638
FXUS61 KBOX 011738
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
138 PM EDT Mon Jul 1 2024

.SYNOPSIS...
An upper level disturbance will bring hit or miss showers today
and possibly an isolated thunderstorm, otherwise dry weather
with slightly cooler than seasonable temperatures. High pressure
brings dry weather and seasonable temperatures with comfortable
humidity for Tuesday and Wednesday. Turning more humid and
unsettled for Independence Day into this weekend with a couple
of disturbances offering chances for showers and thunderstorms.

&&

.NEAR TERM /THROUGH THIS AFTERNOON/...
130 PM update...

Scattered showers developing along the I-95 corridor with
isolated thunder moving into NE MA. Activity is developing
along a convergence zone in eastern MA with E-NE winds along
the coast and N winds a bit further inland. Expect this to
continue near the I-95 corridor in RI and eastern MA for the
next few hours an and isolated t-storm is possible. Isolated
showers further W across the CT valley will diminish. Then
clearing toward evening.

Previous discussion...

Rather robust mid level trough and cold pool will be moving
across SNE this afternoon. Diurnal CU already developing and
will expand across the region as low and mid level lapse rates
steepen. A few showers will develop by late morning, probably
first across portions of eastern CT/RI and central MA where CU
is most developed per day cloud phase, then focus should shift
to eastern MA this afternoon where best moisture is located.
Also can`t rule out an isolated t-storm as there will be
marginal instability with CAPES up to 500 J/kg. Small hail will
be possible given cold temps aloft.

&&

.SHORT TERM /TONIGHT AND TUESDAY/...
Highlights

* Any diurnal clouds erode quickly with clear skies expected
  tonight. Slightly cooler than seasonable for lows.

* Dry with comfortable humidity and seasonable temperatures on
  Tue.

A ridge axis will be in place across the central/eastern Great
Lakes tonight. The ridge builds into the eastern Great Lakes and
Mid Atlantic by late Tue. High pressure builds into the eastern
Great Lakes and Upstate NY tonight. By Tue the high will be
overhead.

Dry and quiet weather expected through this timeframe. Only
question in the forecast really is how quickly does the pressure
gradient slacken tonight. This will impact how well we are able
to radiate given the clear skies. For now have gone with the
25th percentile of guidance for lows heading into Tue. The
result is it will be somewhat cool with lows in the 50s.

Abundant sunshine expected on Tue with high pressure overhead.
Could start to see some high clouds pushing into western areas
late as a shortwave lifts into the eastern Great Lakes. High
temps will be around seasonable levels with comfortable
humidity.

&&

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

* Dry and warm with tolerable humidity levels for Wed.

* Turning more humid and active for Independence Day, and
  potentially into Fri/Sat too, with clouds, showers and storms
  possible. Exact timing remains uncertain.

01/00Z guidance suite was in rather good agreement with the overall
synoptic pattern, but still exhibited some detail differences with
the smaller scale features. These become important during the summer
months when convection is more prevalent. Rather subtle changes can
have a big impact on on the outcome. Have high confidence in the
forecast through Wednesday, then only average confidence in the
details from Independence Day into next weekend.

High pressure at the surface moves offshore Wednesday, leading to
another warm day with slightly higher humidity. No rainfall expected.

More unsettled conditions start to develop Wednesday night into
Thursday. A passing mid level shortwave along with a warm front
passage may trigger some showers, mainly across northern MA. But this
will be influenced by how far offshore the high pressure can get. If
it is just a little closer, then the expected showers would be
shunted farther north, or at least great diminished due to some
lingering subsidence.

This in turn feeds into the Thursday forecast. High pressure still
parked over the North Atlantic, with a cold front approaching from
the west. This front is expected to move into our region some time
late on Independence Day into Thursday night, then stall heading
into Friday. This frontal boundary should move back north as a warm
front into Friday night, only to be followed by a cold front
Saturday night into Sunday. While not raining the entire time from
Wednesday night into Sunday, not seeing much opportunity for a
clearly dry period either. Have at least a slight chance for
rainfall during this time, with measurable rainfall more likely
heading into this weekend due to the increased humidity.

Temperatures generally above normal for this portion of the forecast.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

Through 00z...

VFR cigs around 5k ft with scattered showers and an isolated
t-storm near the I-95 corridor through 21z. Clearing toward
00z. E wind 10-15 kt along the eastern MA coast and N 10-20 kt
further inland.

Tonight through Tuesday night...High confidence.

VFR. Diminishing N wind tonight with sea-breezes developing Tue
along the coast.

KBOS TAF...High confidence.

Included a VCTS until 20z for ongoing convection to the north
drifting southward. Otherwise VFR cigs with clearing this
evening. E wind will become light N by 00z. Sea-breeze
develops around 15z Tue.

KBDL TAF...High confidence.

Outlook /Wednesday through Friday/...

Wednesday: VFR. Breezy.

Wednesday Night: VFR. Breezy. Slight chance SHRA.

Independence Day: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA.

Thursday Night: VFR. Breezy. Slight chance SHRA.

Friday: Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today...High confidence.

Winds shifting to the NW as a cold front crosses the waters.
Should see winds turning northerly toward daybreak. Wind speeds
of 10-15 kts with some 15-20 kt gusts. Seas diminish to 2-4 ft.

Tonight...High confidence.

Winds out of the N to NW at 5-10 kts. Dry weather with seas 1-3
ft.

Tuesday...High confidence.

Winds out of the N to start, but will quickly diminish and shift
to the E/SE as high pressure moves overhead. Seas 1-3 ft with
dry weather.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday: Winds less than 25 kt.

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

Independence Day through Thursday Night: Winds less than 25 kt.
Seas locally approaching 5 ft. Slight chance of rain showers.

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

&&

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

&&

$$

SYNOPSIS...Belk/BL
NEAR TERM...KJC
SHORT TERM...BL
LONG TERM...Belk
AVIATION...Belk/KJC
MARINE...Belk/BL