026
FXUS61 KBOX 060603
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
203 AM EDT Sat Jul 6 2024

.SYNOPSIS...
Warm and very humid weather expected over the next few days.
Early morning showers this morning give way to brief dry
weather, although scattered thunderstorms are expected to
develop in the interior this afternoon. Some could produce
heavy downpours. Another risk for showers and storms for
Saturday. Mainly dry Sunday afternoon through early Tuesday, but
more unsettled weather is on the horizon for middle of next
week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1000 PM Update:

Most persistent area of thunderstorms current are coming off
southeast Litchfield County CT into far southern Hartford
Counties in CT and adjacent portions of southern CT. Radar all-
tilts and cross-sectional reflectivity trends continue to
indicate these storms are still capable of producing frequent
lightning but otherwise the main risk with these is from
torrential downpours. Fortunately they are moving along at a
fair clip; they should still be capable of lightning and
downpours as they move into southern Tolland and southern
Windham Counties but general weakening trends are expected as
they`re moving into a more stable air mass. Further north into
western/north-central MA, earlier line of storms in
has really fallen apart over the last hour and that should also
continue. It`s a quite humid night and it won`t take much to
pop a shower at any time but drier weather should then prevail
for most of the night. Early look- ahead at pre- dawn/early Sat
indicates another round of storms is possible, as activity over
central PA and southern NY moves ENE, but this isn`t well agreed
upon. Will continue to monitor these trends with incoming
guidance.

Otherwise, much of the area is blanketed in stratus and expect
that to continue to expand north and west over the next few
hours of the night. A very warm and muggy night given dewpoints
are in the low to mid 70s, and temps are already close to those
values. Lows should also range in the low to mid 70s.

Previous Discussion...

Not much change to the overall synoptic pattern tonight. Very
humid air remains in place, with a frontal boundary lingering
to our north. Weakly forced environment with rather poor mid
level lapse rates. Latest SPC mesoanalysis showed 2,000-3,000
J/kg most-unstable CAPE values. Regional radars showed showers
increasing in coverage as they moved into western southern New
England late this afternoon. Still mostly concerned about
downpours leading to flooding. However, given the amount of
available energy, will need to monitor the storms for
development. The most likely outcome is for a stronger storm to
develop, then rain itself out shortly thereafter as there is
not enough shear to organize these cells to separate the updraft
from from the rainfall.

The lack of shear also suggests these storms will most likely
diminish in intensity with sunset. Although, there still could
be a thunderstorm overnight, these should be more of the
garden-variety type.

High dew points around 70F should keep low temperatures in that
same range.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
Not a lot of confidence in the details Saturday into Saturday
night. Synoptic environment not really changed, except that a
cold front should be closer to southern New England. Still
mostly concerned about possible flooding issues, with a slightly
higher chance for stronger thunderstorms due to the presence of
the front.

Still not likely raining the entire day, and questions remain on
the impact of morning showers on the afternoon convective
environment. Should at least have periods of showers Saturday
afternoon into Saturday night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Highlights:

* Summer heat & humidity thru next week, with heat headlines
  possible Mon and Tue as heat indices of 95+ possible

* Sunday: chance of morning showers/thunderstorms/coastal fog,
  then a drying trend likely in the afternoon northwest to
  southeast

* Mainly dry Monday into Tue, then next chance of
  showers/thunderstorms late Tue into Wed

* Drying trend possible late next week, but remaining warm/humid

Sunday...

Short wave trough moving across the St Lawrence River Valley
Sunday morning will traverse east and shift the axis of the
tropical PWAT plume currently over New England to the south
coast and then eventually offshore. Thus, highest chance for
showers/thunderstorms along with areas of fog will be in the
morning over RI and southeast MA, then sliding offshore in the
afternoon. Hence, drying trends for the afternoon northwest to
southeast. Remaining very warm and humid, with highs 85-90,
cooler along the south coast. Dew pts in the upper 60s and lower
70s. Winds SW 5-10 mph, 10-15 mph across southeast MA.

Monday/Tuesday...

In the wake of the departing northern stream short wave Sunday,
the east coast subtropical ridge reinserts itself with height
rises and 591 dam contour traversing SNE. Hence, steamy with 925
mb temps rising to +24C to +25C, warmest across northern MA.
These temps combined with SW surface winds will yield highs in
the upper 80s and lower 90s, with Monday likely the hotter of
the two days. Some relief along the south coast and islands,
with highs in the upper 70s to mid 80s. Mainly dry weather
prevails. Chance of late day showers/storms western MA/CT
Tuesday, pending the speed/arrival time of next upstream trough.
Remaining humid both days with dew pts in the upper 60s and
lower 70s. We may need heat headlines as heat indices Mon and
Tue could reach the mid to upper 90s back to back days.

Wed/Thu...

