Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 270824

Area Forecast Discussion
National Weather Service New York NY
424 AM EDT Thu Oct 27 2016

Low pressure approaches from the west today and passes through
tonight. High pressure then builds back in on Friday and lasts into
Saturday. A cold front will approach from the north Saturday
night, then sink through the area on Sunday as low pressure moves
along it. High pressure then returns Monday and Tuesday, with a
weak cold frontal passage on Wednesday.


Isentropic lift ahead of an approaching warm front will help
precipitation enter the western zones near sunrise. Precipitation
then spreads east through the rest of the forecast area during the
rest of the morning in to early afternoon.

Most of the forecast area is expected to have an all-rain event,
however some wintry precipitation should be part of the mix in the
morning for areas north and west of the city. An elevated warm layer
centered near 800mb will try to push in during the morning hours.
Thinking is that there will be some wet-bulbing aloft as there is a
dry layer in the low-mid levels at the onset of precipitation. This
would then counteract the warm nose trying to build aloft as WSW
winds in this elevated layer begin to strengthen. Still, temps aloft
probably get warm enough for some sleet to be part of the wintry
mix, but probably not warm enough for freezing rain. Surface
temperatures will likely be above freezing by the time the elevated
layer warms up enough. Will therefore continue to leave freezing
rain out of the forecast.

Regarding snow totals before the changeover to rain, going with up to
an inch for the higher elevations of Orange county, and less
than an inch for surrounding areas in the Lower Hudson valley and
into the northern fringe of some of our CT zones.

Clouds and precip will hold high daytime temperatures well
below normal. The high temperature for the calendar day for many
spots might not occur until the evening hours.


As the parent low center of the storm moves through eastern Great
Lakes region, a secondary low is progged to develop and move over
the CWA tonight. Associated lift and a developing low level jet will
enhance rainfall, and it could be heavy at times generally over the
eastern half of the CWA. With some elevated instability present, a
thunderstorm cannot be ruled out either. Better chances of this will
be over the southern zones. Rain then ends overnight, and only a
lingering shower will still possible by daybreak for the easternmost

Varying amounts of cloud cover is expected through the day Friday
along with breezy conditions. It still appears that remains dry as
the timing of cyclonic flow aloft, low level heating, and sufficient
moisture won`t coincide well enough. High temperatures will be below
normal once again.


There are some changes in the offing for the weekend. Guidance has
trended more slowly with the cold frontal approach Sat into Sat
night, which should allow a wave of low pressure associated with an
approaching northern stream upper trough to ride east along the
front, and more directly impact the area on Sunday before the front
sinks south Sunday night. Have bumped PoP up to likely for most of
the area on Sunday to reflect this. High pressure should return
thereafter, with only a dry/weak frontal passage expected on

Temps on Sunday are quite uncertain and will depend on the amt of
rain and cloud cover, and the position of the approaching front.
Otherwise with the exception of Monday into Monday night as Canadian
high pressure briefly builds in, temps through the period should be
at or a little above average.


An area of low pressure will approaching from the Ohio valley
today...and move across the area tonight.

Light N/NE winds veer to the NE/E early this morning and then
E/SE. E/SE winds increase during the afternoon with gusts.

Mid and high level clouds continue to overspread the region with
light rain developing around daybreak. At KSWF...precip could start
as a period of wet snow with little to no accumulation expected.
There is a low chance of any freezing rain and/or sleet.

MVFR conds likely develop from west to east during the mid to late
morning with steadier light rain...dropping to ifr in the late
aft/eve in moderate rain. Timing of deteriorating conds may be off
by 1 to 2 hrs...depending on how quickly the low-levels moisten.

Conditions start to improve late in the taf period for the western

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

Detailed information, including hourly TAF wind component forecasts,
can be found at:

KJFK TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

KLGA TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

KEWR TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

KHPN TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

KISP TAF Comments: Timing of deteriorating conditions may be off by
1 to 2 hrs.

.Thursday Night...IFR or lower conditions in rain...improving to
VFR in wake of cold frontal passage after midnight. SE winds
shift to West in wake of cold frontal passage.
.Friday...VFR with strong northwest flow behind a cold front.
Gusts 25-30kt.
.Saturday and Sunday...VFR with gusty southwest flow possible.
Low chance of showers during the afternoon/evening both days.


SCA remains on the ocean waters starting this afternoon. There
could be a few gusts to 25 kt on the other waters late this
afternoon as the pressure gradient tightens. The better chance of
SCA conds on the other waters will be for a period this evening
ahead of the passage of a low center, and late at night when the
low shifts east of the waters. Will go with a SCA for the non-
ocean waters for tonight although there could be an extended
period where advisory conditions might not be met. There is also a
chance on the ocean waters for a few gale force gusts, but
thinking is that frequent gales will be more likely during the day
Friday. Have therefore gone with a gale warning east of Fire
Island Inlet during the day Friday where the pressure gradient on
the backside of the departing storm will be tighter. SCA conds
otherwise for all other waters through the day Friday.

NW gales are lily to continue into Fri evening on the eastern ocean
waters, with SCA conditions most elsewhere. Any respite should be
brief, as WSW flow on Sat well in advance of a cold front should
reach SCA levels on most waters, and may gust to minimal gale force
out east late day Sat. SCA conditions could last on the ocean
thereafter into Sunday morning in advance of the front and low
pressure approaching from the west, then return late Sunday night
into Mon via post-frontal N flow gusting up to 25 kt.


Liquid equivalent precipitation is expected to range from 0.75
to1.25 inches through tonight. The higher amounts are
expected generally over CT and Long Island. Although not likely,
there is at least a chance for minor urbanized/poor
drainage/small stream flooding in heavier downpours that might
occur this evening.

Widespread significant precipitation is not expected for the rest
of the forecast period.


MARINE...Small Craft Advisory from 8 PM this evening to 6 PM EDT Friday
     for ANZ330-335-338-340-345.
     Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Friday for ANZ350-353.
     Gale Warning from 6 AM to 6 PM EDT Friday for ANZ350-353.
     Small Craft Advisory from 2 PM this afternoon to 6 PM EDT
     Friday for ANZ355.


LONG TERM...Goodman
HYDROLOGY...JC/Goodman is the U.S. government's official web portal to all federal, state and local government web resources and services.