000
FXUS61 KOKX 200911
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
411 AM EST Wed Feb 20 2019

.SYNOPSIS...
A low pressure system will impact the region through tonight. A
cold front follows on Thursday with high pressure returning
Thursday night through Saturday. Another low pressure system
then impacts the region Saturday night into Sunday. High
pressure builds back early next week.

&&

.NEAR TERM /UNTIL NOON TODAY/...
Strong high pressure with widespread canopy of cirrus. The high
pressure will slowly move east and offshore into the Atlantic.
The winds will become more SE late morning into early afternoon but
remain under 10 kts. The temperatures are only expected to rise
a few degrees by early afternoon, getting into the mid to upper
20s.

Clouds continue to lower and thicken in advance of a warm front
approaching from the SW. Initially, the forecast soundings show
drier air from the surface through about 15kft. By around noon
time though, most of the atmospheric column becomes saturated
with some remaining dry air below 5kft. Precipitation will be
very close to the region and with chances beginning to increase
for snow late this morning.


&&

.SHORT TERM /NOON TODAY THROUGH 6 PM THURSDAY/...
The vertical forcing becomes more noticeable as 850-700 mb
frontogenesis increases and moves SW to NE across the region and
the atmospheric column will soon become fully saturated. This
will be in advance of a developing warm front that will have low
pressure starting to develop along it. The main parent low will
be moving into the Great Lakes and will be the more dominant
low. Models indicate consistent warming aloft at 700mb that will
coincide with the increasing precipitation developing and moving
across the region.

The snow will become more widespread this afternoon from SW to
NE and is expected to become a moderate steady snow. With the
antecedent environment, wet bulb cooling keeps the temperatures
below freezing and will allow for 1-4 inches of snow to
accumulate with potential for snow to be 1-2 inches higher than
forecast if snow becomes heavy for prolonged periods of time.

For tonight, the surface winds increase out of the SSE to SE,
allowing for coastal locations to warm up above freezing. First
locations to see this will be Long Island and then NYC,
followed by other coastal areas. The winds remain lighter for a
longer period of time farther inland. Winter weather advisory
segmented to mark the time difference with Essex NJ, Union NJ,
Hudson NJ, NYC, Long Island ending at 1AM Thursday and the rest
of the region to the north ending at 6AM Thursday.

Before temperatures rise above freezing even along the coast,
there is expected to be a time window for a wintry mix of
precipitation including sleet and freezing rain with
temperatures rising a few degrees C above freezing in the
850-700mb layer. Long Island only expected to see a brief
period of this wintry mix with trace amounts of ice expected.
Hence, even eastern Long Island remains in the winter weather
advisory due to the ice forecast. Most coastal areas expected to
have a glaze with ice amounts under a tenth of an inch farther
inland with a longer period of freezing rain expected with
inland locations having lighter winds and having terrain block
the southerly flow.

Atmosphere starts to dry out above 700mb especially late tonight
into early Thursday so less ice nuclei would lead to those areas
with enough moisture to either have drizzle if temperatures are
above freezing or freezing drizzle if temperatures are at
freezing or below.

For temperatures, the highest temperatures will actually be
tonight with a non-diurnal trend. Temperatures slowly rise
tonight from mid 20s to lower 30s to lower 30s to lower 40s.

For Thursday, drier conditions are expected. Low pressure will
be moving east of the region into the vicinity of Nova Scotia
while strengthening a little. A cold front moves across during
the afternoon with high pressure then starting to build into
the local region from the west thereafter. A more westerly flow
develops with some gusts developing as well. A mid level
shortwave passes well north of the region with mid level flow
remaining nearly zonal. Expecting highs to be in the upper 40s
to lower 50s with just some weak cold air advection behind the
front.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The cold front moves well offshore Thursday night with a more
seasonable airmass returning its wake. Temperatures will fall back
into the upper 20s inland and the lower 30s closer to the coast.
Deep layered ridging builds over the eastern states on Friday with a
surface high settling across the Tri-State. Highs will be in the low
to middle 40s.

Upper heights continue to rise Friday night into Saturday ahead of
the next storm system. An upper shortwave trough digs into the
Plains on Saturday spawning an intensifying low pressure that tracks
up into the Great Lakes Saturday night. The surface high over the
area will shift offshore with a return southerly developing. The
antecedent air mass may have marginal temperatures that any precip
initially across the interior could be a wintry mix. However, thermal
profiles are supportive of a mostly rain event Saturday night. There
is no high to the north and the model guidance continues to prog a
strong low (around 980 mb) tracking across the Lakes into SE Canada
Saturday night into Sunday.

