong northern stream energy over North Carolina that escapes out to sea and avoids a phase with the main vort. If there is better consolidation with those pieces of energy off the coast there would be an even deeper storm, possibly sub 980 mb (this has been shown by the CMC), which would bring even more dynamics into this system and change the coast over to snow a lot quicker. 850 mb temps. would come crashing down off the coast in a hurry.
This graphic confirms the +PNA spike in the Dec. 7th-10th time period which would help consolidate the H5 energy and amplify a strong storm off the east coast.
12z EURO ENSEMBLES:
The EURO ENS this afternoon showed a very impressive storm off the coast of NJ that would result in rain with a possible change to snow along the immediate coast, with significant snow accumulations for the interior. For the ensemble mean to be showing a strong signal is a good indicator that this storm has a good chance of happening rather than going out to sea. You can see the negative tilt in the closed off upper level trough.
Another player that is going to be key in the eventual track of this storm is where a High Pressure system sets up. The EURO believes a strong 1040 mb HP will set-up just north of Maine and slide east-northeast into eastern Canada to act as a mechanism to keep the storm closer to the coast. A deepening storm off the coast combined with an HP located to the north could bring storm winds to the area. That also has to be watched.
Notice the other piece of energy southeast of the Hudson Bay. That will also phase into the storm system to deepen it even more, which means there could be larger effects for folks up in northern New England (VT-NH-MA-ME).
The latest 00z GFS is completely opposite of the foreign models. It jets the Saturday storm out of the area, so the flow remains fast, which allows the southern s/w to escape off the coast and remain un-phased with the northern s/w. It also does not amplify the ridge as much as the foreign models do. As of now, this model is an outlier and I am leaning against it. With the way a HP is positioned to the north and blocking taking shape to our west and south-central Canada, I would expect the northern stream to dig rather than just hang out in Canada.
Scenario #1 would be a strong coastal low bringing high impacts to the area. The immediate coast would start as rain and the timing of when the cold air comes in, if it does at all, depends on when they change to snow. The timing of the phase will be key for the immediate coast, as a storm that undergoes bombogenesis faster will allow the layers to cool and for cold air to be pulled south and east. Areas NW of I-95 are also likely to start as rain, but should have a good chance of changing to snow obviously faster than the immediate coast. Inland areas would be cold enough to support mainly snow. Of course there are other factors, such as H7 and other upper level low's, but those should be talked about once we get closer to storm day.
Scenario #2 is a storm track further east which lacks dynamics. This would bring mainly rain to the immediate coast (maybe a change to snow) with rain-snow for areas NW of I-95. This scenario is probably a weak storm, between 995-1005 mb, so the impacts would be much less severe.
Scenario #3 would be no storm at all. This scenario does still exist since the models may not have a good grasp of how strong the Saturday system may get. We should have MUCH more clarity of this storm once the Saturday system is over and done with.
I am NOT favoring any one of these scenario's at the moment, but I do doubt the GFS very much at this point so I am not really buying into Scenario #3.
We'll see what happens! Obviously I will keep everyone updated on the forum.
Have a great evening
Francesco Paparatto
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