Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 160544
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
144 AM EDT Fri Jun 16 2017

.SYNOPSIS...
High pressure moves offshore tonight. An approaching warm front
will bring a period of showers and isolated t-storms Friday into
Friday night followed by warm and humid weather over the
weekend. A cold front will approach from the west on Monday and
linger across southeast New England on Tuesday bringing a
chance for showers and thunderstorms.

&&

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

130 AM Update...

No significant changes to prior near term forecast. There were
just a few sprinkles near the NH border at 130 AM. Temperatures
were running near or slightly above the forecast, and dewpoints
were running near to slightly below the forecast.


1015 PM Update...

Have just made minor adjustments to grids to account for current
conditions and trends. Forecast for the most part seems to be
remaining on track. Radar shows some showers trying to make
their way into western Franklin County, but air mass remains
very dry in lower levels with dewpoints generally in the upper
40s. Taking into account high resolution model output, have
slight chance POPs overnight along the route 2 corridor in
northern Mass and along the east slopes of the Berkshires but
even in those areas will most likely just encounter some
sprinkles.

700 PM Update...

Overall trend in the forecast remains on track for this evening.
Showers are drying up as the enter into the Berkshires due to
the amount of dry air over western MA. Still cannot rule out a
few sprinkles but little impact is expected. Bulk of the showers
across upstate NY will remain north of the region overnight,
however cannot rule out a few isolated showers north of the Pike
in the morning. Otherwise made only minor updates to account
for current conditions.

Previous Discussion...
High pres moves offshore tonight but wedge of dry air will hold
on for much of the night. Higher theta-e air remains west of
New Eng with best chance of showers and t-storms across central
and northern NY into VT where best elevated instability and
moisture advection at the nose of the 850 mb jet. Low risk a few
showers could clip far N/NW MA, otherwise, mainly dry weather
tonight with increasing clouds. Lows in the 50s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
Friday...

Showers will overspread the region from the southwest as low
level warm front lifts north into the region. Models show good
moisture advection with increasing KI and higher theta-e air
as southern extent of the low level jet moves through. A few
showers may develop in the morning in the west, but best chance
will be during the afternoon and can`t rule out a few t-storms
as marginal elevated instability develops.

Given high PWATs increasing to 1.75+" and elevated instability,
potential exists for locally heavy rainfall and some of the hi-
res guidance is signaling this with best chance in the interior.

Surface warm front will remain to the south with SE flow which
will keep temps in the 60s to near 70 degrees. SE wind gusts to
20-30 mph possible near the coast in the afternoon.

Friday night...

Focus for heavier showers and isolated t-storms will shift to
the coastal plain during the evening assocd with the high PWAT
axis and low level jet which eventually slides off the coast.
Stratus and patchy fog expected as sfc warm front not likely to
lift to the north until Saturday with abundant low level
moisture persisting through the night.

&&

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

* Heat and Humidity returns Sunday into Monday
* Hit or miss showers possible Saturday and Sunday
* Increasing chance for thunderstorms on Monday and possible Tuesday

Pattern Details...

12z guidance remains in relatively good agreement for the long term
forecast. Still have the normal timing and strength issues of each
system but overall confidence is improving. Strong upper level
ridging over the desert southwest as well as the Bermuda high off
the eastern seaboard will be the two main features for the long
term. This will result in troughing across the Great Lakes. Several
waves progressing through the base of the trough will eject into the
Northeast which will result in an unsettled weather pattern.
Southwest flow through much of the period will increase the moisture
and heat especially on Sunday/Monday. A cold front will slowly move
eastward across the Great Lakes and then the Northeast by late
Monday into Tuesday with a cool down projected for mid next week.

Details...

Saturday into Sunday...Moderate confidence.

Approaching warm front to the west as Bermuda ridge continues to
strengthen an build. Onshore flow during the morning could result in
fog and stratus across the coastlines. Anticipate lingering showers
after 12z across the east but a drying trend by mid-day. BUFKIT
cross sections indicate some mixing during the late morning hours
which could lift any fog that does develop. 850 mb temps continue to
be on the rise during the day which will help push temperatures back
into the upper 70s to low 80s. It could be higher if clouds break
up, but still a lot of deep layer moisture in the area thanks to
persistent southwest flow tapping into tropical moisture. This
moisture overriding the front will result in showers across the
region. As the warm sector approaches, cannot rule out a pop-up
thunderstorm during the afternoon as well. Better instability and
shear values will be across the west, but cannot rule out the
potential reaching eastern MA.

