187
FXUS61 KBOX 112351
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
751 PM EDT Mon May 11 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Dry weather with cooler than normal temperatures tonight
  through Tuesday night.

- Unsettled weather returns later Wednesday. Widespread showers
  Wednesday night and Thursday with lingering showers possible
  Friday.

- Warmer temperatures return this weekend. Potential for
  isolated to scattered showers and perhaps a thunderstorm.

&&

.DISCUSSION...
KEY MESSAGE 1...Dry weather with cooler than normal temperatures
tonight through Tuesday night.

Cold front from early this morning along the southeast waters is
still bringing a canopy of midlevel cloudiness to most of Southern
New England. This front will be slowly trudging southeastward
through early tonight; sfc ridge of high pressure then builds in
from the northwest through Tuesday, under midlevel troughing
associated with a cool airmass works its way in.

Clearing skies for tonight and a gradually slackening northwesterly
wind should allow for at least some radiational cooling. 925 mb
temps around +2 to +4C are rather cool for this time of year and
temps under clear/calm conditions could allow for temps supporting a
light frost in NW MA; there are mixed signals though on if winds
will really drop below 5 mph and if we`ll stay fully clear. NAM and
GFS show a 500 mb vort maximum now over Michigan moving ESE through
Southern New England late tonight into the overnight, which could
bring at least some enhanced cloudiness and/or keep winds mixed
enough to preclude frost from developing. The frost/freeze program
is now active in all zones in Southern New England, but I think the
above caveats are enough where frost headlines probably won`t be
necessary for northwest MA. A few areas in northwest MA could drop
into the mid to upper 30s, but lows elsewhere in the upper 30s to
mid 40s.

High pressure then continues to build in on Tuesday, with mostly
clear skies, dry weather and northwesterly breezes. Seabreezes are
likely on both southern and eastern coasts by late morning, but it`s
otherwise a cool but pleasant Tuesday with highs mid 50s to lower
60s. Bit warmer temperature profiles for and increasing cloud cover
should support somewhat milder nighttime lows Tuesday night in the
mid 40s.

KEY MESSAGE 2...Unsettled weather returns later Wednesday.
Widespread showers Wednesday night and Thursday with lingering
showers possible Friday.

High pressure shifts offshore during the day Wednesday ahead of an
approaching shortwave trough. Deterministic and ensemble guidance
has shown sufficient agreement with a 500mb low cutting off from the
deep trough as it moves across eastern Great Lakes then tracking
eastward toward southern New England late-week.

Flow becomes southwesterly Wednesday ahead of the trough with a
plume of slightly above normal moisture advecting in through the
day. Moisture generally appears to arrive late morning-afternoon
with showers developing sometime in the afternoon. Timing remains
uncertain still; however, across most model guidance there is a
consensus with shower chances increasing from west to east through
Wednesday afternoon. A round of rain is possible in the afternoon
followed by more widespread showers/rain developing Thursday night.
Rain likely continues through the day Thursday. The mid-level closed
low and surface low stay fairly stacked and shift just offshore or
across southeast southern New England late Thursday into Friday.
Most model guidance is leaning slower improvements on Friday as the
low slowly exits, especially in eastern areas. This may keep
scattered showers around at least the first half of the day.

In terms of rain amounts, ensembles show a range 0.40" to around
1.0" as more likely. The ECMWF ensemble leans on the wetter side
compared to the GEFS with the ECMWF ens 75th percentile showing
potential for areas to receive 1.0 to even 1.25" while the GEFS tops
out under 1.0" within their respective 75th percentile. Regardless,
this is looking like an overall beneficial rain for most areas of
southern New England. Temperatures mid to late week will lean cooler
than normal.

KEY MESSAGE 3...Warmer temperatures return this weekend.
Potential for isolated to scattered showers and perhaps a
thunderstorm.

The upper trough and low exits the region by Saturday morning with a
mid-level ridge moving in from the west during the day. Across
ensemble guidance, this ridge brings along the signal for
temperatures moderating Saturday with above normal temperatures for
Sunday. There is potential for a few shortwave troughs to move
through the flow over the weekend. Timing and strength of the waves
are uncertain at this time which will factor into the precipitation
chances. For now, see it as a low probability (< 30%) for a round or
two of isolated to scattered showers and perhaps a thunderstorm.
There is not signal for widespread activity or heavy rainfall at
this time.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

00z TAF Update:

Tonight: High confidence.

VFR; there could be some lower-VFR decks and perhaps a sprinkle
or light shower at absolute worst 03-09z BDL-PVD south and
east. NW winds around 5-10 kt, though becoming 5 kt or less
overnight.

Tuesday and Tuesday Night: High confidence. Moderate for sea
breeze potential at BOS, PVD.

VFR. NW winds around 7-10 kt. Seabreezes remain possible for
BOS and PVD developing around 15-16z. If NW winds are a touch
stronger, sea breeze may stay just offshore or wavering in/out for
a couple hours in the afternoon. Winds become light WNW/W
overnight.

KBOS Terminal...High confidence in TAF. Moderate for sea breeze
potential Tuesday.

Light NE winds this evening becoming light NW by 03Z tonight.
For Tuesday, NW winds early morning. Seabreeze remains possible
 developing around 15-16z. However, NW winds are a touch
stronger, sea breeze may stay just offshore or wavering in/out
for a couple hours in the afternoon before shifting SW/W.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday Night through Saturday/...

Wednesday: VFR. Breezy. Chance SHRA.

Wednesday Night: Mainly VFR, with local IFR possible. Breezy.
SHRA, patchy BR.

Thursday: Mainly VFR, with local IFR possible. Breezy. SHRA,
slight chance TSRA.

Thursday Night: Mainly VFR, with local IFR possible. Chance
SHRA, slight chance TSRA, patchy BR.

Friday: VFR. Chance SHRA, slight chance TSRA.

Friday Night: VFR. Chance SHRA.

Saturday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

High confidence.

Winds and seas to remain below small craft advisory criterion
through Tuesday night. NW winds increase some to around 15 kt
tonight, then continue around 10-15 kt Tue and Tue night. Seas 4 ft
or less all waters.

Outlook /Tuesday Night through Saturday/...

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Seas locally approaching 5 ft. Slight chance of
rain showers.

Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Seas locally approaching 5 ft. Chance
of rain showers.

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Rain showers, slight
chance of thunderstorms.

Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, patchy fog.

Friday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain
showers.

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...Loconto/Mensch
AVIATION...Loconto/Mensch
MARINE...Loconto/Mensch