New England Weather This Week: Calm Start; Rain & Wind to End

We’ll start off calm and seasonable, but a storm will be moving into the region later Thursday. At this time, the height of the storm looks to be Thursday evening through Friday morning for most.

MONDAY-WEDNESDAY

This week will start off with troughing at the upper levels and high pressure at the surface. This high pressure system will be centered to the north of New England through midweek. This setup will allow for cool afternoons and mainly dry weather, with a low chance for quick sprinkles or showers (basically a continuation of the past few days). Tuesday will be the driest day with the most sun for most of New England (the exception will be coastal areas of southern New England). A storm system will pass well south of New England later Tuesday into Wednesday. 

The rather strong high pressure to the north of New England, a lack of phasing with the northern stream and the overall weak nature of this storm will keep it well offshore of the region. Despite its offshore track, low-level northeast flow will likely lead to a thick cloud cover developing over coastal areas of southern New England, particularly the south shore and Cape Cod. These areas will be the most likely to see a few ocean-enhanced showers later Tuesday and Tuesday night.

Below: HRRR showing the system pass well south of New England, with some ocean-enhanced showers pushing into southeast Massachusetts:

THURSDAY & FRIDAY

Around the middle of this week, a more organized storm system will take shape in the east’s deep trough. This system will form in the deep southeast before pushing up the eastern United States and into New England. Confidence has increased that the track of this storm will be more of an “inside runner” with the primary low pressure system passing just west of New England. A secondary, coastal low may still form on this system’s triple point (where a warm, cold and occluded front meet). This will result in a period of windswept rain across much of the region.

Timing this system out has been a trial in futility over the past few days. With that said, we seem to be homing in on the system arriving around the second half of Thursday and pushing northeastward through Friday. The big question is just how progressive the storm will be. Some guidance shows the storm pushing out of New England completely by Friday afternoon, with just scattered residual showers leftover, while others show a later arrival more toward Thursday night with rain continuing through much of Friday. 

The height of this storm may be rather brief, with several hours of a moderate to heavy windswept rainfall. This band of heavier rainfall and stronger wind looks to move from southwest to northeast across New England later Thursday through Friday morning. Just how much rain falls in this band will likely be dictated by how much interaction occurs with Hurricane Melissa. Melissa will pass well offshore of the eastern United States late this week, but a plume of tropical moisture will likely get injected into our non-tropical storm, which would help enhance rainfall.

Another determining factor for rainfall will be the strength of both the primary and secondary low pressure systems. Recent trends have pointed to a stronger primary low, with the storm’s central pressure dropping to around 990mb. This would support a widespread 1-2 inches of rainfall across a wide portion of New England, with some areas potentially pushing toward 3 inches. Amounts would be lesser across Vermont and northernmost New Hampshire and Maine. 

There are currently low probabilities for 4+ inches of rain, mainly across southern New England. For amounts to reach these numbers, a stronger secondary low near the coast would have to form. While recent trends have been toward a weaker secondary low, should it become stronger, higher rainfall amounts will become more likely. At this point, only minor nuisance flooding is expected with a widespread 1-2 inches over a period of 12-18 hours. If trends start heading toward a stronger secondary low once again, the potential for flooding will increase, which will be something to watch over the coming days.

Below: Current five-day rainfall outlook:

The pressure gradient between the high pressure to the north and the strengthening low pressure passing near New England will support a period of strong winds as well. This pressure gradient does not look like it will support truly significant wind, but gusts of 30-50mph will be possible across the coastal plain. Winds will be less farther inland. With a stronger primary low, winds will be out of the south-southeast (rather than the northeast, which was expected to create a nor’easter in earlier forecasts). 

Again, Friday will likely see the height of the storm push out of most of New England through the day Friday. Scattered showers from the remaining instability will likely hang around for a while, but Friday evening looks mainly dry for most at this time. It will also likely remain breezy well after the storm passes due to the continued tight pressure gradient, so Friday evening will likely still be seeing gusts of 20-30mph. 

WEEKEND

The upper-level low responsible for this storm will likely slowly depart into the Canadian Maritimes through the weekend. At this point, seasonable weather is expected to kick off November.