Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 210753
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
353 AM EDT Fri Jul 21 2017

.SYNOPSIS...
Another round of hot and humid weather today. Cooler and drier
air moves in tonight with another warm and dry day on Saturday.
A pattern change to below normal temperatures along with
showers at times are expected Sunday through Tuesday, but the
entire period will not be a washout. A drying trend is likely by
the middle of next week with slowly moderating temperatures.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

400 AM Update...

Overall trend in the forecast remains on track early this morning.
Patch fog continues to develop across the typical low lying regions.
Nantucket and portions of the Cape are socked in dense fog as of 4
AM, anticipate this trend to continue over the next few hours until
mixing takes place later this morning.

Otherwise convection remains well south of the Islands early this
morning. But cannot rule out a spot shower near Nantucket as the
environmental is still quite unstable and LLJ moving through.

Today...

Northwest flow aloft will take hold of the region as weak troughing
occurs across the Hudson Bay. Any morning fog will dissipate as
mixing takes place dragging lower dewpoints to the surface. This
will especially occur across the western half of the region.
Dewpoints across the immediate south coast may still linger around
70, but should feel some relief compared to the previous two days.
This mixing will help increase gusts to around 15 to 20 MPH this
afternoon. These winds may keep the sea breeze at may for sometime,
but feel it will still make its way onto the immediate coast.

Otherwise a dry forecast for today. Temperatures will sore back into
the 90s similar as yesterday. In fact because of the due westerly
flow, may actually reach a degree or two higher than yesterday. Many
sites will see 90+ away from the higher terrain.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...

Tonight and Tomorrow...

Quiet tonight as the flow remains northwest. Some high level clouds
may filter into the region overnight. A bit cooler as temperatures
will drop into the mid to low 50s as radiational cooling occurs.
This is due to light winds and drier conditions. Urban region will
remain warmer with lows around 70.

Weak shortwave will move through the flow early Saturday. Otherwise a
quiet day as dry weather will prevail. In fact, appears that
Saturday is the pick of the weekend with mostly clear skies with
temperatures warming once again into the upper 80s to low 90s. Sea
breezes across the immediate coastline may occur.  Clouds will begin
to filter into the region from the west in the later half of the
day. This is due to approaching MCS cluster that may develop across
upstate NY and transfers to the southeast.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

Highlights...

* Sun/Mon/Tue below normal temps with showers at times
* Drying trend by mid week with slowly moderating temperatures

Details...

Saturday night and Sunday...

A very difficult forecast as guidance depicts another MCS impacting
a part of the Northeast and/or Mid Atlantic States Sat night into
Sun.  Guidance is all over the place in regards to its track and
timing.  In this case, will side with the bulk of the MCS tracking
southwest of our region, where the greater instability will reside.
Based on that we are not expecting severe weather and probably not
even any thunder. However, we may see some showers develop north of
the main complex and impact our region. Confidence on that is
uncertain, but worth carrying chance pops.

As for high temps Sunday, it will be cooler than recent days given
easterly flow and perhaps lots of clouds even if we escape most of
the showers. Highs should mainly be in the 70s, but its possible a
few locations reach the lower 80s if there are some peeks of sun.

Monday and Tuesday...

Anomalous closed upper level low across the Canadian Maritimes will
send a piece of strong shortwave energy southward.  This will carve
out a northeast trough resulting in below normal high temps along
with showers at times.  While the entire period will not be a
washout, onshore flow and lots of clouds will likely hold highs in
the 70s. In fact, some locations may struggle to break 70 on one of
those days.

Wednesday and Thursday...

The upper trough begins to lift northeast.  Still plenty of
uncertainty this far out, but current guidance indicates a drying
trend by the middle of next week. Temps should gradually moderate,
but they still probably will remain a bit below normal with highs
well up into the 70s to lower 80s.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

Short Term /through Saturday/...High confidence.

Before 12z...
VFR, outside of ACK where IFR conditions will remain most of
the night. MVFR vsbys across the south coast will improve by
the morning.

Today and tonight...
VFR conditions through the period. Patchy MVFR vsbys across the
Cape and Islands once again tonight. W/SW winds continuing with
gusts up to 20 kts this afternoon.

Tomorrow...
Mainly VFR. High level cirrus by the afternoon. A spot shower
possible across CT late in the day.

KBOS Terminal...High confidence in TAF. Low prob of late day sea
breeze.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday night through Tuesday/...

Saturday night through Tuesday...Low confidence. Periods of low
clouds, showers, and fog patches will impact the region at times.
However, also expect periods of VFR conditions thrown into the mix.
Timing of these conditions though is highly uncertain, but guidance
indicates Mon and Tue have the best chance of featuring the lower
cigs/vsbys.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

Short Term /through Saturday/...

Today and tonight...
W/SW winds through the day dissipating fog. Will shift W/NW
overnight ushering in drier air. Gusts below 20 kts. Seas below
4 feet.

Saturday... Great boating weather on Saturday. Winds switching
to a more southwesterly direction, as near shore waters could
gust to near 15 kts. Seas will remain below 4 feet.

Outlook /Saturday night through Tuesday/...

Saturday night through Tuesday...Moderate confidence.  A couple
waves of low pressure will likely track south of the waters over
this time frame.  The result will be persistent northeast winds
which should gust to 20 knots at times.  Timing uncertain, but
marginal small craft seas may impact our outer waters. Some showers
and fog patches will also impact mariners at times.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until 8 AM EDT this morning for MAZ024.
RI...None.
MARINE...None.

&&

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



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