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Area forecast discussion 
National Weather Service Taunton Massachusetts
947 PM EDT Thursday Aug 28 2014

high pressure will build in with drier weather and less humidity
for tonight and tomorrow. Hurricane Cristobal will continue to
bring dangerous surf and rip currents to the cape and Nantucket
tomorrow. Pleasant late Summer weather will continue on Saturday.
A front will slowly move across New England late Sunday and Monday
bringing scattered showers and thunderstorms.


Near term /until 6 am Friday morning/...

A few cloud patches over the islands/greater Hartford-
Springfield/northern Vermont-New Hampshire all drifting south-southeast. Expect
these clouds to break up overnight and skies to become mostly
clear all areas. Northwest winds around 5 knots west and 10g15
knots east...also trending lighter. With dew points 45-50f there
is room for min temperatures in the M-u40s in the colder spots. Temperatures
and dewpoints have been about 2f lower than hourly
we bumped these values and the min temperatures down 2f.

Seas will trend lighter overnight...but still high enough to
general rough surf along the South Coast. The high surf advisory
continues until morning.


Short term /6 am Friday morning through Friday night/...
Friday and Friday night...

Upper level ridge will build over southern New England tomorrow and
tomorrow night. This will push a surface high pressure over the
region. Expect light winds and mostly sunny skies. Could be a few cumulus
developing as there is some lingering moisture in the mid-levels.
Otherwise temperatures will warm into the middle to upper 70s with cooler
conditions along the coastline thanks to seabreeze development.

Have extended the surf advection for the cape and Nantucket for tomorrow
as swell will still be about 4 to 5 feet with a period of around 11
second. Although the surf will not be as high as it is today...there is
still the danger of a rough wave as well as a high rip current risk.
Beachgoers should use caution when venturing into the waters
tomorrow and swim at life guarded beaches.

High pressure will begin to move offshore late tomorrow night.
This will allow for return flow across the region and being to
slowly increase the moisture. Some patchy fog overnight is
possible...but have a lower confidence.


Long term /Saturday through Thursday/...
*/ highlights...

- hot and humid weekend
- best chance of wet-weather late Sunday into Monday
- cold front across the region Tuesday
- dry and seasonable forecast for the rest of the week

*/ overview and model preference...

Noting ensemble signals of a negative to near-neutral nao and pna
pattern...prefer a zonal flow with higher heights and weak ridging
across the NE-Continental U.S. Into early September. Broadly speaking over the
long-term forecast expecting seasonable to above-average
temperatures and muggier conditions. Likely there will be periods in
where more refreshing air will dive S out of Canada...yet averaging
over the forecast period will likely yield anomalously higher values
of temperature and moisture as hinted by ensemble members.

But also anticipate a subdued weather pattern. Any Pacific energy
troughing across west North-America should be kept well north of the region if
not stretched through the confluent zonal-flow pattern...again north of
the region. While convective periods are expected...stretched middle-
level impulses and less amplified pattern should yield
limitations in convective well as keep convective
episodes mainly confined during the daytime periods...diffusing
overnight...heat and moisture being the main fuel to the fire.

Have high praise for the European model (ecmwf) / ecens which has remained fairly
consistent run-to-run over the past three days. Though not ignoring
outcomes from other model solutions...will place greater weight on
the European model (ecmwf) / ecens towards the forecast. Highlights/confidence are
broken down in the daily discussion below.

*/ Day-to-day details...

Saturday into Saturday night...

Will continue with a dry forecast. Ridge of high pressure. Dry-
subsidence inversion in place. A well-mixed boundary-layer will
allow for breezy S-winds...scattered cumulus...and low-80s highs.

Overnight...quiet under light S-flow. Increasing surface moisture.
Some question as to whether low clouds seep in from the S or rather
more clear conditions allow for the development of patchy fog...or a
combination of both. Drizzle possible with increasing moisture
content undergoing weak upslope? Could not rule it out along the S-
shore. Mild night with lows around the mid-60s.


A building convective environment. Falling heights in a region of
middle-level ascent per differential vorticity advection within decent
850 mb-7 lapse rates...above collocated low-level moist-instability
axes into the lower Hudson Valley / SW New England. While better low-
level wind profiles / frontogenesis / 300 mb jet dynamics resides north and
west...signals of middle-level moist-convergence in an area of favorable
ascent should yield some activity. Modest instability and 0-6 km
bulk shear. Also would expect orographic lift along S/W-slopes of
high terrain aiding with ascent.

Expect convection to develop north/west sliding southeast with time. No confidence
as to specifics nor storm severity...but do expect the brunt of it
to remain north/west of the forecast region parent with better dynamics.
While a warm-sector is expect through the interior with highs into
the upper-80s...clouds may be a hinderance along the S/southeast coastline
especially during the morning period...hopefully eroding with an
increase in SW-winds...blustery at times.

Sunday night...

