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Monday, February 2, 2009

Tuesday storm too far east and some milder temps may follow this week's chill

And by not updating the blog when i should have been I have avoided some of the back and forth drama with this weather system. This is a storm which will start as a disorganized area of precipitation in the southeast and then get a big kick in the pants as strong upper level energy from Manitoba injects itself into the playing field. The storm will grow rapidly into a classic noreaster but its track is too far east for a major Vermont impact and snow from the storm will be limited to areas such as Cape Cod if even that. Temperatures have warmed above the freezing mark on Sunday for the first time in over a month and will make a gradual descent Monday followed by a rapid decent back into frigid territory on Tuesday. I don't expect the light snow or flurries to amount to much Monday or Tuesday and temperatures will fall through the teens on Tuesday. Wednesday and Thursday will be bone chilling with temperatures in the single numbers through much of the day and well below zero at night. Wind chill temps late Tuesday into Wednesday will be even lower.

Mild air makes a push at us this weekend into next week but hopefully without the rain
A strong negative NAO has established itself and will act as the regions "insurance policy" through the first half of February. I put it this way because underneath the blocking across the Davis Straits and Greenland will be a changeable jet stream. One capable of producing a big storm last week followed by milder weather Superbowl Sunday into Monday and then much colder weather for the balance of the week. The colder weather is of course the result of a big trough amplification but this regime will not get any reinforcement and a series of Pacific impulses will again put the center of attention on the west for powder beginning this weekend while the east sees another push of milder temperatures. I have faith in downstream northern latitude blocking and the negative NAO and I continue to think that it will prove instrumental in avoiding any big time rain events even if the weather turns mild for a few days between the 6th-10th of the month. Systems with any real moisture will be shunted southward and be forced under the blocking to the north. I can see temperatures reaching the 40's for as many as 2 days in this stretch up through the 10th and there may be a little rain but I don't a base killing Christmas debacle part II. In terms of snowfall, we actually may get a few inches in front of the milder push of air going into the weekend. Models are then hinting at a more organized system early next week (Feb 9th) which will require help from the NAO to produce as I mentioned.

In to middle February
As the blocking continues to hold its ground after the 10th I would expect the situation to get more exciting. Long range ensembles can only assess the situation loosely but there are indications that energy from the Pacific will pass through the Rockies and across the country more fluidly. This will mean another period of more active weather beginning around the 11th or 12th of the month. We have not had the benefit of much of a southern branch this year and have relied on a consolidated but not overbearing Pacific jet which has sent a few healthy snow producers across the country and into New England. The snowfall contrast from north to south because of this lacking southern branch is dramatic but we are not complaining nor should we be surprised. The lack of a southern branch of the jet is tied closely to the lack of an El Nino which has helped allow the cold to be more dominant this year. The lack of rain/ice over the last month can be attibuted to the weaker La Nina. This may have helped produce a drier month of January but after the storm last week I will happily trade less precipitation and give up the ice and rain.

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