739
FXUS61 KBOX 191127
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
727 AM EDT Thu Sep 19 2024

.SYNOPSIS...
Rain chances increase from south to north tonight into tomorrow,
with the best chances across the Cape and Islands decreasing
significantly to the north and west. Rain chances continue
through the first half of the weekend, highest over the Cape
and island. Gusty northeast winds will keep temperatures near or
below normal for much of the region tomorrow into the weekend.
Next chance of rain comes around mid week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Tweaked precipitation timing based on the last few runs of the
HRRR and the NationalBlend. This lined up well with regional
radar data. Brought temperatures back in line with latest
observations as well. Overall theme of the forecast remains
unchanged.

Previous Discussion...

Area of low pressure south of southern New England has stalled
due to a blocking area of high pressure centered off the coast
of Nova Scotia. This feature will dominate the weather pattern
in southern New England through the weekend. Persistent
northeast winds will support unsettled weather and cloudiness
over the coastal areas through at least Friday afternoon. Today,
expect steady periods of rain over portions of southeastern MA,
Cape Cod, and The Islands. Some uncertainty with respect to how
far north and west shower activity will extend, but thinking
roughly the I-95 corridor will be the boundary between wet and
dry. Cloudiness and onshore flow will support cooler
temperatures in the upper 60s to low 70s this afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Tonight and Tomorrow

Little change in the overall pattern through tomorrow.
Temperatures cool to the low 60s overnight with persistent
northeast winds and continued shower activity across eastern MA,
RI, and especially Cape Cod and The Islands. Northeast winds
strengthen into tomorrow afternoon with some gusts from 20 to 30
mph possible. High temps in the mid to upper 60s across eastern
MA and RI while the CT RIver Valley will be a bit warmer in the
low 70s. While there will be considerable cloudiness across
southern New England through Friday afternoon, locations out
west could see a few breaks of sun and should stay clear of the
shower activity associated with the offshore low.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* Rain chances linger into Saturday, especially across eastern
  MA. Trending drier late this weekend.

* Temperatures will trend below normal with the lowest on Sunday
  before steadily increasing next week.

* Minor coastal flooding possible along the east coast of MA
  during Saturday afternoon`s high tides.

Guidance starting to come into better agreement with some of the
forecast details into this weekend. However, that is not to say
that all uncertainty has been resolved. Southern New England
will still be between a large high pressure trying to nudge
south from eastern Canada and a lingering low pressure well SE
of our region. Where the northern edge of the steadier
precipitation will be something to monitor with later forecasts.
Still have the greatest confidence in rainfall lingering across
eastern MA, and especially the Cape and islands.

Eventually, the high pressure to the north will wind out,
driving the low pressure farther offshore and returning dry
weather early next week.

Near normal low temperatures with below normal high temperatures
expected during this portion of the forecast.

Gusty NE winds through this weekend will result in rough seas.
Given existing higher astronomical tides, some minor coastal
flooding is possible during the Saturday afternoon high tide.
Much will depend on how much water can retreat during the Friday
night low tide along the east coast of MA.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

Today..High Confidence in trends

Steady northeast winds will support LIFR/IFR conditions for
most of the day. Some improvements to MVFR ceilings possibly by
mid-afternoon. Interior terminals remain VFR with low chances
for any precipitation.

Tomorrow Night... Moderate Confidence

Rain continues over the eastern terminals with IFR/MVFR ceilings
near 1000 feet. Some MVFR vsbys possible in SHRA. Some
uncertainty in westward extent of lower ceilings, especially at
ORH which will be close to the transition from MVFR to VFR
ceilings. VFR continues at BAF/BDL.

Friday...

More MVFR/IFR ceilings and showers at the eastern terminals.
Northeast winds increase to 15 to 20 knots at coastal terminals
and 10 to 15 knots across the interior. Cape/Islands terminals
could see gusts from 25 to 30 knots.

KBOS TAF...High Confidence in trends. Moderate confidence in
timing.

KBDL TAF...High confidence in TAF.

Outlook /Friday Night through Monday/...

Friday: MVFR/IFR conditions possible. Windy with local gusts up
to 30 kt. Chance SHRA.

Friday Night: Mainly VFR, with areas IFR possible. Breezy.
Chance SHRA.

Saturday: Mainly VFR, with local IFR possible. Windy with local
gusts up to 30 kt. Chance SHRA.

Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.

Sunday: Mainly VFR, with local MVFR possible. Windy with local
gusts up to 30 kt. Slight chance SHRA.

Sunday Night through Monday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Friday

Marine conditions deteriorate over the next 48 hours as an area
of low pressure meanders south of the coastal waters. Northeast
winds from 15 to 25 knots with gusts up to 25 knots today will
increase on Friday with some gale force gusts possible.
Confidence in widespread gale force gusts is low at this time,
so no gale warnings are in effect, but Small Craft Advisory will
be in effect likely through much of the weekend. The persistent
northeast winds will also result in building seas over the east
coastal waters with significant wave heights rising to 8 to 10
feet by Friday afternoon. High surf advisories will likely be
needed for eastward facing shorelines. Furthermore, there will
be a risk for minor coastal flooding for several high tide
cycles through the weekend.

Outlook /Friday Night through Monday/...

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 10 ft. Rain showers likely.

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 10 ft. Chance of rain
showers.

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 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 11 ft. Chance of rain
showers.

Sunday: Strong winds with gusts up to 30 kt. Rough seas up to
11 ft. Slight chance of rain showers.

Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft.

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 11 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents through this evening for MAZ007-019-020-
     022>024.
RI...High Risk for Rip Currents through this evening for RIZ006>008.
MARINE...Small Craft Advisory from 1 PM this afternoon to 8 PM EDT
     Friday for ANZ231-251.
     Small Craft Advisory until 8 PM EDT Friday for ANZ232>235-237-
     254>256.
     Small Craft Advisory until 8 PM EDT Friday for ANZ250.

&&

$$

SYNOPSIS...Belk/RM
NEAR TERM...Belk/RM
SHORT TERM...RM
LONG TERM...Belk
AVIATION...Belk/RM
MARINE...Belk/RM