BOX issues Area Forecast Discussion (AFD) at Sep 26, 1:21 PM EDT601
FXUS61 KBOX 261721
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
121 PM EDT Fri Sep 26 2025
.SYNOPSIS...
Mainly dry and warm today with increasing sunshine as a front
moves to the east. Other than a risk of some showers late
Saturday night into Sunday morning, continued warm and dry
weather this weekend into early next week. Then a strong cold
front will deliver a fall airmass Wednesday and Thursday with
much cooler temperatures.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:
* Warm and humid today with increasing sunshine
* Low risk for a brief shower late in the day in the interior
Weak front moves to the east this morning but stalls near the coast.
However, enough mid level drying moving in from the west will lead
to clouds giving way to partly to mostly sunny skies from west to
east. A fairly robust shortwave and pocket of cooler temps aloft
moves into the region late in the day. Some of the hi-res CAMs do
show a few widely scattered showers developing in the interior which
can't be ruled out, but otherwise dry conditions. Not much low level
cooling today with 925 mb temps 18-19C and westerly flow at the
surface so expect highs to reach upper 70s to lower 80s. It will
remain humid as dewpoints start out in the mid-upper 60s in the
coastal plain with only a slight drop in the afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Key Messages:
* Clearing and comfortably cool tonight
* Warm and dry Saturday
Mid level shortwave moves offshore this evening followed by clearing
skies with light winds. Decent radiation cooling will allow temps to
fall into the low to mid 50s across much of the interior, with upper
50s to lower 60s closer to the coast. Elevated dewpoints combined
with cooling may lead to some patchy late night fog developing.
Weak high pres will build across New Eng Sat maintaining dry
weather, although high clouds will begin to overspread the region
from the south from south to north during the afternoon. Another
warm day as 925 mb temps 17-18C. Highs will reach the upper 70s, but
a bit cooler near the coast as sea-breezes develop. Dewpoints
expected to be in the upper 50s and lower 60s so still a tad humid,
especially closer to the south coast.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Key Messages:
* Chance of showers late Sat night into Sunday morning, especially
near the south coast
* Mainly dry Mon through Thu
* Above normal temps Sun through Tue, then turning much cooler Wed
and Thu
* Humberto will remain offshore next week, but will result in
increasing surf and rip currents Tue and especially Wed
Uncertainty remains Sat night into Sun with northern extent of sub-
tropical moisture. Confluent flow aloft complicates matters as there
will likely be a sharp cut off on the northern edge of the precip
shield. GFS is still the furthest north of the global guidance but
ECMWF has crept northward a bit. Canadian and UKMET keep moisture to
the south as does the NAM. Based on GEFS and EPS ensemble guidance,
there is some risk for showers getting into SNE late Sat night and
early Sun, especially near the south coast but confidence remains
below normal given expected sharp northern gradient to the precip.
Even if showers do reach SNE they will be moving out by Sun morning
and much of the rest of the day is expected to be dry with some
sunshine developing from N to S in the afternoon.
Mon looks warm and dry with potential for 80 degrees then a potent
northern stream trough will drop south from eastern Canada through
midweek and will serve to deflect Humberto to the east Tue-Wed as it
is forecast to remain well offshore. However, it will likely bring
increasing swell and high surf to the beaches Tue and especially Wed
with highest surf along the south coast. This trough will bring a
dry cold front southward across the region on Tue and will keep
another potential tropical cyclone across the SE US from advancing
northward with tropical moisture remaining well to the south.
Warm weather will linger into Tue, then much cooler airmass settles
south across SNE Wed and Thu in post-frontal airmass as strong high
pres builds to the north with NE flow developing.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through 00z...
VFR. Blend of clouds, diurnal SCT to BKN Cu developed 030-050 across
interior of southern New England. Cu fades this evening. Winds are
west to northwest 8 to 12 knots, with infrequent gusts to 18 knots.
Overnight...High Confidence.
VFR, mainly clear skies will give way to patchy valley fog and IFR
conditions (~004) towards the second-half of the overnight. Low
confidence in extent of development, will mention a "FEW" group for
the prone terminals; ie KBED & KBAF. For now, will omit from KBDL.
Northwest winds are 5 to 10 knots, becoming calm.
Saturday and Saturday Night...High Confidence.
Mid-level VFR clouds (050-080) during the day, increasing low-level
clouds (015-030) for the south coast, Cape, and Islands during the
overnight, resulting in areas of MVFR ceilings. Sea-breeze possible
on Saturday for coastal terminals and a light south/southeast wind
overnight.
KBOS Terminal...High confidence.
VFR. Breezy wind W to NW 10 to 15 knots today, then overnight less
than 8 knots. Sea-breeze develops for Saturday.
KBDL Terminal...High confidence.
There is a low probability for fog to develop during the second-half
of the night, which could lead to a brief period of IFR condition
early Saturday morning.
Outlook /Saturday Night through Tuesday/...
Saturday Night through Sunday: VFR. Slight chance SHRA.
Sunday Night through Tuesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Friday through Saturday Night...High Confidence.
Cold front moves off shore today, shifting wind direction from the
southwest to the northwest during the first-half of the overnight. A
weak area of high pressure develops on Saturday and wind direction
becomes northeast to east/northeast. Throughout the forecast period
wind speeds are generally less than 10 knots, with gusts below 15
knots. Seas today are 3-4ft and lowering Saturday between 1-3 ft.
Mostly dry during this period, a few showers are possible across the
southern waters late Saturday night through early Sunday.
Outlook /Saturday Night through Tuesday/...
Saturday Night through Sunday: Winds less than 25 kt. Chance of
rain showers.
Sunday Night through Monday: Winds less than 25 kt.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Tuesday: Winds less than 25 kt. Local rough seas.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...KJC
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...KJC
AVIATION...Dooley/RM
MARINE...Dooley/RM
Source:
BOX issues Area Forecast Discussion (AFD) at Sep 26, 1:21 PM EDT----------------
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