044
FXUS61 KBOX 240754
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
354 AM EDT Mon Jun 24 2024

.SYNOPSIS...
Other than the chance of a spot shower, dry weather prevails Monday
along with lowering humidity this afternoon and not as hot as
Sunday, as a cold front exits offshore. Dry and very warm weather is
on tap for Tuesday, but with comfortable humidity. Hot and humid weather
returns Wednesday with another round of showers and thunderstorms
possible Wednesday afternoon and night as a cold front approaches
from the west. The showers may linger into Thursday as the front
moves through, followed by dry and seasonable conditions Friday
and Saturday. Another cold front will bring an increasing risk
of showers and thunderstorms Saturday night into Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

4 AM Update:

Today...

* Drier and less humid
* Mainly dry weather & seasonably warm

Cold front was entering eastern NY during the predawn hours and will
continue moving steadily eastward, with post frontal/drier/less
humid airmass overspreading the region later this morning and
afternoon. Ahead of the front, a spot shower is possible early this
morning. Dry slot overspreads the region today and this will support
dry weather. Cold pool aloft does overspread SNE later today with
500 mb temps cooling to -10C to -12C. However, the column is very
dry, therefore limiting any diurnal convection to a spot shower or
sprinkle given high cloud bases, with lots of subcloud dry air, as
dew pts fall into the upper 50s this afternoon. Much more
comfortable than Sunday. This cold pool aloft will yield morning
sunshine giving way to SCT-BKN diurnal CU/SCU. The cold pool aloft
also yield 850 mb temps lowering from +15C at 12z to +11C by days
end. This will result in a very tranquil/pleasant day with highs 80-
85, upper 70s western-central MA into northern CT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...

4 AM update...

Tonight...

* Dry, cooler and comfortable humidity

Dry, cool NW flow across SNE in response to vertically closed low
over the Gulf of Maine. Derived mins from a blend of the cooler MOS
guidance and the milder NBM. Should be enough WNW pgrad to preclude
cooler MOS guidance from verifying, thus followed a blend, which
still yields cool temps, with lows in the upper 50s to lower 60s.

Tuesday...

Could be pick of the week, with dry NW flow continuing. However,
temps will be warming aloft as vertically stacked low over the Gulf
of ME exits into the Maritimes. 850 temps warm from +12C to +16C by
days end, along with 925 mb temps warming to +22C. These temps aloft
combined with WNW winds 10-15 mph shifting to WSW support highs of
85-90 Tue afternoon. Although, not humid with dew pts in the 50s.
Given dry column (PWATS ~0.75 inches) and dew pts in the 50s, not
expecting much if any clouds, hence full sun.

&&

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

Key Points...

* Hot and humid Wed with showers/t-storms Wed afternoon and night
* Showers may linger SE New Eng Thu AM, otherwise improving
  conditions
* Dry & seasonable Fri and Sat
* Humidity increases Sat night and Sun with risk of showers/t-storms

Wednesday into Thursday...

Next mid level trough and shortwave amplifies across the Gt Lakes
Wed before moving into northern New Eng Thu. Pre-frontal SW flow
will bring increasing temps and humidity with highs likely reaching
upper 80s to lower 90s away from the south coast, while dewpoints
increase to near 70. The heat and humidity will help to generate
modest instability beneath favorable mid level lapse rates from a
remnant EML. While we do expect scattered showers and t-storms to
develop in the afternoon, better chance will likely be during Wed
night when best height falls move into the region along with right
entrance region of upper jet at a time when diurnal instability will
be diminishing. So there is some uncertainty with severe weather
risk as peak forcing will not be lining up with peak diurnal
instability. Still have to monitor this closely as deep layer shear
will be increasing and it is possible we have a narrow window for
severe potential late Wed and Wed evening when instability and shear
overlap. It is interesting that CSU machine learning probs have
ramped up on severe wind potential for Wed-Wed evening. Heavy
rainfall will also be a concern Wed night as deep moisture axis
moves across the region with PWATs increasing to near 2 inches.

Cold front will be moving across SNE overnight Wed night and likely
stalling in the coastal plain on Thu. However, moisture axis will
shift to SE New Eng by 12z Thu with good drying moving in from the
west during the day. Showers may linger in SE New Eng during Thu
morning, otherwise expect improving conditions with increasing
sunshine developing from west to east. Highs will reach upper 70s to
mid 80s with decreasing humidity in the afternoon, especially
interior.