Chance of showers/storms as upstream trough approaches.
However, ensembles suggest trough deamplifies as it approaches
SNE, in response to east coast subtropical ridge remaining
robust. Hence, highest pops for showers/storms will be across
northwest MA, lowest over southeast MA. Given cloud cover and
risk of showers/storms, not quite as hot, with highs in the 80s.
But remaining summery with dew pts in the upper 60s and lower
70s.

Friday...

Ensembles suggest mean trough axis beginning to move east of
New England, followed by rising heights. Thus, a drying trend
possible and remaining warm and humid, highs in the 80s and dew
pts again in the upper 60s to lower 70s.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:

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

06Z TAF Update:

Through 12z Saturday: Moderate confidence.

MVFR-IFR due to stratus, with not much categorical change.
Wouldn`t rule out 3-6 SM BR at times but shouldn`t be persistent.
Best chance for showers thru 09z Sat at PVD, FMH and HYA. SW
winds around 10-15 kt with gusts 20-23 kt for the Cape and
Islands, with lighter SW winds (5-10 kt) elsewhere.

Today: Moderate confidence overall, low on timing and areal
coverage of SHRA/TS.

Somewhat stronger confidence in ceiling trends, with MVFR-IFR
ceilings being more persistent/stubborn to improve in RI and
southeastern MA today. Elsewhere, MVFR-IFR to start but offering
one-category improvement to BKN VFR/MVFR north and west after
14z. SW winds around 10-15 kt today.

On SHRA/TS...given available guidance, confidence in timing and
coverage of showers and thunderstorms and their evolution today
is poor. Message is that SHRA/TS are expected today, more so
than currently reflected in the TAFs, but really couldn`t get
specific given this low confidence. Proactive use of TEMPOs will
be needed today to highlight more specific timing. In general,
airports to the north and west have a somewhat better chance at
seeing SHRA/TS and less so for PVD and the Cape airports, but
they can`t be ruled out anywhere and virtually at any time.

Tonight: Moderate confidence overall, low on timing of SHRA/TS.

Sub-VFR likely thru midnight for most airports, as weak frontal
boundary sags SE toward the coastal waters. SHRA/TS likely to
be ongoing somewhere in the airspace, with trend being for a
gradual SE shift towards the south coast. Should see gradual
improvement in flight categories from NW to SE, but sub-VFR
likely to continue into early Sun AM for the south coast. Winds
continue SW around 5-10 kt, though will turn WSW late.

Sunday: High confidence.

Improvement to VFR expected on Sunday for most, but can`t rule
out periodic SHRA and sub-VFR at ACK (more so in the morning)
as frontal boundary stalls. WSW winds 5-10 kt.

KBOS TAF...Moderate confidence overall, low confidence on
SHRA/TS timing and coverage. MVFR to begin, with some
scattering/lifting of cloud bases into VFR/MVFR range late this
morning. SHRA/TS possible virtually anytime today, and will
need TEMPOs to provide more specifics as current fcst confidence
on those aviation parameters are low. Better chance tonight as
boundary sags southward. SW winds around 10 kt.

KBDL TAF...Moderate confidence overall, low confidence on
SHRA/TS timing. IFR ceilings to start, but should see
improvement toward VFR-MVFR range. Better chances for SHRA/TS
here today, but the timing is uncertain and could occur
virtually anytime. Will need TEMPOs to provide more specific
timing. S winds around 10 kt, shifting to WSW late tonight.

Outlook /Sunday Night through Wednesday/...

Sunday: VFR. Slight chance SHRA.

Sunday Night through Monday Night: VFR.

Tuesday: VFR. Slight chance SHRA, isolated TSRA.

Tuesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, isolated TSRA.

Wednesday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, isolated TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Saturday Night: Moderate Confidence.

Persistent S to SW flow with winds around 10-15 kt through the
period, and seas could get near 5-ft thresholds given the long
SWly fetch. Marginal Small Craft Advisories posted for the
southern coastal waters. Greater risk for showers and
thunderstorms reducing visibility over the southern waters Saturday,
but widespread storms not expected.

Outlook /Sunday Night through Wednesday/...

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

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

Monday through Tuesday: Winds less than 25 kt.

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 10 PM EDT this
     evening for ANZ235.
     Small Craft Advisory from 2 PM this afternoon to 6 PM EDT this
     evening for ANZ237.
     Small Craft Advisory from 2 PM this afternoon to 10 PM EDT
     this evening for ANZ254.
     Small Craft Advisory from 9 AM this morning to 8 AM EDT Sunday
     for ANZ255.
     Small Craft Advisory until 8 AM EDT Sunday for ANZ256.

&&

$$

SYNOPSIS...Belk/Nocera
NEAR TERM...Belk/Loconto
SHORT TERM...Belk
LONG TERM...Nocera
AVIATION...Loconto/Dooley
MARINE...Loconto/Dooley