Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 180246
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
946 PM EST Sun Feb 17 2019

.SYNOPSIS...
Low pressure approaches from the south and west, then redevelops to
our south and passes to the south and east late tonight into Monday
morning. High pressure briefly returns for Tuesday, followed by
another low pressure system for Wednesday into Thursday. High
pressure then returns for Thursday night into Friday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Precip beginning to break out across the region this evening.
There are growing concerns with lack of snow growth aloft as
reports of mainly rain with a few ice pellets in NE NJ and
across the NYC metro. Light snow has been reported across the
interior where best frontogenetic forcing may set up through the
night.

Made some minor adjustments to the snowfall forecast, mainly for
the coast to lower just a bit.

Otherwise, potential still exists for 2 to 4 inches across the
interior of the Lower Hudson Valley, interior CT and interior NE
NJ with 1 to 3 inches for coastal CT and portions of NE NJ
closer to NYC. These amounts are less certain due to potential
of earlier mixing cutting down on totals. There will be a
transition to a wintry mix of light snow and fzra towards
daybreak all advisory area as mid levels level begin to dry but
ample low-level moisture remains ahead of approaching
shortwave. A light glazing of ice on top of snow covered roads
likely for the morning commute in this advisory area.

For LI and NYC/NJ metro, this area may be in between two best
frontogenetic zones to the N and S overnight. The north shore of
LI and norther NYC could see around an inch with less than an
inch across the southern half. If precip intensity remains
light, the amounts may be further reduced. Any wintry precip
should transition to all rain in these locations around 1-2am
southern half to 2-4 am northern half. Do not think temperatures
will stay at or below freezing for long, if they do in fact
drop to these levels so no significant icing concerns.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Only low level moisture will remain into the first half of
Monday with any snow and ice tapering off early across far
northeastern sections of CT, and some leftover drizzle and light
rain for the remainder of the CWA. May take a little while to
clear out during Monday afternoon, but increasing cold air
advection should aid in drying and clearing things out by the
late afternoon. Temperatures will drop well below average into
Monday night with teens north and northwest, with widespread
lower 20s closer to the coast, with some single digit and lower
teen wind chills late at night and early Tuesday morning. Winds
may briefly gust to 30 mph in some locations during Tuesday
evening as the storm intensifies and pulls away out over the
Atlantic.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
The region transitions under a confluent upper flow Tue into Wed,
between upper ridging south of Bermuda and polar low sliding across
central Quebec and Canadian Maritimes. At the surface, Canadian high
pressure builds overhead on Tuesday into Tuesday Night and then
slides eastward Wednesday.

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. Although
forcing with this system does not look to be overly strong, deep
layered lift ahead of shortwave and right rear of 175+ kt llj
combined with gulf tap of 2-3 +STD pwats is trending towards a
moderate precip event for late Wed into Thu morning. Thermal
profiles appear cold enough to start as all snow Wed/Wed eve, then
gradually transitioning to wintry mix interior and all rain
city/coast Wed Night into Thu morning, before gradually tapering off
Thu afternoon as mid-level shortwave passes. Too early to talk about
snow/ice amounts, but potential for a light snow/sleet accumulation,
before transition to rain city/coast, and some icing interior.

Thereafter, generally zonal PAC influenced upper flow for late week
into the weekend, lending to slightly above seasonable temps. Next
feature of interest will be the timing/amplitude of the late week SW
trough as it ejects eastward across the country this weekend.
Considerable timing spread exists, as well as degrees of interaction
with northern stream. With available gulf moisture, this energy will
likely bring the next chance of significant precip from low
pressure/s. At this point too much uncertainty in evolution to
diagnose p-types.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Low pressure will impact the terminals into Monday.

Light SE winds will continue to shift to the E as the wintry
mix develops overnight and then NE by day break. The flow will
become NW by Monday afternoon and increase into Monday evening
becoming gusty, 20-30 kt.

Conditions will lower to MVFR and IFR overnight as a wintry mix
develops. Precipitation tapers of to a drizzle Monday morning
with gradual improvement into the evening. The precipitation
type is expected to rapidly transition to rain 06z-09z at NYC
terminals and KISP. Elsewhere, a wintry mix including a few
hours of -FZDZ, especially at KSWF, KHPN and KBDR may be
possible into the late morning. Conditions should gradually
improve Monday afternoon.

There is the potential for 2 to 3 inches of snowfall overnight at
KSWF with 1 to 2 inches most elsewhere. Lowest totals expected
for NYC terminals and KISP where generally less than an inch is
forecast before changing to rain.

.OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.Monday night into Tuesday...VFR. NW winds G20-30kt for the
evening into overnight, diminishing early Tuesday 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. NW gusts 15-20 kt possible in the evening.
.Friday...VFR.

&&

.MARINE...
Low pressure approaches from the southwest, passing to the
south and east late tonight into Monday. Sub SCA conditions are
expected tonight through much of the day on Monday, before
winds and seas increase later Monday afternoon. SCA conditions
will then return to the ocean waters, and the eastern sound and
eastern bays during Monday night. This will be a short-lived
event though as high pressure quickly builds into the waters on
Tuesday with conditions falling below SCA.

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

&&

.HYDROLOGY...
There are no hydrologic concerns through the end of the week.

&&

.TIDES/COASTAL FLOODING...
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 localized minor coastal flooding during the Monday morning
high tide.

Affected areas will be the most vulnerable locales of the south
shore bays of Queens and Nassau County, W Long Island sound, and
along lower NY/NJ Harbor.

Surge of 1 to 1 1/2 ft and, locally 2 ft, is needed for minor flood
thresholds to be reached.

&&

.EQUIPMENT...
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.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 10 AM EST Monday for CTZ005>012.
NY...Winter Weather Advisory until 10 AM EST Monday for NYZ067>071.
NJ...Winter Weather Advisory until 10 AM EST Monday for NJZ002-004-
     103>105.
MARINE...Small Craft Advisory from 7 PM Monday to 7 AM EST Tuesday for
     ANZ330-340.
     Small Craft Advisory from 3 PM Monday to 7 AM EST Tuesday for
     ANZ350-353-355.

&&

$$
SYNOPSIS...JE/NV
NEAR TERM...JE/NV/DS
SHORT TERM...JE
LONG TERM...NV
AVIATION...DS
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...
EQUIPMENT...


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