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045
FXUS61 KBOX 161750
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
150 PM EDT Mon Sep 16 2024

.SYNOPSIS...
Strong area of high pressure over the northeast will continue
the dry and quiet weather through Tuesday, with above normal
temperatures. A broad low brings our next shot of unsettled
weather around late Wednesday and/or Thursday. Risk for showers
greatest along the south coast. Turning drier late in the week
and into the weekend, with near to cooler than seasonable
temperatures.

&&

.NEAR TERM /THROUGH TONIGHT/...
10 AM Update:

Another quiet morning weather-wise thanks to to high pressure in
place across the region. Satellite imagery shows the remaining
areas of valley fog in the CT river valley eroding out this
morning. The forecast remains on track for a warm and mainly
sunny day across southern New England. No changes were needed
for this update.

230 AM Update:

Broad area of high pressure extends from Nova Scotia SSW
through Southern New England and on SW into NJ/NE PA area early
this morning. As has been the case for much of the past week,
excellent radiational cooling conditions driven by clear skies
and calm winds has brought rather cool temperatures, which range
into the low to mid 50s. The exception is over Boston where
current temps are in the low 60s owing to enough of a light
south wind. Fog and stratus has not been nearly as extensive as
was the case 24 hours ago, although we could still see some
patchy development in the CT Valley and into portions of
southeastern MA. Thus far, coverage has not been persistent
and/or extensive enough to warrant any fog statements for
prospective morning commuters, and nor it is not expected to
become widespread, but we will be monitoring its coverage as we
move toward sunrise.

So for today, we`re still expected yet another pleasant Monday
weatherwise, with high pressure both at surface and aloft
maintaining dry weather. Full sun is expected, although with an
increasing canopy of cirrus particularly over western MA, CT
and into western RI late in the day. We still will see
seabreezes on both southern and eastern coasts by late morning
with speeds near 10 mph. This will keep coastal areas cooler in
the 70s, but inland highs should reach again into the lower to
mid 80s.

&&

.SHORT TERM /TUESDAY/...
230 AM Update:

Tonight:

Still under influence of high pressure for tonight, so we are
still expecting another night of dry weather. Even though there
will be an increasing canopy of high level moisture/cirrus
clouds, very good radiational cooling again is expected.

With the surface ridge axis over the southern third of Southern
New England, a southerly return of dewpoints mid 50s to low 60s
being advected into the cooling airmass should support
development of fog. Thinking the fog/stratus coverage ends up
being greater near and south of the CT-RI-southeast MA Route 44
corridor, although it is possible it may slip a little further
north. I phrased as areas of fog in the Wx grids as most model
visby solutions show reduced visbys in this general area. With
little significant change in airmass, used bias- corrected MOS
lows in the upper 40s to mid 50s.

Tuesday:

Early-day fog and stratus could take until mid-morning to fully
dissipate and/or shift into the waters. However most of the rest
of the day will again be high and dry, although sun could be
more filtered than prior days, as the high cloud canopy
continues to advect northward from what is designated as
Potential Tropical Cyclone 8 near the Carolinas. Highs mainly in
the 70s to low 80s, with cooler mid 70s high temps due to
onshore flow/seabreezes near both coasts.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Highlights:

* While cloudy, Wednesday is trending drier with arrival of rain
  late afternoon or as late as overnight. Shower chances continue on
  Thursday with considerable uncertainty Friday into this weekend.

* Cooling trend with highs in the 70s late week and then 60s for the
  upcoming weekend.

Tuesday Night through Friday...

The next chance of rain could come from Potential Tropical Cyclone
Eight, which is forecast to develop into Helene (heh-LEEN) sometime
today. Not anticipating any direct impacts from this system, as it
is forecast to move from the waters off the coast of the Carolinas
inland near the border of South Carolina and North Carolina late
this evening.

