Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 261822

Area Forecast Discussion
National Weather Service Taunton MA
222 PM EDT Wed Oct 26 2016

The coldest air of the season so far will bring patchy clouds and
chilly temperatures today. High pressure will push across the region
this afternoon and tonight. Strong low pressure will push across the
region late Thursday into Friday, which will bring a period of
wintry weather well inland at the start, rain heavy at times
elsewhere along with gusty winds at the coast. A drying trend
develops later Fri along with temperatures becoming more
seasonable this weekend and probably into early next.


220 PM Update...Scattered clouds across the southern New England
this afternoon with the densest clouds over the Cape and Islands
currently. Did not make any major changes to the forecast with
this update. Believe current forecast is generally on track. While
winds are starting to shift more to the north on the outer Cape,
it appears that any ocean effect showers that were occurring this
morning have dissipated. Therefore, think the better chance for
ocean effect showers will be during the overnight.

Large high pressure ridge will build E during the late morning
and afternoon, with N-NW winds at around 10-15 mph. Some gusts up
to 25-30 mph will linger through midday along east coastal areas.

Short range models continue to signal ocean effect clouds across
the outer Cape, possibly reaching into Nantucket and portions of
the mid Cape this afternoon. With sea surface temps in the upper
50s, noted strong signals on the lake effect parameter on the NAM
4 KM and GFS BUFKIT soundings for later this afternoon at KCHH for
at least ocean effect clouds and possibly a few showers. Only
question at this point will be whether the wind direction will be
more northerly to bring in the showers. At this point, should
remain mainly NW through today there.

With cold airmass in place across the region, with H85 temps in
the -6C to -8C range, will be tough for temps to climb out of the
40s today. Might see a few readings up to around 50 along the
immediate S coast though.



High pressure will slowly build east tonight. This should allow
lighter winds, veering mainly from the N across the eastern
waters. As mentioned above, short range models continue to signal
best shot for any ocean effect clouds and showers to push into the
mid and outer Cape and well as Nantucket during the overnight
hours. Winds may start to veer to more N-NE toward daybreak, which
could push the clouds closer to the coast from Plymouth to the
Cape Cod Canal. If any showers do occur, best chance will be from
Provincetown to Chatham.

In the meantime, the high will build E overnight. Overrunning
well ahead of low pressure across the eastern Great Lakes will
bring clouds into central and western areas mainly after midnight.
The ridge will hold off the precip until during the day Thursday.

Expect temps to fall back to the 20s across most inland areas,
ranging to the mid 30s to around 40 along the immediate coast.
The lows may occur around midnight or so, then may level off or
slowly rise as winds shift to light northeast.


Updated 427 AM...


- A period of snow possible high terrain Thu
- Rain heavy at times late Thu into Thu night
- A period of gusty winds possible Thu ngt south coast


Snow Potential...very cold airmass in place early Thu with 850 temps
down to about -4C at 12z. Airmass is very dry as well and this
yields large potential for evaporative cooling. This will support a
deep layer of cold air that will be conducive for ptype of snow.
However models have trended deeper/stronger with parent low moving
from OH to western NY. This results in a longer duration of ESE low
level winds across the region triple point low development
is delayed until Thu evening somewhere vicinity of PHL-NYC-CT coast
corridor. As a result this yields more boundary layer warming with
freezing levels only dropping to about 1500 ft per model soundings.
Heavy qpf would be able to offset this blyr warmth and lower
freezing levels but only the NAM is showing robust qpf Thu. Even the
Hi Res ARW and NMM cores are much lighter than the NAM. Appears the
NAM mid level winds /700 mb/ are much stronger than the remainder of
the guid and this is resulting in the higher NAM qpf. Thus have
followed a non-NAM solution here. This scenario supports precip
beginning as snow across northern CT (esp higher terrain) into
western-central MA including the Worcester Hills. Given the marginal
blyr and surface temps any minor accumulations would likely be
confined to the highest elevations /esp above 1500 ft/. Also given
precip intensity may be lacking accumulations more likely on non
paved surfaces. As of now not expecting much impact...however still
need to watch this unfold closely because if models trend weaker
with parent low and give way to triple point low quicker...blyr will
be colder across our region and yield a higher snow potential.

Heavy Rain Potential...

good trough amplification Thu night along with mid level trough
taking on a negative tilt in concert with dry slot approaching from
the west. This will yield rain heavy at times Thu afternoon and
night with heaviest rain possibly 06z-09z as nose of dry slot
approaches. Any poor drainage flooding should be minor as non-NAM
model consensus on QPF is 0.75 to 1.25 inches with isolated higher
amounts given convective potential on nose of dry slot. System is
dynamic but remains progressive which will limit qpf to some extent.

Strong Winds Potential...

low level southeast jet strengthening up to 50 kt as it moves across
RI and southeast MA Thu night. With triple point low expected to
track along or near the I-95 corridor warm sector likely to
overspread coastal RI into southeast MA. This will lessen the low
level convergence and increase the probability of gusty winds aloft
reaching the surface. Model soundings indicate potential up to 40-50
kt gusts at BID/HYA/CHH and ACK. In addition some elevated and
surface based instability in warm sector. So more robust showers or
isolated Thunder may increase the risk for strong winds. So
eventually may need a wind advisory for this region Thu night.


