Area Forecast Discussion
Issued by NWS Boston, MA

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920
FXUS61 KBOX 262324
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
724 PM EDT SUN JUN 26 2016

.SYNOPSIS...

High pressure remains in control through Monday. A cool front
will slowly approach the region, bringing showers and thunderstorms
Tuesday and Wednesday. High pressure then brings dry seasonable
weather for the late week. Another cold front may bring more
showers and thunderstorms around Saturday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...

730 pm update...

Upper level ridge remains over the region tonight as surface high
pressure continues to move offshore. Stout dry inversion just above
the surface beneath which S winds continue to advect moisture N.
Surface dewpoints have risen slightly and are expected to continue
to do so overnight. Coupled with mostly clear conditions, expect
another round of radiational cooling. Temperatures overnight won`t
drop as low as they did during the early morning hours Sunday, but
still low enough such that there is the threat of patchy ground
fog or stratus. Focus across E CT into W RI. Perhaps even Southeast
MA where radiational cooling is most favorable. Lows falling down
into the mid 50s. Elsewhere upper 50s with urban centers in the
low 60s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...

Monday...

Pre-frontal trough will push through the Great Lakes region
resulting in southwest flow across southern New England. Offshore
mid-level low will stall the trough keeping Monday mostly dry.
Clouds will begin to increase from west to east during the afternoon
hours. Due to increasing pressure gradient, southwest flow will
increase aloft. Appears mixing will reach up to 900 mb which would
allow for gusts near 20-25 mph. Otherwise temperatures will warm
into low to mid 80s across the area, cooler conditions along the
South Coast due to onshore flow. Can`t rule out upper 80s to near
90s across the Merrimack Valley due to good mixing in southwest
flow.

Monday Night...

The pre-frontal trough will slowly approach from the west but weaken
on Monday night. Very weak forcing and limited upper level dynamics
as this system moves through. Still plenty of moisture to work with
so expect isolated to scattered showers overnight. Appears that
there will be some elevated instability, so cannot rule out a rumble
of thunder.

Aside from the convection potential, higher dewpoints will spill
into the region overnight. This will result in muggier conditions,
and the potential for fog development. Overnight temps will only
drop into the low to mid 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...

*/ HIGHLIGHTS...

 - Showers and thunderstorms Tuesday into Tuesday Night
 - Interior wet weather for Wednesday as cooler air settles in
 - Dry, seasonable, comfortable Thursday and Friday
 - Another shot of wet weather for Saturday
 - Looking to return dry and seasonable beginning next Sunday

*/ DISCUSSION...

Forecast solutions seemingly coming into consensus. An analysis of
atmospheric teleconnections, leaning with low pressure maintaining
over the Gulf of Alaska with ridging over the W and Central CONUS.
Further downstream troughing prevails from the Hudson Bay region of
Canada down into the Great Lakes. New England for the most part
resides along the E periphery of the trough up against the Atlantic
ridge. It is through the troughing pattern we`ll see several waves
of activity bringing chances of wet weather throughout the long-term
forecast period. Still believe these N impulses will interact with
the sub-tropical flow round the Atlantic ridge. Setups can vary as
to whether deeper moisture is drawn N, or rather a squeeze play
setup evolves between the two areas of disturbed weather drawing a
region of higher heights and drier weather, a trend that has been
seen extending SW to NE from Newfoundland, Nova Scotia, across the
Gulf of Maine and into SE New England. Focusing on a broader view
evaluating synoptics parent with moisture, lift and instability
should it be present. Closely following ensemble means as well as
probabilistics with this forecast. Overall the forecast does not
put an end to the rainfall deficits, hardly, but it is welcoming.

Expect the first wave Tuesday into Wednesday. Increasing moisture
from the S beneath mid level vortex energy sweeping N/E across New
England and diffluence aloft, a fair amount of forcing ahead of an
initial pre-frontal boundary Tuesday met up with a cool front for
Tuesday night before exiting E early Wednesday will yield a prolonged
period of showers and thunderstorms. Column moistens with pwats up
to 1.5 inches as the profile becomes conditionally unstable yielding
a measure of instability especially if there`s any diurnal heating.
Still a challenge to nail down cloud cover as we could be dealing
with marine stratus / fog in addition. Perhaps some initial activity
early Tuesday, remnants from Monday along the pre-frontal boundary.
Otherwise as ingredients come together ahead of the cool front out
of Upstate NY / PA should see chance to likely PoPs N/W, lesser S/E
under the influence of continuing subsidence and drier air. This
changes into Tuesday night as the environment shifts N/E. Big
question is whether offshore sub-tropical moisture becomes involved
or whether SE New England remains in a squeeze play as outlined
earlier.

