580
FXUS61 KBOX 071117
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
717 AM EDT Mon Oct 7 2024

.SYNOPSIS...

A cold front approaches the region today, bringing a period of rain
showers and a few embedded thunderstorms. This system is
progressive...so expect partial sunshine to develop behind the
front in western Massachusetts and northern Connecticut by mid
to late afternoon. Trough and cold pool aloft for the rest of
the work week will support fall-like weather as morning lows
drop into the 30/40s and afternoon highs crest in the 50s/60s.
No significant precipitation is expected from Tuesday through
early Saturday, though rain chances increase to close out the
holiday weekend.

&&

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

7 AM Update...

* A 3-5 hour period of shower and a few embedded t-storms sweeps
  across the area from west to east through mid-afternoon

A modest southerly LLJ & Pwat plume nearing 1.25 inches has
allowed a cluster of showers and a few embedded t-storms to
develop. Latest SPC Meso-analysis indicates mid-level lapse
rates near 7C/KM which was resulted in a few hundred J/KG of
MUCape. Therefore...a few embedded t-storms will accompany this
activity. This system is fairly progressive and generally
expect just a 3 to 5 hour period of showers. The back edge of
the widespread showers should have departed western MA/CT by
early afternoon with partial sunshine developing by mid to late
afternoon. The main band of showers should depart the
Cape/Islands by late afternoon/early evening. A few brief
additional showers may develop with the actual surface cold
front...but any of this activity will be scattered and very
short- lived.

The clouds and showers will probably hold high temps mainly in the
middle to upper 60s today. However...portions of the lower CT River
Valley may see highs in the lower 70s with partial sunshine
developing by mid to late afternoon.

&&

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

Key Points...

* Dry & cool tonight with lows well down in the 40s for most locales
* Partly sunny Tue with highs mainly in the middle to upper 60s

Details...

Tonight...

The shortwave/cold front departs early this evening. Otherwise...a
dry northwest flow of cooler air works into the region. Overnight
low temps will bottom out well down in the 40s in most
locations...to the lower 50s in the urban heat island of Boston and
the outer-Cape. Thinking enough dry air with northwest flow will
prevent much if any fog...but can not rule out a touch of it in a
few of the typical low-lying spots.

Tuesday...

Closed upper level low will be amplifying across Quebec. This result
will be a westerly flow of dry air. 850T will drop to around
+3C/+4C...but given the atmosphere will be well mixed high temps
should still recover into the middle to upper 60s in most locations.
Sunny skies are expected for much of the morning with a mix of
sunshine and fair weather clouds for the afternoon. The cyclonic
flow and the associated cold pool aloft will likely result in
scattered to broken strato-cu to develop during the afternoon
especially across the interior.

&&

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

* First prolonged period of true fall weather develops mid week and
  persists into early Friday

* Dry weather prevails until perhaps very late next weekend and into
  the holiday.


Wednesday through Friday...

Trough/cold pool that begins to settle over SNE on Tuesday will
remain in place over New England and southern Quebec through early
Friday. Cold pool peaks early Thursday morning as 850mb temperature
dip to either side of 0C as weaker shortwaves pulse around the
parent low settled to our north. Anticipating chilly mornings and
cool afternoons with many areas dipping into the 30s and low 40s
each morning and only warming into the upper 50s to low 60s each
afternoon. This hit of seasonably chilly air will provide the first
opportunity for widespread frost across the interior. Headlines
will likely be  mixed bag, given this frost will occur later than
climatological average for portions of the interior where the
frost/freeze program ended on October 1st. In areas away from the
Berkshires and northern Worcester County, the frost/freeze program
remains active, so headlines will likely be necessary.

Aformentioned parade of shortwaves and a weak frontal passage on
Wednesday evening may lead many to expect a dreary week across SNE,
but quite the opposite is expected. Very dry airmass in place, with
PWATs around 50% of normal, keeps precipitation chances at a
minimum, with perhaps just some showers across far northwestern
MA late Wednesday into Wednesday night.

Columbus Day Weekend...

Trough that brings below normal temperatures to southern New England
during the work week moderates towards zonal flow with an attempt at
weak mid level ridging on Saturday. Ridging for the weekend
certainly looks lest robust than it did 24 hours ago, but the
anticipated warm up will be aided by downsloping westerly winds and
a well mixed airmass that will tap into 850mb temperatures as warm
as 10-11C early Saturday morning. So, for those who want to hold
onto the last moments of Summer, they will get their opportunity
with temperatures warming into the low and perhaps mid 70s to Start
the weekend.

Beyond Saturday, the weekend could get a bit unsettled with a weak
shortwave pivoting south from Quebec late Saturday and a stronger
trough developing late Sunday into Monday. With ample dry air in
place on Saturday evening, don`t expect much by way of precip to be
associated with the shortwave, with the potential for more
appreciable precip coming for the Columbus day holiday.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...

Forecast Confidence Levels:

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

12z TAF Update...

Today...Moderate Confidence.

Showers and a few embedded t-storms were beginning to blossom
early this morning...so plan on including VCTS for several hours
this morning. This system is fairly progressive and the back
edge of the widespread showers should exit western MA/CT by mid
early and allow conditions to improve to VFR. The back edge of
the widespread showers and MVFR conditions will reach the I-95
corridor by late afternoon. SE winds 5 to 10 knots will shift to
the NW by late afternoon to the northwest of the I-95 corridor.

Tonight...High Confidence.

Any lingering MVFR ceilings near the coast will exit the region
early this evening. Otherwise...VFR conditions tonight with NW winds
5-10 knots.

Tuesday...High Confidence.

VFR despite a deck of scattered to broken strato-cu developing
during the afternoon especially across the interior. WNW winds
around 10 knots.

KBOS TAF...Moderate Confidence in TAF. Main concern is the
potential for thunder in the vicinity of the terminal...greatest
risk in the 13z to 17z time frame.

KBDL TAF... Moderate Confidence in TAF.

Main concern is the potential for thunder in the vicinity of
the terminal...greatest risk in the 12z to 16z time frame.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday Night: VFR.

Thursday through Friday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Tuesday...High Confidence.

Very distant tropical systems in the Atlantic will result in
easterly swell of 3 to 6 feet into Tuesday across the outer-waters
where small craft headlines are posted. We did continue the small
craft advisories for later today into early this evening for a
period marginal 4/5 foot swell getting into Block Island Sound and
Cape Cod Bay. In addition...a cluster of showers with perhaps a few
embedded t-storms will move across the region through mid to late
afternoon.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft.

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

Wednesday Night: Winds less than 25 kt.

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

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 20 kt. Areas of seas approaching 5 ft.

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

&&

.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 ANZ232-235-237.
     Small Craft Advisory until 4 AM EDT Wednesday for ANZ250-254-
     255.
     Small Craft Advisory until 5 PM EDT Tuesday for ANZ251.
     Small Craft Advisory until 5 PM EDT Tuesday for ANZ256.

&&

$$

SYNOPSIS...Frank/KS
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...KS
AVIATION...Frank/KS
MARINE...Frank/KS