Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 171449

Area Forecast Discussion
National Weather Service New York NY
949 AM EST Sun Feb 17 2019

High pressure builds offshore this afternoon as low pressure
approaches from the southwest. The low passes to the south and
east of the area late tonight into Monday morning. High pressure
briefly returns for Tuesday, followed by another low pressure
system for mid week.


Made just a few minor adjustments to reflect current conditions
with regard to temps and sky coverage.

Satellite imagery indicates a few clouds upstream in PA from 10
to 20 kft, otherwise skies should be mainly clear into the
early portion of the afternoon, especially for the eastern half
of the CWA. Towards 17-18z is when a more tangible increase in
upper and perhaps a few mid level clouds will get underway as
weak 500 mb ridge passage takes place downstream of confluent
flow from SW flow aloft. Therefore the thinking is high pressure
will slide across today, with skies remaining mostly sunny
overall until later in the afternoon. The increase in late day
cloud cover will be in advance of the low pressure system that
will impact the area tonight.

High temps will be in the upper 30s and lower 40s, which is
close to average.


Guidance has come into reasonable agreement on the thermal and
sensible wx details accompanying the low pressure system
approaching tonight from the west. Light snow should develop mid
to late evening ahead of primary low pressure moving up the
western spine of the central Appalachians; then as a secondary
low develops along the southern Mid Atlantic coast, warming
mainly aloft and then also loss of ice nucleation as mid levels
dry out will bring a transition to wintry mixed precip, then
rain along the coast and freezing rain inland, but not before
widespread snowfall of 2-3 and locally 4 inches falls north of
NYC, where a winter wx advisory is now in effect for late this
evening into mid morning Monday. For NYC, the immediate western
burbs of NJ and Long Island, warming aloft and at the sfc
should bring about a cleaner transition to rain, and snowfall
should be lighter, in the 1-2 inch range.


Traveling conditions Mon night could again become locally
hazardous for untreated surfaces, with black ice becoming an
issue throughout.

Region then transitions into a confluent upper flow Tue into Wed,
between upper ridging south of Bermuda and polar low sliding across
central Quebec. At the surface, Canadian high pressure builds into
the region Monday Night and overhead on Tuesday.

Region comes more under the influence of the southern stream
midweek, as early week SW US trough shears eastward towards the
Great Lakes and New England, while SW troughing is reinforced once
again. In the SW flow aloft, weak southern stream energy lifts up
towards the region Tue Night into Wed, with associated southern low
gradually approaching Wed and tracking near the region Thu. At this
point, forcing with this system does not look to be too strong with
another light precip event likely. Thermal profiles appear cold
enough to start as all snow Wed/Wed eve, then gradually
transitioning to wintry mix interior and all rain coast Wed Night
into Thu morning, before gradually tapering off late Thu as mid-
level shortwave passes.

Thereafter, generally zonal PAC influenced upper low for late week
into the weekend, lending to slightly above seasonable temps. Next
chance of significant precip possible for late weekend into early
next week as northern and southern stream show signs of


High pressure over the terminals this morning moves offshore
this afternoon. Low pressure impacts the terminals tonight into
Monday morning.

N-NE winds less than 10 kt this morning veer to the SE in the
afternoon, then back to the E tonight.

VFR through this evening. Conditions will lower to MVFR and IFR
overnight as a wintry mix develops after 00Z. Precipitation
tapers of to a drizzle Monday morning with gradual improvement.

There is the potential for 2 to 3 inches of snowfall overnight
at KHPN and KSWF with a slushy 1 to 2 inches at the coastal

.Monday...Areas of drizzle at the coast and freezing drizzle
inland. Gradual improvement to MVFR.
.Monday Night and Tuesday...VFR. NW winds G20-25kt overnight,
diminishing in the morning.
.Wednesday...Snow possible with MVFR or lower conditions in the
afternoon and evening, changing to a wintry mix at night.
.Thursday...MVFR or lower in a wintry mix inland and rain at the
coast in the morning.


High pressure retreats to the east this afternoon as low pressure
approaches from the southwest. As the low passes to the south
and east late tonight, easterly winds briefly  ramp up through
Monday morning, but look to fall just short of SCA on the ocean
waters. SCA conditions will then become more likely Monday
night as the pressure gradient tightens between the departing
offshore low and high building in from the west. This will be
short-lived event though as the high quickly builds into the
waters on Tuesday.

The next chance for SCA conds will likely be Wed night through
Thu night with next low pressure system moving over or south of
the waters.


There are no hydrologic concerns through the middle of next


A low pressure system tracking to the south of the region
tonight into Monday, and a full moon on the 19th, will combine
to bring potential for minor coastal flooding during the Monday
morning high tide. At this point it appears to be a low-end
event across the most vulnerable locales of the south shore bays
of Queens and Nassau County, W Long Island sound, and a few
spots in lower NY/NJ Harbor. Surge of 1 to 1 1/2 ft and,
locally 2 ft, is needed for minor flood thresholds to be


NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable. Parts are on order.

NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.


CT...Winter Weather Advisory from 9 PM this evening to 10 AM EST
     Monday for CTZ005>012.
NY...Winter Weather Advisory from 9 PM this evening to 10 AM EST
     Monday for NYZ067>071.
NJ...Winter Weather Advisory from 9 PM this evening to 10 AM EST
     Monday for NJZ002-004-103>105.


SHORT TERM...Goodman
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