BOX issues Area Forecast Discussion (AFD) at Oct 28, 7:18 AM EDT685
FXUS61 KBOX 281118
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
718 AM EDT Tue Oct 28 2025
.SYNOPSIS...
Canadian high pressure will result in cool temperatures through
Wednesday with scattered showers possible, mainly near and
southeast of I-95. Strong low pressure follows with a period of
heavy windswept rain for southern New England sometime Thursday
into Thursday night. A few showers may linger into Friday with
gusty winds possible. Drier weather is likely by Saturday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:
* Breezy NE winds, mainly for Cape/Islands with gusts 20-30 mph.
* Slightly below normal temperatures with a few showers possible
mainly southeast of I-95.
Details...
A high pressure system is expected to remain positioned over Quebec
with high pressure extending southward across the northeast U.S.
today. A weak wave passes well to the southeast during the day. This
will generate a more enhanced pressure gradient across southeast MA
with NE surface winds across southern New England. It will be
breezier for the Cape and Islands where the gradient is stronger,
with gusts 20-30 mph. Moist, cool northeasterly flow will help
generate some light ocean-effect showers across the eastern portion
of southern New England, especially across the Cape and Islands.
High temperatures will be mainly in the low to mid 50s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Key Messages:
* Cooler temperatures continue Wed with scattered ocean-effect
showers mainly near/southeast I-95.
Details...
Tonight:
Winds stay elevated across eastern southern New England overnight,
especially across southeast MA. Gusts up to 20 mph are possible for
the east MA with gusts 20-30 mph for SE MA (Cape/Islands). The
elevated NE flow will keep temperatures overall warmer than Monday
night. Lows stay in the 40s in east/southeast MA. Relatively cooler
for the interior with lows in the mid to upper 30s for most.
Wednesday:
Similar conditions prevail for Wednesday with another weak wave/low
pressure passing well off to the southeast of Benchmark. Expect
another day with breezy NE winds and scattered light ocean-effect
showers, mainly near/southeast of I-95. Temperatures remain slightly
below normal with highs in the low-mid 50s for most areas with some
upper 40s for the high terrain spots of the interior.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Key Messages:
* Period of heavy rainfall and gusty winds expected Thu into Thu
night.
* Brief nuisance street flooding possible & 30-50 mph gusts on
the coast
* Gradual clearing Friday with potential for gusty westerly
winds.
Details...
Anomalously deep shortwave digs southward over the SE CONUS and
ejects northeast Thursday morning. Continuing to see guidance
show cyclogenesis early Thursday over the Mid Atlantic. Earlier
model runs hinted at the potential for secondary cyclogenesis
near the coast but has since trended away from that outcome.
Additionally, moisture from Melissa may be transported northward
even as it appears likely that we will escape direct impacts
from the system. Forecasted integrated vapor transport from the
Center for Western Weather and Water Extremes (CW3E) shows
values approaching 1200 kg for a roughly 12-hour period Thursday
night into Friday. This efficient moisture transport combined
with ample forcing from a 50-60 kt low level jet may result in a
period of moderate to heavy rainfall Thursday night. DESI
indicates mean 6hr rainfall rates increasing to 1-1.5" for most
of the night Thursday. The saving grace is that the system does
look to be fairly progressive and with the upper level centers
passing to our west...the duration of heavy rain may be somewhat
limited.
In terms of impacts there are few changes to make from the
previous update. While the system will be progressive in nature,
most areas can expect a widespread 1-3" of rainfall. NBM 90th
percentile guidance shows a reasonable worse case scenario with
a widespread 2-4 inches of rain falling. We should note that
DESI is indicating some low probabilities of 4+ inches of rain
with this system. If we can get stronger secondary development,
that may increase that potential. So there is a low probability
of more significant flooding...but currently thinking this will
be more of the typical brief nuisance street flooding. Certainly
something to monitor over the next few days. By Thursday
afternoon, we may also see a period of 30-50 mph east southeast
wind gusts with the strongest near the coast. Thankfully we
aren't expecting a long duration strong wind event as the low
center quickly approaches from the southwest later Thursday
night.
