Dec 8, 2016 11:40 PM
NH1 First Alert Weather: Cold Pattern Ahead, Snow By Monday
NH1 Chief Meteorologist
National Weather Service Text Product Display Cold NW winds will develop Friday and will deliver our first round of real Arctic air this weekend. Upslope mountain snow showers should be favorable for moderate accumulations over parts of Northern NH. It is not out of the question that a winter weather advisory may be needed for a few spots in the far north, but the accumualating snow will be highly localized. Farther South...Sunny to Partly sunny skies as high temps will struggle towards freezing with as a push of Arctic air will heading towards New England thru the day. Wind gusts will top out with gusts to 25 to 35 at times...making it feel even colder. A clear colder night Friday night with lows dropping into the teens. Active winds will prevent a big temperature drop but it will be blustery!
The weekend begins with cold high pressure building into the region. Mountain Snow showers will come to an end of Saturday with clearing skies. Winds will decrease through the region. Highs will only be in the 20's for the afternoon hours. Overnight temperatures will drop to near zero through the mountains... with isolated valleys below zero. Most will fall into the single digits and teens Saturday night.
On Sunday clouds will start to move in from the west in advance of a developing system moving up the Ohio river valley for Monday. Skies will turn mostly cloudy through the day with highs in the upper 20's and Lwr 30's. The trend over the past few days has been to push back the timing of the storm... with precipitation not moving into our southwestern areas until Sunday night or early Monday morning. Still there is a chance some light snow may try to develop later Sunday afternoon.
Expect precipitation to begin as snow region wide and spread across the region through the day on Monday. There are still uncertainties with storm track, temperature and the potential for some mixing. By Monday night the possibilities expand with the changing storm track. With high pressure for Saturday and Sunday the cold temperatures are likely to remain dammed at the surface, so warm air aloft would put a period of mixed precipitation near the Seacoast and southern Maine. While some mixing is possible...it is not definite. Increasing strength of cold air aloft could also drive the storm track slightly further south keeping any above freezing temperatures offshore...and keeping the precipitation all snow.
At this point, we lean with our trusted Euro model, which has the colder snowy solution, in part because of the strength of existing cold air mass ahead. The track of the storm will also have an impact on the winds. A low tracking farther south will result in a more classic nor`easter type set up with gusts too around 30 along the coast. A inland and warmer scenario keeps the center of the storm over us and results in lower wind speeds. So for now we are leaning with the colder, snowy solution with potential for some gusty winds.
There will be the potential for several inches of snow Monday with the timing estimated to last from early Monday Morning through Monday night. It is too early to say exactly where the heaviest snow will fall, but it is a safe bet to say this will be a plowable snowfall with the potential for some areas to pick up at least 6" of snow
The active pattern continues through next week with another chance for some snow on Wednesday, with another significant blast of Arctic air to end next week. The cold Arctic air is building in Canada an ready to be unleashed. It will come in waves with periodic blasts of intense cold likely right through December 23rd. We'll see if it lasts through the rest of the month!