639
FXUS61 KBOX 031941
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
341 PM EDT Wed Jul 3 2024

.SYNOPSIS...
A warm front lifts north across the region late tonight
bringing increasing humidity levels and a few showers or
thunderstorms in the interior on Thursday. Very warm and humid
weather this weekend and into early next week. Saturday will
have the highest humidity levels. While there is a risk of rain
and thunderstorms throughout the weekend and early next week,
it won`t rain continuously. There will be significant dry
periods, with Saturday into Saturday night having the greatest
chance for heavier rains.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
High pres near the SNE coast drifts offshore tonight with broad SW
flow in place. A mid level warm front will move across the region
late tonight and will be accompanied by a modest instability burst
as higher PWAT air and decreasing static stability advect into the
region from the west. This may result in a few showers developing
late tonight in the interior. Otherwise mainly dry conditions with
increasing clouds. The evening will start out with just some high
clouds so will likely see a period of radiational cooling with lows
dropping to 60-65 before temps stabilize overnight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday...

A few morning showers possible with the mid level frontal
passage, otherwise partial sunshine although expect more clouds
than sun as the column will be quite moist with PWATs exceeding
2 inches. A weak shortwave approaches from the west in the
afternoon which may lead to a few showers or a t-storm
developing across interior MA into CT where marginal instability
exists with CAPES around 500 J/kg. But areal coverage will be
limited. No instability in the coastal plain which should remain
dry. Temps aloft are pretty warm with 17C at 850 mb but cloud
cover will prevent temps from achieving full potential. Highs
generally low-mid 80s, except upper 70s near the south coast.
But humidity levels will be increasing as dewpoints rise to the
mid- upper 60s.

Thursday night...

Any lingering evening convection in the interior should dissipate,
then will have to watch for a renewed area of showers and
isolated t- storms possibly developing and moving across the
region late Thu night as a weak front sags south into the
region. Areal coverage of any convection is uncertain as hi-res
CAMs are not in agreement on the most preferred location. 2+
inch PWAT axis will shift southward but the south coast will
remain on the northern edge of these higher PWATs and this may
be where best chance of showers and a few t- storms will be.
Given the high PWATs and a weak boundary, localized heavy
rainfall will be a risk with any convection that develops. It
will be a mild and humid night with lows 65-70.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Highlights:

* Few showers possible on Friday, otherwise dry, warm and muggy.

* Humidity becomes oppressive for Saturday along with the potential
  for heavier rains and thunderstorms.

* Unsettled period continues Sunday though early next week,
  although there will be dry periods, and continued heat and muggy
  conditions.

Friday:

Heading into Friday, there are subtle height rises along with weak
shortwave energy traversing through the zonal mid-level regime. The
best forcing remains to our northwest, over the Great Lakes, though
bouts of shortwave energy does break off and travel east because of
the near zonal mid-level pattern. Given a moisture rich atmosphere,
PWATS are 1.5" to 1.8", and 2.0" plus along the southern coast a few
showers cannot be ruled out. Timing out the is difficult, will have
to utilize the high-res guidance to sort it out. With anomolously
high PWATs, dew points are elevated, it is the type of humidity you
can feel. Dew points climb into the low 70s and is accompanied by
highs in the low to middle 80s.

Saturday:

Unsettled conditions heading into the upcoming weekend. Shortwave
energy ejects out of the Great Lakes for Saturday, and with several
hundred units of MUCAPE, convective showers are possible. The warm
cloud layer is from 12,000 feet to 15,000 feet, meaning there is the
potential for efficient rain makers, with PWATs near max of climo,
with forecast values as high as 2.0 to 2.5", daily climo max per the
sounding archive is around 2.05", with the max of all soundings
at 2.73" for CHH. Heavy rains are possible. WPC mentioned the
western CWA in day four excessive rainfall outlook, most of
Connecticut and central to western Massachusetts.

Saturday afternoon is warm and very muggy with dew points in the low
to potentially the mid 70s, down right tropical! Highs are between
the low and middle 80s.

Sunday through Tuesday:

Southern New England is still on the outer periphery of a mid-level
ridge that is anchored over Bermuda. Model guidance continues to
show bouts of shortwave energy riding the ridge, leading to a daily
chance for daily chances for convective showers. While the risk
continues into early next week, it won`t rain continuously. There
will be significant dry periods as well.

Guidance continues to indicate warm and muggy conditions with highs
well into the 80s to 90 degrees and lows in the 60s to low 70s. High
PWATs linger as well, likely leading to dew points in the upper 60s
to 70 degrees.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

Through 00z:

VFR. S wind 10-15 kt with gusts to 20 kt. Sea-breeze along
eastern MA coast kicks out 21-22z with wind shift to S.

Tonight: High confidence.

VFR cigs. Low risk of a shower 09-12z in the interior. SW wind
5-15 kt.

Thursday: High confidence.

Mainly VFR cigs, but patchy MVFR possible over higher
elevations. Isolated morning shower possible, then a few
showers or a t-storm possible in the afternoon in the interior.
SW wind 10-20 kt.

Thursday night: Moderate confidence.

Cigs gradually lowering to MVFR with IFR possible near the south
coast. A few evening showers possible, then scattered showers
and possibly a t-storm near the south coast after midnight.

KBOS TAF...High confidence in TAF. Sea-breeze kicks out 21-22z
with wind shift to S.

KBDL TAF...High confidence in TAF.

Outlook /Friday through Monday/...

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

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

Saturday: MVFR/IFR conditions possible. Breezy. Chance SHRA,
isolated TSRA.

Saturday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA, isolated TSRA.

Sunday through 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.

Winds and seas below SCA thresholds. Light SW winds tonight, then SW
10-20 kt Thu and Thu night. Areas of fog and reduced vsbys should
develop Thu night with scattered showers and possibly a t-storm late
Thu night.

Seas through the period generally 3 ft or less on all waters.

Outlook /Friday through Monday/...

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

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers, isolated thunderstorms.

Saturday through Saturday Night: Winds less than 25 kt. Seas up
to 5 ft. Chance of rain showers, isolated thunderstorms.

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Slight chance of rain showers, isolated thunderstorms.

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

Monday: Winds less than 25 kt.

&&

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

&&

$$

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