NWS Forecast Area Discussion - New England Area

FXUS61 KBOX 250204

Area Forecast Discussion
National Weather Service Boston/Norton MA
1004 PM EDT Sat Aug 24 2019

High pressure in Canada will contribute to developing low
clouds and light showers later tonight into Sunday, especially
across southeast New England. High pressure lingers into
midweek, with seasonable and dry conditions to continue. Still
have an eye on the tropics at this time, with potential high
surf and dangerous rip currents for the Atlantic-exposed
shoreline of New England.



No significant changes planned for the forecast.

High pressure centered over Eastern Canada continues on its
path to the Maritimes. An east-northeast flow around that high
is crossing the Gulf of Maine and moving into Southern New
England. Expect this to bring increasing low-level moisture in
the form of low clouds/light showers/drizzle late tonight. Most
likely to be affected would be Eastern Mass.

Observed temperatures were in the 60s at 9 PM, with dew points
in the 50s. Expect min temps in the 50s inland and around 60 in
areas in Eastern MA that get the low clouds.


2 pm update...


Low clouds, showers linger S/E. Looking pleasant N/W. As noted in
the TONIGHT discussion, following low-level H925-85 thetaE dry air
advection. Continued H8-7 dry-subsidence inversion beneath which the
profile remains cool, destabilized, daytime heating plus convergent
elements of H925-85 winds, broken to overcast low clouds and light
shower chances are likely to continue over SE New England whereas
more scattered to broken cloud decks and dry prevail NW MA and CT.
Showers mainly during the morning, thinking daytime heating and
boundary layer mixing should limit the deep-layer moisture profile
with some dry-air contamination. Continued preference to consensus
of near-term high-res guidance. Another tricky high-temperature
forecast dependent on cloud shield edge. Should see blustery NE
winds for all locations, strongest of course along the coast.

Sunday night...

Low clouds linger, however shower chances diminish. Mid to upper
level high nudging S round which H925-85 dry air advection should
finally sweep through all New England, the accompanying subsidence
inversion deepening down to the surface through the atmospheric
column. Moisture continuing to pool beneath through which NE long-
fetch flow prevails, low clouds seem likely over SE New England
whereas over mostly clear NW MA and CT it`s another night of
radiational cooling and patchy dense fog within the valleys. Once
again a tricky low-temperature forecast given the uncertainty as to
the cloud-shield edge. Mild SE, cooler NW.



* Below normal temperatures early next week, especially across
  eastern Massachusetts into Rhode Island
* Onshore winds will bring spotty light rain or showers at
  times into mid week
* Temperatures return to near normal levels around mid week,
  becoming warmer than normal by Friday
* Another chance for showers late Wednesday through Thursday


Monday through Tuesday...

A large high pressure will continue to be the primary influence on
our weather. Strong subsidence inversion present in the model
soundings from pretty much all of the guidance. The question remains
if there will be enough of a near surface layer beneath this
inversion where the onshore flow could push enough moisture into
southern New England for some spotty drizzle. The moisture is very,
very shallow, so trended the forecast in a drier direction.

Below normal temperatures expected during this time, especially
towards RI and eastern MA.

The easterly winds may become gusty as the pressure gradient
increases around the southern section of the high from Monday
into Tuesday. May see gusts up to 20 to as high as 30 mph,
highest across Cape Cod and the islands.

Wednesday through Friday...

This is the most likely period for our next round of wet weather.
Mid level flow is rather amplified, and not translating east very
quickly. Thus, expecting a low pressure over central Canada to take
a long time to push a series of fronts our way. The first cold front
is currently thought to arrive sometime Thursday into Friday. A
second front, may arrive sometime Friday night into Saturday. Given
this time range, and the mid level flow pattern, am expecting this
timing to change a bit over the coming days.

Still monitoring the tropics. Latest forecasts still take a
disturbance off the SE USA coast out to sea. The most likely impact
from this system may be a period of rough surf along ocean-exposed
beaches, particularly those which are also south-facing.

Temperatures should be a bit higher with increased southerly flow
ahead of the approaching cold front. Near normal towards mid week,
and perhaps slightly above normal late next week.


Forecaster Confidence Levels...

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

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

E/SE MA and RI, VFR through 3 AM with ceilings lowering to MVFR
after that. Light showers/drizzle forecast with the clouds.
Persistent 10 to 15 kt E/NE winds.

VFR for most of the rest of Srn New England. Will be watching
the potential for developing fog in the CT Rvr Valley and the
usual fog spots. IFR in any fog late tonight.

Conditions lift and improve to VFR across NW New England with SCT
low-end VFR CIGs. E/NE winds around 10 kts. SCT-BKN MVFR continues
along with morning -SHRA across SE New England with E/NE 10 to
15 kts with gusts around 20 kts.

Sunday night...
FEW-SCT across the interior with light winds, the threat of IFR
FG once again. SCT-BKN MVFR continues across SE New England with
breezy E/NE winds 10 to 15 kts.

KBOS Terminal...
High confidence in trends. Moderate confidence in timing for
lower cigs.

KBDL Terminal...
High confidence in TAF.

Outlook /Monday through Thursday/...Moderate confidence.

Monday: VFR. Breezy.

Monday Night through Tuesday: VFR.

Tuesday Night: VFR. Slight chance SHRA.

Wednesday through Wednesday Night: Mainly VFR, with local MVFR
possible. Chance SHRA.

Thursday: VFR. Slight chance SHRA.


Forecaster Confidence Levels...

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

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

Long-fetch E/NE winds the height of which will occur on Sunday
with gusts up to 30 kts and seas building up around 5 feet. This
as high pressure builds over the Maritimes while low pressure
lingering well offshore to the south. A downward trend Sunday
night into Monday as high pressure wins out and builds across
the region. SMALL CRAFT ADVISORIES in effect for a majority of
the waters, especially S/SE, beginning early Sunday morning.

Scattered light showers at times, developing late tonight and
continuing into early Sunday.

Outlook /Monday through Thursday/...Moderate confidence.

Monday through Tuesday: Winds less than 25 kt. Seas up to 5 ft.

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers.

Wednesday through Thursday: Winds less than 25 kt. Seas up to
5 ft. Chance of rain showers.


MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Sunday for
     Small Craft Advisory from 10 AM to 6 PM EDT Sunday for ANZ231-
     Small Craft Advisory from 10 AM to 8 PM EDT Sunday for ANZ235-
     Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for


NEAR TERM...WTB/Belk/Sipprell
SHORT TERM...Sipprell

NWS BOX Office Area Forecast Discussion