The day begins with triple pt low over eastern MA at 12z and
continuing to deepen/strengthen as it tracks northeast to off Cape
Ann midday. However its slow to exit as mid level low captures
surface reflection just offshore late Fri. This results in a
blustery day with NW winds gusting 30 to 40 mph. Although post
frontal airmass fairly seasonable so expecting highs in the 50s.
Will feel cooler given the gusty northwest winds. Warmest readings
will be over southeast MA where warm sector airmass overspreads the
area Thu night with temps rising into the 50s to near 60 late Thu
night into early Fri.

The Weekend...

Deterministic and ensemble guid continues to struggle with the
amplitude of northern stream short wave energy moving across the
northeast this weekend. Not expecting a washout but there will be
the risk for a period of showers sometime over the weekend. So
followed a model blend given the uncertainty. More certain on temps
not being as cold as previous days with highs close to normal both
days...55 to 60 with Sunday possibly the milder of the two days.

Next week...

Ridge over the MS valley Mon builds northeast into New England Tue.
This will support dry weather along with near seasonable temps Mon
trending to slightly warmer than normal Tue-Wed.


Forecaster Confidence Levels.

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

Short Term /through Thursday Night/...

Through 00Z...High confidence.  Mainly VFR.  Brief periods of low
end VFR to MVFR ceilings over Cape Cod and Nantucket in ocean effect
clouds.  NW winds continue to gust up to 20 to 25 kts this afternoon.

Tonight...High confidence.  Mainly VFR.  Low end VFR to MVFR
ceilings expected over Cape Cod and Nantucket.  Low probability of
periods of MVFR conditions in ocean effect snow showers in this
area.  Northerly winds diminish except for on the Cape and Islands
where gusty winds continue.

Thursday...High confidence in trends, lower on timing.  Conditions
quickly diminish as a mix of snow and rain showers sweep into
southern New England from SW to NE. Most likely period for snow will
be during the morning hours and across northern CT and western and
central MA. Elsewhere, rain is expected.  Snowfall will be light and
no accumulation is expected on pavement.  In fact, any accumulation
will likely be limited to the higher elevations (greater than 1500-
2000 ft). All areas of snow should change to rain quickly by 18Z.
Northerly winds shift to the east during the day but remain fairly
light until after 21Z, when the low level jet kicks up and areas
along the south coast, Cape, and Islands will see gusts starting to
increase up to 25 to 30 kts.

Thursday night...High confidence in trends, lower on timing.  Rain
will continue through the night with a periods of heavy rain
possible.  Expect a mix of MVFR/IFR conditions in rain/fog.  On the
coastal plain, the south coasts of RI/MA, the Cape and Islands,
easterly to southeasterly winds will gust up to 35 to 40 kts at
times.  Elsewhere, winds will be a bit lighter, gusting up to 20 to
25 kts along the east coast and below 20 kts across the interior.

KBOS TAF...High confidence in trends, lower confidence in timing.

KBDL TAF...High confidence in trends, lower confidence in timing.

Outlook /Friday through Monday/...

Friday...Moderate confidence.

Winds back out of the W towards Friday morning, becoming VFR.

Saturday and Sunday...Low confidence.

Mostly VFR. Perhaps a mix of MVFR/VFR to places N of the Mass Pike
in widely scattered showers. W/SW winds throughout. Gusts up to 20


Forecaster Confidence Levels.

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

Short Term /through Tonight/...High confidence.

Through Today...NW winds gusting up to around 25 kt across the
open waters, but will diminish as high pressure builds east. Seas
up to 5 to 7 ft, but will subside through midday across the near
shore bays and sounds. Small crafts will expire there, but will
continue through the day mainly on the eastern outer waters as
seas remain high.

Tonight...North winds diminish. Small crafts on the eastern outer
waters should end as seas finally subside by midnight. Scattered
ocean effect rain showers mainly east of Cape Cod, but may extend
into eastern Cape Cod Bay and Nantucket Sound overnight.

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

Updated 427 AM...

Thursday into Friday...

Low pres over western NY state Thu gives way to a new low along the
Southern New England coast Thu ngt...intensifying into a Gale Center
as it tracks into the Gulf of ME Fri. Could see a period of SE gales
Thu night followed by NW gales Fri. Vsby may drop below 1 mile Thu
afternoon and night in periods of heavy rain and fog...improving
around daybreak Fri.

Saturday into Sunday...

Modest westerly winds Sat ahead of a weak cold front...followed by
modest northwest winds Sun behind the front becoming NNE Sunday


MARINE...Gale Watch from Thursday evening through Friday morning for
     Gale Watch from late Thursday night through Friday morning for
     Small Craft Advisory until 11 PM EDT this evening for ANZ250-


LONG TERM...Nocera
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