Did reduce POPs from NBM on Tuesday night into early Wednesday with
the most recent update due to the later arrival time of the surge of
moisture. While clouds likely increase from south to north during
the overnight, leading to slightly warmer nighttime lows, do think
the first-half of Wednesday remains dry, albeit cloudy. Warmest
temperatures are further north, here there should be a little more
in the way of filtered sunshine, mainly northern Massachusetts along
the border with Vermont and New Hampshire - highs here are in the
upper 70s and low-80s, while the south coast of Rhode Island and
Massachusetts are in the low-70s.

While there is some increasing confidence for rain late this week
there still remains a great amount of uncertainty with the timing
and total QPF. 00z guidance shows a staggered approach to the time
of arrival, with GEM coming in earliest with precipitation, around
21z Wednesday afternoon, GFS 03z on Thursday, and ECMWF shortly
there after at 06z Thursday. With the surface low in our vicinity it
continues the chance for showers into Thursday and possibly into
Friday. But at this point, Friday could trend drier, it is just too
soon to say given the spread in the model guidance.

As for rain amount`s, per GFES ensemble a 30% to 50% chance for
totals AOA 0.5" south of the Mass Pike, with 20% to 30% AOA 1.0"
cross Cape and Islands. ECMWF ENS has very similar probabilites for
areas AOA 0.5" though slightly more widespread AOA 1.0" across
Connecticut, Rhode Island, and southeast Massachusetts.

Cooler weather late this week, with highs on Thursday and Friday
only reaching the low and mid-70s. Overnight lows bit warmer on
either side of 60F.

Saturday and Sunday...

The uncertainty continues into this weekend, as high pressure over
eastern Quebec expands south, but could interact with the remains of
our sub-tropical low-pressure system. This could lead to on shore
flow and feeding moisture into southern New England. Not expecting a
washout, but potential remains for showers along with below normal
temperatures with highs in the 60s and lows in the 50s.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

18z TAF:

Today: High confidence.

VFR conditions this afternoon. Light south winds in the
interior, with seabreezes around 10 kt at BOS and at PVD.
Seabreezes become light southerly by 22-00z.

Tonight: High confidence overall, though moderate for CT-RI-
southeast MA.

VFR along and north of the Mass Pike. IFR fog and stratus are
likely to develop over the waters by early evening and then
expand northward to the Route 44 corridor in CT-RI-Southeast MA
as the night progresses. BDL, PVD, airports are most at risk
for fog/stratus but the exact timing and northward extent is
still unclear. Potential for fog/stratus for the Cape Cod
airports has decreased, so didn`t include in the TAF. Can`t
rule out the low chance these conditions make it far enough east
to impact the Cape. Light winds, calm at times.

Tuesday: High confidence.

Fog and stratus from the overnight south of the Mass Pike
gradually diminishes in the 12-15Z timeframe. VFR thereafter.
SE winds around 4-8 kt.

KBOS TAF...High confidence in TAF. VFR. SE seabreeze around 10
kts, becoming southerly 22-00z.

KBDL TAF...High confidence in TAF. VFR with light winds. IFR
fog/stratus could develop around 08-10z Tue.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Mainly VFR, with local MVFR possible.

Wednesday through Wednesday Night: VFR. Chance SHRA.

Thursday through Thursday Night: Mainly VFR, with local MVFR
possible. Chance SHRA.

Friday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Forecaster Confidence Levels:

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

245 AM Update:

Through Tuesday: High confidence.

High pres over the waters will continue to result in favorable
boating conditions with winds below 20 kt, varying from E to S,
and seas 3 ft or less. Areas of marine fog expected to develop
over south coastal waters Mon night leading to reduced vsbys.

Outlook /Tuesday Night through Friday/...

Tuesday: Winds less than 25 kt.

Tuesday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers.

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

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Slight chance of rain showers.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Loconto/Dooley
NEAR TERM...Loconto/Mensch
SHORT TERM...Loconto
LONG TERM...Dooley
AVIATION...Dooley/Mensch
MARINE...Loconto/Dooley