Weekly Significant Weather Outlook
The focus for this outlook is on the increasing potential for a robust nor’easter late in the week into the weekend with potentially significant coastal impacts, wind, and rain. There is good agreement among the various deterministic and ensemble model runs of a large nor’easter off the Northeast coast but with variations on important details including track, timing, and intensity. This looks to be a slow-moving storm and so duration could be a very important factor. Will briefly discuss some synoptic features and then provide more information on potential impacts.
Synoptic Set-up
An especially strong surface high pressure area will build over eastern Canada this week and by itself help produce a stiff northeast flow across our region. Meanwhile, an upper-level trough moving toward the east coast will help spawn a surface low pressure area east of the mid-Atlantic coast. There is considerable consistency in the model data that points toward significant intensification of this coastal storm with development of a strong northeast low-level jet (potentially over 75 knots) to the northwest of the low center. With strong high pressure to the north, this system is expected to move very slowly to the north or north northeast, possibly to a position near the 40N 70W benchmark with the upper-level trough closing off. This system may not weaken and slowly exit the area until late in the weekend or possibly even early next week. Hence, we will need to monitor closely the projected evolution of this system as it could pose multiple weather risks for southern New England.
Marine
Boaters may wish to check moorings in the next couple of days as rough seas may develop along the southern New England coastline, perhaps as early as late Wednesday or Thursday. Any offshore trips may become problematic by Thursday and remain so through the upcoming weekend. Mariners should closely monitor the latest forecasts and be prepared to adjust plans if necessary. Gale and even Storm Force winds may develop near or over the coastal waters late this week. Seas over 20 feet may eventually develop with this system off the New England and mid-Atlantic coastlines.
Coastal Impacts
Beach erosion will likely be an issue along portions of the MA and RI coastline – probably most significant along exposed MA east facing shorelines. Coastal flooding will potentially be an issue as well during high tides starting Friday and possibly lasting through the weekend. A cause for concern is the expected long duration of this event. That will allow an increase in storm surge, wave amplitude, and wave period over time. The astronomical high tides are not especially high this week but increase during the weekend. The track, timing, and strength of the coastal storm will determine just how significant the beach erosion and any coastal flooding will be.
Wind
There is a risk of damaging northeast winds along the immediate MA and RI shorelines, especially across the Cape and Islands. How strong and how far inland the stronger winds intrude will depend upon the track and intensity of the coastal storm. The period of peak winds looks to be in the Friday to Saturday timeframe, but that timing could change.
Rain
How much rain falls and where will depend upon the eventual track of the storm. This could result in a long duration of periods of rain with the potential for significant multi-day totals. We should have a clearer picture of the rain and other impacts to expect in the coming couple days or so.
Tropics
Makes some sense to check on tropical activity since today marks the 88th anniversary of the 1938 Great New England Hurricane. That intense and fast-moving Category 3 hurricane devastated southern New England with a deadly storm surge, widespread damaging winds, and destructive interior freshwater flash flooding.
So far this year, the vertical wind shear induced by the El Nino phenomenon continues to suppress tropical cyclone activity in the Atlantic Basin. Tropical Storm Fay way out in the east central Atlantic has started to feel the impacts of vertical wind shear and will soon encounter drier air. It’s expected to weaken into a post tropical remnant low pressure system in a couple of days.
In the eastern Pacific, Polo is expected to explosively intensify into a major hurricane as it establishes a northwest motion. Although probably remaining offshore, Polo may have impacts on southwestern Mexico and possibly later across portions of Baja California.
Next Message
Additional weather blog messages are likely this week due to the expected development of a large late week/weekend coastal storm with potentially multiple impacts to the southern New England area.
About this Blog and Disclaimer
The National Weather Service monitors the weather 24/7 and updates forecasts, watches, and warnings as necessary. For most of southern New England, refer to your local Weather Forecast Office for the latest forecast/warning information at weather.gov/box. For information from other Weather Forecast Offices, go to weather.gov and click on the location of interest on the map.
The frequency of this blog will depend upon the nature of the weather threat and availability of the author. Thus, for the latest information on weather forecasts and warnings, refer to the National Weather Service, which monitors and forecasts the weather 24/7.
Blue Hill Observatory and Science Center (BHOSC)
The BHOSC maintains a continuous daily observation record that dates from February 1, 1885 without interruption and provides educational information on weather and climate to area students and the community at large. Your support of BHOSC is much appreciated and enables this nonprofit organization to maintain the long-term climate record at the Blue Hill Observatory (longest continuous record in North America) and provide valuable educational resources on weather and climate via outreach to schools, site visits/tours, webinars, and conferences. For more information on the Blue Hill Observatory and Science Center, explore bluehill.org.
Message issued September 21, 2026 by:
Bob Thompson
Retired National Weather Service Meteorologist