Following closely with ensemble probabilistics and consensus of the
forecast guidance. Heavier rainfall amounts forecast N/W around half
an inch with lesser S/E. Not a soaker and not one that`ll put an end
to the drought-like conditions. Will keep shower and thunderstorm
wording similar throughout the sweep of the cool front behind which
for Wednesday cooler air follows and lapse rates steepen. An
environment beneath continued cyclonic flow and additional mid level
energy, diurnally-forced convection is expected though a greater
probability further N beneath the crux of the cold pool and closer
to stronger dynamics, this in addition to orographic influences.
Chance PoPs mainly N/E of the MA-CT border.

UPDATE: 26.12z EC has slowed the cool frontal progression as was the
case with yesterday`s model runs. 26.12z UKMET is not that far off
from the EC. Some handling challenges with mid level vortex energy
lifting N/E through the timeframe. A time difference of 6-12 hours
between model solutions. Will linger activity into Wednesday but
looks to clear out into Thursday.

For Thursday and Friday, expect a quiet forecast period. Seasonably
dry weather, comfortable with low humidity. Initial N/W flow
Thursday reverts S into Friday ahead of disturbed weather for the
weekend. Will see increasing humidity and dewpoints Friday night
into Saturday morning. Could see some emerging issues with marine
stratus and fog.

Over the weekend, placing most of the emphasis on Saturday. Strong
low over the S Hudson Bay region of Canada. Cyclonic flow through
which jet dynamics and mid level energy promote an environment of
decent forcing, pulling cooler air S the leading edge of which
becomes a focus for showers and thunderstorms across the NE CONUS.
Increasing moisture along and ahead with the atmospheric profile
becoming conditionally unstable. Instability grows with any diurnal
heating. Overall synoptics seem stretched within the flow and not
sharp, thus leaning more of a daytime event supported by diurnal
heating. Will keep similar shower and thunderstorm wording within
PoPs.

Thereafter for Sunday into early next week, going with a dry and
seasonable forecast beneath continued cyclonic flow and a cooler
airmass across the region. Appearing dry as high pressure sweeps the
NE CONUS.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...

Forecaster Confidence Levels.

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

Short Term /through Monday Night/...

0z update...

Tonight...High Confidence.

VFR though watching E CT and W RI, perhaps even SE MA for IFR-LIFR
potential with patchy ground fog or stratus. Light S winds.

Monday...High Confidence.

VFR. Any IFR-LIFR fog / cigs quickly eroding. Expect S/SW winds
gradually increasing, gusts up to 20-25 kt during the afternoon.

Monday night...Moderate Confidence.

Mainly VFR. Conditions could deteriorate as SHRA and isolated TSRA
move into W New England. IFR-LIFR stratus and fog could develop
ahead of approaching showers over S/E portions of New England.

KBOS TAF...High confidence. S winds increase Monday, gusting up
to around 25 kts during the afternoon hours

KBDL TAF...High confidence. VFR. Very low chance for MVFR-IFR
conditions in patchy fog 07Z-11Z tonight and again Monday night.
May reside just to the S/E.

Outlook /Tuesday through Friday/...

Tuesday into Wednesday...Moderate confidence.

SHRA and TSRA. Low end VFR / MVFR during the day. MVFR / IFR during
the evening periods. May be contending with LIFR marine stratus
along the S coast as well. TEMPO lower conditions with any RA /
TSRA. S winds ahead with potential gusts up to 20 kts at times.
Clearing out Wednesday as winds back W though there is a chance of
additional SHRA / TSRA activity across the N/W interior with TEMPO
MVFR / IFR.

Thursday into Friday...Moderate confidence.

VFR. N/W winds Thursday turning out of the S into Friday. SCT to BKN
low-end VFR cigs possible during the day.

&&

.MARINE...

Forecaster Confidence Levels.

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

Short Term /through Monday Night/...

730 pm update...no major changes to the forecast.

Tonight...High Confidence. Quiet boating weather tonight.

Monday into Monday night...Moderate Confidence. High pressure
moving offshore as system approaches from the west. Near shore
winds will gust close to 25 kts during the afternoon tomorrow. SCA
may be needed but confidence is low. Increase LLJ across northern
waters will result in seas building to 5 feet. SCA will continue.

Outlook /Tuesday through Friday/...

Tuesday into Wednesday...Moderate confidence.

Showers and thunderstorms moving into the waters late Tuesday on
through Wednesday morning associated with a sweeping cool front.
Ahead of this likely to see S winds with gusts up to 20 kts. Some
marine stratus / fog possible with visibility restrictions, focusing
on the S/SE waters. Potentially soupy. With cool frontal passage
during the early half of Wednesday, winds back W and conditions
should improve. Waves up to 5 feet.

Thursday into Friday...Moderate confidence.

Good boating weather. N/W winds but not expected to be gusty behind
the front. Wave action diminishing rather quick. Winds veering out
of the S into Friday.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...

CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory for hazardous seas from 1 PM Monday to 2
     AM EDT Tuesday for ANZ250.

&&

$$

SYNOPSIS...Dunten/Sipprell
NEAR TERM...Dunten/Sipprell
SHORT TERM...Dunten
LONG TERM...Sipprell
AVIATION...Dunten/Sipprell
MARINE...Dunten/Sipprell



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