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Area forecast discussion 
National Weather Service Taunton Massachusetts
737 PM EDT Thursday Sep 18 2014

Synopsis...
a weak...dry cold front will cross the area this evening. Cold
high pressure builds into New England tonight and Friday. Some
frost may form across portions of southern New Hampshire late
tonight. The high will drift offshore through the weekend
resulting in a brief return to milder temperatures. A cold front
moves through early Monday...followed by cooler weather toward the
middle of next week.

&&

Near term /until 6 am Friday morning/...
730 PM update...

Just minor tweaks needed to the forecast this evening. Brought
near-term conditions back in line with observed trends.

Previous discussion..

Tonight...high pressure bring push of cold air across the region...
though short range models indicating core of coldest 850 mb air
will remain north of the region. Expect skies to clear from north-S
overnight...first across S New Hampshire by around midnight or 1 am. Some
clouds may linger along the S coast through the night.

Noting pressure surge behind the front on the model wind fields.
Expect north-NE winds to increase quickly early tonight across the
waters east of Cape Ann then working down the coast. Could see gusts
up to 20-25 knots along the immediate East Coast from about Boston
southward to the cape and islands through the night. Further
inland...winds will drop off to light/variable or calm especially
across the normally prone areas near the CT valley and Cheshire
County.

With the light winds and clearing skies...this will allow for a
period of radiational cooling after midnight. Expect the best
chance for very chilly temperatures across northern Cheshire and northwest
Hillsborough counties...and could see some pockets of frost. Have
issued frost advisory for these areas.

Overnight lows will drop to the Lower-Middle 30s in the frost advisory
area...ranging to the Lower-Middle 50s along the immediate East Coast.

&&

Short term /6 am Friday morning through Friday night/...
Friday...the center of large high pressure builds across New England
during the day. Will see leftover gusty winds along the East Coast
Friday morning then...as high pressure builds in...winds will
diminish. Expect mainly clear skies but temperatures will be much cooler.
Highs will only be in the middle 50s in the normally colder inland
locales to the middle 60s in the lower CT valley.

Friday night...high pressure slowly pushes offshore so...while skies
will be mainly clear...noting that the dewpoints will begin to rise
as light winds shift to S-southeast overnight. Will also start to see
high clouds push into western areas after midnight. May still see
temperatures fall to the upper 30s in the normally prone cooler spots...
though most locales will be in the 40s to lower 50s.

&&

Long term /Saturday through Thursday/...
overview and model preferences...this portion of the forecast
still looks like it will be defined by a developing middle-level
trough across the northeast USA late this weekend and early next
week. This trough looks like it moves into the Maritimes toward
the middle of next week. Overall...there is decent agreement among
the 18/12z guidance suite through the middle of next week. After
then...timing differences become more prevalent...but should not
have a major impact on the sensible weather. Will continue to
favor a consensus blend to minimize these detail differences.

Saturday and Saturday night...a large high pressure over the
North Atlantic near Nova Scotia continues to move farther out to
sea. This leaves southern New England in a progressively weaker
ridge axis with time. Dry weather the most likely outcome as the
airmass remains quite dry. Slightly below normal high temperatures
expected Saturday...with above normal low temperatures Saturday
night as southerly winds continue.

Sunday into Monday...
this period is starting to look like a race between a weak
coastal low pressure moving north and a cold front moving east.
This front is increasingly looking moisture-starved as it crosses
southern New England. The 18/12z GFS appears to be a western and
faster outlier...when compared to the other guidance
sources...with its handling of this coastal low pressure. While
not expected to be a potent storm...it could supply the moisture
this passing front would need to produce more significant
rainfall. There are many areas across CT...Rhode Island and southeast Massachusetts
which could really use some rainfall.

At this time...will only mention a chance of showers with rainfall
totals less than one quarter inch. There has been a recent trend in
the guidance of being too aggressive with rainfall amounts. Will
wait until the timing issues between this front and coastal low can
be ironed out. Thinking it most likely this coastal low passes by
too far offshore to have much impact.