With daytime heating concluding and the bulk of middle-level energy
stretched / sheared to the north...expect activity to weaken southeast with
time. Approaching surface frontal boundary becoming diffuse against
the dominant west-Atlantic ridge. Yet better low-level moisture along
with collocated middle-level lapse rates ahead of the front should
yield some ascent to allow scattered showery weather to continue.
Abundance of clouds and moisture under SW-flow...a very mild night
with lows down to around the upper-60s.

Monday into Monday night...

Cooler air digging southeast into the NE-Continental U.S. Yielding conditionally
unstable middle-level profiles above a well-mixed boundary layer...
should see subsequent daytime lift of available moisture yielding
scattered showers maybe even a thunderstorm. Minor instability and
weak shear...any storms would appear to be airmass related beneath
the weak cold pool. Best activity may occur across high terrain with
west-winds undergoing orographic lift providing favorable ascent.

Otherwise scattered to broken cumulus. Mild day with highs around
the low-80s. Turning quiet and cooler overnight as high pressure is
anticipated to settle across the region. Light winds and mostly
clear conditions may allow for effective radiational cooling.


Expecting a cold front to push into the region ahead of which modest
instability / weak shear collocated with a SW-plume of high moisture
resides over S New England. Once again...with better dynamics north/west of
the region...anticipate trailing scattered showers and thunderstorms
over the forecast area. Zonal-flow and weak ridging should suppress
activity to some degree in addition to the lacking dynamics...
potentially diffuse more so should the front sweep the region during
the evening period. Highs again around the low-80s with a mild night
with lows around the mid-60s.

Wednesday into Friday...

Favor the European model (ecmwf) with the zonal-flow pattern of higher heights. Shall
prevail with high pressure. Expecting conditions around seasonable
levels and overnight periods which may turn cool with effective
radiational cooling at times under light winds. Weak impulses
through the zonal flow will need to be monitored for the potential
of likely clouds and possible showers...but so late in the forecast
period...just too difficult to suggest outcomes.


Aviation /02z Friday through Tuesday/...
forecaster confidence levels...

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

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

VFR. Patchy MVFR-IFR fog possible across the CT-River Valley under
lessening north/northwest flow. Light winds Friday with accompanying sea-
breezes by late morning...diminishing during the evening hours.
Could see patchy fog / stratus during the Friday overnight period.

Kbos terminal...high confidence in taf. Sea-breezes towards noon.

Kbdl terminal...high confidence in taf.

Outlook...Saturday through Tuesday...

Saturday into Sunday...moderate confidence.

VFR. Breezy S/SW winds. Scattered ceilings 4-6 kft Saturday. MVFR-IFR ceilings /
visibilities possible along the S-coast Saturday night. Rain showers/thunderstorms and rain possible
for north/west New England late Sunday.

Sunday night into Monday...low confidence.

Mix of low-end VFR to MVFR. Widespread rain showers across the terminals.
Possible thunderstorms and rain across the interior Monday. Continued S/SW winds.

Tuesday...moderate confidence.

Cold front sweeping across the terminals. Low-end VFR. Chance of
rain showers/thunderstorms and rain across the interior. Winds backing out of west behind the


forecaster confidence levels...

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

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

Tonight... south to southeast swell from Hurricane Cristobal will
slowly subside overnight. However the combination of the long period
and descent swell and waves will continue to create a risk for high
surf. Have extended the Small Craft Advisory for hazardous seas and
increased it to anz250 as the northeast trajectory could create 5

Tomorrow... high pressure builds over New England and the waters.
This will mean light wind...becoming onshore near the coast. Seas
will diminish through the day. However rough seas may linger on the
waters south and east of Cape Cod and Nantucket. Have continued the
Small Craft Advisory for the outer waters through the day.

Tomorrow night...waves will be below 5ft and winds below 15 kts as
high pressure sets up over the waters.

Outlook...Saturday through Tuesday...

Saturday into Sunday...moderate confidence.

Increasing S/SW-winds. Prolonged fetch lending to wave heights in
excess of 5-feet across the S/southeast waters on Sunday. Fog possible
during the overnight hours...especially along the S-coast.

Sunday night into Monday...moderate confidence.

Breezy S/SW winds continuing. Seas of 5-feet on the S/SW waters.
Showers impacting the waters. Patchy dense fog possible during the
overnight period...but with brisk winds...have greater confidence
towards low clouds. Wet weather clearing out late in the day on

Tuesday...moderate confidence.

Expecting a period of quiet weather over the waters with breezy S-
winds ahead of a cold front expecting to sweep the waters towards
Wednesday morning.


Box watches/warnings/advisories...
Massachusetts...high surf advisory until 8 am EDT Friday for maz020-023.
High surf advisory until 9 PM EDT Friday for maz022-024.
New Hampshire...none.
Rhode Island...high surf advisory until 8 am EDT Friday for riz006>008.
Marine...Small Craft Advisory for hazardous seas until 8 am EDT Friday
for anz235-237.
Small Craft Advisory for hazardous seas until 9 PM EDT Friday
for anz250-254>256.


near term...wtb/dunten/sipprell
short term...dunten
long term...sipprell

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