Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 282151
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
551 PM EDT Wed Oct 28 2020

.SYNOPSIS...
The remnants of Zeta will pass by south of the area on Thursday
followed by a secondary coastal low Thursday night into Friday
morning. Strong high pressure will quickly build Friday night
and into the first half of the weekend. A cold front then moves
through Sunday night, followed by high pressure returning
through the middle of the week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Forecast on track this evening. Dry conditions will remain in
place under mostly cloudy skies and fairly light winds as a
brief ridge of weak high pressure moves over the area tonight.
Temperatures tonight will be in the middle 40s for the Interior
and low 50s near and along the coast.

The remnants of Zeta will approach the area from the southwest
overnight with rain showers possible from the city south and
west toward daybreak.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
As moisture overspreads the region from west to east, a persistent
steady rain is anticipated to encompass the entire region by mid-
morning. The steady rain will become moderate in intensity through
the afternoon as winds pick up from the Northeast. The remnant low
of Zeta will pass by south of Long Island toward evening bringing
with it some pockets of locally heavy rain along the coast. Once
Zeta pushes offshore by Midnight on Friday, the heaviest rain will
have moved offshore with it. However, persistent light rain or rain
showers will remain likely through all of Friday night as a
secondary low develops in the wake of Zeta, south of the area.

Models have been becoming better in line with how the remnants of
Zeta interact with the longwave trough and upper-level low. Zeta is
moving along quickly enough as to not completely phase with the
large scale trough, preventing the combining of the remnants of Zeta
and the developing coastal low. Models continue to distinguish these
low pressures as two separate features immediately following
each other. The secondary coastal low will allow for the wind to
shift more northerly allowing for the advection of colder air
into the area from the north. The air may be cold enough to
result in a brief mix with some snow flakes for the extreme
northwestern portions of the area early in the morning on Friday
as the precipitation is departing the area.

Overall, rainfall totals of 1 to 2 inches are expected with the
higher values near and along the coast, namely the NYC metro
and Long Island.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Model guidance continues to trend further south and east with the
secondary coastal low early Friday morning. The remnants of Zeta
will be well offshore by this time. The phasing of the northern and
southern streams appears to occur too late for any significant
precipitation with the secondary coastal low, likely due to an
overall progressive flow pattern. Precipitation will continue early
Friday morning, but will likely be gradually diminishing in coverage
an intensity. With the northern stream beginning to sink southward,
colder air will be drawn into the region from the north. Some
interior locations could see the rain mix with or change to snow as
the precipitation ends. It is going to be quite difficult for any
accumulation due to warm grounds, marginal surface temperatures, and
loss of lift within the snow growth zone. While not included in the
grids at this time, some sleet could mix with the rain forecast
soundings indicate loss of saturation above -8C Friday morning.
Elsewhere, all rain is expected Friday morning. Additional liquid
equivalents on Friday should be from around a quarter inch or less.
Trace to a dusting on grassy surfaces is possible inland, mainly
north and west of I-84.

Dry conditions should return Friday afternoon as the low moves well
east of the 40N/70W benchmark. It will remain breezy through the day
with northerly wind gusts 20 to 30 mph, highest near the coast.
Friday will also end up as the coldest day of the 2020 Fall season
with high temperatures not rising out of the 40s. Highs will range
from the lower 40s inland to the middle and upper 40s near the
coast.

Cold high pressure builds over the region Friday night. Low
temperatures look to fall into the 20s inland and the lower and
middle 30s near the coast. Friday night will likely be the first
widespread freeze for much of the region. Winds may stay elevated a
bit near the coast but otherwise skies will be mostly clear along
with dew points well into the 20s. The high settles over the area on
Saturday with highs continued below normal in the 40s to near 50s
degrees. Another chilly night is in store Saturday night with
temperatures around freezing inland ranging to the upper 30s to near
40 elsewhere. The high moves offshore Saturday night into Sunday
morning, setting up a return flow. Warm advection will increase
during this time as the next upper trough and cold front approach
from the west. Some light rain may occur during the day on Sunday in
the warm advection regime. Temperatures rebound close to normal in
the upper 50s to near 60 degrees. The cold front should push through
Sunday night, which will continue a chance of rain and bring another
shot of colder air for Monday.

