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Area forecast discussion 
National Weather Service Taunton Massachusetts
424 PM EDT Monday Jul 25 2016

Synopsis...
a weak cool front may cause scattered showers and thunderstorms
tonight...a few with gusty winds, especially in western and
southern portions of the region. High pressure will bring dry but
hot conditions Tuesday and Wednesday. A cold front approaches the
area on Thursday. This front may linger in our area into this
weekend.

&&

Near term /until 6 am Tuesday morning/...
415 PM update...

First line of thunderstorms has sagged southeastward, with a
severe portion of the line moving across southern Connecticut.
Farther north, scattered showers were developing from Hartford
County to Worcester County. A few other showers were on the sea
breeze in northeast Massachusetts. Downdraft cape is 1200 but across our area
the line is fighting some warm air aloft and poor mid level lapse
rates.

A second area of convection was occurring from central New York
southward through PA. This is associated with the upper level
shortwave trough and a weak cool front. Mid level lapse rates
will be increasing as it approaches. Short-range models move it
east- southeastward, meaning the majority of it passing across CT.
Will carry 40-55 percent probabilities of showers/tstms tonight
across the region...exiting eastern coastal areas around 10-11 PM.
Have removed the severe wording from the grids but will add gusty
winds as enhanced wording mainly in CT and areas along the CT/Massachusetts
and CT/Rhode Island border into the evening hours.

Boston Logan winds had turned to the southeast and within an hour
or so, temperatures could shoot up above 90 degrees there.

Otherwise, dwpts will be slow to decrease even as winds shift
toward the W-NW. Expect some localized ground fog especially where
rainfall is observed. Indications suggest cape/islands see a mix
of marine fog/stratus. Minimum temps mainly 65 to 70.

&&

Short term /6 am Tuesday morning through Tuesday night/...
Tuesday...even with some cooling aloft, high temperatures still
are forecast to soar to the low to mid 90s. This is courtesy of
mostly sunny skies, some downsloping west-northwest flow, and 925
mb temperatures from 23c to 25c.

Tuesday night...dry with high pressure in control. Lows in the 60s
to near 70 along coast.

&&

Long term /Wednesday through Monday/...
highlights...

* lower humidity lingers thru midweek
* hot temperatures anticipated Wednesday away from the coast
* cold front approaches the region on Thursday
* showers and thunderstorms are possible again Friday and possibly
into the weekend

Overview...

25/12z guidance is in decent overall agreement through mid
week.However there continues to be significant differences in
solutions for Thursday night and on. 12z models seem to be in
general agreement on bringing a cold front into our area Thursday or
Thursday night. However, models differ on when the front pushes
south of our area. Will continue to go with a consensus approach
for this forecast.

Details...

Wednesday and Wednesday night...dry weather with high pressure in
control. Still hot, especially away from the coasts. Sea breezes
are expected to develop, which should help to limit high temps along
the shorelines.

Thursday...we should see another day of hot conditions, however a
cold front will be approaching our area from the N/NW. Moisture
increasing along the front should enable isolated to scattered
afteroon T-storms on Thursday/Thursday evening.

Thursday night and Friday...uncertainty increases with this portion
of the forecast. Models differ on how far south cold front pushes,
as well as timing on potential open wave or deeper low pressure
passing near/south of our area. Will have chance pops for showers/T-
storms. Friday high temps expected to be a few degrees lower than
previous days.

Saturday and Sunday...lots of uncertainty remains with this portion
of the forecast, leading to a low confidence forecast. European model (ecmwf) keeps
frontal boundary nearby, with potential low pressure moving along
the front. GFS pushes the front south of our area for much of the
weekend. Will continue with a chance of showers for this timeframe.

Monday...continued significant amount of uncertainty for this
timeframe, could have a drier period with frontal boundary exiting
the area. Will go with only slight chance pop for this period.

&&

Aviation /20z Monday 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/...

Through this evening...moderate confidence. Mainly VFR through
the evening. Widely scattered showers or a thunderstorm late this
afternoon. Then a better chance of showers or thunderstorms,
mainly in CT and areas along the CT/Massachusetts and CT/Rhode Island borders this
evening. Gusty winds, heavy downpours in any thunderstorms.
IFR conditions possible in thunderstorms.

Later tonight...moderate confidence. Most thunderstorms/showers
exit the coast between 03z and 04z with VFR developing initially
then late night fog especially at typically prone airports.
Stratus also possible along the cape/islands especially. Mix of
IFR/MVFR conditions.

Tuesday and Tuesday night...high confidence. Mainly VFR after
early morning fog/stratus dissipates. Winds mainly northwest with gusts
15-20 kt during the afternoon hours.

Kbos taf...moderate confidence in taf. Winds shifting back to
south-southwest by 21-22z. VFR but chance of showers or
thunderstorms until about 04z.

Kbdl taf...moderate confidence in taf. Chance of a few strong
thunderstorms this evening. IFR possible in any localized heavier
thunderstorm. Otherwise VFR except localized MVFR visibilities in
patchy fog late tonight.

Outlook /Wednesday through Saturday/...moderate to high
confidence.

High confidence Wednesday. Moderate confidence Thursday through
Saturday.

VFR conditions expected on Wednesday. Mainly VFR conditions
Thursday, except MVFR cigs/vsbys possible in scattered
afternoon/eveningshowers/thunderstorms.

Thursday through Saturday...mainly VFR, except MVFR cigs/vsbys
possible in periodic showers and thunderstorms. Potential for patchy
low ceilings/fog at night.

&&

Marine...
forecaster confidence levels.

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

Short term /through Tuesday night/...high confidence.

Seas remain below sca, although they may build to 3 to 4 ft along
the South Coast on Tuesday. Winds from the west-SW tonight will shift
to mainly west to northwest on Tuesday with some gusts to 15-20
kt. Scattered showers and thunderstorms, especially in the
southern coastal waters tonight. Light northwest winds Tuesday
night.

Outlook /Wednesday through Saturday/...moderate to high confidence.

Quiet boating weather is expected for Wednesday. During Thursday
into Saturday winds and seas are expected to remain below Small Craft Advisory
criteria, but the potential exists for areas of low clouds, fog, and
scattered showers and thunderstorms which would limit visibilities
at times.

&&

Fire weather...
during Tuesday, behind the departing cool front, much drier
conditions are expected across southern New England. Minimum
relative humidity during Tuesday is expected to range from 30 to
40 percent across much of the area. The exception is along Cape
Ann and the cape/islands, where minimum relative humidity values of 40 to 60
percent are forecast. Northwest winds around 10 mph may gust to 20
mph at times during Tuesday.

Winds are expected to be lighter on Wednesday with nearshore sea
breeze develompent. However, minimum relative humidity will drop to 30 to around 40
percent across the interior. Along east coastal Massachusetts and southern RI,
sea breezes will allow for higher minimum relative humidity of 40 to 70 percent.

&&

Box watches/warnings/advisories...
CT...heat advisory until 6 PM EDT this evening for ctz002>004.
Air quality alert until 10 PM EDT this evening for ctz002-003.
Massachusetts...air quality alert until 11 PM EDT this evening for maz004>016-
026.
Heat advisory until 6 PM EDT this evening for maz005-010>013-
017.
Rhode Island...heat advisory until 6 PM EDT this evening for riz001.
Marine...none.

&&

$$
Synopsis...gaf/nmb
near term...gaf
short term...gaf
long term...nmb
aviation...gaf/nmb
marine...gaf/nmb
fire weather...nmb

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