Area Forecast Discussion
Issued by NWS Upton, NY

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810
FXUS61 KOKX 191450
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
950 AM EST Sun Feb 19 2017

.SYNOPSIS...
A weak cold front moves through today, followed by a stronger one
tonight. High pressure then builds in Monday before shifting
offshore on Tuesday. A warm front will approach Tuesday night
followed by a weak cold front becoming nearly stationary in our
vicinity Wednesday through Friday. A separate cold front approaches
from the west Friday through Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A cold front moving through Massachusetts through the Lower
Hudson Valley and into northeastern Pennsylvania was producing
mid and high cloudiness. With the front pushing slowly south
this morning, increased clouds with this feature.

Also, with a shortwave to the south mid and high clouds were
across the southern portion of the CWA. The wave was moving off
the DELMARVA and will track east to southeast with clouds
clearing the region.

Temperatures remain the tough part of the forecast with a wide
range across small areas, and from coastal areas to inland.

Cold air advection during the day is on the weaker side and
there is a tendency for MOS guidance to underestimate high temps
in a setup like this in spite of progged cooling temps at the
top of the mixed layer. Mixing across the CWA will be deeper
than yesterday with a W-NW flow, and there will be a little
contribution from compressional heating due to this downsloping
wind. So in spite of some cloud cover, thinking is that most of
the southern zones reach the 60s as the offshore flow should be
just strong enough to hold off or at least temper sea breezes
for a good portion of the day. Even many spots across the
northern zones should be around 60. Record high temperatures are
being forecast in some instances. See the climate section below
for the records.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Stronger cold advection occurs tonight with a stronger cold front
moving through. Again, moisture is lacking so expect a dry passage.

For Monday, surface high pressure builds in with slow ridging aloft.
Sunny with cooler temperatures, but still above normal. MAV and NAM
MOS look too warm given temps at the top of the mixed layer, so went
with SuperBlend. Good radiational cooling conditions then set up for
late Monday night with a clear sky and light to calm winds as the
surface ridge axis shifts into the region.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
High pressure ridge drifts offshore during Tuesday. Overrunning PCPN
ahead of a warm front to the west may sneak in by late over the
westernmost zones. Otherwise, expect increasing clouds with highs
near normal. CHC PoPs for Tuesday night as a warm front/cold front
combination approach the region. Good model agreement in that the
elevated warm layer will be warm enough for primarily rain, except
for a chance of sleet across the northern zones during the evening.
With clouds increasing and warm air advection with a lack of a cold
air damming pattern, thinking is that temps remain above freezing
through the night everywhere. Have therefore removed the chance of
freezing rain across the northern zones.

With the trailing cold front departing in the morning, it looks like
a dry day for most if not all of Wednesday. The exception would be
lingering chances of rain over the eastern zones in the morning.
Cold air advection behind the front is not strong, and temperatures
are expected to be well above normal.

Will maintain previous PCPN forecast for Thursday/Thursday night at
this time, although might need to include low chance PoPs in
association with a weakening cold front. Did however bump up high
temp forecast based on temps aloft. An onshore flow will keep
coastal sections cooler, but all areas once again will have high
temps above normal.

A low pressure system then approaches late in the week with
increasing chances of rainfall.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
A weak cold front moves across the region today. High pressure
builds in late.

Anticipate VFR conditions through the TAF period with mainly high
clouds forecast.

West-northwest flow this morning expected to gradually become
more northwesterly through the afternoon. A few gusts in the 15
to 20 kt range are possible, especially across NYC metro
terminals.

Across NYC, wind directions around 310 Magnetic are expected in the
afternoon.

Northwest winds diminish somewhat at night.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday...VFR. NNW gusts near 20kt.
.Monday night-Tuesday evening...VFR.
.Tuesday night-Wednesday...MVFR possible in rain.
.Thursday...VFR.

&&

.MARINE...
Winds and seas forecast on track with no changes with the
morning update.

Low pressure will pass well north of the waters today. Winds
and seas will remain below Small Craft levels. A cold front will
push across the area waters this evening and overnight,
building seas to 4 ft and providing some occasional gusts to 25
kt into Monday morning. Will hold off on any headlines at this
time, thinking that any SCA conditions may only last for a few
hours, if they occur at all. No precipitation is expected with
the frontal passage.

Following the cold frontal passage and as canadian high pressure
builds southeast across the area. The next potential chance of
marine impacts will be late in the week on Friday/Saturday as winds
strengthen ahead of an approaching low pressure system.

&&

.HYDROLOGY...
No hydrologic impacts are anticipated through the next 7 days.

&&

.CLIMATE...
The following are record high temperatures for today, and
forecast highs:

Central Park....66 (1997).....67
LaGuardia Apt...65 (1997).....67
JFK Apt.........66 (1997).....65
Islip Apt.......60 (1997).....64
Newark Apt......66 (1997).....67
Bridgeport......61 (1997).....59

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...JC/MD
NEAR TERM...JC/MET
SHORT TERM...JC
LONG TERM...JC/MD
AVIATION...BC
MARINE...BC/MD/MET
HYDROLOGY...JC/MD
CLIMATE...



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