BOX issues Area Forecast Discussion (AFD) at Nov 12, 12:32 AM EST
524
FXUS61 KBOX 120532
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1232 AM EST Thu Nov 12 2026
.WHAT HAS CHANGED...
Gale watches issued for our open waters Thursday night through
Friday night. Mainly a widespread cold rain expected later Thursday
into Friday...but some minor wet snow accumulations are possible too
mainly in the high terrain.
&&
.KEY MESSAGES...
- A few showers possible across the interior near daybreak Thu.
Otherwise...a widespread cold rain focused late Thu into Fri.
Rain may flip to or mix with wet snow with the greatest risk
for that in the high terrain. Any snow accumulations look
minor at this time.
- Cool with mainly dry conditions Saturday through early next week.
&&
.DISCUSSION...
KEY MESSAGE 1...A few showers possible across the interior near
daybreak Thu. Otherwise...a widespread cold rain focused later Thu
into Fri. Rain may flip to or mix with wet snow with the greatest
risk for that in the high terrain. Any snow accumulations look minor
at this time.
Low pressure across the north central plains will shift eastward
tonight and emerge off the mid-Atlantic coast Thu. This low will
intensifies as it tracks near or inside the Benchmark into Friday.
We will break things down in much greater detail below.
As the surface low moves east tonight...mid/high level cloudiness
will begin to overspread the region. As the system approaches the
mid-Atlantic a S-SE low level jet will develop near daybreak across
the interior. This may result in some lower clouds along with a few
showers developing at this time as well. As this low pressure system
emerges off the coast...a modest E low level jet will develop during
the day Thursday. However...model soundings indicate that there is a
lot of dry low level air hanging around along the coastal plain...so
much of Thu may end up dry/cloudy with just a few spot showers.
Therefore...bulk of showers on Thu likely confined to the interior
for much of the day and amounts on the lighter side.
The steady/widespread rain will overspread the region Thu after 4-5
pm into the evening hours as deeper forcing/moisture arrives. This
will be a result of the surface low pressure intensifying as it
passes near or just inside the Benchmark into Fri.
Therefore...expect a cold rain for much of the region Thu night into
Fri. The question then becomes do thermal profiles become cold
enough for the rain to flip to a period of wet snow. Thermal
profiles are very marginal and the exact track of the mid level
centers along with precipitation intensity will determine if this
happens. Right now the greatest potential for this is across the
interior high terrain...mainly the east slopes of the
Berks/Worcester Hills. However...some of the guidance especially the
REFS indicate a track further south. This actually brings the
greater risk of wet snow further south into the CT/RI Hills. In
fact...there is even a low risk for rain to briefly mix/change with
wet snow even right the I-95 corridor. We should have a better idea
on this potential in the next 24 hours...but regardless any impacts
will likely be rather limited at this point. A coating to 2" of
slushy wet snow is a possibility in the high terrain with a low risk
of 3". Greatest risk for this would be at elevations near or above
800 feet and particularly near 1500 feet. Of course this will be
dependent on the track of the 700 mb low pressure system and if
precipitation rates can be heavy enough.
The other story on Friday will be the unseasonably cold
temperatures. Given N low level flow along with clouds and
precipitation...daytime temperatures will generally be in the 30s to
the lower 40s! Bulk of the precipitation should wind down later
Fri...but a few left over showers can not be ruled out near the
coast Fri night.
KEY MESSAGE 2...Cool with mainly dry conditions Saturday through
early next week.
The surface low pressure system slowly shifts further eastward into
the Atlantic Saturday. The bulk of the precipitation will have
exited with the low. While it will likely be dry in most areas,
residual moisture flow may support some isolated/"pop-up" showers. A
below normal airmass will be positioned across the region supporting
highs in the mid to upper 40s with the higher terrain areas in the
upper 30s to low 40s. Breezy NW winds make temperatures feel more
like the mid 30s to low 40s. Expect a chilly night Saturday night
with temperatures falling into the 20s and 30s. High pressure slowly
builds in from the west Sunday into early next week bringing a
period of dry conditions. Another breezy cool day Sunday with winds
decreasing by Monday as the pressure gradient relaxes. Temperatures
slowly moderate closer to seasonable values Tue/Wed.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update...
Through 12Z...High confidence.
VFR. Light and variable winds. One round of -RA moving through
CT/central MA exits by 10z but another round of -RA is then
moving into western MA/CT.
Thursday...High confidence.
VFR to start, lowering to MVFR after 18Z with -RA overspreading
the region. IFR possible at ORH after 18z. NE winds 10-15 kts,
then gusting 20-25 kts at times after 18z. Periods of 25-30 kt
gusts possible across Cape and Island terminals after 18z.
Thursday night...Moderate confidence.
MVFR/IFR in -RA, with -SN possible at ORH toward 12z. NE winds
10-15 kt gusting 20-30 kt.
Friday...Moderate confidence.
MVFR/IFR in -RA and -SN (for ORH). Precipitation exiting south
by 00z Sat.
KBOS Terminal...High confidence in TAF through 18z, then some
uncertainty on exacting timing arrival of MVFR and rain in the
afternoon.
KBDL Terminal...High confidence in TAF through 18z, then some
uncertainty on exacting timing arrival of MVFR and rain.
Outlook /Saturday through Monday/...
Saturday: Mainly VFR, with local IFR possible. Breezy. Slight
chance RA.
Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Sunday: VFR. Breezy.
Sunday Night through Monday: VFR.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Friday night...
* Gale Watch for the open waters Thu night through Friday night
The main forecast concern is low pressure which will emerge off the
mid-Atlantic coast. In response...the pressure gradient will
increase and have hoisted Gale Watches for our open waters Thu night
through Fri night for the potential of N-NE wind gusts up to 35
knots. Seas will also become quite rough. Have also hoisted small
craft advisories for Boston Harbor/Narragansett Bay during this
time.
Outlook /Saturday through Monday/...
Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 8 ft. Chance of rain.
Saturday Night: Winds less than 25 kt. Rough seas up to 8 ft.
Chance of rain.
Sunday: Winds less than 25 kt. Areas of rough seas. Slight
chance of rain.
Sunday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 6 PM this evening to 7 PM EST Friday
for ANZ230-236.
Gale Watch from late tonight through Friday evening for
ANZ231>235-237-255-256-282-283.
Gale Watch from this evening through Friday evening for ANZ250-
251-254-280-281.
&&
$$
DISCUSSION...Frank/Mensch
AVIATION...BW/McMinn
MARINE...Frank/Mensch
Source: BOX issues Area Forecast Discussion (AFD) at Nov 12, 12:32 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202611120532-KBOX-FXUS61-AFDBOX)
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