The upper trough axis swings across on Monday. The flow aloft will
be cyclonic and some of the models indicate lake effect moisture
making it into the area. Have left the forecast dry, but it would
not be out of the question for a rain or snow shower to make it into
the interior in the afternoon Monday. The trough moves further
offshore Monday night with high pressure and building heights
Tuesday into Wednesday. Temperatures will be below normal Monday,
then slowly trend towards normal by middle of the week.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
Weak high pressure builds in from the west through tonight.

Mainly MVFR to start, improving to VFR late aftn/early evening.
NW-W winds under 10 kt.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Amendments likely for timing of category changes with the
improvement to VFR this afternoon.

.OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
.Thu PM...IFR in rain. NE gusts 20-25 kt.
.Thu Night...IFR. Rain with NNE winds 20-30 kt. Higher gusts
possible near the coast..
.Fri...IFR early, improving to VFR late. Rain ending, possible
mixed with snow as it ends at KSWF. N winds gradually
decreasing. NE-N winds near 20 kt with gusts 25-30 kt during the
day along the coast.
.Sat...VFR with light SW flow.
.Sun...MVFR and -shra possible with SW winds near 15 kt with
gusts 25-30 kt.
.Mon...Mainly VFR. NW winds 15-25kt with gusts 30-35kt.

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

&&

.MARINE...
Sub SCA conditions will take place tonight with the winds relatively
light. Seas on the ocean will be mainly around 3 to 4 feet through
Thursday morning.

Seas will then begin to build later Thursday afternoon and
especially into Thursday night as the winds and waves increase
from south to north. SCA conditions quickly go to gale
conditions for the ocean waters during Thursday evening,
potentially followed by the non-ocean waters during Thursday
night. By late Thursday night into Friday morning, seas on the
ocean will build to around 10 ft. Gale conditions will likely
continue on the ocean during the first half of Friday, followed
by small craft conditions late in the day and evening. Winds on
the sheltered waters should be weaker and closer to small craft
levels on Friday. Winds diminish Friday night, but ocean seas
will remain elevated above 5 ft, possibly through Saturday. Sub
SCA conditions are forecast on all waters Saturday and Saturday
night, then increase to SCA levels on the ocean Sunday into
Sunday night. Gusty NW winds are expected on Monday on all
waters leading to SCA conditions.

&&

.HYDROLOGY...
Rainfall for Thursday into Friday morning averages around 1.5
to 2 inches. Most of this should be of fairly long duration,
with only minor impacts. The period of moderate to occasionally
heavier rainfall is for Thursday afternoon and evening, but
nothing more than nuisance urban poor drainage type flooding is
expected at this time.

&&

.TIDES/COASTAL FLOODING...
The combination of a strengthening NE flow Thursday into Thursday
night along with the approach of the full moon this weekend raises
the potential for a widespread minor coastal flood event for the
high tide cycle Friday morning. A few locations on the south shore
of Nassau county, but not enough confidence for a coastal flood
watch.

Model trends have continued to show a more elongated low and farther
SE secondary low pressure and a better agreement on winds becoming
NNE for the Friday morning high tide. Guidance has trended downward
and the preference at this time was to average ETSS, ESTOFS, with a
slightly higher weight to NYHOPS. This results in a surge of 2 to 2
1/2 ft with a low probability of up to 3 ft.

Localized minor coastal flooding is possible with Friday night high
tide in the south shore back bays.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Gale Watch from Thursday evening through Friday afternoon for
     ANZ330-335-338-340-345.
     Gale Warning from 8 PM Thursday to 2 PM EDT Friday for ANZ350-
     353-355.

&&

$$
SYNOPSIS...DS/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...DS
AVIATION...JC
MARINE...DS/MW
HYDROLOGY...DS/MW
TIDES/COASTAL FLOODING...



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