A major winter storm will pound the northeastern United States on Tuesday, dropping very heavy snow and whipping the coastline with damaging winds and rough surf. While Sunday and Monday will be tranquil in the northeast, it will be very cold with highs forecast to be about 15-25 degrees below normal. Meanwhile, the ingredients will be coming together for a significant storm to form off the North Carolina coast by Monday afternoon.
This storm will rapidly intensify and go through a process called bombogenesis. Bombogenesis is defined as a mid-latitude cyclone that drops in surface barometric pressure by 24 or more millibars in a 24-hour period. With an abundant moisture supply, great support from upper layers of the atmosphere, and a set-up that’s ripe for rapid development, a major Nor’easter will blossom and move up the northeast coastline late Monday evening into Tuesday. By Wednesday morning, the low pressure center should be near eastern Maine, bringing trouble to the Canadian Maritimes while the US begins the big dig-out.
Meteorologists making forecasts are aided by computer forecast models that digest large volumes of data and spit out robust data sets profiling different layers of the atmosphere; two of the most popular global models are the American (GFS) and European (ECMWF.) They each have their strengths and weaknesses, although this winter the European model has generally performed better than its American counterpart with big storms.
While we’re less than 4 days away from the storm, there’s still decent disagreement between these models and their opinions they render. The American model appears to be a western outlier, bringing a track of the primary low pressure system very close, if not a hair inland, over the coast. The European model shows a track further out to sea. A track closer to the shore line would produce much more precipitation, but it would also increase the odds of a a more northern rain/snow line that would cut snow amounts down due to non-snow such as sleet and rain falling. A track more offshore would keep cold air in place, bringing up snow totals along the coast. Tracks far off shore could also keep most of the available moisture to work with off-shore as well. At this time, the National Weather Service’s Weather Prediction Center believes a blend of those solutions will occur.
At this time, Weatherboy believes it is too early to commit to a forecast path. Beyond the complexity of the future track is the future structure of this system. Because this overall system is really the sum of many parts and it is not yet completely understood how Mother Nature will assemble those parts, there is no early, crystal-clear solution as there have been with past major storms such as the March Superstorm of 1993 and the Boxing Day Blizzard of 2010. In those storms, the pattern and available track for those storms to pursue was understood and “locked-in” several days before the storms impacted the northeast. Unfortunately, the same just isn’t true yet for this system.
There are two probable paths for the storm to pursue: hug the coast or head off-shore. In our snow maps here, we’ve illustrated how those very different paths would lay down very different snow amounts across the northeast. The coastal hugger would bring the threat of rain, sleet, or a mix of rain/sleet/snow up into New Jersey, keeping snow totals low along and south of I-95 in the Garden State south into Delaware and Maryland. But a coastal hugger would also slug more moisture inland, bringing 1-2′ snow to portions of Pennsylvania and New England. The off-shore track would pull the impacts of the storm further east, bringing the heaviest snow to portions of central New Jersey and southeastern New England. If the storm were to head even further off-shore, that heavy snow would go with it. While a well off-shore solution would eliminate change-over or mixing chances with rain or sleet, it would also cut snowfall amounts dramatically as you move away from the coast.
More data needs to be analyzed before confidence is increased in the forecast specifics, especially as it relates to snow. That confidence may not rise until Sunday afternoon. In the meantime, the National Hurricane Center has confirmed that Reconnaissance Aircraft typically used to investigate hurricanes have been deployed to this developing system to sample the atmosphere. These samples and assorted readings throughout their journey in the atmosphere will provide us with a greater level of detail of the set-up that’ll eventually impact the track and intensity of this storm.
Regardless of the storm track, the northeast will be hit by typical harsh Nor’Easter conditions: damaging wind gusts, coastal flooding, and beach erosion are all possible from the Delaware Beaches up the Jersey Shore to the South Shore of Long Island to Nantucket, Martha’s Vineyard, Cape Cod, and Block Island. While confidence is low with snow accumulation specifics, confidence is moderately high that there will be severe winds at the coast. The prime period for damaging winds would be from early Tuesday morning through Tuesday afternoon along the northeast. The best chance of coastal flooding will be during times of high tide on Tuesday.
By Wednesday, the low should quickly pull away. While the storm heads into the Canadian Maritimes, there could be lingering snow showers throughout the day, especially over northeastern Pennsylvania, northwestern New Jersey, and the higher terrain of New England. High pressure will build in during the day on Wednesday with another storm threat arriving later Thursday.