Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 070754

Area Forecast Discussion
National Weather Service Boston/Norton MA
354 AM EDT Wed Jun 7 2023

Sunshine returns Wednesday morning, especially across CT, RI and
southeast MA. However, low pressure over the Maritimes moves
westward into Maine, resulting in clouds building this afternoon
along with scattered showers. Similar conditions expected
Thursday, Friday and Saturday, not a washout, but scattered
afternoon showers each day. Temperatures will continue to run
slightly cooler than normal. There will also be some near ground
level smoke at times this afternoon, as a result of the ongoing
Canadian wildfires. Brief dry weather with a warming trend for
Sunday, before our weather turns more unsettled with our next
chance for widespread showers or thunderstorms either Monday or



345 AM Update:


Sunshine to begin the day, especially across CT/RI and southeast MA.
Across northern MA, lots of mid level clouds retrograding south from
northern New England, as mid level low over New Brunswick moves
westward into ME. Mid level warm air wraps cyclonically around this
circulation (TROWAL) into northern MA this morning, along with the
threat of some spotty light rain/sprinkles. Very atypical setup for
early June.  Cyclonic flow and cold air aloft will result in another
round of diurnal showers this afternoon. Although with the mid level
low tracking closer to SNE, short waves will pivot cyclonically
farther south and west around SNE. Therefore less synoptic scale
lift and not quite as cold aloft will yield less instability. Hence,
showers not as widespread as yesterday and given less instability,
not expecting any strong storms along with threat of lightning much
lower than Tue. Overall, many hours of dry weather especially this
morning, then scattered afternoon showers.

Slightly cooler than normal with highs in the upper 60s and lower
70s. Modest NW wind 10-15 kt. Unfortunately another plume of smoke
from Canadian wildfires advects across western-central MA and
CT later today in NW flow aloft.



345 AM update...


Still under the influence of vertically stacked low over Maine. Any
early evening diurnal showers taper off with sunset. Slightly cooler
than normal temps continue with overnight lows in the 40s
regionwide.  Partial clearing across CT/RI and southeast MA, but mid
level clouds hanging tough across northern MA, as mid level warm air
continues to circulate cyclonically around closed low over ME. Light
NW winds.


More clouds with mid level low nearly stationary over Maine.
Cyclonic flow combined with cool air aloft will result in another
round of diurnal scattered showers. Not a washout with many hours of
dry weather, but will have to dodge a few afternoon showers. Cooler
than normal with highs 65-70. Light and variable winds, but becoming
onshore along the coast.




* More diurnal showers and thunderstorms on Friday

* Warmer this weekend with showers on Saturday and drier weather on

* Area of low-pressure may bring substantial rainfall to southern
  New England early next week


The upper-level low that`s been meandering over The Northeast this
week will remain in the vicinity through at least Friday. Model
guidance supports an upper-level cold pool associated with this low
settling over southern New England on Friday afternoon. -21C temps
at 500 hPa will support steep lapse rates through the column on
Friday afternoon which will support diurnal showers and
thunderstorms. Temperatures are forecast to be on the cooler side on
Friday with highs unlikely to escape the 60s. Therefore, instability
will be limited. Ensemble mean SBCAPE values on Friday afternoon
continue to trend toward modest levels (200 to 300 J/Kg). Thus, the
potential for any diurnal thunderstorms to become severe is low. The
best thunderstorm chances will reside across the interior where the
greatest instability/steepest lapse rates will reside.

This Weekend

Upper-level low finally ejects east away from southern New England
Friday night in to Saturday. This will allow westerly flow to advect
warmer air over southern New England for the weekend. While temps
will be a bit warmer on Saturday, cloud cover and diurnal showers
will limit temperatures to the low 70s. Sunday appears to be the
pick of the weekend as drier low-level air should support more sun
than clouds and allow temps to get into the mid to upper 70s. Some
spotty diurnal showers will be possible across western MA/CT
but most areas should remain dry.

Next Week

Early next week an upper-level low will dig south over The Great
Lakes before propagating east toward southern New England with more
wet/unsettled weather. A surge of moisture over the region and
robust forcing associated with this disturbance will bring an
opportunity for substantial rainfall across southern New England
during the Monday/Tuesday time frame. Details are vague at this time
range, but the probability of 24 hour rainfall exceeding 1 inch
between Monday and Tuesday is 20 to 30 percent across southern New
England. These probabilities are derived from a grand ensemble of
the GEFS,EPS, and GEPS.


Forecaster Confidence Levels:

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

06z TAF Update:

Thru 12z...high confidence.

MVFR in areas of fog across southeast MA. Otherwise VFR and
mainly dry weather. However some spotty light rain/sprinkles
across northern MA to the VT/NH border. Light NW winds.

After 12z...high confidence.

VFR but scattered showers develop this afternoon regionwide,
with low risk of an isolated -TSRA. Another smoke plume likely
enters western MA/CT around midday, then spreads eastward into
RI and eastern MA late in the day. Vsbys may lower to 3 to 5
miles. Light NW winds, except SW along the south coast.

Wednesday Night...High Confidence.

Mainly VFR with spotty light showers across northern MA. Light
NW winds.

Thursday...high confidence.

Mainly VFR but marginal MVFR across northern MA. Showers develop
during the afternoon. Light NW winds becoming locally onshore.

KBOS Terminal...High Confidence in TAF. After 15z scattered
showers develop. Low risk of an isolated thunderstorm. NW winds
10-15 kt. Smoke may reduce vsby to 6 nm after 21z.

KBDL Terminal...High confidence in TAF. VFR with scattered
showers developing this afternoon. Low risk of an isolated
thunderstorm. Smoke may reduce vsby to around 6 nm after 18z.

Outlook /Thursday Night through Sunday/...

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

Friday: Mainly VFR, with areas MVFR possible. Chance SHRA,
isolated TSRA.

Friday Night: VFR. Chance SHRA.

Saturday: Mainly VFR, with local MVFR possible. Chance SHRA,
isolated TSRA.

Saturday Night through Sunday: VFR. Slight chance SHRA.


Forecaster Confidence Levels:

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

345 AM update...

Low pressure over New Brunswick moves slowly west into Maine tonight
and Thursday. Mainly dry weather prevails but can`t rule out
scattered diurnal showers near shore at times.

Outlook /Thursday Night through Sunday/...

Thursday Night: Winds less than 25 kt. Slight chance of rain

Friday through Saturday: Winds less than 25 kt. Chance of rain

Saturday Night: Winds less than 25 kt.

Sunday: Winds less than 25 kt. Slight chance of rain showers.



345 AM update...

Latest model simulations have the next plume of smoke from
Canadian fires entering western-central MA into CT this
afternoon, then into RI and eastern MA this evening. Vsbys may
drop to 3-5 miles at times along with the smell of smoke.



345 AM update...

Astro tides remain high (11.1 ft at Boston and 4 ft at Nantucket)
and combined with residual surge, very minor coastal flooding took
place overnight. We may need to extend the coastal flood advisory
into Thursday.


MA...Air Quality Alert until midnight EDT tonight for MAZ002>024-


NEAR TERM...Nocera
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