Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 231459
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
959 AM EST Fri Feb 23 2018

.SYNOPSIS...
High pressure will give way to a warm front and then a cold
front late today and tonight. Low pressure moving into the
upper Great Lakes will send a warm front toward the area
Saturday night into Sunday, then a trailing weak cold front will
pass through Sunday night. High pressure will build in from
Monday through Wednesday. Another low forming over the Plains
states during mid week will then likely approach from Wednesday
night into Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast overall on track with slight adjustments made to
temperatures, dewpoints, and POPs to better match observed
trends. Forecast temperatures and dewpoints are within a few
degrees of observed values. A chance of sleet was added to
forecast zones for NYC and locations N/W with some reports of
sleet mixing in rain. The temperature profile in some of these
areas exhibits a cold and deep enough sub-freezing layer below
the warm nose for sleet to form.

Main forecast challenge is onset of rain, and expected
temperatures during that time across NW zones. Main concern
for any light freezing rain is across Orange County and the
highest elevations of adjoining zones late this morning to
around midday. Winds funneling down the Hudson Valley into the
valleys of Orange County could maintain a cold air supply as
steadier precip moves in later this morning. SPS remains in
effect for spotty light freezing rain or freezing drizzle in
these areas.

Temps should warm to just above freezing across the interior
around midday, with the rest of the area climbing above the
freezing mark before that. This is thanks to a departing high
off the New England coast, and shifting winds to the
east/southeast which will allow for at least some warming.

Otherwise, rain chances increase from west to east this afternoon as
the warm front draws near. Mainly light rain is expected, with a
tenth of an inch to a quarter inch of rain accum.

Temperatures warm through the 40s, and should rise just above 40
near the coast.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
A warm front followed quickly by a cold front pass tonight as
low pressure tracks well to the north. Any lingering light rain
ends this evening, and some breaks in the clouds are possible as
high pressure builds across the Great Lakes Region. As winds
shift to the SW, then west, and plenty of clouds remain, expect
temperatures to hold steady for most of the night, mid 30s to
around 40.

On Saturday, high pressure to the north once again yields to an
approaching low pressure center and warm front. Rain chances will
increase late in the day ahead of this more robust system.
Temperatures warm through the 40s, likely exceeding 50 degrees
across the area.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
The last in a series of upper level impulses riding atop the upper
ridge to our  south will approach Sat night into Sunday, bringing a
shot of moderate rain and gusty E winds ahead of a warm front
lifting toward the area from the south. As the associated primary
low lifts across the upper Great Lakes into Ontario, a weak triple-
point low should form close to the area late day Sunday, with the
chance that parts of Long Island could briefly get in the warm
sector before a weak cold front passes through at night.

Forecast for Mon calls for dry conditions as sfc high pressure
builds in, but may have to keep an eye on a weak low passing to the
south Mon night for any northward trend as its associated upper
trough passes across. Broad upper ridging should build in its wake
for Tue-Wed. High Temps Mon-Wed will be on the mild side, with highs
close to 10 degrees above avg.

A broad area of WAA ahead of low pressure forming over the Plains
states should bring precip chances beginning Wed night, and then
more so Thu into Thu night. Weak in-situ cold air damming as sfc
high pressure pulls away could result in a period of light wintry wx
well inland late Wed night into Thu morning, otherwise rain expected
into Thu evening. Per current operational 00Z GFS/ECMWF forecast, a
secondary low fcst to develop off the Mid Atlantic coast could pull
enough cold air down from the N-NE to change precip back to snow or
a wintry mix especially inland late Thu night.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Strong high pressure shifts off the northeast coast today as
another wave of low pressure approaches from the west.

Mainly MVFR this morning with some VFR across southern
Connecticut. Conditions should gradually lower to IFR by this
afternoon as light rain develops. Light rain will continue into
the evening with IFR continuing for much of the night. There is
a low chance for LIFR overnight. Improvements to VFR are
expected by Saturday morning.

NE winds become E and then SE this afternoon 10 kt or less.
Winds diminish this evening before becoming W-WNW early
Saturday morning.

A brief period of LLWS is forecast tonight.

     ...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: IFR may develop +/- 1-3 hours from forecast.

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

KLGA TAF Comments: IFR may develop +/- 1-3 hours from forecast.

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

KEWR TAF Comments: IFR may develop +/- 1-3 hours from forecast.

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

KTEB TAF Comments: IFR may develop +/- 1-3 hours from forecast.

KHPN TAF Comments: IFR may develop +/- 1-3 hours from forecast.

KISP TAF Comments: Ceiling could fluctuate between MVFR and IFR
this morning before prevailing IFR this afternoon.

.OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
.Saturday...Mainly VFR. Chance rain late.
.Saturday Night-Sunday...MVFR/IFR in rain. E winds G20-25KT on
Sunday.
.Sunday night...Becoming VFR.
.Monday-Tuesday...VFR.

&&

.MARINE...
With gusty easterly winds this morning, and seas running around 5
ft, SCA remains in effect over the ocean waters.

Conditions improve as a warm front, then cold front pass late in the
day and this evening. SE winds shift to the west tonight, then
lighten as they turn to the NW Saturday.

E winds between departing high pressure and an approaching warm
front should reach SCA levels on all waters late Sat night into
Sunday morning. These winds could reach minimal gale force on the
ocean Sunday morning. Too early for any headlines, but a gale watch
might eventually be required if confidence in this scenario
increases. Hazardous ocean seas could linger thereafter into Mon
morning.

&&

.HYDROLOGY...
No hydrologic impacts are expected late today and tonight with
rainfall amounts less than a quarter inch.

Expecting up to an inch of rain on Sunday with the last in a series
of passing disturbances. Another 1/2 to 1 inch liquid equivalent
possible Wed night into Thu night, mostly in the form of rain.
Rainfall intensity/duration do not suggest more than local nuisance
ponding for Sunday.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ350-
     353-355.

&&

$$
SYNOPSIS...Goodman/PW
NEAR TERM...Goodman/JM/PW
SHORT TERM...PW
LONG TERM...Goodman
AVIATION...DS
MARINE...Goodman/PW
HYDROLOGY...Goodman/PW
EQUIPMENT...



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