Wednesday, December 26, 2007

One - Two Punch Thursday

We have got ourselves a wintery day on the way for tomorrow. A coastal low has developed off the tidewaters of North Carolina this morning and is gathering steam and heading NNE. High cloudiness is already streaming into SNE this afternoon from this storm system. It will still be a graze for SNE, but we really do not need to worry about this first part of wintery weather in SNE. Tomorrow morning will feature mainly rain from Route 495, points S&E. Boston will see mainly light to perhaps moderate rain tomorrow morning as the LP passes just south of Nantucket. This will result in heavier rain down in SE Mass and the South Coasts of RI and CT. Rainfall amounts up to one-half to one inch are possible in these areas. NW of Rt. 495 may feature some very light freezing rain or sleet as temperatures by tomorrow morning in these areas will be very borderline, with temperatures probably in the 30-32 degree range. Closer to Boston, temperatures will likely be more in the 33-34 degree range, keeping them rain...for the morning. Temperatures aloft should cool towards late morning and early afternoon ahead of the development of a 'Norlun' signature developing off of the morning coastal. This will develop a finger of snow from the LP dying over Upstate NY and the coastal moving away from the SE coast of Massachusetts. This will give much of SNE and up to NNE a good 6-8 hour period of light to moderate snow with a band of heavy snow probably developing somewhere from Portsmouth, NH to Conway, NH to Portland, ME

This is outlined in my map for snowfall in Part 2 of tomorrow's wintery weather. Where that band of heavy snow develops as always with 'Norlun' type setups, that is where the heaviest snowfall accumulations will be. Last week it setup from Portsmouth, NH to Boston, MA. Much of NE Mass and NH picked up 6-10" of snowfall, after having morning news outlets forecasting 1-2" Boston the morning of the event. So this will be a very changeable forecast. Right now, I think that is where the heavy snowfall will take place, but there will be a wide swath of light to moderate snowfall with this one for much of New England, unlike last week with some places seeing close to a foot and others some twenty miles away seeing coating. There will be a wide swath of 2-4", with locally 5" of snowfall with this one from north of the Mass Pike all the way into central VT and northern NH and central ME. Boston will be on the line, so a couple inches is possible in the city itself, which would be enough to break the December snowfall record of some 37 years. Down on the South Coast to the Cape, it will be cold enough for snow, but I think you will be removed from the heaviest of the precipitation, so you will see generally under one inch of snowfall. Extreme northern New England will be removed from the heaviest of precipitation as well so 1-2" for much of northern ME to under one inch along the Canadian border.

This is a very changeable forecast that will likely turn into a 'nowcast' type of event. Right now, I like my maps for this event up above, so expect a wintery ride home tomorrow because most of this snow will be falling in the 3PM - 8PM timeframe, just perfectly placed to ruin your drive home. I will have updates all day today and tomorrow with any advisories that get posted from the NWS. I could see some warnings being posted in SW Maine, but that is yet to be determined. Check in later.

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