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000
FXUS61 KBOX 121443
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1043 AM EDT Fri Apr 12 2024

.SYNOPSIS...
A potent frontal system and its accompanying heavy rain and
strong winds will exit offshore late this morning, followed by
improving conditions this afternoon and into tonight. Although
it will be mostly cloudy and turning seasonably cool into
Saturday. Generally dry Saturday night through Tuesday outside
of the chance for light shower activity late Sunday and Sunday
night. Warming trend develops with temps making a run at 70F
Monday and Tuesday. Mild but unsettled Wednesday and beyond.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...

1030 AM Update:

No major changes with this update, as previous forecast verifying
nicely compared to current observations. Low level SSE jet
exits offshore 15z-16z. Still gusting up to 47 kt at BID & UUU!
Thus, will hold onto wind headlines for a bit longer.

Winds will slacken in two intervals, after 15z as core of low
level jet moves offshore, then after 18z as wind fields aloft
begin to weaken. There will be a pulse of wind from the SW with
the cold frontal passage, arriving 4-7pm from west to east with gusts
up to 40 mph at times.

Dry slot beginning to advect across CT into western-central MA.
However, scattered low top showers developing in this region.
Although, not a washout this afternoon, just lighter scattered
showers. Area of showers upstream associated with trailing short
wave across eastern PA into NJ will pivot across CT and
western- central MA this afternoon. Therefore, driest conditions
this afternoon will be across RI into eastern MA.

Remaining mild with temps 60-65, feeling mild too with dew pts
55-60. Cold front well to the west across eastern PA &
approaching the Catskills of NY.

As for coastal flooding along coastal RI into Narr Bay and south
coastal MA into buzzards bay, high tide occurs 1130-12pm, thus
we will continue with those headlines as well. More info below
in coastal flood section.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SATURDAY/...

345 AM Update:

Tonight and Saturday:

Our weather pattern transitions to deep cyclonic flow aloft for
tonight into Saturday, with an associated pocket of low level colder
air. This will serve to keep our weather unsettled tonight into
Saturday. Though we should see more in the way of cloudy breaks in
this forecast period, all in all it is a mostly cloudy period.
Scattered instability type pop-up showers are possible on Saturday
in western New England but should be mainly dry most of the time.

Cold advection begins in earnest tonight and continues into
Saturday. So despite the cloud cover around, it should also be a
pretty blustery period, especially on Saturday where westerly gusts
around 25-35 mph should be pretty common. We could have gusts in and
around the higher terrain near 40 mph at times.

Low temperatures tonight are in the 40s with the cloud cover and WSW
breezes. Meanwhile high temps are forecast in the lower 50s for
western and central MA/CT, and the mid 50s for eastern MA and
RI.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

Highlights:

* Dry period Saturday night through Sunday afternoon before shower
  chances increase Sunday evening

* Dry and mild Monday and Tuesday

* Next chance for appreciable precipitation comes mid next week

Saturday Night into Sunday

Dry period expected as any lingering day-time showers dry up as
shortwave pivots well northeast into the Canadian Maritimes
overnight. With weak mid level ridging building in from the west,
mostly dry conditions will persist through much of Sunday ahead of a
weak low pressure dropping south out of Ontario. Guidance currently
tracks the low a bit to our north, across VT/NH before moving
seaward of southern New England late Sunday night.

Guidance has come into better agreement that shower activity
associated with this low/shortwave will begin around 21Z Sunday
before diminishing between 06 and 09Z Monday morning. Emphasis
should be placed on the word "showers" as widespread, stratiform
precipitation is not expected for the region. CMC and GEFS QPF
probabilities for 0.1" of QPF are quite low, between 10 and 30% for
southeastern MA, CT, and RI, with a gradient to between 60 and 70%
across far northwestern MA. The ECMWF, which takes a bit more of a
southerly track with the low, illustrates the highest probabilities
of 0.1" across the south coast. Nonetheless, QPF probabilities of
0.5" are zero across all GEFS, ECWMF, and CMC suites. In general,
between 0.05 and 0.15" of rain can be expected; a very minor event
for our area given the deluge of water we`ve seen since the
beginning of the year.

Monday and Tuesday...

Lingering shower activity should be well seaward of southern New
England by 12Z Monday as drying WNW flow sets up across the region;
leading to clearing skies. More robust mid level ridge builds across
the northeast allowing strong WAA to develop, as 850mb temps briefly
surge to as high as 8C early Monday. Expecting temperatures to reach
well into the 60s to perhaps 70F both Monday and Tuesday.

As for winds, should see diminishing winds through the period as
925mg LLJ pulls offshore Monday morning. Winds at the top of the
mixed layer max out between 15 and 20kt by mid day Monday, with
gusts of 10-15kt possible at the surface. The NBM again shows a
terribly high bias, so cut winds significantly using CONSALL. Future
forecasters will need to remain cognizant of this NBM bias
surrounding the Patriots Day forecast. May see some increasing high
cloud cover late Tuesday ahead of our next precip maker, but all in
all it will be a great 36 hour period!

Mid-week and Beyond...

