631
FXUS61 KBOX 070751
AFDBOX

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

.SYNOPSIS...

A cold front approaches the region today, bringing a period of rain
showers and perhaps 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/...

345 AM Update...

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

An approaching shortwave will increase the forcing for ascent with
the help of a modest southerly LLJ & Pwat plume nearing 1.25 inches.
This should allow a cluster of showers to blossom through mid-late
morning. Latest SPC Meso-analysis indicates fairly steep mid level
lapse rates across our region. This will help to result in a bit of
elevated instability...so a few embedded t-storms will be possible
which is also supported by the latest HREF guidance. 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 /08Z MONDAY THROUGH FRIDAY/...

Forecast Confidence Levels:

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

06z TAF Update...

Today...Moderate Confidence.

Conditions should deteriorate to mainly MVFR thresholds from
west to east through mid morning with some localized IFR
conditions possible too. This will be accompanied by a
widespread band of showers with perhaps a few embedded t-storms.
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.

KBDL TAF... Moderate Confidence in TAF.

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 from 8 AM this morning to 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