342
FXUS61 KBOX 231809
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
209 PM EDT Mon Sep 23 2024

.SYNOPSIS...
Weak high pressure will build over our region into Tuesday, but
continued onshore winds should keep cloudiness in place,
especially near the coast. Rain chances return late Wednesday
into Thursday as a front moves through the area. Dry and warmer
weather looks to follow through the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Area of light showers assocd with a weak shortwave are moving
into SE NY and SW CT and will remain mostly south and west of
Hartford county this afternoon where deeper moisture present.
Further E across CT drier air in low-mid levels should prevail.
Meanwhile a few very light showers continue to back in from the
ocean across eastern MA into RI so can`t rule out a spot light
shower or sprinkle into this evening.

Weak upper trough moves east of New Eng tonight followed by mid
level ridging moving in from the west. Meanwhile, surface ridging
will build south into SNE. Surface and deeper layer ridging will
promote large scale subsidence with wedge of drier air from the
north resulting in dry conditions. Varying amouts of cloud cover
expected and patchy late night fog possible in the CT valley. Lows
will range from the upper 40s interior to low-mid 50s coastal plain.
Still a bit breezy over the Cape/Islands with gusts to 20 mph at
times.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Tuesday...

Very little change in the pattern with surface and upper level
ridging in place. Wedge of somewhat drier air in the column
persists with deeper moisture remaining to the west. Expect
another mainly dry day, although considerable cloudiness again
with a low risk for a few light showers or sprinkles from
persistent easterly flow and low level moisture. Very similar
low level temps to today will lead to highs mid-upper 60s to
around 70 in parts of the CT valley, with E-NE winds 10-15 mph.

Tuesday night...

Upper level ridge axis shifts to the east as a weak shortwave
moves to the north and west. Deep moisture plume assocd with the
shortwave approaches but bulk of showers will remain to the
west where best moisture and forcing is located. Just a low
risk for a shower spilling into western MA late at night. Lows
will range from the upper 40s to mid 50s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Key Points:

 * Showers possible late Wed-Thu with passing front
 * Dry and warmer pattern follows through early next week

Main focus is on Wed-Thu time frame as deepening upper trough and
its associated fronts cross region bringing our next chance at any
appreciable rainfall which is certainly needed despite parts of SNE
receiving a good dose of rain over weekend. Not seeing a lot of
parameters that suggest much in way of rainfall, more like 0.25 to
0.50 inch this time, and even convective indices are not overly
impressive or favorable for thunderstorms, though a few cannot be
ruled out due to decent lapse rates and limited surface-based CAPE.

Once this system departs Thu, it appears we`re in for another
stretch  of dry and seasonably warm weather into  at least early
next week. Broad upper ridge builds from Great Lakes into New
England which takes appearance of an omega block, meaning ridge
doesn`t go anywhere for several days and maintains troughing over
middle of country and over north Atlantic.

&&

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

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

18z TAF update...

Through Tuesday...High confidence.

Persistent conditions with mainly VFR cigs which may at times
lower to MVFR, especially east of CT valley. Patchy late night
fog possible in the CT valley. E-NE wind 5-15 kt, with gusts to
20-25 kt at ACK.

Tuesday night...Moderate confidence.

Cigs expected to lower to MVFR with areas of late night IFR
possible. But uncertainty with areal coverage of lower cigs.
E-NE wind less than 10 kt.

BOS TAF...High Confidence in TAF. Mainly VFR cigs but occasional
SCT MVFR layer may go BKN at times.

BDL TAF... High Confidence in TAF.

Outlook /Wednesday through Friday/...

Wednesday: Mainly VFR, with areas MVFR possible.

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

Thursday: Mainly VFR, with areas IFR possible. Slight chance
SHRA.

Thursday Night through Friday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Tuesday night...High Confidence.

NE flow will gradually weaken through tonight. Gusts to 25 kt
over SE waters will diminish below SCA tonight with E-NE wind
10-20 kt Tue abd Tue night. Rough seas, up to 9 ft, over outer
waters will slowly subside Tue into Tue night but remain above 5
ft through the period. SCA for outer waters extended through Tue
night.

We extended the High Surf Advisory through tonight, then
transitioned it to a high rip current risk for Tuesday. Seas are
slowly subsiding but leftover easterly swell will support
dangerous rip currents.

Outlook /Wednesday through Friday/...

Wednesday: Winds less than 25 kt. Areas of rough seas.

Wednesday Night: Winds less than 25 kt. Areas of rough seas.
Slight chance of rain showers.

Thursday: Winds less than 25 kt. Local rough seas. Slight
chance of rain showers.

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

Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Surf Advisory until 8 AM EDT Tuesday for MAZ007-019-020-
     022>024.
     High Risk for Rip Currents from Tuesday morning through Tuesday
     evening for MAZ007-019-020-022>024.
RI...High Surf Advisory until 8 AM EDT Tuesday for RIZ006>008.
     High Risk for Rip Currents from Tuesday morning through Tuesday
     evening for RIZ006>008.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ231>235-237.
     Small Craft Advisory until 8 AM EDT Wednesday for ANZ250-251-
     254>256.

&&

$$

SYNOPSIS...KJC/JWD
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...JWD
AVIATION...KJC/JWD
MARINE...KJC/JWD