Wednesday, November 30, 2011

December 4-9 Major Snow Event Discussion (Updated 11/30)

Bear in mind track is not set in stone and will likely shift before event occurs.
The models continue to shift northward, and because the GFS is moving towards the ECMWF solution, as are the ensembles, we have deemed it appropriate to make a rough sketch of a graphic. We are expecting a strong ridge of high pressure to hold in place on the East Coast and also keep much of the East warmer. This ridge will be pulling in warm, moist air from the Gulf of Mexico, creating an apt environment for some showers, depending on the moisture amount when the system comes through. To the west of the storm track, a cold blast of air may come down from portions of Canada in the wake of this storm. As this storm moves towards the north, a potential cold front extending from it will likely push away the warmer air and also help along the colder air. On the bottom side of the storm track, rain is widely expected thanks to the massive ridge in the East. This system will be grabbing the warm air and using it as moisture, which may help along the snowfall and rainfall totals in the end. For areas on the north side of this system, snow will occur. It is expected that the heaviest snowfall totals will occur right next to the track itself, where the moisture bands will be the tightest swirling around the low. This colder air that may also be in place would help the potential for snow as well.
The reason why this storm is not going south is because of the ridge and the cold air. It is a 'sandwich' situation, with two factors on the outside and the storm in the middle. The stronger component (ridge or cold air) will be the more determining factor for this storm. At this point, it appears that the ridge will be stronger and thus will push the storm farther west and north. If, for some reason, the models backtrack and decide that the ridge will be much weaker, then the storm track would likely short farther south. What is interesting about that is how the GEM model is following that potential of a stronger cold blast.
What may also be a factor is how fast the storm moves, and may play a bigger part than we may be noticing. The GEM has the storm track more south because that cold blast is coming out first instead of the storm as the storm moves slower and is thus pushed south. The ECMWF moves very fast, much faster than some other models. Thus, the storm comes first rather than the cold air. This would be a lose-lose situation, because less snow would fall and more rain would fall as the storm moves faster and is actually a bit north of the forecast graphic above.
We are consulting with other weather enthusiasts for their take on the storm track, so if you have anything to offer, drop a comment below- we'll respond to any questions you have.

Remember- this graphic is nowhere near set in stone, and was created to show current model guidance. The situation will change, and it looks like the situation should get itself intact going into the weekend.

12 comments:

Anonymous said...

Is it possible that the northeast will see snow from the storm if it goes farther south.

Mike Paulocsak said...

Hello Andrew.Like anonymous says,could the Ohio valley recieve snow from this also if it decides to take the southern route? Alot of the storms we had last year in the Ohio area started off as rain and then ended as a little snow as the storms departed and the cold air rushed in behind the storm.I hope i didn't confuse you.

Anonymous said...

if the northeast does get snow from the storm how much could southeastern PA get?

Andrew said...

Looks like we have a lot of Northeast folk on here!

Anonymous #1: The Northeast may see snow from the second system if it goes farther south. We have not mentioned it, but there are two systems.

Mike: The Ohio Valley may also receive some snow from the second system, and that seems the more likely area to receive snow at this point in time.

Anonymous #2: SEPA does not appear to be in line for snow right now, but this is all subject to potentially major change.

Anonymous said...

How cold will it get arther the storm in northern Texas

Anonymous said...

will the southeast get in on this too?

Andrew said...

Anonymous #1: The cold spell might reach into Texas, but that remains to be seen.

Anonymous #2: Most likely not. The only reason that the Southeast would get in on the action is due to the ridge, which produces nice weather.

Anonymous said...

well if the storm push's into the ohio valley dont you think the southern states like Ga,Sc and Nc get some snow from it?

Andrew said...

If the storm pushes into the Ohio Valley, the Ohio Valley will get snow and the South will get rain because it is below the storm track.

Anonymous said...

Do you think the southeast would get any snow from anyone of the storms forming?

Andrew said...

The Southeast is always at a climatologically unfavorable position for snow, so if there is potential it will be mentioned on here.

Anonymous said...

Line of heaviest snow may be centerted a little bit more West than anticipiated...but good forecast!