Area Forecast Discussion
Issued by NWS Upton, NY

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458
FXUS61 KOKX 180612
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
112 AM EST Mon Feb 18 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 THIS MORNING/...
Precipitation has become spotty across the area as of midnight,
with the best frontogenetic forcing to our north and a low
beginning to take shape to the south. Any precipitation that
does fall will generally remain a mix of snow, sleet, and
freezing rain across the far northern interior zones where
temperatures remain several degrees below freezing. Along the
coast, any precipitation through the early morning hours will
primarily be in the form of rain or sleet as temperatures remain
at or a few degrees above freezing. Some freezing rain is
possible as well in areas where surface temperatures are able to
drop to freezing. A SPS has been issued for all of Suffolk and
northern Nassau County on Long Island highlighting this
potential.

Otherwise, high resolution models continue to indicate that
precipitation will fill back in across the region over the next
several hours, although with intensities expected to remain
light, not expecting coastal locations to see much in the way of
snow through the remainder of the event. Across the advisory
area, a period of freezing rain or drizzle is possible towards
daybreak as the 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.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
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 NIGHT 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 /06Z MONDAY THROUGH FRIDAY/...
Low pressure will impact the terminals today. High pressure builds
from the west tonight.

Light winds under 10 kt will become E-NE early this morning.
The flow will become NW by afternoon and increase into the
evening with gusts developing, mainly 25-30 kt. Gusts will
gradually weaken tonight.

Conditions will continue to lower to MVFR and IFR. The predominate
precipitation type at NYC and Long Island terminals will be rain
although some brief light freezing rain cannot be ruled out on Long
Island until 08z. The precipitation should taper off to a
drizzle at the coast and freezing drizzle inland around or just
after day break. Conditions gradually improve this afternoon.

The more wintry precip of snow, sleet, and freezing rain will be
across KSWF, KHPN, KBDR, and KGON. Here there remains potential
for 1 to 3 inches of snow/sleet early this morning at KSWF and
1 to 2 inches at HPN, BDR, and GON with a glaze of ice.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.Tonight into Tuesday...VFR. NW winds G20-25kt diminishing
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 this morning for
     CTZ005>012.
NY...Winter Weather Advisory until 10 AM EST this morning for
     NYZ067>071.
NJ...Winter Weather Advisory until 10 AM EST this morning for
     NJZ002-004-103>105.
MARINE...Small Craft Advisory from 7 PM this evening to 7 AM EST
     Tuesday for ANZ330-340.
     Small Craft Advisory from 3 PM this afternoon to 7 AM EST
     Tuesday for ANZ350-353-355.

&&

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



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