BOX issues Area Forecast Discussion (AFD) at Oct 15, 7:47 AM EDT326
FXUS61 KBOX 151147
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
747 AM EDT Thu Oct 15 2026
.WHAT HAS CHANGED...
No significant changes.
&&
.KEY MESSAGES...
- Dry today with seasonably cool temperatures.
- Fast-moving system expected to bring periods of rain Friday,
followed by much colder and drier conditions Saturday.
- Quiet and seasonable weather Sunday through Tuesday.
&&
.DISCUSSION...
KEY MESSAGE 1...Dry today with seasonably cool temperatures.
High pressure settles in over the region today along with a notably
drier airmass. Initially breezy conditions early this morning will
wane heading into the late morning/early afternoon. A cooler, more
seasonable airmass moves overhead today, dropping 925 mb
temperatures from the 16-18C range to generally just below 10C. This
will be more supportive of highs back in the upper 50s and low 60s
across southern New England. Humidity also notably drops as drier
air moves in, dropping dew points into the 40s and PWATs to
generally around 0.25".
KEY MESSAGE 2...Fast-moving system expected to bring periods of rain
Friday, followed by much colder and drier conditions Saturday.
High pressure today drifts off to the east and offshore later
tonight ahead of a strong northern stream shortwave trough
progressing east through the Great Lakes and into the northeast.
Compared to last night's guidance, the timing for this front appears
to have slowed down slightly, though this is still expected to be a
quick moving system. The associated surface low is slated to track
through the Great Lakes region, deepening as it moves northeast and
reaching the 1000 mb mark (and possibly lower) by Friday morning,
centered over southeast Ontario. Ensembles are in strong agreement
with this threshold being crossed especially as it tracks into
northern NY and VT by early Friday afternoon. Deterministic global
guidance takes it to around 995 mb by the evening hours. Out ahead
of the low, a warm front is expected to track into the region which
will be the main driver for our first round of rain. Based on the
latest guidance, rain is expected to move in closer to the 4-8 AM
time range from west to east, spreading over the region. Once the
warm front moves through, the warm sector settles in overhead. 925
mb temperatures climb up again into the 16-18C range, especially in
the afternoon, and anomalous PWATs increase up to around 1.75" with
the moisture plume advected in by this system. Highs will be warmer
than that of Thursday given this warm sector overhead during the day
Friday, but not to the same level we saw Wednesday; highs will
likely top out in the upper 60s with some places brushing 70. With
the first round of rain out of the region by the afternoon, we're
left with a muggy, breezy, and mild day. Some showers during this
lull aren't out of the question, though, given the strong WAA.
Round two moves in toward the evening hours Friday ahead of the
low's strong cold front. This front will provide strong forcing in
an environment with bulk shear at 0-6 km expected to be at and above
50 kt. A southerly LLJ sets up over much of eastern MA, RI, reaching
40-50 kt at 925 mb and up to 60 kt over the region from the SW at
850 mb. CAPE values top out around 500 J/kg based on the latest CAMs
and global guidance, so while widespread severe weather is not
expected, some embedded thunderstorms are not out of the question.
With regards to rainfall totals, ensembles appear to have trended
totals down slightly, generally ranging between 0.30"-0.60".
Probabilities for totals reaching or exceeding an inch within
southern New England have dropped considerably, though the GEFS does
have a 20% chance across much of MA and into northern CT. Even with
these low probabilities, the chance that there could be some
convective features combined with these high PWAT values keeps the
chance for some locally higher rainfall totals in play.
Breezy winds are expected for Friday given the aforementioned LLJ,
though latest guidance has trended the intensity down slightly. This
appears to be driven by the presence of a low-level thermal
inversion noticeable in forecast soundings. Generally, gusts to 30
mph seem most likely, though the waters may very well see gusts to
the 35 mph range and higher given the warmer ocean temperatures.
As the cold front crosses southern New England Saturday morning,
strong CAA kicks off in its wake. 925 mb temperatures fall below 0C
heading by Saturday evening, and PWATs fall below 0.25" once more as
colder, drier air sets in. Lows Friday night fall into the 40s and
upper 30s (towards the high elevations). Highs Saturday may struggle
to reach the low 50s across the interior and lows Saturday night
will likely dip below freezing across the region, with the
exceptions being areas closest to the coasts and urban areas.
Though, those areas will likely be sitting just above freezing
overnight, with low 40s possible for the Cape and Islands. In the
midst of this colder air, strong NW winds prevail, gusting well into
the 30 mph range with some gusts to 40 mph not to be ruled out.
KEY MESSAGE 3...Quiet and seasonable weather Sunday through Tuesday.
High pressure builds in Sunday and a more seasonably cool airmass
moves into the region, and the tighter gradient between the strong
exiting low and approaching high pressure slackens. This will allow
winds to let up as well, diminishing slightly heading into the
second half of the weekend and the start of next week.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12Z TAF Update:
Thursday...High confidence.
VFR. Brief period of gusty/high winds between 12z-15z before
winds diminish through the rest of the day. Winds remain
generally NNW, then shift more NE to E in the afternoon/early
evening for coastal terminals.
Thursday Night...Moderate confidence.
Becoming MVFR to IFR with -SHRA moving in from west to east
between 06Z and 12Z. S-SW winds develop with gusts nearing 20 kt
closer to sunrise.
Friday...Moderate confidence.
IFR to LIFR with SHRA. Brief respite from SHRA possible in the
afternoon hours, though low ceilings continue. Will need to
monitor for the risk of some embedded TSRA and convective
features. Gusty S to SW winds up to 30 kt with higher gusts
possible near the coasts and higher elevations.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Friday Night through Monday/...
Friday Night: Mainly VFR, with areas MVFR possible. Windy with
gusts up to 30 kt. Chance SHRA.
Saturday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 30 kt.
Saturday Night: VFR. Breezy.
Sunday through Sunday Night: VFR.
Monday: VFR. Breezy. Slight chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Seas around 3-5 ft on most waters through today, with dry
weather and good visibility expected. Gusts should subside below
SCA criteria by late this afternoon.
A frontal system brings SW winds back into the SCA range on
Friday (25-30 kt), which will also bring periods of light to
moderate rain reducing visibility through Friday early evening.
A short period of small craft advisories will likely be needed
once the existing SCAs expiring Thursday afternoon expire.
Looking ahead into Friday night and into Saturday...a period of
strong northwest winds are forecast. We've issued a Gale Watch
on most waters for Friday night into Saturday, with seas
becoming increasingly rough at up to 12 ft. Dry weather is
expected by Saturday.
Outlook /Friday Night through Monday/...
Friday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 10 ft. Rain showers likely.
Saturday: Low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 10 ft. Chance of rain showers.
Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 10 ft.
Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Sunday Night through Monday: Winds less than 25 kt. Slight
chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for
ANZ230>234-250-251-254-255.
Gale Watch from Friday evening through Saturday evening for
ANZ230>237-250-251-254>256-280>283.
&&
$$
DISCUSSION...Hrencecin
AVIATION...McMinn
MARINE...Loconto/Hrencecin
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 15, 7:47 AM EDT----------------
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