Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 230201
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1001 PM EDT Wed Mar 22 2017

.SYNOPSIS...
High pressure builds in tonight from the Great Lakes, moving
more into the region on Thursday. The high moves offshore
Thursday night. A warm front passes Friday, followed by a cold
front Saturday. The front will wobble across the area on Sunday
before lifting back north on Monday as a warm front. Additional
areas of low pressure may impact the area starting late Monday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Just some minor adjustments made based on latest observations,
with temperatures a bit cooler than forecast.

An unseasonably cold airmass across the region will result in
overnight lows some 15 to 20 degrees below normal. This combined
with gusty NW winds will result in wind chills in the single
digits to lower teens.

Surface pressure gradients remain up through most of the night,
however, the general theme is for gradually diminishing winds.
Some record lows may get reached or tied tonight, see the
climate section below.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Surface high pressure will slide southeast from the Great Lakes
Thursday morning toward the Delmarva Peninsula by Thursday
afternoon. This will result in a clear sky with northwest winds
shutting off by the late morning and winds turning to the west
to southwest by the afternoon which will push readings back to
near 40 in The City with lower 40s in urban sections of
Northeastern NJ and the 30s elsewhere. Ample sunshine will help
take the edge off the early spring chill.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
The good news is the really cold weather is on the way out,
however, so is seeing the sun during much of the extended as an
unsettled weather pattern sets up.

A warm front will lift north across the area Thursday night into
Friday morning in advance of an area of low pressure ejecting
out of the southern Plains. As the Plains low gets closer
an increase in moisture will take place and spread light
precipitation into the area on Friday morning - possibly as
early as 5 to 8 AM. Given temps will be near to below freezing
especially inland in the normal Klondike spots of Orange,
Putnam, Passaic and CT, there will be the risk for frozen
precipitation before temperatures gradually rise above freezing
with the passage of the warm front. Forecast model soundings all
show a warm nose or warm layer aloft with shallow cold air so
the risk for a variety of frozen precipitation exists. Across
North Jersey and the Lower Hudson Valley, frozen precipitation
may start as snow but quickly go to sleet or more likely
freezing rain as the warm layer aloft surges in. Model soundings
look a little better for a bit more in the way of snow across
interior CT, where at Danbury snow may last a little longer
before mixing with sleet and/or freezing rain for a bit before
transitioning to all rain. Either way, QPF amounts are mainly a
tenth of an inch or less so this will not be a big event but
perhaps just enough to create some slick spots on roads if it
lasts long enough. If precip is slower to arrive, then p-type
will be more likely just rain as temps will warm up by later in
the morning. However, this short lived cold snap will chill any
road surfaces allowing for even a light amount of precip to get
slick except in spots where a hefty salt still sits on the
roads.

By Friday night, the warm front should push far enough north
that most of area dries out except for inland CT where some
light rain may linger.

The southern Plains low advances east on Saturday toward St.
Louis. Our area should be in the warm sector, though still see a
decent amount of clouds. Depending on if we get any sun, temps
may crack 60 especially from The City on west. Southerly flow
off the chilly waters will hold max temps down on The Island,
CT and southern parts of Brooklyn and Queens into the 50s.

The warm front to our north will start to get shoved back south
by later in the day in response to a surface high pressure over
eastern Canada. Model consensus is there as to a backdoor cold
front moving toward the area Saturday evening and thus we showed
an increase up in PoPs in that time frame from east to west
across CT and Long Island. Also given the marine push, I added
in patchy fog as we may end up seeing more drizzle at times than
actual light rain. Temps will slowly fall through the night.
Inland we may see a little frozen precipitation if colder air
seeps in better than expected.

Sunday the main issue is where does the front stall out. The
ECMWF on the 00Z operational run was warmer by about 10 degrees
in spots than the 12Z operational GFS. For now I played temps
in between but suspect from The City on east the cooler scenario
will win on out but there is certainly some bust potential with
temps. In many spots readings may hold steady or even fall
through the day depending on what the front decides to do. We
kept in a chance of rain through the day as the approaching low
from the west and the front overhead should keep enough lift in
place to keep things wet most of the time.

Beyond Sunday waves of low pressure are expected to impact the
area with a frontal boundary near or north of the area. The
first wave should pull east by Monday morning but model
agreement was poor after this with timing and the track of the
lows. Given the pattern, frozen precipitation may be possible at
times well inland especially at night where any cold air is
trapped. If the frontal boundary hangs up further south then
frozen precipitation is possible further toward the coast. Most
likely though the flow aloft is west to southwest, so I have
favored a warmer forecast. I bumped up temps a bit over the
previous forecast based on a blend of the operational GFS and
ECMWF. There could be some breaks in rain at times, but this far
out exact timing of features is difficult.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR through the TAF period with mainly clear sky.

NW winds near 25KT with gusts up to 40KT peaking this afternoon.
Gusts begin to drop off toward sunset and diminish after
midnight. Winds pick up again for a few hours midday Thursday
but likely drop off in the early afternoon as high pressure
settles across the area.

     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: No unscheduled amendments expected.

KLGA TAF Comments: No unscheduled amendments expected.

KEWR TAF Comments: No unscheduled amendments expected.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 18z THURSDAY THROUGH MONDAY...
.18z Thursday..VFR. NW winds becoming SW-W 10-15 KT.
.Friday...MVFR possible. Chance of SHRA. SW gusts 25 kt.
.Saturday...Mainly VFR. Chance of mid-late afternoon MVFR in
CIGs and -SHRA.
.Saturday night and Sunday...MVFR/IFR and rain. E-SE gusts
20-25 kt.
.Monday...MVFR possible in showers.

&&

.MARINE...
Gale warnings have been converted to SCAs as wind gusts are
below 35 KT, however can not rule out an occasional higher gust
prior to midnight. The SCA will expire near daybreak for the
Harbor, Bays, and Sound, and then by late morning for the
ocean.

Freezing spray was kept in for later tonight into Friday morning
especially for the ocean waters and eastern end of The Sound.

High pressure moves across the waters Thursday night, and passes
well to the east Friday. Winds diminish during this time, but begin
to increase from the SW later Friday into Friday night.

A cold front approaches from the north Saturday, and settles near or
just south of the waters Saturday night into Sunday. Winds diminish,
and turn toward the E/NE. Speeds increase yet again Sunday as high
pressure builds well to the north.

&&

.HYDROLOGY...
Unsettled weather from this weekend through early next week may
result in an inch or more of precipitation. However, this would
occur over a prolonged period and would be intermittent, so no
hydrologic concerns are anticipated. Snowpack melt in interior
sections will continue at a slow rate through Thursday with
most areas likely loosing any significant snowpack by Saturday
as temperatures rise to above normal readings and lows even
remain above freezing.

&&

.CLIMATE...
The following are record low temperatures for Thursday March
23, 2017 along with the forecast low temperatures.

Record Low Temperature          Forecast Low Temperature
----------------------          ------------------------
Central Park........12 (1875)         20
LaGuardia...........20 (1959)         22
Kennedy.............20 (1959)         20
Islip...............15 (2004)         18
Newark..............13 (1934)         19
Bridgeport..........19 (2004)         17

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ330-335-
     338-340-345.
     Small Craft Advisory until 11 AM EDT Thursday for ANZ350-353-
     355.

&&

$$

SYNOPSIS...DW/CS
NEAR TERM...DW/CS
SHORT TERM...CS
LONG TERM...PW/CS
AVIATION...IRD
MARINE...DW/CS
HYDROLOGY...CS
CLIMATE...//


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