Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 221106
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
706 AM EDT Sun Oct 22 2017

.SYNOPSIS...

High pressure south of New England will result in unseasonably
mild and dry weather into Monday. Seabreezes along both coasts
today will make it a little cooler there. A slow moving cold
front will bring rounds of heavy rain showers Tuesday into
Wednesday with a period of strong to damaging wind gusts
possible. A few lingering showers are possible Thursday, but the
trend towards drier and more seasonable temperatures are
expected Thursday into Friday. Above normal temperatures may
return by next weekend.

&&

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

705 am update...

Previous forecast in good shape and patchy fog across the far
southeast New England coast should burn off in the next hour or
two. The only fly in the ointment is some high resolution
guidance has low clouds moving onto the eastern MA coast this
afternoon. We think this is overdone and too fast, so did not
bite but something the next shift will need to watch closely.

High pressure will remain in control of our weather today, but
will be centered more to our northeast today. The resulting
light winds will set the stage for a seabreezes along both
coasts, which in turn will mean lower max temperatures today.
Highs across the eastern MA coast will reach between 65 and 70,
while portions of the Connecticut River valley will see highs
reach into the upper 70s to near 80.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Seabreezes diminish early this evening, to be replaced with a
light south synoptic flow. Another mild night in store, with
slowly increasing dew points. Dry weather continues. Still some
concern for low clouds and patchy fog across portions of
southeast MA, as dew points may get close to the water
temperatures just offshore. Just don`t have much confidence in
that outcome, yet.

Monday is still expected to be mostly dry. Overrunning lift
should get underway by the afternoon. The main limitation for
rainfall will by the abundant relatively dry air near the
ground. Many members of the 22/00Z guidance suite bring light
rainfall into southern New England during the daytime Monday.
Thinking this is likely a bit overdone, especially across the
eastern half of southern New England.

Will continue to have a chance of showers during the afternoon
into evening hours across the western half of southern New
England, owing to the proximity to the approaching cold front.
There should be better low level moisture convergence to help
overcome the drier air a little quicker.

Temperatures should be a little lower with increasing clouds,
but still well above normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...

Highlights...

* Period of strong to damaging wind gusts possible Tue into Wed am
* Heavy rain will result in an urban/street flooding threat Tue-Wed
* More seasonable late October temps finally return Thu/Fri

Details...

Monday night...

Upper level ridging will gradually lose its grip on our region as
low level jet increases ahead of low pressure lifting northeast
towards the Great Lakes. While just a few spot showers are possible
Monday evening, the threat for scattered showers will increase after
midnight across the interior.  Increasing low level moisture/lower
clouds will hold overnight low temps in the upper 50s to lower 60s
which may actually rise a bit toward daybreak.

Tuesday and Wednesday...

The two main concerns will be revolve around the potential for heavy
rain and an urban/street flooding threat along with a period of
strong to damaging winds.

Deep trough to our west will continue to dig into the southeast
states inducing meridional upper level flow into southern New
England. The result will be a southerly low level jet/Pwats both
increasing to 2-3+ standard deviations above normal. Timing of the
cold front still uncertain, but strong LLJ/high Pwats coupled with
strong forcing will bring periods of showers with heavy rainfall Tue
into Wed. The front will be slow moving and both the GEFS/EPS
showing decent probabilities of 2+ inches of rain with even some low
probs of 4+ inches. Therefore, an urban/street flooding threat will
exist Tue afternoon into Wed especially if the higher
rainfall amounts are realized.

The other concern will be the potential for a period of strong to
damaging wind gusts Tue into Wed morning.  Most of the guidance
indicates a 925 mb southerly LLJ on the order of 45 to 60 knots.
While some of this wind will remain aloft given an inversion in
place, surface temps well up into the 60s to the lower 70s are
expected Tue into Wed.  This may allow some more of the wind to mix
down than we normally might expect.  In addition, the potential
exists for a fine line with embedded thunder given we may see up to
500 J/KG of Cape with dewpoints in the 60s coupled with strong
forcing. The potential exists for a period of southerly wind gusts
of 40 to 50 mph especially along the coastal plain.  If a fine line
or any convection develops ahead of the front, a low risk for a few
gusts up to 60 mph would be possible. Given most trees are fully
leafed, these potential wind gusts will bring an enhanced risk for
tree damage/isolated to scattered power outages. There is a pretty
good bet that some wind headlines will likely be needed Tue
afternoon into Wed am with the highest risk along the coastal plain.