High temperatures expected to be well above normal
Sunday...before returning to more seasonable values by Monday
morning.

Tuesday into Thursday...
a large high pressure moves into our region...providing prolonged
dry weather and slightly below normal temperatures.

&&

Aviation /00z Friday through Tuesday/...
forecaster confidence levels...

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

Short term /through Friday night/...high confidence.

Tonight...VFR. Clearing skies from north-S as front pushes offshore.
North-NE winds may gust to 20-25 knots along East Coast from Boston S to
Cape Cod and the islands overnight.

Friday-Friday night...VFR. Mainly clear skies through early Friday
night...then high clouds increase across western areas. NE winds
gusting to 20 knots early Friday across Cape Cod and the islands then
diminishing. East winds 10 knots or less late Friday...shifting to S-southeast Friday
night.

Kbos terminal...high confidence in taf. Sea breeze through 22z-23z.

Kbdl terminal...high confidence in taf.

Outlook...Saturday through Tuesday...

Saturday into Sunday morning...high confidence. Mainly VFR through
this period. Although some patchy ground fog is possible both
Saturday and Sunday mornings at typically prone airports. Winds
mainly S-SW...with gusts up to 20 knots possible Sunday.

Sunday afternoon into Monday...moderate confidence. A cold front
crosses the region during the early morning hours Monday. Scattered
showers with MVFR/IFR conditions may move through with this front.
Otherwise...improving back to VFR by late day Monday.

Tuesday...high confidence. VFR.

&&

Marine...
forecaster confidence levels...

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

Short term /through Friday night/...high confidence.

Through 00z...cold front crosses the waters by this evening.
Expect northwest winds to shift to N-NE. Long ground swells of 3 to 4 feet
continue from distant Hurricane Edouard. May see brief swells to 5
feet on the outer waters S and east of Cape Cod and Nantucket which
should slowly subside.

Tonight...will see pressure surge working down from the north across
the waters as colder air moves across the milder waters. Expect north-NE
wind gusts up to 25-30 knots mainly after midnight. Have raised small
craft for Rhode Island Sound.

Friday...NE winds remain gusty Friday morning...then diminish as high
pressure builds north of the waters. Seas build up to 6-7 feet on the outer
waters. Small crafts continue...though conditions should improve
on the near shore sounds and bays by early afternoon.

Friday night...light east winds in place. Leftover seas on the outer
waters should subside below small craft criteria by around
midnight.

Outlook...Saturday through Tuesday...moderate confidence.

Saturday-Sunday...winds shift to south with daytime gusts up to 20
knots nearshore. Seas will remain 2-4 feet. A cold front approaches
late Sunday with a chance of showers Sunday night.

Monday...a cold front crosses the waters early in the day. West
winds behind this front will remain less than 20 knots. Seas will
build to 5-7 feet on the outer and exposed waters...as a south
swell increases to 3-5 feet. Small craft advisories may be needed.

Tuesday...northwest winds and subsiding seas expected as a high
pressure moves over the waters. Seas will take longest to
diminish across the outer coastal waters.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...frost advisory from 1 am to 8 am EDT Friday for nhz011-015.
Rhode Island...none.
Marine...Small Craft Advisory from 2 am to 2 PM EDT Friday for
anz232>235-237.
Small Craft Advisory from 2 am to 5 PM EDT Friday for anz231-
251.
Small Craft Advisory from midnight tonight to 8 PM EDT Friday
for anz250.
Small Craft Advisory from midnight tonight to midnight EDT
Friday night for anz254-255.
Small Craft Advisory from 2 am to 10 PM EDT Friday for anz256.

&&

$$
Synopsis...Belk/evt
near term...Belk/evt
short term...evt
long term...Belk
aviation...Belk/evt
marine...Belk/evt

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