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Area forecast discussion
National Weather Service New York New York
629 PM EST sun Feb 19 2017

Synopsis...
low pressure near the Canadian Maritimes moves east tonight as a
cold front passes through the region late tonight into early
Monday morning. Meanwhile high pressure builds in from the north
through Monday night. The high pressure shifts offshore on
Tuesday ahead of a warm front that moves across Tuesday night
into early Wednesday. A weak cold front then follows later on
Wednesday, and then remains nearby into Thursday. The front
lingers near the region on Friday before lifting north as a warm
front Friday night into Saturday. Another cold front may move
across late Saturday or Saturday night.

&&

Near term /until 6 am Monday morning/...
forecast on track this evening. Just made minor adjustments to
hourly temperatures and dewpoints to reflect latest
observations.

Deep cyclonic flow will remain across the region with upper low
pressure across eastern Canada that will be shifting east
tonight. A weak shortwave rotates through the upper low, with
the energy remaining well to the north. A weak cold front is
expected to pass through the region late tonight as heights
build to the west after 09z. Cold advection will be weak. And
decoupling is not expected, possible occurring just before 12z.
Overnight temperatures will remain above seasonal averages.
Moisture will be very limited with the front, with a dry frontal
passage and minimal cloud cover.

&&

Short term /6 am Monday morning through Monday night/...
a deep northwest flow will remain across the region Monday into
Monday night as heights slowly rise through the period. A upper
ridge axis will be just west of the County Warning Area by 12z Tuesday. A cooler
airmass will be across the region Monday, however, high
temperatures will still be above seasonal normals, with
temperatures fairly uniform across the region.

Monday night winds are expected to decouple with nearly clear
conditions as the ridge nears the region, and a wide range of
temperatures is forecast, with lows closer to normal.

&&

Long term /Tuesday through Sunday/...
the main story of the long term period is well above normal
temperatures. Models are in general agreement on the overall pattern
through next weekend, with differences increasing by the end of the
week into early next week.

The coolest day in the period is likely to be on Tuesday surface
high pressure and mid and upper level ridging dominate. Forecast
highs will be near seasonable normals in the lower and middle 40s.
The ridge axis and surface high move offshore late Tuesday as a warm
front approaches from the west associated with low pressure
traversing across southeast Canada. A subtle shortwave moves across
Tuesday night as well. This system is going to run into ridging over
the east with best jet dynamics remaining well to the north and
west. Chance pops continue to look good with the main change with
this forecast package is to remove sleet across the interior.
Thermal profiles are too warm to support anything other than liquid.
Increasing southerly flow and cloud cover Tuesday evening should
prevent temperatures from falling below freezing across the interior
so forecast shows plain rain everywhere. Lows Tuesday night are in
the middle and upper 30s.

Heights rise behind the departing shortwave and the warm front
passage on Wednesday. A weak cold front gradually approaches with
high pressure off the southeast coast. Flow around the high and
ahead of the cold front will transport Spring-like temperatures back
to the region. Highs on Wednesday are forecast in the upper 50s and
lower 60s. These highs fall short of record highs for Feb 22.

The cold front may stall near or just west of the area Wednesday
night into Thursday. This means unseasonably warm conditions will
continue. Westerly flow in the middle and upper levels with core of
jet to our north continues to pump warm air into the region from the
west. MOS and model consensus blends are likely several degrees too
cool for Thursday. Have raised highs for Thursday with forecast
readings approaching 70 degrees in the NYC Metro and NE New Jersey and lower
to middle 60s across the lower Hudson Valley and interior CT. See
climate section below for Feb 23 record highs. Coastal CT and Long
Island may end up closer to 60 due to an onshore component of the
wind.

Dry conditions continue Thursday night as cold front attempts to
move across. A new wave of low pressure develops across the central
states on Friday and then tracks through the Great Lakes Friday
night and into southeast Canada on Saturday. Unseasonably warm temperatures
continue, but should be more in the 50s to near 60 due to increased
cover. Timing of associated frontal passages differ among the
deterministic and ensemble guidance. Chances for showers increase
however Friday night into Saturday. Since this is a day 6/7
forecast, have capped pops at high chance. If the cold front does
move through by Sunday morning, a return to more seasonable temps
are expected.

&&

Aviation /00z Monday through Friday/...
high pressure builds tonight and Monday from the west.

Northwest winds remain 10 kts or less tonight. Then, an increase to 10 to
15 kt is expected after 13-15z Monday. A few gusts to 20 kt are
possible. Winds remain NW, then turn toward the north late in the day
and lighten.

Anticipate VFR conditions through the taf period with little cloud
cover.

Outlook for 00z Tuesday through Friday...
Monday night-Tuesday evening...VFR.
Tuesday night...MVFR possible in rain.
Wednesday-Thursday night...VFR.
Friday...sub-VFR in showers possible.

&&

Marine...
low pressure well north and east of the forecast waters will
continue to track east of the Canadian Maritimes tonight into
Monday morning with a cold front expected to pass through the
waters late tonight into early Monday morning. Meanwhile high
pressure will be building in from the north. A cyclonic flow
will remain across the waters with winds and seas below Small
Craft Advisory levels. With the cold frontal passage weak cold
advection increases along with the pressure gradient force.
There may be occasional gusts right around 25 knots for a couple
of hours, especially across the eastern forecast waters.
However, with the uncertainty and brief nature of the gusts,
will not issue an advisory at this time.

With high pressure building over the waters Monday and Monday
night winds and seas will remain below Small Craft Advisory
levels.

High pressure slides offshore on Tuesday ahead of an approaching
warm front. This front moves across Tuesday night and will be
followed by the approach of a cold front. This cold front likely
remains near the waters through the end of the week. The pressure
gradient will remain relatively weak with winds and seas below Small Craft Advisory
levels.

The next chance for Small Craft Advisory conditions will be Friday night into
Saturday as the next low pressure and associated frontal system
approaches.

&&

Hydrology...
no hydrologic impacts are anticipated through the next 7 days.

&&

Climate...
the following are record high temperatures for Thursday February 23,
2017

Central Park........70 (1985)
LaGuardia...........66 (1985)
Kennedy.............62 (1990)
Islip...............61 (2012)
Newark..............68 (1985)
Bridgeport..........60 (2012)

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.

&&

$$
Synopsis...ds/met
near term...ds/met
short term...met

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