Area Forecast Discussion
National Weather Service Boston/Norton MA
233 AM EDT Mon Sep 28 2026
.WHAT HAS CHANGED...
Some Small Craft Advisories have been dropped, as has the High
Surf Advisory. Next bout of unsettled weather possible toward
next weekend but confidence in this outcome is low.
.KEY MESSAGES...
- Windswept rain with minor coastal flooding/beach erosion continues
Monday. Localized urban and street flooding possible.
- Minor coastal flooding continues through Monday evening.
- Conditions improve Tuesday, followed by mainly dry and warmer
weather through Friday. Forecast confidence decreases next
weekend.
.DISCUSSION...
KEY MESSAGE 1...Windswept rain with minor coastal flooding/beach
erosion continues Monday. Localized urban and street flooding
possible.
The center of circulation according to nighttime satellite imagery
and surface observations early this morning is sitting on the New
Jersey coast. Regional radar shows bands of precipitation continuing
to be pulled north and west into southern New England this morning.
Over the next 12-18 hours the low will weaken and lift north,
passing over SNE this evening and into the Gulf of Maine on Tuesday.
Thus, not expecting a wholesale change in conditions today. What
we've got out there now...low clouds, off-and-on showers, breezy
winds...will be the story the rest of the day. Now that damaging
wind concerns are done, the primary hazard is potential flooding
from additional rainfall. SNE has received anywhere from 1"(western
MA) to 5-7" (RI and southeast MA) over the last 2-3 days. Even
though the dynamics aren't as impressive as they were, the
atmosphere remains very moist with PWATs approaching 1.5"; we could
squeeze out an additional 1-1.5 inches in some locations before rain
tapers off Monday night. Thus, the Flood Watch remains in effect.
Urban and poor drainage flooding will be possible under the heaviest
downpours, and few small rivers and streams will continue to rise
into minor flood stage including the Taunton River at Bridgewater.
KEY MESSAGE 2...Minor coastal flooding continues through Monday
evening.
The secondary concern behind the additional rainfall is for pockets
of minor coastal flooding owing to the continued northeast winds and
high astronomical tides. Fortunately several tide gauges including
Boston Harbor and Nantucket have managed to remain just below flood
stage overnight. However, Monday afternoon's astronomical high tide
is higher than Sunday's so given the still expected ~1.5' of storm
surge we will continue to monitor for minor coastal flooding during
Monday's high tide (morning along the south coast, early afternoon
for the east coast).
KEY MESSAGE 3...Conditions improve Tuesday, followed by mainly dry
and warmer weather through Friday. Forecast confidence decreases
next weekend.
The weekend's long-duration nor'easter exits east-northeast as the
mid-level flow becomes less amplified and blocking diminishes.
Through the remainder of the week, the mid-level flow becomes fairly
zonal with a few weaker impulses passing through during the mid to
late week. These may bring a low probability of a light shower or
two, but otherwise mainly dry weather is expected. Expect marked
improvement Tuesday as the decaying nor'easter exits the region and
winds shift to the northwest. This northwest flow will advect lower
PWATs into southern New England, bringing any lingering early
morning showers to an end. While PWATs remain somewhat elevated into
the afternoon, there is little forcing to support additional
precipitation. Thus, clouds may hang tough through much of the
afternoon before some breaks develop later in the day. Northwest
flow will also keep temperatures a few degrees below climatological
normals, though it will be noticeably warmer than this past weekend.
Highs Tuesday reach the upper 60s to around 70 degrees.
A mid-level ridge builds across the southeastern CONUS this week,
while surface high pressure settles south of the region Wednesday
through Friday, leading to a stretch of quieter and warmer weather.
Guidance hints at a weak northern-stream shortwave Wednesday night
into early Thursday, followed by a secondary shortwave Thursday
night into Friday. PWATs Wednesday night into Thursday remain below
1.2 inches and do not align particularly well with the best forcing.
Outside of a brief light shower, would anticipate more clouds than
anything. PWATs increase to around 1.5 inches Thursday night with
the passage of the secondary weak shortwave, when a few light
showers could brush the region. No significant impacts are
anticipated with either disturbance. Temperatures trend warmer
through the middle and latter half of the week, though the latest
guidance has trended somewhat cooler compared to previous runs.
Highs generally return to the lower and middle 70s, with Thursday
potentially the warmest day as temperatures reach the middle to
upper 70s. No notable cold is expected overnight, with lows
generally falling into the 50s.
Forecast confidence decreases next weekend due to considerable
disagreement among the guidance. Interestingly, some solutions
depict a setup somewhat similar to earlier this week, with another
strong area of high pressure over eastern Canada and low pressure
developing off the Carolinas. Other guidance instead settles the
high over New England while low pressure develops across the Ohio
River Valley and approaches the region late in the weekend or early
the following week. Given these significantly different scenarios at
this range, expect changes to the forecast as guidance comes into
better agreement.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update:
Through 12Z: Moderate confidence.
IFR prevails with continued rain and NE winds. Ceilings a mix of
MVFR (west) and IFR/LIFR (east). Gradual, very slow easing
trends to NE gusts in the 18-25 kt range, strongest near the
northeast coast.
Monday: Moderate confidence.
Continued IFR. Rain begins to taper to more intermittent
showers. NE winds around 10-15 kt with gusts in the low 20s kt
range.
Monday Night: Moderate confidence.
Categories should trend to MVFR with stratus lingering around
but rain should be tapering off to drier conditions by early Tue
AM. NE to N winds around 10 kt.
Tuesday...Moderate confidence.
Gradually clearing skies with the best chance for clearing over
western southern New England while low to mid clouds hold on
much or part of the day. Thus, mix of FR (west) to MVFR (east).
NW winds 5-10 kts.
KBOS Terminal...Moderate confidence in TAF.
KBDL Terminal...Moderate confidence in TAF.
Outlook /Tuesday Night through Friday/...
Tuesday Night: Mainly VFR, with areas MVFR possible.
Wednesday through Wednesday Night: VFR.
Thursday through Thursday Night: VFR. Breezy.
Friday: VFR.
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through Tuesday...
The nor'easter will continue to weaken resulting in the
gradual weakening of winds/gusts through Monday. Winds will
still gust 25-30 kts on the eastern waters into Monday. Seas
diminish to 5-7 ft by Monday evening. Highest seas will linger
across the northern waters Monday. Lingering higher seas will
keep Small Craft conditions around through Tuesday, especially
for the outer waters.
Outlook /Tuesday Night through Friday/...
Tuesday Night: Winds less than 25 kt. Seas up to 5 ft.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft.
Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft.
Thursday: Winds less than 25 kt.
Thursday Night through Friday: Winds less than 25 kt. Seas up
to 5 ft.
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Flood Watch through late tonight for MAZ004>007-012>024-026.
Coastal Flood Advisory until midnight EDT tonight for MAZ007-
015-016-019-022>024.
RI...Flood Watch through late tonight for RIZ001>008.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ230-
231.
Small Craft Advisory until 2 AM EDT Tuesday for ANZ250-251-
254>256.
DISCUSSION...BW
AVIATION...BW/Dooley
MARINE...BW