NWS Forecast Area Discussion - New England Area

FXUS61 KBOX 270002

Area Forecast Discussion
National Weather Service Boston/Norton MA
802 PM EDT Wed Jun 26 2019

Summer like warmth is expected through Saturday. There will be
a risk of a few showers or thunderstorms this evening across
western portions of MA/CT. While conditions should be mainly dry
late this week, there will be a risk for a few showers or
thunderstorms Friday evening into early Saturday as a cold front
approaches. A series of cold fronts will move across the region
this weekend, bringing another chance for showers and scattered
thunderstorms along with somewhat cooler temperatures. High
pressure returns early next week with dry conditions and
seasonal temperatures.


Biggest question tonight will be the extent of fog across
eastern MA later tonight, and whether or not a Dense Fog
Advisory will be needed. Latest satellite data showed a rather
extensive stratus deck over the ocean. Some of the hourly
updated near term guidance, the LAMP in particular, really drive
this stratus inland with visibility being reduced to 1 mile or
less. Trends have been rather steady the past two hours.
Thinking this stratus will make it onshore in the next couple of
hours. The boundary layer should be cooling, making fog more

Will start out with a Special Weather Statement for poor
visibility until a better sense of how widespread the poor
visibility will be.

Previous Discussion...

Seasonable warm weather in progress across the region late this
afternoon with mostly sunny conditions, temps in the 80s and dew pts
in the 60s, except 70s at the coast with seabreeze/onshore winds.
GOES-16 satellite imagery showing some modest buildups across
southern/central RI in response to seabreeze convergence and lifting
airmass with dew pts in the 60s. However mid level dry air providing
a cap/lid on updrafts and should preclude any shower development.
Although can`t rule out a brief spot shower into early this evening
over this region.  Nevertheless dry weather prevails.

Other area of interest is convection firing in north-central PA into
central NY state. These storms approaching western MA/CT at or after
sunset. Given the loss of daytime heating, poor mid level lapse
rates and deep layer shear lagging well behind the convection, these
storms are expected to weaken upon entering western MA/CT. Thus not
expecting any severe weather and storms should completely fizzle
before reaching central MA/CT later this evening. Good agreement
among models especially CAMs on this storm evolution.

Seasonably warm overnight with dew pts 60-65 restricting temp mins to
this range.

Finally, challenging forecast regarding stratus over eastern MA
waters and coming onshore into Cape Ann, coastal Plymouth and outer
Cape Cod. Unfortunately none of the guidance is capturing this well.
Strong June sunshine heating the land into the 70s and 80s should
erode stratus and fog as it comes onshore especially the mainland.
However as sunset approaches and especially thereafter with boundary
layer cooling expected stratus and fog to overspread much of eastern
MA as leftover seabreeze circulation provides the advection.
Forecast confidence is low regarding how far inland this low level
moisture will track. Nonetheless highest prob of areas of low clouds
and dense fog will be coastal eastern MA including Cape Cod and the


4 PM update ...

Thursday ...

Behind departing short wave from overnight, good column drying with
PWATs falling below an inch across the area along with dry mid level
RH values. This combined with weak flat flow aloft should support
dry weather. Morning low clouds and fog especially over RI and
eastern MA will burn off to mostly sunny conditions by midday or
earlier. Another seasonably warm day with mixing up to or above 850
mb and temps at this level around +14C.  This will support highs in
the 80s and 70s at the coast given seabreezes. Dew pts in the 60s
will provide a summer-like feel.

Thursday night ...

Should remain dry with short wave trough passing well north of our
region. Seasonably warm with lows from the upper 50s to lower 60s.


4 PM update ...

26/12Z guidance remains in reasonable agreement for a nearly zonal
mid level flow to become more amplified into this weekend as a mid
level cutoff moves over the Northeast USA. This mid level cutoff is
then expected to slowly move over the Maritimes early next week.

At the surface, this pattern would have some significant impacts.
The first of which will be the progress of a weak cold front as it
moves south across New England Friday, and where it would stall into
this weekend. At this point, thinking is this front should stall
close to the south coast. The proximity of this front would mean
some clouds a prolonged risk for some showers, and perhaps a few
thunderstorms, through this weekend. This is not to say it will be
raining all this time.

Temperatures are expected to be near to above normal during this
time, with perhaps the exception of Sunday which may tend to be
slightly below normal depending upon how much sunshine we


Forecaster Confidence Levels...

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

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

Tonight...High confidence on trends, but low confidence on
areal extent of low clouds coming onshore into RI/MA.

Any weakening convection across western MA/CT dissipates by
03z/04z. Then focus turns toward low clouds/stratus farther
east. Uncertain how far inland these low clouds and fog will

Thursday...high confidence.

Low clouds and patchy fog early over RI and eastern MA lifts
and dissipates giving way to VFR, dry weather and light winds
except seabreezes near shore.

Thursday night...high confidence.

VFR and light winds. Very low risk of an isolated shower over
northeast MA and adjacent coastal waters.

KBOS Terminal...high confidence this afternoon but then
uncertainty on timing and duration of low clouds tonight.

KBDL Terminal...low risk of an isolated T-storm tracking close
to the terminal 00z-03z. Otherwise VFR, dry and light winds.

Outlook /Friday through Monday/...Moderate confidence.

Friday: VFR.

Friday Night: VFR. Chance SHRA, isolated TSRA.

Saturday: VFR. Breezy. Chance SHRA.

Saturday Night: VFR. Chance SHRA.

Sunday: VFR. Chance SHRA, isolated TSRA.

Sunday Night: VFR. Breezy. Slight chance SHRA.

Monday: VFR. Breezy.


Forecaster Confidence Levels...

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

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

Main issue will be reduced vsby in areas of dense fog tonight into
Thu morning especially across eastern MA waters. Otherwise dry
weather prevails along with light winds. Fine boating conditions
from Thursday afternoon into the night.

Outlook /Friday through Monday/...Moderate confidence.

Friday: Winds less than 25 kt.

Friday Night through Saturday: Winds less than 25 kt. Chance of
rain showers, isolated thunderstorms.

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, isolated thunderstorms.

Sunday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.




NEAR TERM...Belk/Nocera

NWS BOX Office Area Forecast Discussion