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FXUS61 KBOX 192306
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
706 PM EDT Mon Aug 19 2019

.SYNOPSIS...
Very warm and humid conditions Monday will be accompanied by
scattered thunderstorms as a weak cold front sweeps across the
area. Behind the front, a brief period of drier and less humid
weather Tuesday. The front returns Wednesday as a warm front
with humid and very warm conditions overspreading the region Wed
afternoon through Thursday. The return of this summer-like
airmass will be accompanied by the risk for scattered
thunderstorms Wed and Thu. A cold front sweeps across the area
late Thu setting the stage for dry and less humid weather Friday
into the weekend.

&&

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

7 PM update ...

*** Severe Thunderstorm Watch Has Been Cancelled ***

Cluster of storms over RI and southeast MA still producing lots
of lightning however continuing to move steadily east-southeast
and will be offshore and weaken within another 1-3 hours.

Behind this short wave and attending surface trough post frontal
airmass with dew pts in the 60s and eventually the 50s
overspreads the region second half of the night.


&&

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

445 PM update ...

Tuesday ...

Post frontal airmass settles over the region tomorrow with good
column drying as PWATs fall below 1 inch, providing abundant
sunshine. This dry air mixes to the surface with dew pts in the
mid to upper 50s, although afternoon seabreezes will keep dew
pts in the low to mid 60s. Still much more comfortable than the
mid 70 dew pts of today.

Not as hot as today but warm with highs in the mid to upper 80s,
just more tolerable with dew pts in the mid to upper 50s.
Overall a real nice late summer day by New England standards.

Tuesday night ...

Pleasant during the evening hours with dry weather and
comfortable humidity hanging on. Second half of the night warm
front approaches from the southwest with risk of showers and
thunderstorms toward daybreak. Also patchy fog possible late.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...

*** Will update after thunderstorms exit ***

Highlights...

* Shower and thunderstorm chances Wednesday-Thursday
* A cold front brings dry & cooler conditions Friday through the
weekend

Details...

Tuesday night through Thursday....

A series of shortwaves and a strong cold front will bring periodic
shower and thunderstorm chances through Thursday. Starting late
Tuesday/early Wednesday a warm front will begin to make its way
north across the region. With this warm front comes a very humid
airmass (dewpoints rising from the 50s Tuesday to the low 70s early
Wednesday, and PWATs back up near 2"). As mid level energy
associated with a weak shortwave moves through and interacts with
the warm front it initiates showers and thunderstorms. There is
potential for some strong thunderstorms given the moist warm sector
and CAPE values 2000-3000 J/kg with moderate to good bulk shear (35-
45kts). Any storms that form could produce gusty winds and heavy
downpours given how much moisture is in the column. At the moment
the best chance for heavier rainfall looks to be areas north and
west, with less QPF over southeast MA/coastal RI. However, we're
still too far out to nail down specifics with much confidence.

The surface low and upper trough over the Great Lakes region then
slides north and east late Wednesday to Thursday dragging its cold
front across southern New England overnight Thursday. Along and
ahead of the front we again see shower and thunderstorm chances with
>2000 J/kg CAPE and good shear parameters (>40 kts bulk shear).
Temperatures remain relatively steady through this period in the
80s before a cool down arrives to end the week.

Friday through Sunday...

The cold front exits off the south coast or in the vicinity by
Friday morning leaving a cooler and much drier post frontal airmass
in its wake. PWATs drop to 0.5" while surface dewpoints in the low
50s will make the air feel refreshing compared to the previous week.
Surface high pressure and mid level ridging builds in through the
period bringing dry and pleasant weather through the weekend. Cold
pool aloft (850mb temps 7-10C) will allow for surface highs in the
70s each day.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Short Term /through Tuesday Night/...Moderate confidence.

23z update ...

Thunderstorms over southern RI and south coast of MA will slowly
weaken and move offshore between 8 pm and 10 pm. Otherwise VFR
and dry weather. However MVFR/IFR conditions may linger over
Natucket overnight at times.

Tuesday ...

VFR and dry weather. Afternoon seabreezes near the coast.

Tuesday night ...

VFR and dry to start but becoming MVFR with chance of showers
and thunderstorms toward morning.

KBOS Terminal...TSRA risk over by 23z.

KBDL Terminal...TSRA threat has now shifted east of BDL as of
21z.

Outlook /Wednesday through Saturday/...Moderate confidence.

Wednesday: Mainly MVFR, with areas VFR possible. Chance SHRA,
chance TSRA.

Wednesday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA, chance TSRA.

Thursday: Mainly MVFR, with areas VFR possible. Chance SHRA,
chance TSRA.

Thursday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHRA.

Friday: VFR.

Friday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Saturday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

5 pm update ...

Short Term /through Tuesday Night/...High confidence.

Tonight ...

Scattered T-storms ending 7 pm to 10 pm from west to east. Then
improving.

Tuesday ...

Very pleasant weather with light winds and good vsby.

Tuesday night ...

Tranquil dry weather in the evening, then lowering vsby toward
daybreak in fog and chance of showers and thunderstorms.

Outlook /Wednesday through Saturday/...Moderate confidence.

Wednesday: Winds less than 25 kt. Chance of rain showers,
chance of thunderstorms.

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, chance of
thunderstorms.

Thursday: Winds less than 25 kt. Local rough seas. Chance of
rain showers, chance of thunderstorms.

Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, chance of
thunderstorms.

Friday through Friday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft. Slight chance of rain showers.

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.

&&

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

&&

$$
SYNOPSIS...Nocera
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...BW
AVIATION...Nocera/BW
MARINE...Nocera/BW
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