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Thursday, December 6, 2012

Storminess on the way, just not exactly how we would want it

Although not under the most ideal circumstances, there is some very active weather on the immediate horizon. The storminess will stem from what will be a highly amplified jet stream and all the ingredients that typically come with it like mild and moist air from the Gulf of Mexico and Arctic chill from Canada. I was almost expecting that a massive storm would be churned up out of all this; but were that to happen in this set up, it would suck very mild weather deep into interior New England. Instead of one big storm however. this massive baraclinic zone will produce not one, but two and quite possibly three separate storm systems. Cold air is in short supply but it's better than no supply.

The first and weakest of the series of potential weather systems arrives Saturday into a stale and deteriorating airmass. Precipitation will mostly occur early Saturday and will be in the form of rain with a few pockets of freezing rain. As completely useless as this weather system would seem, its passage will help allow some arctic air to jam its way into the Green and White Mountains in spite of a very adverse upper air weather pattern. The cold will arrive late Saturday and will be firmly in place on Sunday as the next system gathers strength in the Great Lakes and tracks toward the St Lawrence Valley. This track, unless it changes, will make it tough for any significant to snow fall when precipitation recommences Monday, but a period of mixed precipitation including a little snow is becoming likely. Ultimately, the mild push of air later Monday could prove to be too much and change all precipitation to rain but we could see some significant icing and if we are lucky, a nice base layer of concrete to build on. I had mentioned the possibility of a third wave in this series. Such a storm would be more of a snow producer Tuesday into Wednesday. Most of the model guidance has downplayed this possibility but the most recent run of the Euro showed some support for this.

Ensembles continue to show hints of another warm up beginning around the 13th of the month and persisting for a few days. The constant pushes of warmth still stem from Pacific ridge or the "evil empire" as we have been calling it. This ridge will migrate westward and set up an interesting dichotomy as we proceed toward Christmas with the PNA and NAO contradicting each other. With the Pacific ridge out of play however, the door will open for Arctic air to make its way into the northern part of the country and for the storm track to get pushed well to the south. In the end, some very positive developments should result. Stay tuned.


4 comments:

R Lawson said...

Hi - I really enjoy your blog here and I'm reading it intently as we've booked a trip to MRG starting 12/19. Can you elaborate on your "favorability rating?" What is the scale. I take it + is good for conditions/snowfall.

R Lawson said...
This comment has been removed by the author.
afk121411 said...

Josh, Have you been updating the favorability index? It seems to me that the next seven days will not be very favorable. A mixed bag of precip and marginal temps is hardly a positive, I would think. And with things looking to improve after the 15th or so, shouldn't the 14 day number be higher than the 7 day number?

Mike said...

Josh must have updated the favorability index... they're the highest they've been in well over a year!