Winter storm Janus is here. Like it or not, the Weather Channel names winter storms – and these designations make it much easier to refer to the disturbances — so I will use the names. This storm differs from the previous named storms; spawned by an Alberta Clipper, Janus will be a deep low-pressure center moving up the eastern seaboard — a nor’easter.
Janus in its Youth
The weather pattern has changed since Cleon, Dion, Gemini, and Hercules – storms that originated along a cold front that stretched from Texas to Maine and fed on moisture from the Gulf of Mexico.
Janus began as one of a series of Alberta clippers, storms named for their Canadian place of origin, which move southeast across the U.S. midwest. As clippers move east, they can either turn north over the eastern Great Lakes, continue rapidly east and out to sea, or develop into powerful storms along the coast. Janus will do the latter.
Clippers Lack Moisture
As Alberta clippers develop, they are starved for moisture because they are so far from a source of water vapor. They may squeeze out a few tenths of an inch of water, which can equate to as much as six or eight inches of very light and powdery snow. In addition, there can be bands of heavy lake-effect snow, but these are very localized.
For Janus to produce large amounts of snow over a wide area requires a source of abundant moisture. Enter the Atlantic Ocean.
Winter Storm Janus: A Lot of Water to Fuel the Storm
The relatively warm water of the ocean not only supplies copious amounts of moisture to developing systems, its warmth also heats the air. This creates a front (boundary) between the ocean air and the continental air, increasing the potential energy of the system. This potential energy is turned into the wind (kinetic energy) associated with nor’easters.
Nor’easter Means Northeast Wind
The name nor’easter (a contraction for ‘northeaster’) is derived from the direction of the wind in this kind of storm. The storm itself is moving from the southwest to the northeast. As the storm passes to the east of the major metropolitan cities, the wind changes from east to northeast to north, and finally northwest as the storm ends. The major precipitation falls when the wind is northeast.
Janus: Who Gets The Worst of the Storm?
In a typical nor’easter, the wind off the 40-plus degree water turns the snow to rain. However, all of the precipitation with Janus will be snow, as the polar vortex has brought arctic air to the northeastern portion of the country. Washington will get its heaviest snowfall in three years, probably around half a foot; Philadelphia, New York, and Boston can expect more up to a foot.
Janus May Be a Blizzard
Though the northeast experiences heavy snowfall from nor’easters on a regular basis, true blizzard conditions in connection with these weather events are rare. Janus is different.
Because it is so cold, heavy snow will fall along the coast, where the winds are strongest. The blizzard conditions of a minimum of three hours of wind in excess of 35 miles per hour and visibility below a quarter of a mile in snow and/or blowing snow may be met along the coast from Virginia to Maine.
Elsewhere, away from the coast, blizzard-like conditions will occur, with wind and blowing snow, but not quite up to true blizzard standards.
The Current Weather Pattern
Conditions will remain favorable for Alberta clippers to follow Janus’s path through the midwest for the next couple of weeks. Though some of them may move northeast through eastern Canada, pass quickly out to sea, or just fizzle out, there could be another major storm along the Atlantic coast during that time. The season for nor’easters is far from over.