-- Discussion containing changed information from previous version are highlighted. --
165
FXUS61 KBOX 170509
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
109 AM EDT Tue Sep 17 2024

.SYNOPSIS...
An area of high pressure over the northeast will promote
continued dry and quiet weather through Tuesday, with above
normal temperatures. The next chance for rain comes late Wednesday into
Thursday, but the best chances remain confined to Cape Cod and the
Islands.  Otherwise mainly dry with mostly cloudy conditions and
blustery NE winds through the weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Southern New England continues to remain under upper level ridging
and surface high pressure for the near-term period. On current mid-
level water vapor satellite, potential tropical cyclone eight moving
across the Carolinas. For tonight, light southerly flow under the
ridge, will support sufficient moisture return tonight in the low
levels. With dry air aloft and ample radiational cooling, expect
fog to develop again overnight. Model soundings show shallow
moisture wedged under a temperature inversion. HREF guidance has
highlighted potential for fog/low stratus for areas across RI-
southeast MA around and south of the Route 44 corridor as well
as the CT River Valley (CT, MA). First indications of fog have
shown up south of the Cape and Islands slowly moving north.
Timing- wise, there is general agreement in areas of fog
developing after midnight, continuing through the early morning
hours. One thing to add is that there likely will be a layer of
upper level clouds tonight. In some cases, this could limit
radiational cooling and limit fog formation to the lower lying
areas and south coast. Low temperatures drop into the upper 40s
to mid 50s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Tuesday:

Tuesday morning, areas of fog will gradually improve through the
early morning hours. There may be lingering patchy light fog into
mid morning in spots as it slowly burns off. Remainder of the day
will be dry with warm afternoon temperatures in the upper 70s and
low 80s. Coastal areas will trend slightly cooler in the mid 70s
with onshore sea breezes developing mid-morning on the coasts.

Tuesday Night:

Tuesday night, a plume of moisture associated with the tropical
system advects northward. Cloud covers increases from south to
north. This will result in overnight low temperatures sightly warmer
than the previous couple nights in the low 50s to low 60s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Wed - Fri
Shortwave energy ahead of a cutoff low over the Carolinas
moves north into SNE. A weak coastal low will spin up under the
cyclonic vorticity aloft, streaming moisture into the region and
bringing our next chance for measurable precipitation. Guidance
remains relatively spread out on the potential for precip but has
generally trended drier for much of interior SNE, while the Cape and
Island stand the best chance for rain. The latest ensemble
probability for a half inch of rain from the GEFS shows 30-40% for
the Cape and Islands, while the interior is 10% or less through
Friday. Regardless of who gets rain, onshore flow will keep sky
conditions mostly cloudy to overcast through the end of the work
week, which will moderate high temperatures back into the low to mid-
70s.  Dewpoints through the end of the week stay in the low to mid-
60s, which will also help keep overnight lows mild in the low-60s.
Winds gradually increase from the ENE through Friday, becoming gusty
late Friday at 20-30mph.

Sat - Sun
Winds will continue to increase over the weekend as the
pressure gradient tightens due to being squeezed between low
pressure retreating to the south and high-pressure building from the
north.  Northeast winds are expected to gust 20-30mph, especially
near the waters.  The main impacts expected are rough seas and
strong rip currents heading into the weekend.  There could be minor
coastal flooding during multiple tide cycles starting Friday with
persistent NE flow and increasing astro tides.  Temperatures over
the weekend continue to cool into the upper 60s to low 70s with
partly cloudy skies.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

Through 12Z...High Confidence in Trends

Light southwest or light/variable winds persist this evening.
Fog already developing across portions of the south coast and
southeastern MA. Expect additional areas of fog to develop in CT
River Valley near BDL. Fog/low stratus will likely support some
areas of IFR/LIFR conditions through sunrise.

Today...High Confidence

IFR/LIFR fog/low stratus burns off by 14-15Z. VFR thereafter
with light south winds. Sea-breezes developing along the coast
by 16Z.

Tonight...High Confidence

More patchy fog development tonight with localized IFR vsbys.
MVFR/IFR ceilings over the south coast, Cape, and Islands.
Light and variable winds.

Tomorrow...High Confidence

VFR with shower chances increasing over The Cape/Islands by 00Z.
Light easterly winds 5 to 10 knots.

KBOS TAF...High confidence in TAF. VFR. SE seabreeze kick in
between 15-17z, 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 /Wednesday Night through Saturday/...

Wednesday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

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

Thursday Night: VFR. Chance SHRA.

Friday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA.

Friday Night: VFR. Breezy. Slight chance SHRA.

Saturday: Mainly VFR, with local MVFR possible. Breezy.
-- End Changed Discussion --

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Tuesday: High confidence.

High pressure over the waters will bring quiet 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
tonight into early Tuesday morning, leading to reduced
visibilities.

Outlook /Wednesday Night through Saturday/...

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

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

Friday: Winds less than 25 kt. Areas of rough seas. Chance of
rain showers.

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 8 ft. Slight chance of rain
showers.

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 8 ft.

&&

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

&&

$$

SYNOPSIS...Mensch/KP
NEAR TERM...Mensch/KP
SHORT TERM...Mensch
LONG TERM...KP
AVIATION...RM/KP
MARINE...Mensch/KP