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925
FXUS61 KBOX 281814
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
214 PM EDT Tue May 28 2024

.SYNOPSIS...
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Summer warmth and humidity today. Temperatures then cool off to
more seasonable levels into the mid to late week period, along
with lower humidity. Though dry weather should prevail much of
the time, there will be scattered showers and thunderstorms
Wednesday afternoon into Thursday morning. Then mostly sunny and
dry weather conditions return Friday into at least Saturday,
along with a warming trend.
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&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...

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215 PM update...

Summery weather across the region with temps in the upper 70s
and lower 80s, although only in the 60s to around 70 for Cape
Cod and the islands, as the low clouds and fog just burned off.
Nonetheless, a beautiful late May day with a mix of sun and
clouds and dew pts falling into the 50s from west to east.

As for scattered showers upstream across NY state, much of this
activity and cold air aloft arrives here after peaking heating.
Thus, expecting most of these showers to decay upon reaching
SNE. Best chance of an isolated, brief low top shower will be
late today across the high terrain of western MA/CT. Otherwise,
dry weather prevails. Earlier discussion below.

===============================================================

Dry slot overspreading the region and resulting in low clouds
eroding and giving way to partly to mostly sunny conditions.
This dry slot will limit any diurnal convection to very isolated
and brief activity, with most if not the entire day featuring
dry weather. Highest chance (15-20%) across the high terrain.
Drier/less humid airmass advecting in from the west, with dew
pt falling into the 50s across western CT/MA. This airmass
overspreads SNE from west to east as the day progresses. Hence,
less humid as the day evolves. Still warm air aloft, with 925
temps +18C to +19C this afternoon +13C at 850), warmest across
eastern MA. This will support highs into the low 80s, including
Boston, given SW breeze 10 to 20 mph. Cooler south coast given
SW trajectory off cool ocean with SSTs 55-60.
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&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...

Highlights:

* Mild and dry overnight, followed by a seasonable midweek with
  renewed chance for showers and rumbles of thunder.

Tonight: A dry night ahead with mainly clear skies, clouds do linger
in the higher terrain of northwest Massachusetts. Wind shifts more
to the west, dewpoints fall into the low and middle 50s with
temperatures in the upper 50s and low 60s.

Wednesday: Our next chance at rain comes in Wednesday afternoon with
a shortwave riding the base of the mid-level trough. Do not think
the day will be a washout, but do think there will be a few
scattered showers and rumbles of thunder mainly across Rhode Island
and southeast Massachusetts after 16z/18z. NAM profiles show limited
MUCAPE around 500J/kg, but low level lapse rates are rather
impressive at 8-9 C/km. Limiting the growth are poor mid level lapse
rates, less than 6C/km. FWIW - SPC does keep us in general thunder
on Wednesday. Temperatures return to more seasonable highs,
temperatures aloft are cooling, leading to highs in the middle and
upper 70s, slightly cooler at the coast where highs are in the low
70s. Wind shifts northwest across the interior during the afternoon,
while at the coast wind direction remains out of the southwest.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...

Highlights:

* Temperatures will be cooler on Thursday, increasing steadily each
  day through early next week.

* Rain is expected to continue Wednesday night into Thursday
  followed by an extended stretch of dry weather through at least
  early next week.

Details...

The synoptic pattern for the extended forecast will feature a deep
mid level trough/cold pool aloft leading to unsettled weather
initially, followed by mid level ridging and a drier, warmer pattern
for late week into early next week.

For the Wednesday night through Thursday light rain showers will be
more likely as the trough and associated cold pool move overhead.
PWATs are not overly impressive at around an inch, and total
rainfall isn`t expected to be much more than a half inch or so where
the showers develop which is supported by ensemble guidance. Some
uncertainty as to the areal extent of the showers at this distance
in time, but odds are that not everyone will get a soaking. A
surface cold front sinking through on Thursday together with the
cooler airmass overhead will lead to the coolest day of the forecast
on Thursday, in the upper 60s/low 70s.

Late Friday into the weekend mid level heights will be on the rise
as high pressure moves overhead at the surface. This will lead to a
drying and warming airmass with steadily rising temperatures each
day. High temps will be back to normal by Friday (low to mid 70s)
and then steadily increase each day until by Monday we`re looking at
highs in the low to mid 80s. Humidity will be more comfortable early
in the weekend, with dewpoints steadily rising as we go into early
next week making it feel more humid next week but not excessive.

&&

.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
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Forecast Confidence Levels:

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

18z TAF Update: high confidence through Wed morning, then some
uncertainty on areal coverage and severity of scattered -TSRA
Wed afternoon and evening.

Thru 00z...high confidence.

VFR, dry weather and WSW winds 10-20 kt. Less than 30 percent
chance of an isolated, brief -SHRA across western MA/CT thru
00z.

After 00z... High confidence.

VFR, dry weather with WSW winds 10-20 kt, gusting up to 25 kt
across Cape Cod and islands. Winds then ease and become light
west overnight. Less than a 30 percent chance of MVFR vsbys
across southeast MA, as winds become light.

Wednesday...High confidence on trends, lower on details
including areal coverage and severity of TSRA Wed PM.

VFR to begin the day. Then in the afternoon scattered -TSRA
develops with MVFR conditions, perhaps focused across RI and
southeast MA. A few of the stronger storms may contain small
hail from 18z-00z. Winds, light west winds will become locally
onshore along the coast.

Wednesday night...high confidence on trends, but lower
confidence on timing and details.

VFR/MVFR in early evening scattered -TSRA, then a possible lull
in the activity with a 2nd round of -SHRA & -TSRA second half of
the night. Light onshore winds become north overnight.

KBOS TAF...High confidence thru Wed AM, then some uncertainty
Wed PM with exact areal coverage and severity of storms.
Activity may be focused across RI and southeast MA, with a few
stronger storms there containing small hail. Activity could be
less widespread & less intense northward from KBOS to the NH
border. Given this, inserted a prob30 into the TAF but VCTS
farther south given higher probs.

KBDL TAF...High confidence in the TAF. Some uncertainty on areal
coverage of -TSRA Wed PM. Left out of the TAF for now with
higher prob eastward into RI and southeast MA. We may need to
include prob30 for -TSRA 18z-23z Wed in later TAF.

Outlook /Thursday through Saturday/...

Thursday through Thursday Night: VFR. Chance SHRA.

Friday: VFR. Slight chance SHRA.

Friday Night through Saturday: VFR.
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&&

.MARINE...
Forecaster Confidence Levels:

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

Small craft advisories continue on outer waters tonight through
tonight, with SW winds 20 to 25 kt and seas building to around
4-5 ft.

Today into tonight, SW to WSW winds 15-20 kt, isolated gusts to
25 kt are expected with seas rising to around 4-6 ft on the
southern and eastern outer waters and around 3 ft or less
nearshore.

Wednesday, SW winds 10-15 kt, gust to 20 kt with seas 3-4 ft on
the southern and eastern outer waters and around 2 ft or less
nearshore.

Outlook /Wednesday Night through Saturday/...

Wednesday Night through Thursday Night: Winds less than 25 kt.
Chance of rain showers.

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

Friday Night through Saturday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 5 AM EDT Wednesday for ANZ250-
     254>256.

&&

$$

SYNOPSIS...BW/Dooley
NEAR TERM...Nocera
SHORT TERM...Dooley
LONG TERM...BW
AVIATION...Nocera/BW
MARINE...BW/Dooley