979
FXUS61 KBOX 180215
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
915 PM EST Sun Nov 17 2024

.SYNOPSIS...
Dry weather and above normal temperatures will continue into
Wednesday. A developing low pressure system will likely deliver
much needed, widespread meaningful rainfall Wednesday night and
Thursday. Showers will linger Thursday night and Friday with
potential for some accumulating snow over the highest
elevations. Gradually drying out next weekend and blustery.

&&

.NEAR TERM /THROUGH MONDAY/...
715 PM update...

Dry, quiet weather tonight. Two minor changes to the forecast.
Given high clouds remain fairly thin, combined with light winds,
dew pts in the teen and 20s, along with dry soils, radiational
cooling has allowed temps to fall rapidly. Already down to 38 at
HYA and 42 at ACK. Thus, we lowered overnight mins a bit.
Thicker clouds arrive after midnight, which should result in
temps leveling off somewhat then. Other change was to lower dew
pts and RHs for Monday afternoon, given downsloping winds. NBM
dew pts have been running too high in this weather regime.
Thus, followed the drier guidance. Otherwise, previous forecast
in good shape. Earlier discussion below.

-----------------------------------------------------------------

Quiet end to the weekend this afternoon under high pressure,
providing clear skies and light NW winds. Tonight that high is
suppressed to the south by a shortwave disturbance which brings
increased cloudcover despite being too moisture started for any real
rain chances. Cloudcover will keep temps a bit warmer overnight,
with lows in the mid to upper 30s.

&&

.SHORT TERM /MONDAY NIGHT/...
Fire weather concerns return on Monday as the low departs, replaced
by mid level ridging once again. While dewpoints will be on the rise
meaning increasing humidity, winds also become gusty as cool NW flow
promotes mixing down of a modest LLJ. Expect wind gusts as high as
20 to 30 mph. Temperatures will be similar to today, in the upper
50s/low 60s. Overnight the boundary layer doesn`t decouple, keeping
breezy winds in the forecast, up to 15-20 mph.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key Points..

* Remaining dry with slightly above normal temps Tue-Wed

* Much needed widespread, meaningful rain likely Wed night into Thu
  evening, with 0.50+ inches likely. Some snow possible in the
  high terrain.

* Somewhat unsettled Fri-Sat, with chance of showers at times but
  not a washout. Improving trends later in the weekend.

Precipitation...

Dry weather persist Tue and Wed, but models continue to trend wetter
Wed night into Thu, as a high amplitude Pacific system (with
possibly some remnant tropical moisture from Sara) impacts the
region. Fairly anomalous system, with ensembles offering -3 sigma
heights associated with 500 mb low. Hence, strong jet dynamics and
deep layer moisture with PWATs AOA 1 inches.  This translates into
all 3 ensemble systems (CMC, GEFS and EPS) offering 60-70% of 0.50+
inches of qpf, along with some members, including the UKMET
suggesting areas of 1.0+ inches possible in the upslope regions of
the higher terrain of MA, given low level easterly jet. Exact totals
will hinge on location and track of low and corresponding dry slot.
If system tracks farther north, shorter duration of heavier qpf
given dry slot, but higher totals if system and dry slot track
farther south. Too early to resolve these issues, but nonetheless,
finally meaningful rainfall Wed night and Thu, with high probs for
0.50+ inches. Lighter precip expected Fri and Sat with mid/upper low
over the region. Given column cooling with anomalous mid/upper low,
some snow is possible for the high terrain Fri. Vertically stacked
low slowly pulls away later next weekend, thus, improving trends
possible.

Temperatures...

Brief cool down Monday night behind departing northern stream short
wave. So after a cool start Tue morning, highs Tue afternoon and
again Wed, rebound into the mid and upper 50s, which is 5-8 degs
above normal. Cool nights given dry soils accentuating radiational
cooling. Therefore, leaned toward the cooler MOS guidance to derive
lows. Overall, very pleasant weather by mid/late Nov standards, with
light winds, sunshine and temps slightly above normal. Probably more
sunshine Tue, with mid/high clouds possible Wed. Chilly, wind swept
rain Thu, with highs in the upper 40s to lower 50s. Cooler than
normal Fri and Sat with cold air aloft. Highs only in the 40s to
perhaps near 50s both days. Milder trend possible by Sunday, as
mid/upper low should begin pulling away.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

00z TAF Update...no change from previous TAFs. Earlier
discussion below.

------------------------------------------------------------------

High confidence through Monday night...

VFR through the period. Increasing high clouds late today and
tonight, then some low-mid level cloud cigs Monday morning. NW
gusts to 15-20 kt today, light NW to calm wind tonight, then NW
wind increasing to 10-20 kt Monday afternoon with a few higher
gusts. NW wind gusts diminish Monday night but remain breezy.

KBOS Terminal...High Confidence in TAF.

KBDL Terminal...High Confidence in TAF.

Outlook /Tuesday through Friday/...

Monday Night through Tuesday: VFR. Breezy.

Tuesday Night through Wednesday: VFR.

Wednesday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance RA.

Thursday: Mainly MVFR, with areas IFR possible. Breezy. RA.

&&

.MARINE...
Forecaster Confidence Levels:

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

915 PM update...

We expanded the SCA to the nearshore waters for late Mon and Non
night for a period of G25 kt.

Through Monday night...High confidence.

Seas continue to diminish, falling below advisory criteria this
evening. Seas are between 2 and 4 ft Monday, increasing NW winds
behind a front will then bring wind gusts around 25 kts late
Monday and Monday night with seas increasing to 4-6 ft on the
outer waters.

Outlook /Tuesday through Friday/...

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft.

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

Wednesday: Winds less than 25 kt.

Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft. Chance of rain.

Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Rain.

&&

.FIRE WEATHER...
ELEVATED FIRE WEATHER CONCERNS MONDAY FOR SOUTHERN NEW
ENGLAND...

Conditions are very dry today with min RH values in the upper teens
and 20s this afternoon away from Cape Cod. Light winds continue this
afternoon with some gusts to 10-15 mph.

On Monday, min RH values improve but winds will be stronger, gusting
between 20-30 mph. We are coordinating with our partners to discuss
what type of headline could be needed.

&&

.TIDES/COASTAL FLOODING...
* Coastal Flood Statement for eastern MA coast; including Cape
  Cod and Islands for Monday afternoon`s high tide.*

Astronomical tides have peaked just under 12` MLLW and are slowly on
the decline. Still, there will be minor coastal flooding, which is
best described as sporadic and nuisance flooding, as the surge with
Monday morning`s high tide is close to 1 ft. A coastal flood
statement is in effect for east coastal MA for the afternoon high
tide.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 7 PM Monday to 10 AM EST Tuesday for
     ANZ231-251.
     Small Craft Advisory from 7 PM Monday to 7 AM EST Tuesday for
     ANZ232>234.
     Small Craft Advisory from 4 PM Monday to 7 AM EST Tuesday for
     ANZ235-237.
     Small Craft Advisory from 7 PM Monday to 1 PM EST Tuesday for
     ANZ250-254-255.
     Small Craft Advisory from 1 PM Monday to 1 PM EST Tuesday for
     ANZ256.

&&

$$

SYNOPSIS...BW/Nocera
NEAR TERM...BW/Nocera
SHORT TERM...BW
LONG TERM...Nocera
AVIATION...BW/Nocera
MARINE...KJC/BW/Nocera
FIRE WEATHER...BW/Nocera
TIDES/COASTAL FLOODING...Dooley