For the obvious reasons of impact on life and travel, the prospect of a snowstorm garners far more interest that a rainstorm. The rules of nature and prediction don't change with the increased scrutiny, so issues of exact placement of precipitation amounts, precipitation type, and timing of onset and departure exist just as they do in warm season events. That said, with the stakes higher in wintry weather, here's where we stand:
- Major winter storm for the Mid-Atlantic and Appalachian Mountains, with maximum snowfall amounts in hardest hit areas either side of three feet
- Accumulating and plowable snow very likely to impact Southern New England
- Highest amounts in New England will be found the farther south one is
- Several inches are likely in Southern Connecticut, Rhode Island and Southeast Massachusetts, with less the farther north one goes, but a plowable snow quite possible up to Central New England
- Timing for Mid-Atlantic is Friday to Saturday, for New England is Saturday to Sunday - for most in New England, likely Saturday afternoon or late day to Sunday morning
- Major impact to road, rail and air travel from North Carolina to Southern New England, Friday to Sunday as a region, south to north, respectively
First, let's update the map you saw on our NECN weather broadcasts Tuesday - the probability of a storm. This is equated using in-house methods to determine the chance of a storm's precipitation shield impacting any given area in New England, but in this map, we've included the Mid-Atlantic, as well. Items of note: a nearly certain storm (greater than 90%) in the Mid-Atlantic and Appalachians, and very solid 70%+ likelihood in Southern New England, with a greater than 50/50 proposition all the way up to the New Hampshire border. This is what gives us confidence in saying impact is likely for these areas, particularly Southern New England:
Of course, this only starts to answer the many questions that exist with this storm. Here's a breakdown of the major topics, and what we know at this still-early juncture.
The area of greatest snowfall - truly epic and historic amounts - almost assuredly will be found in the Appalachian Mountains and the suburbs just west of Washington, D.C. In these locations, snow begins later Friday and continues through Saturday, and somewhere around three feet can be expected. Farther north, into Southern New England, the greatest snow will come with a burst of warm and moist air extending northward in the middle levels of the atmosphere, several thousand feet in altitude, that will expand from south to north on Saturday. Timing of snow arrival to New York City and New England are still not set in stone, but a likely arrival of Saturday morning to NYC, Saturday midday or early afternoon to the South Coast of New England, and later Saturday through most of the rest of the southern half of New England seems most likely, continuing Saturday overnight and departing the first half of the day Sunday. Farther north, a clip of the northern edge of the snow shield is possible along the coast of Maine (35-45% probability at this time) but the North Country is not expected to see a significant impact. An early estimate? A larger collection of reliable precipitation estimates will arrive with the night runs tonight as we get within three days of the event end, but for now I wouldn't be surprised to see greater than six inches in Southern Connecticut, Rhode Island and Southeastern Massachusetts with the potential for a foot, 4-6" somewhere near the Massachusetts Turnpike and 2-4" in Northern Massachusetts - but again, it's really early in the world of snow forecasting and we haven't put this on a map yet, as we really want to get inside of that three day window of storm end. Always remember that, regardless of source, accuracy on snowfall forecasts decreases markedly outside of 24-30 hours.
From the Delmarva Peninsula northward up the East Coast through the South Coast of Connecticut and through Cape Cod and the Massachusetts Islands, gusts of 50-60 mph will be possible from the northeast. This will result in scattered power outages and tree/limb damage from the Mid-Atlantic to far Southern New England, but also raises the potential for blizzard conditions to be realized where heavy snow and strong wind intersect - particularly in Central/Eastern New Jersey to Long Island.
With the strong onshore wind comes the potential for coastal flooding. In fact, at least minor coastal flooding is probable from North Carolina northward through Eastern Massachusetts with this storm, with moderate coastal flooding quite likely along the Jersey shore. The time of greatest coastal flood concern for most of the Mid-Atlantic is Saturday evening, though in New England, the greater concern may come for Sunday's midday high tide, after some possible coastal flooding at typically vulnerable spots Saturday night around midnight.
Of course, these forecasts will become more refined as we near the storm's arrival. We'll keep you posted online and on NECN.