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Area forecast discussion
National Weather Service Boston/Norton Massachusetts
648 PM EST Thu Nov 14 2019

Synopsis...
high pressure moving offshore will draw milder air into southern New
England tonight and Friday. Two cold fronts sweep south from Canada
Friday afternoon and night. Neither has more than a few clouds with
it. But behind the second front will be much colder air and gusty
north winds. High pressure will bring a brief period of dry
weather Sunday. A coastal storm will then bring rain and wind,
possibly some ice Sunday night and Monday. A second storm may
impact the region Wednesday and Thursday.

&&

Near term /until 6 am Friday morning/...
630 PM update:

Forecast appears generally on track with only minor, noise-
level changes to hourly temps, dewpoints and winds with this
update.

Warm front continues to lift northward from central into
northern MA, with a considerable amount of at least mid-level
cloud cover areawide on enhanced southwest mid-level flow. Radar
shows some returns back into northwest Massachusetts into northern CT but
any echoes are falling into a still rather dry low-level air
mass. Other than some light showers towards the Outer Cape
(chatham reporting some light showers last hr) that should end
around 9-10 PM, most areas are dry and will continue to remain
so through the balance of the overnight. Will see greater
clearing across interior sections late tonight into overnight as
dry air filters in, with more clouds toward coastal Rhode Island and southeast
mass and adjacent waters.

Forecast lows look on pace at this point - though may need to
give some consideration in later updates towards raising lows
up a couple degrees from Plymouth, Bristol and Providence
counties southeastward, especially if clouds were to linger into
the night.

Previous discussion follows...

A warm front with a few showers shifts north and east of our area
this evening. Moisture along this front is shallow and limited, with
precipitable water values around 0.50 inch as it moves into the Gulf of Maine. This
should mean light amounts where the showers fall, with the most
falling over Cape Cod and islands.

Drier air moves in at all levels after midnight. Expect clearing
skies most places overnight, although clouds may linger on Cape Cod
and islands until morning.

Dew points will range from mid 20s northwest to mid 40s on
Nantucket. This will keep min temps milder than last night with
values ranging from the mid 20s north and west to the mid 40s on
Nantucket.

&&

Short term /6 am Friday morning through Friday night/...
model maps show either two cold fronts, or a pre-frontal trough and
a cold front, moving across southern New England. The first
trough/front moves through Friday afternoon, the second front moves
through early Friday night. Cross sections show limited moisture
with dry air at 850 mb and above. Precipitable water values less than 0.50 inch.
This may be enough for a few clouds but little more.

Mixing depths Friday midday will reach between 925 and 950 mb.
Temperatures in this layer will support Max sfc temps in the upper
40s and lower 50s, cooler in the Worcester Hills and Berkshire east
slopes. This may also tap 20 kt winds at the top of the layer and
draw them to the surface in west-southwest wind gusts.

After the second front moves through Friday night, winds will turn
out of the north and draw much colder air into our area. The winds
will gust 25-30 kt/30-35 mph with strongest winds along the coast.
Temperatures upstream over Saskatchewan were in the teens last
night, and this looks reasonable for US Friday night. The
combination will bring wind chills in the single numbers.

&&

Long term /Saturday through Thursday/...
highlights...

* temperatures moderate to near seasonal levels but pattern looks
unsettled with multiple storm chances.

* An ocean storm may impact southern New England Sun night into Tue morning with rain
and coastal wind along with pockets of ice across the interior.
Low confidence on storm impacts and precip types.

* Another coastal storm may impact the area Wed into Thu but
again low confidence on storm impacts and precip types.

Details...

Saturday night into Sunday...

A cold night with widespread teens in the interior with low to mid
20s for much of eastern Massachusetts and Rhode Island except for the immediate coast and
Cape Cod, which drops into the upper 20s to mid 30s. Expect clouds
to be on the increase Sun morning from the southeast. By Sun afternoon,
expect NE/east-northeast winds to pick up especially near the coast as a storm
comes up the coast. Sunday high temperatures will likely be
warmer than on Sat but still running 5 to 10 degrees below
normal (for reference). And despite temperatures in the mid 40s
in eastern Massachusetts and Rhode Island on Sun afternoon, the winds will make it
feel like the low to mid 30s. Further south, an area of low
pressure along the southeast coast moves northeastwards to the
Carolina coast, which is potentially our next weather maker.
More below.

Sunday night into Monday...

There are still plenty of questions with regards to how fast the
aforementioned storm will track up the coast and how close it will
approach our area given the large spread of model guidance. One
thing to watch is a possible period of ice in interior Massachusetts sometime
on Monday with warm air aloft a cold air mass if the storm were to
come up a little closer. But overall, expect chances of shower to be
on the increase late Sunday night into early Monday morning. GFS
soundings in BUFKIT show a warm nose of +2 to +4c at 850mb in orh on
Monday, with surface temperatures staying at or below freezing the
entire day. However, the European model (ecmwf) shows the storm staying well south of
the 70w/40n benchmark, which would leave most of our area dry with
some isolated rain showers towards the cape. Given the wide spread
in models, opted to go with a model blend. The blend shows a chance
of freezing rain or sleet west of a Torrington CT-Enfield CT-
Worcester Massachusetts line on Mon morning changing over to rain showers early
Mon afternoon before a possible brief Switch Back to freezing rain
on Mon night and finally ending as rain on Tue morning. East of that
line, there could be intermittent rain showers into Tue morning
before drying out on Tue afternoon. At this point, it should be
emphasized that the confidence in specific locations and duration
for possible icing is extremely low. Would definitely have to see
more consistency in model runs before having more confidence. But
with low-level cold air holding its ground and plenty of mid-level
warm air advection associated with low level jet on Monday, the
potential for icing does exist, particularly for interior areas.

