810
FXUS61 KBOX 071042
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
642 AM EDT Fri Jun 7 2024

.SYNOPSIS...
Warmer today with decreasing humidity levels but scattered
afternoon and evening showers developing as an upper level
disturbance approaches. Cooler tonight, then mainly dry and
seasonable conditions Saturday. Unsettled conditions return
Sunday through midweek with a few showers at times but it will
not be a washout.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Stratus and fog along eastern MA coast will lift this morning
leading to plenty of sunshine, but sct-bkn diurnal cu will develop
this afternoon as steep low level lapse rates develop with shallow
moisture at the top of the boundary layer. Upper low sets up north
of the Gt Lakes with shortwave energy rotating around the low which
will likely result in scattered afternoon showers developing,
especially north of the MA Pike closest to the cold pool aloft.
While there is marginal instability with SBCAPES up to 500 J/kg,
soundings show a pronounced mid level cap which will limit updrafts
so not expecting any t-storms, just some low topped showers. Better
chance of thunder will be to the north under the cold pool aloft.
Fairly warm low level temps today with 850 mb temps reaching 12-14C
which will support highs in the low-mid 80s, but 70s along the
immediate coast as sea-breezes develop. Humidity levels will be
dropping in the interior, especially this afternoon as dewpoints
fall through the 50s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Tonight...

The upper low and cold pool will be moving into northern New Eng
tonight with decent mid level cooling southward into SNE. This will
help to continue the shower threat into this evening, then clearing
overnight as cold front moves off the coast with drying W flow. Lows
will settle into the 50s.

Saturday...

The upper low will be lifting to the north with warming 500 mb
temps. Expect plenty of sunshine mixing with some clouds as diurnal
cu develops. Shower threat will be less than today, with just a low
risk for a spot shower across northern MA. Otherwise a dry day but
becoming breezy with W winds gusting to 20-30 mph in the afternoon as
we will have a well mixed boundary layer in post frontal airmass.
Cooler and dry airmass with highs mid-upper 70s, but closer to 70
higher terrain. Dewpoints dropping to the upper 40s and lower 50s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Highlights

* Scattered showers on Sunday

* Drier to start the week with a few spot showers possible on Monday

* Lower than normal confidence for days 5 through 7 which could
  range from a long stretch of unsettled weather to a brief
  unsettled period on Tuesday followed by warmer and drier weather
  to finish out the week

Sunday

A robust short-wave disturbance aloft will traverse across the
Northeast on  Sunday. With sufficient moisture in place to the tune
of 1 to 1.25 inch PWATs, we`re likely to see scattered showers
across the region on Sunday afternoon. Even areas that miss out on
rain are likely to experience overcast skies throughout the day with
cooler temps peaking in the low 70s.

Monday

A cold front associated with the aforementioned upper-level
disturbance pushes through the region Sunday night into Monday. This
should support a drier day for most of southern New England, but
with the quasi-stationary upper-level low still overhead there could
be some unsettled weather as well. Latest suite of model guidance
keeps the core of the cold pool aloft over northern New England
where there will be higher precip chances. Can`t rule out the
possibility for some spot showers at this time, but those details
will be resolved as we edge closer to next week.

Tuesday through Thursday

Forecast confidence drops off substantially early next week as there
is considerable spread in how the latest suite of forecast models
are handling a short-wave embedded in the broader cyclonic flow over
the eastern US. Several solutions favor this short-wave cutting off
as it digs over The Great Lakes and into the Midwest. From there
feature meanders near the northeast for several days which would
support unsettled weather for much of next week. Other solutions
keep the short-wave embedded in the larger flow which would support
an unsettled day Tuesday followed by a mid-level ridge building over
the eastern US to end the week. In this scenario we would see a
warming/drying trend mid to late next week. Given the low confidence
in the forecast , have leaned on the NBM for guidance for days 5
through 7 which places slight chance to chance PoPs across much of
the region daily with seasonable temperatures.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

12Z TAFs: High confidence (70%).

IFR/LIFR from eastern MA to Cape Cod and Islands slowly lifts to
VFR 15z-18z as fog/stratus scatter out, but it`s more
questionable near ACK where IFR may linger most of the day. We
plan to show some improvement to VFR after 18z as we`re hopeful
that fog/stratus will burn off there as well, but it`s possible
these lower conditions prevail all day. Even if there is brief
improvement, LIFR is expected to return toward sunset.

Otherwise VFR today through Sat. There may be some widely
scattered showers this afternoon, especially across western and
northern MA, but coverage should be limited.

Light W/SW winds today through Sat. Coastal sea breezes develop
later this morning.

KBOS TAF...High confidence.

KBDL TAF...High confidence.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Breezy. Slight chance SHRA.

Sunday: VFR. Breezy. Chance SHRA.

Sunday Night through Monday: VFR. Slight chance SHRA.

Monday Night: VFR.

Tuesday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

High confidence through Saturday.

S-SW winds developing this afternoon with locally onshore winds near
the coast as sea-breezes develop. Winds become W tonight behind a
cold front, then increasing W wind Sat with gusts to 20 kt, with
potential for some 25 kt gusts over eastern MA nearshore waters.
Lingering 5 ft seas over southern waters through tonight where SCA
will continue. Areas of fog will reduce vsbys over the southern
waters into this evening, improving overnight as winds shift to
W.

Outlook /Saturday Night through Tuesday/...

Saturday through Saturday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft.

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

Sunday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers.

Monday through Monday Night: Winds less than 25 kt.

Tuesday: Winds less than 25 kt. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ254>256.

&&

$$

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