A warm front likely approaches from the south Saturday night and
then lifts north Sunday morning into Sunday afternoon. Warm
advection precip breaks out Saturday night and continues into Sunday
morning. The trailing cold front should cross the region late Sunday
as the low lifts north of the region. Deepening on how far north of
the region the warm front gets, temperatures could rise into the
50s, especially for NYC and Long Island.

High pressure returns early next week with dry conditions and a
gradual return to near seasonable temperatures.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
High pressure slides offshore this morning as an area of low
pressure approaches from the southwest before crossing the area
overnight tonight into Thursday morning.

VFR conditions expected this morning before MVFR and then IFR
conditions develop from SW to NE beginning this afternoon as snow
overspreads the terminals. Precipitation will change to a wintry
mix, then to plain rain, from south to north tonight. The one
exception to this is KSWF, where precipitation may remain a wintry
mix through the night, with a prolonged period of freezing rain
possible.

Snowfall accumulations will range from 2-4 inches at
KEWR/KTEB/KJFK/KLGA/KHPN/KSWF, 2-3 inches at KISP/KBDR, and around
an inch at KGON.

Light and variable winds through the morning will return out of the
southeast this afternoon at less than 10kt. Winds then back to the
east-southeast by late afternoon/early evening at around 10 kt
before becoming light and variable again overnight. Winds at inland
terminals could remain light and variable through the day today.

...NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http://www.weather.gov/zny/n90

KJFK TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off
by 1-2 hours.

The afternoon KJFK haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KLGA TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off by
1-2 hours.

The afternoon KLGA haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KEWR TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off by
1-2 hours.

The afternoon KEWR haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KTEB TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off by
1-2 hours.

KHPN TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off by
1-2 hours.

KISP TAF Comments: Start time of snow and timing of changes in
precipitation type this afternoon into this evening could be off by
1-2 hours.


.OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
.Late tonight...IFR or lower possible in rain at southern
terminals and a wintry mix changing to rain at northern
terminals. A prolonged period of freezing rain is possible at
KSWF.
.Thursday-Saturday morning...VFR. W-NW winds G15-25KT possible
from late Thursday morning into Friday morning.
.Saturday afternoon-Sunday...MVFR or lower in rain, with a wintry
mix possible across northern terminals Saturday night.

&&

.MARINE...
Conditions will remain tranquil on the waters through this morning
as high pressure remains in control. An area of low pressure then
crosses the waters tonight into Thursday, resulting in an increase
in both winds and seas, especially on the ocean waters. A Small
Craft Advisory remains in effect on the ocean tonight. While winds
briefly diminish Thursday morning, SCA conditions will likely
continue into the day on Thursday as seas on the ocean will remain
around 5 feet and winds increase again during the afternoon.

Marginal SCA gusts may continue Thursday night on the ocean. Ocean
seas will also gradually subside below 5 ft Thursday night into
Friday. High pressure over the waters Friday into Saturday will lead
to sub-SCA conditions. SCA conditions return on Sunday into Sunday
night as the next frontal system likely impacts the waters.

&&

.HYDROLOGY...
Liquid equivalent precipitation amounts today into early
Thursday morning will generally be around one half to eight
tenths of an inch.

A storm system for Saturday night into Sunday could bring 0.5 to 1
inch of rain. It is to early to tell if any hydrologic impacts will
occur with this rainfall.

&&

.TIDES/COASTAL FLOODING...
There is a chance for some minor coastal flooding for high tide
cycles early Thursday, particularly across the South Shore Back
Bays of Long Island and Western Long Island Sound along the
shorelines of Southwest Connecticut.

&&

.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 from 2 PM this afternoon to 6 AM EST
     Thursday for CTZ005>012.
NY...Winter Weather Advisory from 2 PM this afternoon to 1 AM EST
     Thursday for NYZ078>081.
     Winter Weather Advisory from noon today to 6 AM EST Thursday
     for NYZ067>071.
     Winter Weather Advisory from noon today to 1 AM EST Thursday
     for NYZ072>075-176>179.
NJ...Winter Weather Advisory from noon today to 6 AM EST Thursday
     for NJZ002-004-103-104.
     Winter Weather Advisory from noon today to 1 AM EST Thursday
     for NJZ006-105>108.
MARINE...Small Craft Advisory from 6 PM this evening to 6 AM EST
     Thursday for ANZ350-353-355.

&&

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

NWS OKX Office Area Forecast Discussion