Thu/Fri/Sat...

The cold front will probably cross the region by Thursday morning,
but some lingering showers will remain possible Thu afternoon with
the upper level shortwave. Dry weather likely arrives Thu night into
Fri. Temps finally return to more seasonable levels Thu/Fri behind
the cold front, but readings may be back above normal by next
weekend.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Short Term /through Monday/....

Today...Moderate to high confidence. VFR, dry weather and light
winds after patchy fog burns off by 12 or 13z across the
southeast New England coast. Seabreezes develop by mid morning
along both coasts. The only fly in the ointment is some of the
high resolution guidance has IFR Cigs moving onto the eastern MA
coast this afternoon. We think this is too fast and overdone,
but can not rule out a low risk for this occurring so will need
to be watched by the next shift.

Tonight...Moderate confidence.

Uncertainty on how quickly MVFR-IFR conditions overspread the
area from the south. Mainly dry conditions prevail along with
light south winds.

Monday...High confidence.
Mainly VFR, although with a low risk for early AM fog and lower
clouds with isolated IFR conditions possible.

KBOS Terminal...Moderate to high confidence in TAF. We think
northeast winds develop at the terminal by 13 or 14z. As
mentioned, some high resolution guidance has IFR Cigs moving
in off the ocean this afternoon. We think that is too fast and
overdone, but it will need to be watched.

KBDL Terminal...High confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night: Mainly MVFR, with local IFR possible. Breezy.
Chance SHRA.
Tuesday: Mainly MVFR, with local IFR possible. Strong winds
with local gusts to 40 kt. SHRA likely.
Tuesday Night: Mainly MVFR, with areas IFR possible. Strong
winds with gusts to 40 kt. SHRA, isolated TSRA.
Wednesday: MVFR/IFR conditions possible. Strong winds with
local gusts to 40 kt. SHRA, isolated TSRA.
Wednesday Night: MVFR/IFR conditions possible. Breezy. Chance
SHRA.
Thursday: Mainly MVFR, with areas VFR possible. Breezy. Chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Monday/...High confidence.

Very tranquil boating weather for late Oct continues this period
with light winds, dry weather and good vsby. Local seabreezes
develop today by mid morning. Light south winds tonight into
Monday.

Outlook /Monday Night through Thursday/...Moderate confidence.

Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers.
Tuesday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 11 ft. Chance of rain showers.
Tuesday Night: Moderate risk for gale force winds with gusts up
to 40 kt. Rough seas up to 12 ft. Rain showers, isolated
thunderstorms.
Wednesday: Low risk for gale force winds with gusts up to
40 kt. Rough seas up to 16 ft. Rain showers, isolated
thunderstorms. Areas of visibility 1 to 3 nm.
Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 14 ft. Rain showers.
Visibility 1 to 3 nm.
Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 11 ft. Chance of rain showers.

&&

.FIRE WEATHER...
Dry weather continues through at least tonight with minimum RH
values 25 to 35 percent today, lowest values over CT and western
MA. However, with high pressure nearby winds will be very light.
Thus fire weather parameters remaining below Red Flag Warning
criteria.

&&

.CLIMATE...
All the record max temperatures for October 22 were set in 1979.
While being well above normal today, most of these records
appear to be safe

Here are the records for today

Hartford    85 in 1979
Boston      83 in 1979
Worcester   82 in 1979
Providence  86 in 1979

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$
SYNOPSIS...Belk/Frank
NEAR TERM...Frank/Belk
SHORT TERM...Belk
LONG TERM...Frank
AVIATION...Belk/Frank
MARINE...Belk/Frank
FIRE WEATHER...Staff
CLIMATE...Staff



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