Friday and Saturday...

High pres builds across New Eng Fri which will bring sunshine and
somewhat cooler temps, especially along the coast as sea-breezes
develop. High pres moves offshore Sat with increasing SW flow
developing which will result in dewpoints increasing. Dry weather
should hang on for much of the day, but can`t rule out a few showers
in the afternoon.

Saturday night and Sunday...

Unsettled weather returns as next mid level trough approaches from
the Gt Lakes with moisture axis moving into SNE with 2+ inch PWATs.
Expect scattered showers and t-storms through Sunday as cold front
may be delayed until later Sun or Sun night. Rather humid conditions
likely Sun as 70+ dewpoints return.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

06z update...

Through 12z...Moderate to high confidence on trends, but some
uncertainty on areal extent of IFR/MVFR early this morning.

Mainly VFR cloud bases with isolated showers thru 12z. Patchy
areas of MVFR/IFR developing across southeast MA. Uncertainty
how much this area will expand, possibly into RI and eastern MA.
Gusty SW winds 15-25 kt with gusts near 30 kt at times will
gradually ease toward 12z. Until then, this will yield marginal
LLWS over southeast MA.

After 12z...high confidence.

Any IFR/MVFR cigs at 12z along with scattered showers will be
confined to Cape Cod and the Islands. Gradually improving to VFR
by mid to late morning, along with dry weather. Elsewhere, VFR
at 12z will prevail today with VFR cloud bases this afternoon
and just the chance of an isolated shower/sprinkle. Gusty SW
winds 15-25 kt at 12z, will ease to 10-20 kt and shift to the
west this afternoon.

Monday night...High confidence.

VFR cloud bases with an isolated shower/sprinkle possible during
the evening. West winds 10-20 kt in the evening, shifting to NW
10-15 kt after midnight.

Tuesday...high confidence.

NW winds 10-15 kt in the morning, becoming SW 10-15 kt in the
afternoon.  VFR and dry runways.

KBOS TAF...Moderate confidence in TAF.

Only uncertainty is a brief period of MVFR possible through 12z,
along with an isolated shower. Otherwise, VFR cloud bases with
dry weather today, just low risk of an isolated shower/sprinkle
this afternoon/evening. SW winds gusting up to 25 kt thru about
09z, then slowly easing and becoming west later this morning and
continuing into the afternoon.

KBDL TAF...Moderate confidence in TAF

Other than an isolated shower thru 12z, VFR cloud bases and dry
weather. SW winds early this morning, becoming west late morning
in the afternoon.

Outlook /Tuesday Night through Friday/...

Tuesday Night: VFR. Breezy.

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

Wednesday Night: Mainly MVFR, with local IFR possible. Breezy.
SHRA likely, isolated TSRA.

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

Thursday Night through Friday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

*** SCA remains in effect ***

Today...

Robust low level SW jet of 40-45 kt at 2 kft over Cape Cod and
Nantucket, slow exits offshore today. Therefore, SW winds surface
winds of 15-25 kt during the predawn hours, ease this afternoon and
shift to the WSW and then west late. Although, given the long wind
fetch, it will take sometime for seas to subside across the southern
RI/MA waters. Scattered showers and thunderstorms south of the
islands in the predawn hours, slowly moves offshore late this
morning.

Tonight...

Wind shift to the NW 15-20 knots. Seas continue to slowly subside.
Dry weather and good vsby.

Tuesday...

Low pressure over the Gulf of Maine exits into the maritimes. This
yields NW winds 10-15 kt in the AM, WSW in the afternoon. Dry
weather and good vsby prevail.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.

Wednesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers.

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Rain showers likely,
isolated thunderstorms.

Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.

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

Friday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Surf Advisory until 7 PM EDT this evening for MAZ020>024.
RI...High Surf Advisory until 7 PM EDT this evening for RIZ006>008.
MARINE...Small Craft Advisory until 7 AM EDT this morning for ANZ230.
     Small Craft Advisory until 9 AM EDT this morning for ANZ231-
     236-250-251.
     Small Craft Advisory until 8 PM EDT this evening for
     ANZ232>235-237.
     Small Craft Advisory until 2 AM EDT Tuesday for ANZ254>256.

&&

$$

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