Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS61 KBOX 310159

Area Forecast Discussion
National Weather Service Taunton MA
959 PM EDT MON MAY 30 2016

A cold front over New York will swing across Southern New England
tonight. Scattered thunderstorms over Eastern New York will affect
Western MA and CT before weakening. Another batch of showers
moving up the front may graze the South Coast overnight. High
pressure then builds over New England with dry weather for the
middle of this week. Another cold front may bring unsettled
weather by the end of this week. A low pressure may move through
early next week.


10 pm update...
Convection is weakening across western MA and hi-res guidance
continues this trend this evening as it drifts east. Still seeing
SBCAPES of 500-1000 J/kg so will continue to mention chc thunder
next few hours. Otherwise...watching area of rain lifting north
from south of long island. Deeper moisture and omega remains
mostly to the south but is expected to clip the cape/islands where
best chance for a period of light rain. Adjusted PoPs accordingly.

The other concern this evening will be areas of fog along the
south coast. With southerly winds increasing ahead of a cold
front, these areas of fog will likely move farther north into
southeast MA and RI this evening. The front will move through
western MA overnight with notable drop in dewpoints. However, it
will remain humid in the coastal plain. Min temps in the 60s,
except upper 50s Berkshires.


There may be some lingering showers along the South Coast early
Tuesday. But with high pressure building in, the trend will be for
showers tapering off and sky cover diminishing. Drier air will
work into New England with dew points falling through the 50s.

A weak cold front dips south over the region late Tuesday. The
main effect of this front will be to turn winds out of the north
Tuesday night. This may bring dew points a little lower, roughly
upper 40s to mid 50s.

Sunshine Tuesday will create mixing to at least 850 mb, possibly
higher. Temps at the top of the mixed layer will support max
surface temps in the low to mid 80s. The lower dew points will
allow min temps to be a little lower than tonight, generally in
the 50s.



  * Mainly dry with above normal temperatures Wednesday
  * Unsettled weather may return toward the end of this week
  * A low pressure may move through early next week

Medium range models are in good agreement with the overall
synoptic pattern. A mid-level ridge will move offshore Wednesday.
Mid-level troughing then moves into Quebec towards the end of this
work week, and starts influencing our weather with several
shortwaves working around the base of this trough. This will
result in more unsettled weather towards the end of this week.
The latest operational GFS was much more aggressive in developing a
mid-level cutoff late in this forecast period. Favored a solution
closer to the ECMWF, which also had support from the GFS ensemble
mean solution.

Wednesday...A back door cold front arrives. Despite that,
temperatures will still be above normal across the interior. More
seasonable temperatures toward the coastal plain, mainly east of
II-95, due to the onshore flow.

Thursday through Sunday...Mid-level trough moves into Quebec,
allowing several shortwaves rotating through the base of this
trough to move through southern New England. This will result in
periods of showers, particularly Friday into Saturday. Due to the
difficulty in nailing down the timing at this time range, have
kept chance PoPs in the forecast for much of this period. However,
not expecting rain to be widespread, nor for the entire period.
Temperatures will be seasonable for much of this time.

Monday...Potential for an occluded low pressure to move into the
Great Lakes early next week. Not confident in the timing just
yet. Some hints in the GFS of a secondary low pressure developing
more toward the coast early Monday. The GFS is more aggressive in
developing a stronger, more southern, mid-level cutoff than the
ECMWF. This is leading the GFS to a slower timing as well. Will
keep a chance of showers in the forecast until these differences
can be resolved.


Forecaster Confidence Levels.

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

Short Term /through Tuesday Night/...

Tonight...Moderate confidence. Lingering IFR cigs and vsbys in fog
and showers along the south coast. Mixed VFR/MVFR farther north.
Local IFR/LIFR is possible in these areas overnight due to patchy
dense ground fog.

Tuesday and Tuesday night...High confidence. VFR.

KBOS TAF...Moderate confidence in TAF.

KBDL TAF...Moderate confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday...Moderate confidence. VFR. Northeast winds become more
easterly through the day.

Thursday...Moderate confidence. Mainly VFR conditions expected.
Increasing clouds with diminishing conditions through the night,
particularly along the south coast.

Friday and Saturday...Moderate confidence. Mainly VFR conditions
expected. Brief MVFR conditions are possible in SCT -SHRA at


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.

Tonight...Moderate confidence.

Poor visibility due to dense fog, mainly across the southern
waters from Block Island to Nantucket. Winds will remain below
20 knots. Seas will remain below 5 feet.

Tuesday and Tuesday night...Moderate confidence.

A south swell builds into the southern waters Tuesday. Expect the
swell to reach 4 feet during the day, with potential for 4-5 foot
swell Tuesday night. Southwest wind Tuesday shifts from the North
Tuesday night, but remains below 20 knots.

Outlook /Wednesday through Saturday/...

Wednesday...Moderate confidence. Northeasterly winds and seas
will remain below Small Craft Advisory criteria.

Thursday...Moderate confidence. Easterly winds and seas increase.
Seas may rise above 5 feet, especially on the outer waters.

Friday...Moderate confidence.  Easterly winds are expected to remain
below 15 kts.  Seas decrease through this period.

Saturday...Moderate confidence. Southeasterly winds are expected
to remain below 15 kts. Seas continue to decrease through this




MARINE...WTB/Belk is the U.S. government's official web portal to all federal, state and local government web resources and services.