A soaking rain and, for many, leaf-stripping three-to-four-day nor'easter remains in the forecast for New England this week, bringing inches of rain for some, and fall gale-force wind for others.
The culprit is a huge area of intense upper-level atmospheric energy that will swing southeast across the Great Lakes and Ohio Valley, and take up shop along the East Coast. This intense upper level storm will reshape the jet stream winds aloft, which will bend into a large "trough," or dip southward, allowing the storm to slow, strengthen, stall and linger.
Below, the left image represents atmospheric energy aloft (500mb vorticity), and the right image depicts the jet stream wind forecast (250mb wind), both valid this coming Wednesday.
Note the huge pool of atmospheric energy on the left, and the way the strong jet stream winds - the fast river of air aloft that steers our storms and separates cold air to the north from warm to the south - curl around this energy on the right, with one "jet streak," or area of fastest winds within the jet stream, over Maine:
Not surprisingly, a strong surface storm is expected to develop beneath this upper level monstrosity, producing a combination of heavy rain and wind. Exactly where the upper level energy ends up will determine exactly where the surface storm stalls, and where the surface storm stalls determines where the heaviest axis of wind and rain establishes. Right now, it looks like rain will begin Tuesday, with periodic rain lasting all the way from Tuesday through Friday!
In these systems, the worst of the weather almost always sits on the north side of the expansive storm circulation, so heaviest total forecast rain amounts at this point look to be in Northern New England - especially Maine. The wind will not be strong the entire time for anyone in New England, but it will be persistent and onshore, blowing in from the northeast. This will churn the seas, building large waves resulting in pounding surf over the course of the week, particularly from Wednesday onward.
Below, inital forecast of total rainfall through Friday appears on the left, and surface wind gusts valid Wednesday afternoon appears on the right, along with barometric pressure:
By Friday, check out the wave height forecast off New England's coastline! The South Coast, tucked under the belly of the storm, escapes from too much wave action, but that corridor of wind from the Merrimack River northward produces a swath of 15 to 18 foot waves!
This represents a tremendous amount of energy in prolonged, pounding surf, that will contribute to beach erosion for the middle and end of the week. Coastal flooding is a possibility for some, given a New Moon and associated tide of moderate astronomical height.