Late Week/Weekend Nor’easter
Meteorologists are continuing to monitor model projections of a large and slow-moving nor’easter off the U.S. east coast for the Thursday through Sunday timeframe. There is a high probability of a large coastal storm, but uncertainties remain in track, timing, intensity, and location of highest impacts. Despite those uncertainties, this storm will undoubtedly have a high marine impact and a moderate to possibly severe coastal impact along large portions of the Northeast U.S. coastline, including much of the MA and RI coast. Depending upon the eventual track, damaging winds and heavy rain with possible flooding are additional potential impacts for southern New England. We will probably have a significantly better handle on the projected track, timing, and intensity by late Wednesday or Thursday morning. Since this will be a slow-moving storm, duration will likely be a very important factor in the severity of 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. The strong high pressure area will contribute to a tight surface pressure gradient and strong winds on the north and northwest sides of the developing coastal low pressure center. Given weak steering currents and uncertainties in the exact configuration of the upper trough energy that will spawn the surface low pressure system, the various deterministic and ensemble computer models still depict a fair amount of scatter in the track of the storm.
Most of the latest (1200 UTC) deterministic models depict a high impact to the southern New England region except for the ECMWF, which curls the low center to just off the southern mid-Atlantic coast. The ECMWF appears at this time to be somewhat of an outlier but cannot dismiss it given its relatively good history with significant storms. Even the ECMWF model, however, would imply at least moderate coastal impacts to our shoreline. There is fairly good agreement that this storm will contain a relatively large envelope of gale to storm force winds for a long duration. This increases confidence for severe marine impacts and potentially moderate to severe coastal erosion and coastal flooding as well over much/most of the Northeast U.S. Note that astronomical high tides will be on the increase this weekend into early next week given the proximity to the time of the full moon.
The following sections will describe in more detail the potential impacts for southern New England.
Marine
Boaters would be advised to check moorings over the next day or two as seas will become increasingly rough along the southern New England coastline as early as late Wednesday or Thursday. Any offshore trips by small craft will 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 Force winds with possibly Storm Force gusts will develop near or over the coastal waters Thursday into the weekend. Seas not too far offshore may build to as high as 20 to 30+ feet off the southern New England and/or mid-Atlantic coastlines. The large envelope, long fetch, and long duration of strong winds will allow seas to build to dangerous heights.
Coastal Impacts
Moderate to possibly severe beach erosion and coastal flooding are anticipated. How severe of an impact will depend upon storm’s track and location/timing of a strong low level jet (some of which will mix to the surface). Anticipate at least a moderate impact over multiple tide cycles for the following reasons: size of the storm and associated large envelope of gale to storm force winds, relatively long fetch (i.e., distance) of the gale to storm force winds, and duration of strong onshore winds. These factors act to build up large waves and increase the storm surge. And for a longer duration event, would expect an increase in wave period which tends to increase the energy (and destructive/erosion potential) of the wave activity. Also, several models tend to curl the low center to the west (i.e., retrograde) toward the coast, which I suspect in itself could increase the storm surge and the higher waves reaching the shoreline. And in addition to all these factors, we are approaching the full moon and higher astronomical tides. The latest ECMWF model scenario would enable southern New England to escape the worst impacts, although still probably at least moderate erosion and coastal flooding along both the east and south facing shorelines. A worst case scenario (not necessarily the most likely scenario!!) would be major coastal flooding with extensive property damage. Although we will hopefully avoid a worst case scenario, it would be prudent for interests along the immediate coastline to make some preliminary preparations and monitor later forecasts from the National Weather Service.
Although the focus of this blog is on southern New England, the potential for moderate to severe/destructive coastal flooding also exists for Long Island (as well as portions further south along the mid-Atlantic coastline – perhaps even as far south as North Carolina).
Wind
There is a risk of damaging northeast winds, especially along the immediate MA and RI shorelines. How strong and how far inland the stronger winds intrude will depend upon the track of the coastal storm and where the core of the low-level jet sets up. The period of peak winds looks to be in the Friday to Saturday timeframe, but some models have strong winds persisting into Sunday. One factor to keep in mind is that trees are fully leafed out and that could increase the risk of tree damage and downed powerlines.
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
Fay in the east central Atlantic has weakened to a tropical depression. There are no other formative tropical cyclones in the Atlantic Basin, likely in large part to the hostile environment created by the currently strong El Nino episode.
In contrast, the eastern Pacific remains quite active. Polo is now a very dangerous Category 5 hurricane. It’s expected to move generally northwest and parallel to the southwestern Mexico coast. Although Polo should remain offshore, outer portions of the hurricane will have some impact along the southwestern Mexico coast where a Tropical Storm Warning is in effect. Also, Polo may contribute to the injection of moist air into the southwest U.S. monsoon over the coming days and possibly increase the risk of localized flash flooding in that region.
Next Message
Additional weather blog messages for this early season nor’easter are anticipated in the coming days as we attain greater clarity on storm track, timing, and strength.
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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.
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Message issued September 22, 2026 by:
Bob Thompson
Retired National Weather Service Meteorologist
