Weather forecasters are trying to nail down the specifics regarding how a rapidly intensifying storm off the East Coast will affect coastal areas from New Jersey to Boston and downeast Maine on Tuesday and Wednesday. The storm, which Mashable has highlighted as a potential threat for several days now, is forecast to form early Tuesday off the Carolinas, and then race north-northeastward while intensifying at a blistering pace.

The storm is expected to undergo a meteorological process known as "bombogenesis," which is defined as a storm with central pressure that drops by at least 24 millibars in 24 hours. In this case, the upcoming storm is projected to intensify at at least twice that rate, which is a pace rarely seen in the western Atlantic Ocean. By Wednesday, the storm should be so intense, with a minimum central air pressure below 950 millibars, that it will bring the hazards of a full-fledged winter hurricane, posing a dire risk for mariners caught in its path, as well as anyone on land close enough to the storm center. This storm is likely to produce winds greater than 80 mph offshore, along with towering waves higher than 40 feet, according to NWS data.

Due to the storm’s large area of strong winds and heavy precipitation, the National Weather Service (NWS) in Boston has issued a blizzard watch for Cape Cod and the islands of Nantucket and Martha’s Vineyard. However, the storm’s most severe impacts do not appear to be headed for Boston, Providence and New York City.

This may be the biggest northwestern Atlantic storm since Hurricane Sandy, though the two differ in impact. Hurricane Sandy was a far larger system that moved in a different direction, and had both tropical and extratropical characteristics. Hurricane Sandy's coastal impacts were far more severe than this storm, due to its unusual track, large size and timing during astronomically high tides.

The NWS continues to caution, however, that a slight wobble in the storm’s path, on the order of 50 miles closer to the coast than currently forecast, would bring far more serious impacts into highly populated areas. There is an outside chance, on the order of 20% or less, that New York could see six inches or more of snow, and slightly higher odds that Boston could as well, even though these are not the most likely scenarios.

Image: Weatherbell.com

It is the storm’s rapid deepening, or as forecasters put it, “bombing out,” that makes this forecast a high risk one with relatively low confidence all the way up until it actually begins forming. Intensifying storms often bring surprises, and some computer forecast models have been suggesting that areas of heavier snow may move into New York and Boston for a few hours at least before the storm consolidates its energy near its center, like a figure skater spinning faster and faster as she tucks her arms close to her body.

Here is another update of that graphic I showed previously of storm track and model output. pic.twitter.com/vrCKFgch9l

— Gary Szatkowski (@GarySzatkowski) March 24, 2014

 

David Roth, a meteorologist at NWS’ Weather Prediction Center in College Park, Md., told Mashable that there are two main factors that will make this storm intensify at an almost unbelievable rate. The first is a strong difference in sea surface temperatures between the Gulf Stream, which is running up to 7.2 degrees Fahrenheit above average for this time of year, and the Labrador Current, which is currently up to 7.2 degrees Fahrenheit below average.

Non-tropical storm systems derive their energy from such temperature contrasts in the oceans and atmosphere, so this will add a major boost to the storm. It's the equivalent of feeding the storm with cases of an energy drink.

In addition, a deep dip, or trough, in the jet stream is projected to develop across the eastern U.S. This trough will force the fast-moving air at upper levels of the atmosphere to diverge, and will cause air closer to the surface to rise up and replace it, creating strong lift that will produce clouds and precipitation, as well as lower surface air pressure readings.

“The stronger divergence aloft will lead to stronger upward motion and lower pressures at the surface,” says Roth.

Regardless of how close it comes to the U.S., it is clear that the storm will reserve its fiercest blow for the Canadian Maritimes, including Nova Scotia and Prince Edward Island. The Canadian weather experts at Environment Canada have been comparing the storm to one that struck there in February 2004, Roth says. That storm dropped two to three feet of snow, but because this one will be moving faster, only about one to two feet of snow are expected there, along with hurricane force winds of 74 miles per hour or greater.

Plan for near complete travel shutdown Wednesday across the Maritimes. We can take a good punch, but this is a haymaker #atlstorm

— Chris Scott (@ChrisScottWx) March 24, 2014

 

Roth said the storm is not expected to set any all-time low pressure records for extratropical storms (i.e., non-tropical storms and hurricanes), but that is partly because of insufficient historical data for such storms. He said a storm of this magnitude typically occurs about once every 10 to 20 years in the western Atlantic.

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