Guidance continues to trend later with our next significant frontal
passage, which now looks to impact the region late
Wednesday/Thursday; just 24 hours ago impacts were forecast to occur
late Tuesday into Wednesday. Given the delay, expected dry and mild
conditions to persist into at least Wednesday. In fact, most
guidance carries the potential for above normal temps well into late
week. Utilized NBM for this period as uncertainty still surrounds the
timing of the forecast.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

15Z TAF Update...improving trends now that heavy rain and
isolated thunder moving offshore. Just lighter scattered showers
for the afternoon and evening. Strong SSE winds ease after 15z
and decrease even more after 18z. MVFR/VFR conditions overspread
the region from SW to NE beginning 20z-23z. Earlier discussion
below.

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

Today: Moderate confidence.

IFR-LIFR to generally continue at least into the late-morning
hrs. Steady rain, perhaps embedded with a rumble or two of
thunder, to become focused over eastern and southeast MA, RI and
the Cape/Islands approx 12-15z, while diminishing in intensity
for ORH westward. Another opportunity for SHRA/possible TS could
arrive in the 15-19z window for the Berkshires, BDL-BAF-CEF
corridor but the timing and how strong any showers could become
is still a bit unclear.

Flight categories should show improvement by one category into
the IFR-MVFR range by midaftn, but it will take until later in
the day before cloud bases lift into the MVFR-VFR range.

Gusty SE winds 35-45 kt over southeast MA, BOS, PVD airports
thru 15z; winds then become S/SW with a decrease in speed to
12-17 kt with gusts to 25-30 kt thru the aftn.

Tonight: High confidence.

Any sub-VFR trend SCT/OVC VFR for most, but can`t rule out MVFR
bases near the Berkshires. SSW winds around 10-15 kt with gusts
20-25 kt tonight, but become SW/WSW toward daybreak.

Saturday: High confidence.

SCT-OVC VFR bases, psbl MVFR bases in interior MA/CT. WSW winds
increase to 13-17 kt with gusts 25-30 kt, highest around the
Berkshires and the Cape and Islands.

KBOS TAF...Moderate confidence in TAF. IFR/LIFR categories,
strengthening SE wind gusts to 35-40 kt/low-level shear and
areas of steady rain becoming moderate to heavy between ~11-16z.
Rain then shifts offshore with winds becomg S/SW around 15
kt/gusts 25 kt; there could be some 1-category improvement to
IFR/MVFR once winds shift to SW, but better chance for VFR takes
place late-day/tonight.

KBDL TAF...Moderate confidence in TAF. IFR with rain becoming
heavy at times between 09-14z, with SE wind gusts 30-35 kt.
Round of heavy rains shifts eastward by 15z with winds becoming
southerly, although IFR/MVFR cloud bases to continue. Will have
to watch another possible round of SCT SHRA around 15-19z.
Improvement to MVFR/VFR bases not expected until later-
day/tonight.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Mainly VFR, with areas MVFR possible. Windy
with gusts up to 35 kt.

Sunday: VFR. Breezy. Slight chance SHRA.

Sunday Night: Mainly VFR, with local MVFR possible. Windy with
local gusts up to 30 kt. Chance SHRA.

Monday through Monday Night: VFR.

Tuesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

345 AM Update:

** Gale Warnings All Waters Today **

Today: High confidence.

SE to S winds increasing to 35 to 45 kt. Long southerly fetch
will build sees on the order of 8 to 14 feet over the open
waters this afternoon. Rain interspersed with areas of fog on
all waters, although the potential exists for scattered
thunderstorms on the southern waters this morning. Rain showers
then diminish in intensity and covg later this afternoon with
improving visbys.

Tonight and Saturday: Moderate confidence.

Slackening gradient brings SW winds around 20-25 kt tonight,
along with still elevated seas around 7 to 10 ft offshore.
Looking into Saturday, SCA-level SW/WSW gusts are expected on
all waters, although we could get close to Gale force gusts on
the southern waters. SCAs are likely on all waters, but outside
chance at another round of gale headlines on the southern
waters.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 10 ft.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers.

Sunday Night: Low risk for Small Craft Advisory winds with
areas of gusts up to 30 kt. Local rough seas. Chance of rain
showers, isolated thunderstorms.

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

Tuesday: Winds less than 25 kt.

&&

.TIDES/COASTAL FLOODING...

345 AM Update:

* Splashover and very minor coastal flooding on the South Coast
  Fri AM

Coastal flood advisories were maintained for the South Coast.
For the South Coast, storm surge values per tidal gages have
started to increase to a greater degree, and the peak surge is
now expected to take place prior to the late Fri AM high tide.
With a 2-3 ft surge occurring before high tide, it is likely
that splashover/some overwash is the most likely outcome, with
minor coastal flooding likely an absolute worst-case per Stevens
Institute guidance.

For the eastern MA coast, although we could see storm surge
values up to 1.5 ft, the peak surge also looks to be timed just
after low tide. Coastal flooding on the eastern coast is not
expected given these conditions.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Wind Advisory until 2 PM EDT this afternoon for MAZ007-015>024.
     Coastal Flood Advisory until 2 PM EDT this afternoon for
     MAZ020-021.
RI...Wind Advisory until 2 PM EDT this afternoon for RIZ002>008.
     Coastal Flood Advisory until 2 PM EDT this afternoon for
     RIZ002-004>007.
MARINE...Gale Warning until 8 PM EDT this evening for ANZ230>237-250-
     251-254>256.

&&

$$

SYNOPSIS...Loconto/KS
NEAR TERM...Loconto/Nocera/KS
SHORT TERM...Loconto
LONG TERM...KS
AVIATION...Loconto/Nocera/KS
MARINE...Loconto/KS
TIDES/COASTAL FLOODING...Loconto/KS