Friday-Saturday...
Significant mid-level dry slot moves overhead Friday as low
pressure deepens nearly overhead so any lingering showers
should come to an end fairly quickly Friday morning. A few
showers could bubble up Friday afternoon underneath a cold pool.
There is also increasing potential for gusty westerly winds to
develop behind the exiting deep low pressure from the previous
system. A 40-50 kt LLJ positioned across the region within a
cold advection regime will support the potential for the
transport of stronger winds aloft down to the surface. Gusts
30-40 mph are possible Friday. Higher terrain/downslope effects
may support localized higher gusts 40-50 mph. Breezy to gusty
winds continue Saturday, though likely weaker than Friday as the
pressure gradient relaxes. Temperatures lean slightly below
normal for the weekend.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12z TAF Update:
Today: High confidence in TAF/trends but moderate on the timing.
Stratus layer at MVFR levels gradually expands westward through
today. Thinking MVFR bases predominate, but could trend more
VFR/MVFR borderline (SCT030/BKN040) at times during the morning
to noontime. Bases then start to lower but still in MVFR range
starting this afternoon. Could be some really spotty drizzle or
light rain underneath the stratus but more likely dry. Western
interior airports (BAF/BDL) stay in the VFR range all day. NE
winds around 12-15 kt with gusts 20-30 kt for eastern/coastal
areas, and around N/NE 10 kt for BAF/BDL.
Tonight...High confidence.
Mainly MVFR. Few showers across eastern terminals. Elevated NE
winds for coastal terminals 10-15 kts, stronger for Cape/Islands
with gusts 20-30 kts.
Wednesday...Moderate Confidence.
Pockets of MVFR, especially for Cape/Islands. Scattered ocean-
effect showers.
KBOS Terminal... High confidence in TAF.
KBDL Terminal... High confidence in TAF.
Outlook /Thursday through Saturday/...
Thursday: Mainly MVFR, with local IFR possible. Breezy. SHRA
likely.
Thursday Night: Mainly IFR, with areas MVFR possible. Breezy.
SHRA, chance TSRA.
Friday: Mainly VFR, with local IFR possible. Windy with gusts
up to 35 kt. Chance SHRA.
Friday Night: Mainly VFR, with local MVFR possible. Strong
winds with local gusts up to 40 kt. Slight chance SHRA.
Saturday: VFR. Strong winds with local gusts up to 40 kt.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Tuesday Night...High confidence.
Large high pressure anchored over Quebec will combine with a
few weak waves of low pressure passing well southeast of the
Benchmark to generate a strong enough pressure gradient to
result in NE wind gusts of 25 to 30 knots, with a few gusts up
to 35 knots possible right through Tuesday Night. Small Craft
Advisories continue for all open waters. We may briefly touch
gales, but continue to think small craft headlines are more
representative. The long NE fetch will result in rough seas as
well.
Outlook /Thursday through Saturday/...
Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 10 ft. Rain showers likely.
Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Rough seas up to 11 ft. Rain showers,
chance of thunderstorms. Areas of visibility 1 to 3 nm.
Friday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 16 ft. Chance of rain showers.
Friday Night: gale force winds with gusts up to 45 kt. Rough
seas up to 18 ft. Slight chance of rain showers.
Saturday: Moderate risk for gale force winds with gusts up to
45 kt. Rough seas up to 17 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for ANZ231>235-
237-250-251-254>256.
&&
$$
SYNOPSIS...Mensch
NEAR TERM...Mensch
SHORT TERM...Mensch
LONG TERM...Mensch
AVIATION...Loconto/Mensch
MARINE...Mensch
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 28, 7:18 AM EDT----------------
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