Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 132236
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
536 PM EST Fri Jan 13 2017

.SYNOPSIS...
Strong high pressure over the Great Lakes this evening builds east
and into the area by daybreak. The high passes offshore Saturday
afternoon with a weak wave of low pressure passing well to the
south Saturday night. High pressure builds over the region Sunday
into Monday, and moves offshore Monday night as a warm front
approaches, then moves through Tuesday or Tuesday night. A cold
front follows Wednesday into Wednesday night. Weak high pressure
builds in Thursday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A strongly confluent flow aloft between the northern and southern
branches of the polar jet will allow strong high pressure over
the Great Lakes this evening to build east and into the Northeast
by daybreak. At the same time, an upper low off the west coast
will steer plenty of mid and high level clouds across the region
this evening. In addition, a gusty NW flow early will subside as
the high builds in from the west.

Overnights lows will return to nearly seasonable levels, ranging
from the teens well inland to 20 to 25 near the coast.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
High pressure builds across the area in the morning and then
passes to the east in the afternoon. A weak frontal wave passes
well south off the Mid Atlantic coast late in the day. The
general trend in the model guidance the last several days has been
weaker and farther south with this system. While there is some
weak warm advection and moisture in place Saturday afternoon/evening,
the amount of dry air in the low-levels and subsidence will be
difficult to overcome. Thus, have continued to trend down with
the chance of light snow, mainly for the NYC metro and LI during
the afternoon/early evening hours. More than anything, this looks
to be nothing more than a few passing flurries. In a worst case
scenario, amounts look to be under an inch.

Daytime highs under cloud cover will struggle on Saturday to get
out of the lower 30s with lows Saturday night in the 20s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
High pressure builds in from the northwest on Sunday and Monday.
Both days will be dry with high temperatures a little above normal.

Slight ridging continues aloft Monday night into Tuesday morning,
but shortwave lift and isentropic lift ahead of a warm front are
still shown by models. With increasing moisture, there will be at
least a slight chance of PCPN late at night over the western zones,
but PCPN becomes a little more likely across the entire forecast
area during the day Tuesday. A warm nose aloft is still progged to
be warm enough to preclude snow as a likely PCPN type. Rain with a
potential brief period of sleet would therefore be more likely to
occur, with freezing rain for some inland spots until surface temps
warm up enough by late Tuesday morning.

The timing of both warm front and cold front passages thereafter are
uncertain with model disagreement. Will carry chance PoPs Tuesday
night through Wednesday night with rain as the PCPN type.
Temperatures well above normal during this period.

There at least appears to be agreement that we dry out by Thursday
as weak high pressure builds in from the west. A shortwave and weak
surface trough may then bring a shower in spots on Friday. Highs
both days still averaging well above normal.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... Northwest winds
diminish this evening and gradually shift to the north overnight
as high pressure builds to the north. Winds tomorrow will go to
the northeast for the morning, then more southerly in the
afternoon.

Light snow will be possible late Saturday afternoon-evening as a
low pressure system passes to the south, but confidence is too low
to mention in the TAFS.

     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: End time of gusts may be earlier than forecast.

KLGA TAF Comments: End time of gusts may be earlier than forecast.

KEWR TAF Comments: End time of gusts may be earlier than forecast.

KTEB TAF Comments: End time of gusts may be earlier than forecast.

KHPN TAF Comments: End time of gusts may be earlier than forecast.

KISP TAF Comments: End time of gusts may be earlier than forecast.

.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
.Saturday-Saturday night...Sub VFR is possible in light snow late
Saturday afternoon/Saturday evening. Best chance of Sub VFR will be
across southern terminals.
.Sunday...VFR.
.Monday...VFR.
.Monday night-Tuesday...MVFR or lower possible in rain near the
coast, and wintry mix inland.
.Wednesday...MVFR or lower possible in rain.

&&

.MARINE...
SCA conditions are expected on the ocean waters through this
evening. Winds and seas gradually subside tonight as high pressure
builds toward the waters.

Sub-SCA conditions are then forecast through Saturday night. NW
winds develop late Saturday night behind low pressure well to the
south and east.Gusts on the ocean waters could get up to 20 kt by
daybreak Sunday,

Winds diminish later Sunday with tranquil conditions on the
waters following through Tuesday as a high pressure ridge slowly
shifts through the region.

Winds and seas then build Tuesday night into Wednesday as the
pressure gradient tightens in response to an approaching low
pressure system. There will be chance of SCA conditions, mainly on
Wednesday.

&&

.HYDROLOGY...
No significant precipitation is forecast this weekend into next
week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ355.
     Small Craft Advisory until 1 AM EST Saturday for ANZ350-353.

&&

$$
SYNOPSIS...JC/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...JC
AVIATION...JE/NV
MARINE...JC/DW
HYDROLOGY...JC/DW



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