Moisture plume will continue to be over the region on Sunday as the
warm front pushes through the area. The region will be pushed into
the warm sector as temperatures soar back into the mid to upper 80s.
Cooler along the south coast as southerly flow bring onshore marine
air. Chance of precipitation appears less likely as guidance has cut
back on pops due to the ridge to the east pushing closer to southern
New England. Models continue to show better instability however as
mentioned before, a trigger appears to be missing. Still cannot rule
out pop-up showers and thunderstorms during the day. LLJ will also
begin to increase resulting in gusts southwest winds near 25 to
30 MPH during the afternoon.

Monday and Tuesday...Moderate confidence.

Approaching shortwave from the west will begin to break down the
ridge to the east. Southwest flow across the region with high PWATS
nearing 2 inches and increasing LLJ at 925 mb will aid in the
development for showers and thunderstorms. Monday has the better
confidence for precip especially in the afternoon hours. Cannot rule
out a few strong storms due to good instability combined with steep
lapse rates and increased sheared and moisture. If storms do develop
then gusty winds and heavy rainfall will be the main threats.

Increasing LLJ with steep lapse rates will result in an increase in
mixing on Monday. Could see southwest winds gusts to near 25-30 MPH.

Latest guidance continued to slow the timing of FROPA. Thus the
latest trends is showers with iso thunder Tuesday afternoon
depending across southeast half of the region. This is ultimately
dependent on where the frontal system stalls. Temperatures will feel
cooler across the NW but may still be muggy over the southeast
portion of the area as southwest flow continues to keep dewpoints
in the 70s. This can change still depending on frontal placement.

Wednesday...Moderate confidence.

Broad cyclonic flow aloft on Wednesday with guidance hinting at a
weak wave passing through sometime during the day. This will bring
another round of scattered showers with possible thunder.
Temperatures will be more seasonable with highs in the 80s and some
relief in the humidity.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

Overnight...High confidence for most of the area. VFR cigs
expected across most of the area except have noted some MVFR
cigs have made there way into southern CT. We may see those MVFR
cigs spread into northern CT by daybreak.

Friday...Moderate confidence. Conditions lowering to MVFR from
west to east as showers overspread the region, especially in
the afternoon. Areas of IFR possible by late day, especially
interior. A few t-storms possible.

Friday night...Moderate confidence. Widespread MVFR/IFR
conditions with stratus and patchy fog. Sct showers and an
isold t-storm possible.

KBOS TAF...High confidence. Continue to believe that Low clouds
will hold off until after 18z.

KBDL TAF...Moderate confidence. Low clouds could have some impact
on the morning push.

Outlook /Saturday Night through Tuesday/...Moderate confidence.

Saturday through Sunday...Mainly VFR with areas of MVFR within and
heavy shower or iso -TSRA. Low end MVFR to IFR conditions possible
overnight from fog and stratus.

Monday...VFR to start with showers and thunderstorms moving from
west to east during the afternoon from passing cold front. MVFR
conditions possible.

Tuesday...Stalled cold front may result in VFR conditions out west
with MVFR conditions across eastern terminals. Another round of
showers and -TSRA is possible during the morning into mid-
afternoon.

&&

.MARINE...
Forecaster Confidence Levels...

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

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

Sub SCA SE winds tonight with increasing SE flow Fri into Fri
evening as low level jet moves across the waters. Gusts to 25 kt
and building seas with SCA conditions. Winds diminish overnight
Fri night. Vsbys reduced in occasional showers and fog late Fri
and Fri night.

Outlook /Saturday Night through Tuesday/...Moderate confidence.

S to SW gradient and fetch will keep seas to around 5 feet across
the outer coastal waters Saturday. Wind gusts between 20 and 25
knots possible on Sunday and again on Monday this will increase seas
once again above 5 feet. In addition, anticipate areas of fog and
visibilities below 3 miles across the waters during the weekend.
Showers and thunderstorms are possible across the near shore waters
late Monday and again on Tuesday from passing cold front.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 10 AM this morning to 8 AM EDT
     Saturday for ANZ231-232-235-237-250-251.
     Small Craft Advisory from 10 AM this morning to 2 AM EDT
     Saturday for ANZ233-234.
     Small Craft Advisory from 8 AM this morning to 6 PM EDT
     Saturday for ANZ254>256.

&&

$$
SYNOPSIS...KJC/Dunten
NEAR TERM...KJC/Dunten/Thompson
SHORT TERM...KJC
LONG TERM...Dunten
AVIATION...KJC/Dunten/Thompson
MARINE...KJC/Dunten



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