A Volatile Time Ahead...

Hello this is Student Meteorologist Kyle Elliott...and now that December has arrived and the winter cold front has blasted through (with the powerful storms on the 1st of the month), I figured it is about time I get back to more frequent posts as dangerous winter weather could soon be approaching the Mid-Atlantic and Northeastern sections of the United States. If one remembers back to last year, they cannot help but recall the blizzard of December 19, 2009, which destroyed the East with 1-2' + of snow. As the 18z GFS model now showed a storm of similar significance around the 13th of the month, I'm sure many heads have been turned and interest in this storm threat has been piqued as many professional meteorologists have been talking about this time period for quite a while now. While I do agree that the 10th-15th of the month is going to be a volatile time period, I am not ready to bite on the big storm idea quite yet. As for now, there are two specific points I want to make about the pattern.

1) The NAO is not going to be nearly as negative by mid-month as it is now. An encouraging sign, though, is that it is not forecast to reach neutral or slightly positive like the forecasts showed 2 or 3 days ago. Instead, the latest NAO forecast shows it remaining in the tank for most of the next 2-3 weeks, with it heading toward positive until about the 12th of the month. So, what I conclude from this is that, while the NAO is going to remain negative, it is not going to be as negative as I'd like to see it for a big storm along the East Coast. The one monkey wrench in that, though, is that it seems like the best storms occur when the NAO is either on the upswing from a bottomed-out state or on the downswing from a neutral state. So, only time will tell.

2) The 2nd, and in my mind more important, point that I want to make is about La Nina and the pattern in general. During La Nina years, with the exception of 1996, there have really been no big storms to come up the eastern seaboard. Now, yes, there have been the 6-10" type storms, but no 1-2' + storms except for the one in 96'. So in general, do not except a blockbuster type storm like the one we saw last December. I'm not saying it can't or won't happen, it's just not as likely as last year. And the last thing that concerns me is the trough in the east. It is extremely far east-based right now, and it going to take a quite significant lessening of the greenland block and vortexes rotating back into Canada for the trough to set up farther west into a position where a storm can bomb out right off the coast. Now, the encouraging sign is that models predict this...but the other factor that has to work out just perfectly is the Canadian high pressure system sliding in right behind the 1st clipper around December 10th. If that high pressure system does not lock in north of New York State and Vermont, we're in trouble. Either it would slide further south into PA and block the storm out to sea, or it would continue on it's way out over the Canadian Maritimes and allow the 12th-14th storm to cut into the Lakes with only front-end snow for the Mid-Atlantic.

Overall, these are my thoughts as of now and the problems/encouraging factors I see for the mid-month December storm. Only time will tell, and I cannot go out and make a forecast right now because I am not confident enough. My instinct tells me the storm will get blocked too far south and probably slide off the coast of the Carolinas similar to the storm this evening is doing, but I am by no means saying that with much confidence. I need more time to let the models sort themselves out and for the pattern to become clearer. The only thing I am pretty confident of is that the 1st clipper around the 10th also bears watching and could produce a nice swath of snow from Washington to Philadelphia before the possibly bigger storm arrives. So, I will deal with the clipper first over the next few days, and the potentially more significant storm. Those are my thoughts for now, though, so hope ya'll have a good evening and I'll talk to ya'll soon! This is Student Meteorologist Kyle Elliott reporting for the AKStormtracker Forecasting Center!