408
FXUS61 KBOX 051955
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
355 PM EDT Fri Jul 5 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 SATURDAY MORNING/...
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 SATURDAY MORNING THROUGH SATURDAY NIGHT/...
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 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 /19Z FRIDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:

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

Tonight: Moderate confidence overall, but low on timing and
location.

Any TSRA for central/western airports to weaken through 02z. Dry
weather should prevail for several hours, but we could see
another round of SHRA/TS for these same areas later
tonight/overnight. Deterioration toward a widespread IFR-LIFR,
but timing uncertain. Light S winds.

Saturday and Saturday Night: Moderate confidence overall, but
low on timing.


IFR-LIFR generally improves to SCT-BKN VFR, but seems to be a
better chance at TSRA on Sat, especially ORH-PVD north and
west. Timing of TSRA uncertain and subject to adjustment. SW
winds 4-8 kt.

KBOS TAF...Low confidence. IFR-MVFR CIGs likely to continue.
Additional showers and thunderstorms are possible, but have low
confidence in them reaching the terminal, and their timing.
CIGs remain IFR to LIFR overnight into Saturday morning.

KBDL TAF...Low confidence. IFR-MVFR CIGS likely to continue.
Additional showers and thunderstorms are possible, but have low
confidence in their timing reaching the terminal. CIGs remain
IFR to LIFR overnight into Saturday morning.

Outlook /Sunday 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 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 to 10 PM EDT Saturday for
     ANZ235.
     Small Craft Advisory from 2 PM to 6 PM EDT Saturday for ANZ237.
     Small Craft Advisory from 2 PM to 10 PM EDT Saturday for
     ANZ254.
     Small Craft Advisory from 9 AM Saturday to 8 AM EDT Sunday for
     ANZ255.
     Small Craft Advisory from 2 AM Saturday to 8 AM EDT Sunday for
     ANZ256.

&&

$$

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