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By: sullivanweather , 3:49 PM GMT on February 13, 2014
Surely the sky looked grayer than your typical stormy sky this morning. A classic February nor'easter is currently pummeling the Eastern Seaboard from Georgia to southern New England with intense snowfall rates and crippling ice accretions across the Northeast and interior sections of the South. Originating from the Gulf of Mexico, low pressure at the surface has now moved to a position approximately 40 miles east of Wallops Island, Virginia and is moving north-northeast around 30mph. Low pressure is now down to 995mb heading into the 970's by the wee hours Friday morning. Out ahead of this low exists a large shield of precipitation, associated with a surge of isentropic lift with a very intense band of snowfall embedded within thanks, in part, to 850-700mb 2-D frontogenesis which is resulting in 2-4"/hr snowfall rates. This intense band of snow extends from Long Island, back across north-central New Jersey and across the southern tier of Pennsylvania. A band of mostly light to moderate snow strung out along the spine of the Appalachians archs back to the upper level core of the system, which will become a major snow producer in its own right later tonight.
Through the rest of today the large shield of snow (rain along the immediate New Jersey coast) will continue to slowly build north, enveloping New England and reaching the Canadian border by dusk. Within this band of snow will exist the aforementioned frontogenesis band of 2-4"/hr rates. This band will push north around 25-30mph to Scranton/Newburgh/Hartford line before rapidly translating northeast to coastal Maine later this afternoon. 4-8" of snow can be expected during the 2-3 hour long passage of this band. Along the coastal plain of southern New England, the lower Hudson Valley, and down through the urban corridor of northeast New Jersey snow will begin to changeover to sleet and freezing rain after the intense frontogenesis band passes through. This will lead to very treacherous conditions with the ice/6"+ snow combo. Farther northwest of the transition zone, after the frontogenesis bands moves on, a steady light to moderate snow will continue from central Pennsylvania, through upstate New York and interior New England. Areas to the immediate northwest of the transition zone are likely to see the heaviest snowfall accumulations during the course of the day, on the order of 8-14" with locally higher amounts. Amounts will taper to the northwest of this line at roughly 1"/20mi, reaching a terminus over the Allegheny Plateau.
Low pressure in the mid/upper levels of the atmosphere rotates across the Northeast corridor tonight, leading to another round of very intense snowfall moving from south-southwest to north-northeast from southeast Pennsylvania through New Jersey, eastern New York and western New England. In response to the upper level energy swinging through, low pressure at the surface will occlude with the triple point low racing to the Gulf of Maine and the end-occlusion low hanging back toward the Jersey shore before moving northeast in tandem with the upper system, to a position near the Twin Forks of Long Island by midnight. An additional small band of very heavy snowfall associated with intense surface frontogenesis may also form adjacent to the surface low and move across coastal New Jersey, through New York City and Long Island. But the main deformation zone will lie to the northeast of the I-95 corridor. Snowfall rates of 2-4"/hr will once again be achieved with this secondary burst of snow overnight. Areas along the axis of heavy snowfall with this deformation zone will intersect areas which receives heavy snowfall during the daylight hours today, leading to very impressive 20-30" totals in from the Catskills to the northern Berkshires and southern Green mountains. Still some uncertainty whether this area of heavy snow continues on a path into Canada or cuts on a more easterly track toward northern New England. At this time will hedge toward a Canada trajectory given westerly-based guidance success with this storms' history. Either way, for northern New England, this storm will rage during the overnight hours and straight into Friday. Fully-phased, there will be little let up in the precipitation from when it starts to when it ends (morning hours in Vermont and New Hampshire/afternoon hours in Maine). Snowfall totals will range from 8-12" in the eastern Adirondacks to 18-24" across Vermont/New Hampshire and 12-18" across interior Maine.
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