Tuesday...

As mentioned above, showers linger on Tue morning, with potential
icing in interior MA/CT. As temperatures rise, any icy mix in the
interior should transition to rain showers by late morning. Expect
precipitation to taper off late afternoon. Tue evening should be dry
but with plenty of clouds. Afternoon highs range from low to mid 40s
in western Massachusetts/CT to upper 40s to low 50s in eastern Massachusetts and Rhode Island.

Tuesday night into Wed...

The dry period looks to be brief as a storm that develops along the
base of a large trough in eastern U.S. And comes up the coast.
Again, there is a wide spread in model guidance. The GFS shows the
storm tracking well south of the 70w/40n benchmark and intensifying
in maritime Canada. That would amount to limited impacts for our
area. Whereas the European model (ecmwf) shows the storm tracking and intensifying
over Cape Cod, which would mean widespread rain and high winds Wed
into Thu. The biggest snow in this setup would be over interior New
England, though areas near the Berkshires could get some snow. Model
blend shows widespread chance for rain with snow in western Massachusetts on
Wed morning changing over to rain in the afternoon before drying out
overnight. Afternoon highs range from upper 30s in western Massachusetts to mid
40s to low 50s elsewhere.

Thursday...

Thursday looks to be mostly dry with a mix of sun and clouds. Gusty
northwest winds, however, keep high temperatures in the upper 30s and low
40s in western Massachusetts and mid to upper 40s elsewhere.

&&

Aviation /23z Thursday through Tuesday/...
forecaster confidence levels...

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

00z taf update:

Short term /through Friday night/...moderate to high confidence.

Rest of tonight...

Broken-overcast VFR clouds to predominate, much of which are mid-level;
short-lived/brief exception through 03z being toward Falmouth
and Hyannis which may at times drop just below 3000'. Skies to
clear with lingering VFR clouds towards the South Coast, cape
and islands after 06z.

Friday...

VFR. Skies clearing on the cape/islands. West-southwest winds
gusting 15-20 kt.

Friday night...

VFR. Winds shifting from SW to to the north and gusting 25-30
kt early.

Kbos taf...high confidence in taf. Gusty wind shift to northwest
early Friday evening, though confidence on timing the wind
shift is moderate.

Kbdl taf...high confidence in taf.

Outlook /Saturday through Tuesday/...

Saturday: VFR. Windy with gusts up to 35 kt.

Saturday night: VFR. Breezy.

Sunday: mainly VFR, with local MVFR possible. Breezy.

Sunday night: mainly MVFR, with local IFR possible. Windy with
local gusts up to 30 kt. Chance ra, slight chance fzra, slight
chance pl.

Monday: mainly MVFR, with areas IFR possible. Windy with local
gusts up to 30 kt. Chance ra, chance freezing rain.

Monday night: mainly MVFR, with local IFR possible. Breezy.
Slight chance ra, slight chance freezing rain.

Tuesday: slight chance ra, slight chance freezing rain.

&&

Marine...
short term /through Friday night/...high confidence.

Tonight...

A few showers early towards the waters along/southeast of the
Outer Cape, otherwise largely dry elsewhere. Winds have
increased a bit towards the southern coastal/offshore waters,
with buzm3 showing gusts to 25 kts. Marginal/lower-end Small Craft Advisory
conditions look on pace with existing scas looking valid, with
winds 20-25 kts and seas in the 3-5 foot range.

Friday...

Westerly winds pause in the morning, increase in the afternoon. Seas
also subside a little in the morning, then build in the afternoon.
Winds gusting near 25 kt, seas near 5 feet on the open waters.

Friday night...

Cold front moves through early in the night. Winds turn out of the
north and increase as much colder air moves over southern New
England and the waters. Winds increasing to near 35 kt during the
overnight...seas build to 5 to 9 feet on the exposed waters. We
have issued a gale watch for this period and continued into
Saturday.

Outlook /Saturday through Tuesday/...

Saturday: low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 11 ft.

Saturday night: moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Rough seas up to 10 ft.

Sunday: moderate risk for Small Craft Advisory winds with local
gusts up to 30 kt. Rough seas up to 13 ft.

Sunday night through monday: strong winds with gusts up to
30 kt. Rough seas up to 17 ft. Chance of rain.

Monday night: low risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 14 ft. Slight chance of
rain.

Tuesday: winds less than 25 kt. Areas of rough seas. Chance of
rain.

&&

Climate...
record low min temps for Thursday Nov 14

Boston 16/1905 ... this morning 23
Hartford 15/1986 ... this morning 15 ... tied
Providence 16/1905 ... this morning 18
Worcester 10/1986 ... this morning 15

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...gale watch from late Friday night through Saturday morning for
anz231>235-237-251.
Small Craft Advisory until 10 am EST Friday for anz235-255-256.
Gale watch from late Friday night through Saturday afternoon
for anz250-254>256.
Small Craft Advisory until 3 am EST Friday for anz250-254.

&&

$$
Synopsis...wtb/chai
near term...wtb/loconto

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