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000
FXUS61 KBOX 180520
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
120 AM EDT Thu Apr 18 2024

.SYNOPSIS...

Cloudy, much cooler, with scattered light rain continuing for
Thursday. Dry and seasonable for much of Friday with high
pressure in control. A cold front brings another round of light
rain showers Friday night into Saturday morning. Dry for the
rest of Saturday with gusty winds. The dry stretch of weather
continues into early next week with the next chance of wet
weather Tuesday night and Wednesday as a frontal system
approaches.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

935 PM Update...

* Showers mainly southwest of an ORE-PVD-ORH line overnight
* Low temps in the lower to middle 40s

Previous forecast is on track. 850 MB warm front will generally
remain across southwest MA & CT overnight with a mid level ridge
axis blocking its eastward progress. This will confine most of
the showers to the southwest of an ORE-ORH-PVD line overnight.
To the east of this region...nothing more than perhaps a few
brief light showers/sprinkles with the majority of the
overnight hours featuring dry weather. The clouds will keep low
temps mainly in the lower to middle 40s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...

Highlights:

* An easterly wind will lead to a much cooler day, a few showers are
  possible, though a washout is not expected.

Mid-level ridge for Thursday, though a shortwave passage will bring
our a few showers, not a washout by any means. At this point, kept
POPs around 30 ~ Chance Rain. The more noticeable difference is the
east wind, allowing for a raw/cool feel. High temperatures along the
immediate coast are in the middle to upper 40s. Elsewhere, highs are
lower and middle 502. Higher elevations in western Massachusetts are
the coldest in the lower 40s.

East wind are 10 to 15 mph, with gusts along the coast to 25 mph.

Precipitation chances come to an end overnight, though clouds and on
shore flow does continue into the overnight hours. Do think spots
along the eastern coast could see spot drizzle, but didn`t have the
confidence to include it in the WX GRID. Guidance this afternoon
remained split on how much low level moisture would linger, so OPT
to leave it out. Similar to the night before, our temperatures are
in the upper 30s and low 40s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

Key Points...

* Mainly dry and seasonable Friday

* Scattered showers Fri night into early Sat followed by mild and
  breezy conditions Sat afternoon

* Dry conditions return for Sun into Tue. Cooler Sun, then milder
  Mon and Tue

* Shower chances increase by Wed

Details...

Friday into Saturday...

Mid level shortwave departs by early Fri with weak shortwave ridging
following. This will bring dry conditions for much of the day,
although next shortwave and cold front will be approaching from
western NY in the afternoon. We should see some sunshine develop,
especially in eastern New Eng but trend will be for increasing cloud
cover in the afternoon. Low risk a few showers could spill into
western MA by days end but bulk of shower activity should hold off
until Fri night. Near normal temps Fri.

Weak cold front moves into SNE Fri night with modest increase in
moisture as PWATs increase to near 1" ahead of the front. This
should bring a round of scattered showers Fri night which will
likely linger into Sat morning, especially in the east as the front
gets hung up near the coast. Then drying out in the afternoon with
somewhat gusty W winds developing in the afternoon. Given the colder
airmass will be lagging to the NW assocd with a secondary cold
front, it should be a mild afternoon with temps reaching the 60s,
and some upper 60s possible in SE MA.

This secondary cold front is tied to a decent shortwave passage late
Sat-Sat evening. The column is drying at this time but there may be
a brief window for a few showers with the front late Sat in the
interior. Did not include in the forecast at this time as confidence
is low, but will re-evaluate in later forecasts.

Sunday through Wednesday...

Cooler post-frontal airmass settles in on Sunday with seasonable
temps and abundant sunshine. Dry weather continues Mon and Tue with
moderating temps. A potent shortwave is forecast to move off the mid
Atlc coast Mon night-Tue but global ensemble guidance keeps moisture
well to the south with a minimum in PWATs across SNE. Next northern
stream shortwave approaches from the west Tue night and Wed. Timing
and amplitude of the system is uncertain but risk for showers will
increase by Wed.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...

Forecast Confidence Levels:

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

06z TAF Update...

Today...High Confidence.

Mainly VFR conditions prevail east of the CT River
Valley despite an abundance of mid level cloudiness and a few
showers at times. Marginal MVFR conditions near and west of the
CT River Valley. The scattered showers will be mainly focused
across the interior today...but a few brief showers will
probably survive into eastern MA although the majority of the
day should be rain free in that region. ENE winds 5 to 15 knots
with gusts of 20-25 knots developing near the south coast and
Islands.

Tonight and Friday...High Confidence.

Mainly VFR conditions despite plenty of mid level cloudiness. NE
winds 5 to 15 knots tonight becoming SE on Fri.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Friday Night through Monday/...

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

Saturday: VFR. Breezy. Slight chance SHRA.

Saturday Night through Sunday Night: VFR. Breezy.

Monday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Thursday Night...High Confidence.

* Small Craft Advisory for Block Island Sounds and waters south
  of Block Island tonight and into Thursday.

A weak wave of low pressure drops southeast across the mid-
Atlantic with high pressure moving across the eastern Canadian
Maritimes into Thursday. A few spot showers and perhaps a
rumble of thunder possible. This will result in SE winds this
evening shifting to the E by Thursday morning at speeds of 10
to 15 knots. Some gusts up to 25 knots with marginal 5 foot seas
for the southwest waters, hence the newly issued Small Craft
Advisory through much of Thursday. Seas may remain elevated
enough to warrant the advisory to be extended into Thursday
night for the waters south of Block Island. Future forecasts may
want to include this.

Outlook /Friday Night through Monday/...

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

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

Saturday: Winds less than 25 kt. Chance of rain showers.

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

Sunday through Monday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 5 AM early this morning to 5 PM EDT
     this afternoon for ANZ237.
     Small Craft Advisory from 5 AM early this morning to 8 PM EDT
     this evening for ANZ256.

&&

$$

SYNOPSIS...KJC/Dooley
NEAR TERM...Frank
SHORT TERM...Dooley
LONG TERM...KJC
AVIATION...Frank/KJC
MARINE...KJC/Dooley