Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 240536

Area Forecast Discussion
National Weather Service Taunton MA
136 AM EDT SUN JUL 24 2016

Hot conditions continue this afternoon/early evening with the risk of
some strong to severe thunderstorms particularly in northern
and eastern MA. Otherwise, excessive heat and humidity is expected
at times through the middle of next week, at least away from
the immediate coast. Another risk for scattered showers
and thunderstorms is possible late next week with a cold front
dropping south.


10 pm update...
Outflow boundary from MCS moving S across the region well out-
paced the main convection, cutting off its connection to low level
vorticity and instability. This gust front is well offshore now
and as such the remnant convection continues to weaken as it moves
offshore as well. Otherwise, drier air already moving in and anvil
CI already clearing the area leading to a relatively pleasant
night. Some fog possible later, especially N and E MA where
rainfall moved through this evening.


Shortwave ridging aloft and very dry column will bring sunshine
and very warm temps, although a bit cooler than today as low level
temps are cooler. Still expecting highs in the mid 80s to around
90 degrees. Best chance of 90+ in the lower CT valley but portions
of RI and interior E MA will likely be near 90 degrees. Afternoon
seabreezes are likely.

Sunday night...
Quiet night as mid level ridging in control. Weak shortwave moving
over the ridge will bring some mid/high level clouds, otherwise
partly cloudy. Mins mostly in the 60s with dewpoints climbing into
the mid 60s toward daybreak.



* Excessive heat at times through mid week at least away from the
  immediate coast and especially Monday

* Mon/Mon night is the highest risk for scattered showers/t-storms
  with the threat for some severe weather and even very localized
  urban type flooding

* Cold front may bring another risk for scattered
  showers/thunderstorms sometime late next week but timing uncertain


Upper level ridge over the southern half of the country will
generate a westerly flow of air aloft and anomalously hot
temperatures, especially for the first half of the week.  GFS
Ensembles indicate 925T between 1 and 2 standard deviations above
normal for most of next week.  So confidence is fairly high in above
to at times much above normal temperatures.  ECMWF ensembles are
pretty much in agreement as well.


Currently, Monday looks like it may be the worst in terms of heat
and humidity.  850T near +20C should allow high temps to rise into
the mid to upper 90s away from any coastal sea breezes.
Surface temps may even reach 100 in a few locales if clouds do not
get in the way. In addition, low level moisture may pool ahead of a
pre frontal trough/cold.  This may push heat index value to 100+ and
decent shot will need heat advisories for portions of the region.

The heat/humidity combined with frontal boundary/pre-frontal trough
in the vicinity may lead to scattered showers and thunderstorms
developing during Monday afternoon and night.  Pretty good shot at
MLCapes reaching or exceeding 1500 J/KG.  0 to 6 KM shear initially
not impressive, but increase to between 25 and 35 knots during the
late afternoon and especially the evening with approaching
shortwave. A lot will depend on timing, but there certainly is the
risk for scattered severe thunderstorms.  If they are develop the
primary risk would be strong to damaging straight line wind gusts.
While activity may be hit and miss, will have to watch if any low
level boundary washes out or becomes stationary.  If this happens,
there may be a very localized urban type flood threat as well with
PWATS over 2 inches.  Lots of uncertainty at this point, but in
addition to the excessive heat/humidity potential is there for
some severe weather and perhaps even a very localized flood risk
later Monday into Monday night.

Tuesday and Wednesday...

Assuming cold front clears the region by early Tuesday morning, dry
weather should prevail Tue into Wed but certainly not a guarantee
this far out.  High temps should still be mainly in the 90s Tue and
Wed away from at least the immediate coast.  Should be somewhat less
humid Tue, but some more humidity may return Wed.  Either way it
will likely be hot away from any onshore flow.

Thursday through Saturday...

Above normal temps will continue over this time, but
probably not quite as hot as early in the week.  A frontal boundary
may drop down and bring the risk for a round of two of
showers/t-storms by late in the week but timing highly uncertain
and by no means a washout.


Forecaster Confidence Levels.

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

Short Term /through Monday/...

Today and tonight...high confidence.
VFR, only ACK may see some localized late night fog. Otherwise, NW
winds slacken through the day, allowing sea breezes to develop.

Monday...moderate confidence.
VFR starts the day, although very hot and hazy weather expected.
Late day, localized thunderstorms and showers may bring some
temporary IFR/MVFR conditions.

KBOS TAF...High confidence. VFR. Sea breeze expected today,
although start time may be an hour or so later than typical.

KBDL TAF...High confidence.

Outlook /Monday Night through Thursday/...

Monday...Moderate confidence.  Mainly VFR outside of lower
conditions in scattered showers/thunderstorms mainly Monday
afternoon and evening.

Tuesday and Wednesday...Moderate to high confidence.  Mainly VFR
other than a few hours of early morning patchy fog in the typically
prone locations.

Thursday...Moderate confidence. Mainly VFR outside the risk for
scattered showers and thunderstorms.


Forecaster Confidence Levels.

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

Short Term /through Monday/...High confidence.

Thunderstorms with strong wind moving across the E MA waters this
evening, otherwise quiet boating weather with winds and seas
below SCA.

Outlook /Monday Night through Thursday/...Moderate to high confidence.

Winds and seas should generally remain below small craft advisory
thresholds over this time.  A period of southwest wind gusts of 20
to perhaps up to 25 knots are possible near the south coast for a
few hours Monday afternoon.  Otherwise...main concern is the risk
for scattered thunderstorms mainly late Monday into Monday night and
perhaps again on Thursday.


The KBOX radar is back in service but is operating in a degraded
state. Radar returns are running about 10 dBZ too high. Please
keep this in mind when evaluating storms. We apologize for the




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