White Christmas still possible in Northeast thanks to Alberta clipper storms

Dec. 22 -- A weather pattern favoring fast-moving storms and just enough cold air could allow snow to fall before, during and just after Christmas in parts of the Northeast.

Record-challenging warmth is forecast to bring spring- or summer-like temperatures to a large part of the country this holiday weekend. Some milder air is forecast to creep toward the mid-Atlantic region, but it won't overspread the entirety of the Northeast, keeping the chances alive for some that a white Christmas may take shape.

Snow covering the ground along much of the Interstate 95 corridor is still likely to be a slim possibility through this weekend. However, there will be some outside chances for it to happen thanks to a pattern that will allow Alberta clipper storms to travel along the northern tier of the Midwest and make a slight southward dip in the Northeast in the coming days.

Alberta clipper storms tend to originate from western Canada and move swiftly along. Since these storms often do not have much chance to grab moisture from the Gulf of Mexico and the Atlantic, they tend to bring light to moderate precipitation.

The storms often move along a north-to-south temperature contrast zone and bands of snow, wintry mix and rain can be quite narrow as a result. The pattern through this weekend will bring a storm about every 24-36 hours.

The first round of snow for parts of the Northeast will come on Wednesday as two storms nearly merge. One of those will be the storm that brought drenching rain and gusty thunderstorms to the southeastern corner of the nation early this week. The other storm was responsible for producing accumulating snow over the Upper Midwest Tuesday.

Even though these two storms are likely to remain separated, there will be just enough cold air and moisture around for wintry precipitation to unfold.

Several inches of snow are most likely to fall over northern Maine, but some accumulating snow is also expected farther south in the state as well as over parts of the White Mountains in New Hampshire, the Green Mountains in Vermont and the Adirondacks in northern New York, according to AccuWeather Senior Meteorologist Brett Anderson.

"Farther south, a narrow zone of ice is anticipated from parts of coastal Maine to southeastern New Hampshire, central and western Massachusetts, northwestern Connecticut and parts of the Hudson Valley and Catskills of southeastern New York state," Anderson said.

Icy spots cannot be ruled out in parts of eastern Pennsylvania, northwestern Rhode Island and northwestern New Jersey as well.

On Tuesday night, ice began to develop in parts of northeastern Pennslyvania, southern New York and northwestern New Jersey, traveling northeastward into New England. Ice may develop and cause problems mainly during the daylight hours across areas farther to the north Wednesday.

The next round of precipitation, which will include the possibility for some snow and a wintry mix, will arrive from Thursday afternoon to Friday midday as a weak clipper storm moves from the central Great Lakes to the southern New England coast.

The clipper system is likely to produce a brief period of snow or flurries from western and central New York, as well as central and northern Pennsylvania during Thursday night to northern New Jersey and southwestern New England later Thursday night to early Friday.

A dusting to a light coating of snow could create slippery road conditions and sidewalks in some locations.

There could even be a couple of flurries and a little natural pre-Christmas cheer that will sweep through the New York City area and some of the northern suburbs of Philadelphia from Thursday night to early Friday.

Farther south, a light wintry mix can occur in parts of Ohio, southwestern Pennsylvania, northern Maryland, northern Delaware and southern New Jersey.

Not too long after the clipper storm of late Thursday to early Friday clears the coast, a new clipper storm will already be rolling across the Upper Midwest.

This end-of-the-week clipper storm will be considerably larger than the preceding system and could deliver more significant wintry precipitation in parts of the Northeast just in time for Christmas, according to Anderson.

The National Weather Service defines a white Christmas as any location where there is an inch of snow on the ground on Christmas morning.

"Those dreaming of a white Christmas should get their Christmas wish from areas north of the New York State Thruway into northern New England, thanks to a fast-moving storm from late Friday into Saturday," AccuWeather Chief On-Air Meteorologist Bernie Rayno said.

This zone has the potential to pick up a few inches of snow since temperatures are most likely to stay below freezing during the bulk of the storm. Those skiing in the Adirondacks and the mountains of northern New England should have some fresh natural powder in time for Christmas Day.

Areas farther south may have enough of an intrusion of warm air to limit snow due to mixing with sleet and rain or perhaps just all rain from late Friday to early Christmas day. But, kids at heart in the Northeast may be thrilled with the chance of a light coating of snow Christmas Eve.

Areas from western and central New York, part of the lower Hudson Valley and even central New England may get enough snow in the mix to squeeze out a coating. Cities in the zone that may get a light covering of snow, prior to a mix with or change to rain, include Syracuse and Albany in New York and Boston and Worcester, Mass.

For snow to fall and produce even as much as a coating, the clipper storm would have to track farther south than forecast. For that to happen, the midweek pair of storms would have to merge, strengthen significantly and stall over southeastern Canada.

However, that won't be the end of the storm parade. There is yet another clipper storm forecast to roll through over the Christmas weekend.

A storm is forecast to travel farther south during Christmas Day over the Ohio Valley and reach the central Appalachians Saturday night. By Sunday, it is expected to drift off the coast of the upper mid-Atlantic and southern New England regions.

Despite this storm's more southern track, cold air in its path will be stale after having been in place for several days and will lose some ability to create snow as precipitation moves through. Except for all but the northern tier of New York state and New England, the storm is likely to bring rain.

Unfortunately for those hoping for snow in Virginia, much of Maryland, Delaware and southern New Jersey, none of the clipper storms are likely to track far enough south for snow just before, during or just after Christmas this year.

Snow for Washington, D.C., and Philadelphia will have to be left to the imagination, but forecasters say there is at least a "chance" for a white Christmas in New York City and Boston.