Area Forecast Discussion
Issued by NWS Boston, MA

Home | 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
000
FXUS61 KBOX 282252
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
652 PM EDT Wed Sep 28 2016

.SYNOPSIS...
Onshore winds will bring patchy drizzle and fog across southeast New
England into tomorrow morning with a brief break by tomorrow
afternoon. A wave of low pressure passing south of the region will
result in cloudy/cool weather with periods of showers Friday into
Saturday, which may linger into Sunday. Some improvement in the
weather is expected early next week, but still can not rule out a
period of showers.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...

650 pm update...

Large/strong high pressure will continue to build south from eastern
Canada tonight.  Mid levels of the atmosphere are quite dry, so not
expecting more than patchy drizzle tonight mainly across RI/SE MA
where low levels are quite saturated.

Otherwise, given an abundance of low clouds and northeast winds,
temps will only fall a few degrees from their current readings. Lows
should bottom out mainly in the upper 40s to the middle 50s.
Pressure gradient will allow for gusty northeast winds between 20
and 30 mph along the coast tonight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Tomorrow and tomorrow night...

Interesting set-up tomorrow as 500mb cut-off low moves over the
Tennessee Valley allow for upper level ridging to occur over the
Northeast. In the mid-levels, appears that the high pressure will
nose into northern New England with a nose of dry air intruding into
northeast MA by late in the afternoon. This could result in a break
from the drizzle and low clouds for a brief period. Southern New
England appears to be on the edge for this dry nose so while Boston
has the potential to possibly see the sun tomorrow, Hartford may
struggle. This also has resulted in a temperatures spread in the
forecast. If we do clear out then current temperatures will be to
cool. Because of the uncertainty, did a blend in the guidance for
temperatures.

Cross-sections continue to show dry air moving into the area during
the overnight hour. This could limit the amount of the clouds over
the area. However there is also the potential for fog to develop
overnight due to advection. Otherwise the focus then turns too the
approaching wave rounding the upper level low. This wave will begin
to spread precip into the region closer to the predawn hours of
Friday.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

Highlights...

* Periods of showers and drizzle Fri into Sat with cool afternoons
* Some showers and drizzle may linger into Sun
* Drier weather Mon-Wed but a period of showers remain poss.

Details...

Friday and Saturday...

Strong high pressure across eastern Canada will combined with a wave
of low pressure emerging off the mid Atlantic coast.  Although the
surface low is not too strong, pressure gradient will result in a
925 mb easterly jet 2 to 3+ standard deviations above normal and
gusty northeast winds along the coast. Timing uncertain, but expect
periods of showers Friday into Saturday along with areas of
drizzle/fog patches.  While measurable rainfall will occur, its
uncertain if 1+ inch amounts will make it into any of our region or
remain to our south where better low level forcing resides.

Onshore flow, clouds and periods of showers will keep high temps
below normal for late September mainly in the upper 50s to the
middle 60s.  In addition, gusty northeast winds of 25 to 35 mph are
expected along the coast and perhaps a bit stronger across Nantucket.

Sunday...

Initial wave of low pressure moves east of the region and low level
jet weakens.  However, surface high pressure over the Canadian
Maritimes will still still generate a moist/northeast flow of air at
the surface. Depending on the exact timing, some showers and drizzle
will probably linger into Sunday especially along the eastern MA
coast. High temps will likely remain below normal given lingering
low clouds.

Monday through Wednesday...

Another high pressure system will build down into eastern Canada and
northern New England early next week.  While a shortwave may bring a
period of showers, a good shot at dry weather for a decent portion
of this time frame. Northeast winds at the surface much of the time
will probably continue to hold high temps mainly in the 60s to
perhaps near 70.

We also will have to keep a close eye on what is expected to become
Hurricane Matthew over the Caribbean in the next 24 hours.  Most
model guidance suggests this system will remain south of our region
through Wednesday of next week.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
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...MVFR Cigs will dominate the region tonight, but some IFR
conditions expected across southeast MA/RI as well as the Worcester
Hills.  Northeast wind gusts of 20 to 25 knots expected along the
coast.

Thursday into Thursday night. Northeast flow with gusts near
25-30 kts will continue into the period. Lingering IFR cigs
possible with improvements during the day to MVFR. Dry air could
nose into the northeast by late day improving conditions Thursday
night. Still cannot rule out IFR potential along the south coast.

KBOS TAF...Moderate to high confidence in TAF.

KBDL TAF...Moderate to high confidence in TAF.

Outlook /Friday through Monday/...

Friday through Sunday...Moderate to high confidence.  Mainly MVFR to
IFR conditions in low clouds, periods of showers/drizzle and patchy
fog.  Northeast wind gusts of 20 to 30 knots expected Fri/Sat along
the coast, and perhaps a bit stronger across Nantucket.

Monday...Low to moderate confidence.  May see improvement to mainly
VFR conditions.

&&

.MARINE...
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.

Northeast flow will continue across the waters well into Thursday
night. Pressure gradient will continue to tighten resulting in gusts
between 25 and 30 kts tonight increasing to gales by tomorrow night
across the southern waters. Gale watch has been posted where
confidence is highest. Seas will slowly build in response up to 9-10
feet by tomorrow.

Outlook /Friday through Monday/...

Friday...Moderate to high confidence.  High pressure across eastern
Canada combined with a low pressure system exiting off the mid
Atlantic coast.  This will generate northeast wind gusts of 25 to 35
knots.  Strongest of the winds across the southern waters, where
Gale Watches are posted and seas are expected to build to between 8
and 11 feet.

Saturday...Moderate to high confidence.  Small craft headlines will
be needed for all waters as pressure gradient will support northeast
wind gusts of 20 to 30 knots.

Sunday and Monday...Moderate confidence.  Pressure gradient weakens
so expect winds and seas to remain below small craft advisory
thresholds.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from late Thursday night through Friday evening
for      ANZ232>234-254.
     Small Craft Advisory until 4 AM EDT Friday for ANZ232>234-254.
     Small Craft Advisory until 9 AM EDT Friday for ANZ230-231-236-
     250-251.
     Gale Watch from late Thursday night through Friday evening for
     ANZ235-237-255-256.
     Small Craft Advisory until 2 AM EDT Friday for ANZ235-237-255-
     256.

&&

$$
SYNOPSIS...Dunten/Frank
NEAR TERM...Frank
SHORT TERM...Dunten
LONG TERM...Frank
AVIATION...Dunten/Frank
MARINE...Dunten/Frank



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.