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000
FXUS61 KBOX 220807
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
407 AM EDT Sat Jul 22 2017

.SYNOPSIS...
Dry, hot weather today with lower humidity. High pressure from
Canada builds over northern New England Sunday, then moves off
to the east. Several waves of low pressure will pass to the
south of southern New England Saturday night and Sunday. It will
be cooler in eastern sections Sunday but still warm in the
Connecticut Valley. A couple waves of low pressure will bring
some showers at times along with cooler than normal temperatures
Sunday night through Tuesday. Temperatures will moderate a bit
by mid to late next week, but still remain below normal with
another chance for some showers Thursday and/or Thursday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
405 AM update...

Dew point front progressing southward across CT/northern RI per
surface observations (61 at BDL but still 69 at IJD) and on
Doppler radar. 925 mb jet now exiting southeast MA. Showers out
ahead of these features extended from Long Island eastward
across Block Island. The HRRR forecasts these to move rapidly
east-southeast and exit the waters south of Nantucket by 12Z.

Today will be dry but still hot. 925 mb temps of +22C should
yield highs in the upper 80s to lower 90s. This could be the
5th day of the heat wave at BDL. We are watching a solid area of
mid level cloudiness covering western and central New York
state. Mid and high cloudiness is forecast to increase over
southern New England this morning and afternoon, but as is often
the case in the summertime, it is likely to erode after
sunrise. Satellite imagery already showing some signs of the
leading edge eroding. With enough filtered sunshine, we should
still hit the upper 80s/loweA couple waves of low pressure will bring some showers at times
along with cooler than normal temperatures Sunday night through
Tuesday. Temperatures will moderate a bit by mid to late next week,
but still remain below normal with another chance for some showers
Thursday and/or Thursday night.r 90s away from the coast. Winds
will be diminishing along the eastern MA and RI coasts early
this morning and thus expect onshore sea breezes to take hold
late this morning and early this afternoon.

Although the atmosphere is dry, K and TQ indices rise to 28 and
17, respectively late in the afternoon in northeast MA.
Although most shower activity should remain to our northwest,
have introduced a slight chance of a shower in the Merrimack
Valley of northeast MA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Tonight...

Southern New England will be in between sprawling high pressure
over southeast Canada and northernmost New England...and low
pressure somewhere along the Mid-Atlantic coast from NJ to
DelMarva. The low to our south will likely be the remnants of a
mesoscale convective system affecting that area late this
afternoon and tonight. For us, winds will turn to a
northeasterly direction. Skies will be cloudy and there is a
chance of showers, mainly over northern CT, RI, and southeast
MA, closer to the low pressure. Lows in the 60s.

Sunday...

A bit of a tricky forecast. Low pressure will continue passing
southeast of the region. It may cause scattered showers mainly
along the south coast in the morning. But then we should see a
period of increasing sunshine during the late morning through
mid afternoon. Light easterly wind flow will keep eastern MA
temperatures cool...in the mid 70s near the coast, but the
partial sunshine could allow the CT River Valley to soar well
into the 80s. ECMWF would suggest 88 degrees but model consensus
is much lower. Have bumped temperatures above the consensus, to
the mid 80s in that region.

Late Sunday afternoon, chances of showers increase again, mainly
in northern CT and western MA, ahead of advancing low pressure.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...

Highlights...

* Sun night/Mon: Below normal temps with some showers likely at times
* Tue: A few leftover showers possible w/below normal temps
* Temps moderate mid to late next week but still below average
* Another round of showers possible Thu/Thu night but not a washout

Details...

Sunday night and Monday...

A complex forecast as another MCS will likely pass well to our
southwest Sun night towards the axis of greatest instability.  While
we should not be directly impacted by that complex, impressive
shortwave trough will approach from the Great Lakes.  This should
increase the forcing for ascent resulting in showers at times Sunday
night/Mon, but specific timing uncertain at this point.  Severe
weather threat looks quite low across our region given lack of
surface instability, but some isolated thunderstorms can not be
ruled out with a bit of elevated instability.

High temps on Monday should be rather cool for July standards.
Northeast surface winds and an abundance of clouds should keep highs
mainly in the 70s.  In fact, it is possible a few locations struggle
to break 70.

Tuesday...

Models indicate that the best synoptic forcing will have exited the
region, but low clouds and moist northeast flow may persist.  May
end up with just a few leftover spot showers, but an abundance of
clouds with another day of below normal temps. Highs again mainly in
the 70s and it is possible that a few locations struggle to break
70.

Wednesday through Friday...

A long way off so this is certainly subject to change.  Based on
latest model data though, initial upper trough lifts out by
Wednesday as a ridge of high pressure builds across the region. This
should allow for dry weather on Wed. However, another impressive
shortwave trough may bring a period of showers/isolated
thunderstorms Thu/Thu night with perhaps dry weather returning by
Friday.  Temps should moderate some from earlier in the week, but
this next trough will likely keep readings below normal through the
end of the work week.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

Short Term /through Sunday/...High confidence.

Today...VFR. Increasing mid and high level cloudiness.
Onshore sea breezes at the coast. Slight chance of a shower near
Nantucket around sunrise.

Tonight...VFR. Mainly mid-high clouds. Could see lowering
toward low-end VFR overnight. Local IFR ceilings in areas of fog
possible on the south coast, mainly Cape Cod and the Islands.
Chance of showers late, mainly in CT/RI/SE MA. Wind becoming NE
and gusting to near 20 kt over the eastern MA coast well after
midnight.

Sunday...VFR except IFR/MVFR southeast MA and southern RI in the
morning. Scattered showers southeast MA and RI in the morning
and in western MA and northern CT late in the afternoon.

KBOS Terminal...VFR. Sea-breezes forecast around 15z today.

KBDL Terminal...VFR.

Outlook /Sunday Night through Wednesday/... Moderate confidence.

Sunday night through Tuesday...Moderate confidence. VFR conditions
early Sunday evening should deteriorate to MVFR-IFR later Sun night
into Mon morning from west to east in some showers, low clouds and
fog patches. MVFR-IFR conditions will likely persist the rest of
Monday and possibly into part of Tuesday.

Wednesday...Moderate confidence. Mainly VFR conditions expected.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

Short Term /through Sunday/...High confidence.

Today...Light northwest winds allowing for daytime sea breezes.
Winds becoming south over the eastern MA waters this
afternoon/evening. Seas 1-3 ft.

Tonight...Winds shifting to the northeast as high pressure
builds to our north and low pressure passes to our south. Winds
gust to 20 kt, especially from Cape Ann to Mass Bay and
Provincetown. Chance of showers late. Local visibilities reduced
to 1-3 miles in fog late. Seas 1-3 ft.

Sunday...Northeast winds continue at 15-20 kt with seas building
to 3-4 ft. Chance of showers, especially south coast in the
morning.

Outlook /Sunday Night through Wednesday/... Moderate confidence.

Sunday night through Tuesday...Moderate to high confidence.  A
couple waves of low pressure tracking near or south of our waters
will generate an persistent east to northeast winds.  The result
should be marginal small craft conditions at times across our
eastern waters, where wind gusts of 20 to 25 knots and 3 to 6 foot
seas are expected.  Some showers and fog patches will also reduce
vsbys for mariners at times.

Wednesday...Moderate to high confidence.  Ridge of high pressure
temporarily builds across the waters which should keep winds/seas
below small craft thresholds.

&&

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

&&

$$
SYNOPSIS...Field/Frank
NEAR TERM...Field
SHORT TERM...Field
LONG TERM...Frank
AVIATION...Field/Frank
MARINE...Field/Frank