Winter storm with heavy snow, ice expected to reach Northeast later this week

An enormous cross-country storm that has unleashed blizzard conditions in the northern United States and will continue to trigger a severe weather outbreak in the South this week also has its sights set on the Northeast.

AccuWeather meteorologists expect the enormous storm to create a spinoff system near the Atlantic coast that is likely to bury some locations of the interior Northeast with a foot or more of snow later this week as well as trigger areas of icy conditions and coastal flooding.

"A storm will develop near southeastern Virginia on Thursday, and will track just off the New Jersey coast on Friday and finally spin near southeastern New England on Saturday," AccuWeather Meteorologist Mary Gilbert said. The positioning of the storm will allow cold air from Canada to be pulled south into the Northeast and help produce a widespread snowfall for a large part of the region, she added.

Rain will be the primary form of precipitation in the Interstate 95 corridor from Boston to New York City, Philadelphia and Washington, D.C. The heavy rainfall, when combined with gusty winds, will lead to urban flooding and poor travel conditions. Motorists are likely to encounter ponding and poor visibility, while airline delays will be possible due to visibility, wind and slick runways at the major hubs.

A winter storm watch was issued for a large swath of central Pennsylvania, western Maryland and northern Virginia Tuesday. Cities in this area include State College and Williamsport, Pennsylvania and Harrisonburg, Virginia.

Portions of the winter storm watch area were upgraded to an ice storm warning on Wednesday morning. The ice storm warning is in effect for cities including Johnstown and Somerset, Pennsylvania and Cumberland, Maryland.

The rain will pivot across the Washington, D.C., and Philadelphia areas Thursday, but it should hold off in New York City until Thursday night. The worst of the storm for New York City will likely be Friday, with Boston in store for an extended period of stormy conditions from Friday to Saturday.

The air will trend progressively colder in areas not too far to the north and west of I-95, and precipitation will transition from a snow and rain mix in some of the suburbs to all or mostly snow over the mountains, according to AccuWeather meteorologists.

If the storm were to track slightly farther to the east, it could pull cold air down the Hudson Valley and allow some snow to reach New York City. In a similar scenario, then Boston could end up receiving heavy snow rather than wind-swept rain.

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At this early stage, "the greatest chance of 6 inches or more of snow will be from near and north of I-80 in Pennsylvania, north through upstate New York and in central and northern New England," Gilbert said.

"Not only does the storm have the potential to produce a heavy rate of snow, but in some locations from Pennsylvania to New England, snow could fall for more than 24 hours," AccuWeather Senior Meteorologist Courtney Travis added.

The storm's slow movement will increase the potential for a foot (30 cm) or more of snow to fall from east-central New York to the ski country of northern New England.

AccuWeather forecasters have highlighted an area north and west of Washington, D.C., and Baltimore, along stretches of I-68 and I-70, where an accumulation of ice is expected from Wednesday night to Thursday. This zone includes about 200 miles of the Pennsylvania Turnpike in southern Pennsylvania from near Lancaster through Harrisburg to Bedford and east of Pittsburgh. For a brief time, at the onset of the storm, a bit of freezing rain and sleet can occur in the cities of Washington, D.C., Baltimore and Philadelphia late Wednesday night to morning rush hour on Thursday.

This icy mix zone that may include some sleet will extend into parts of southern and central Pennsylvania. The most significant icing is forecast to occur over a small area of south-central Pennsylvania, western Maryland, northeastern West Virginia and northwestern Virginia, where at least 0.25 of an inch of ice can accumulate, potentially bringing down some tree limbs and causing power outages.

Along with the likelihood of heavy rain along I-95 and snow and/or ice inland in the Northeast, "a six-hour period of coastal flooding is in store from Norfolk, Virginia, to New York City and Boston as the storm moves slowly along," AccuWeather Chief On-Air Meteorologist Bernie Rayno added.

Coastal flooding will likely be minor and generally limited to around the times of the high tide. Tides are expected to range from 1-2 feet above normal in most cases but could be somewhat higher in eastern Massachusetts from Friday to Saturday.

The initial massive storm over the Central states will drag the coldest air of the season southeastward across the Plains, Mississippi Valley and Midwest late this week. The spinoff storm in the Northeast will then help drag some of that air farther to the east.

Because of the indirect route Arctic air will take, the cold will not be maximized in the Northeast, but temperatures will tumble from this weekend on. Areas of slush and standing water will freeze solid, forecasters warn.

Multiple days with highs no better than the 20s and nighttime lows in the teens and single digits are expected in the mountains next week. In the I-95 cities from Boston to Washington, D.C., multiple days with highs in the 30s and nighttime lows in the 20s are in the offing for next week.

As the cold air blasts across lakes Huron, Erie and Ontario, bands of heavy lake-effect snow will set up this weekend. There is the potential for 1-3 feet of snow where the snow bands persist across portions of western and northern New York state to part of northwestern Pennsylvania.

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