Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 232008

Area Forecast Discussion
National Weather Service New York NY
408 PM EDT Sun Oct 23 2016

Low pressure over southeastern Canada, extending into the
northeast, will meander across southeastern Canada through
tonight. A low pressure and associated cold front move the area
late tonight into early Monday morning. High pressure will build
across from late Monday into Wednesday night. A frontal system
will approach from the west on Thursday and move across Thursday
night into early Friday, followed by weak high pressure later
Friday into Saturday. A series of weak frontal systems will then
approach Saturday night into Sunday.


With the heating of the day and a well mixed boundary layer,
higher winds managed to mix to the surface. With the loss of
heating this evening winds and gusts are expected to diminish. In
addition with a weak surface low over the upper midwest expected
to move into the eastern Great Lakes and then through the region
this evening and late tonight, the surface pressure gradient
weakens and winds will subside as a result.

The shortwave was moving quickly through the northern stream and
will moves into the upper closed low and negative trough across
eastern Canada. The vort max begins to shear out late tonight.
Also the low was tracking a little farther to the north, so
adjusted likely pops northward.


The front and low should be off shore by 12Z. Cold advection sets
up and continues through Monday, and gusty northwest winds
develop. Low level winds will not be as high as Saturday and
Sunday and peak gusts will be in the 25 to 30 KT range.

A deep northwest flow will continue across the region Monday night
as the upper trough remains over eastern Canada. Inland winds will
decouple Monday night and with clear skies temperatures are
expected to fall into the mid and upper 30s. There still will be
enough of a wind and drying will occur, so do not expect a
widespread frost.


An upper trough will remain over the Northeastern states and eastern
Canada through Wednesday. A gusty NW flow will prevail, and with
cyclonic low level flow expect more in the way of clouds on Tue,
especially across the interior where downslope effects will not dry
out the column as much.

As the high builds across on Wed, it should be quite cool, with high
temps only from the mid 40s to lower 50s. Strong radiational cooling
under the high Wed night could lead to a hard freeze across much of
the interior especially NW of NYC, with lows ranging from the mid
20s to lower 30s, and falling even to the mid 30s in NYC.

A passing frontal system will bring the next chance of rain from
Thursday afternoon into early Friday morning, with the bulk of the
rain falling Thursday night. Bumped PoP up to likely for Thu night
as a result. If the system moves through as quickly as latest
guidance suggest, Friday could be dry throughout, but held onto a
morning chance for eastern Long Island and SE CT.

Forecast certainty diminishes after Friday, with big timing
differences noted with a series of frontal systems moving through.
Have only a broad-brush slight chance PoP from Sat night into
Sunday, and this could change as the more likely time periods for
rain come into focus in later forecast cycles.


High pressure builds to the south today with strong low pressure
over eastern Canada. A cold front moves through late tonight into
early Monday.

WNW winds gusting 30-35kt through early this evening.
Winds decrease and gusts end this evening. Winds will back to the SW
overnight, generally around 7-10 kt. After the cold front passage
early Monday, winds will shift to the NW and increase with gusts 20-
25 kt by late morning.

VFR through the TAF period. There is a low chance for MVFR in
light rain late tonight into early monday morning.

.Outlook for 18Z Monday through Friday...
.Monday Afternoon-Monday Evening...VFR. NW winds G20-25 kt.
.Tuesday...VFR. NW winds G25-30 kt, diminishing Tuesday night.
.Wednesday...VFR. NW-NNW G20 kt possible near the coast.
.Thursday-Friday...MVFR or lower possible late Thursday into early
Friday in rain.


Winds and gusts have been just under gale warning levels during
the afternoon. Winds and gusts are expected to diminish early this
evening as low pressure near the western Great Lakes moves east
and the pressure gradient across the waters begins to weaken. A
gale warning remains in effect through 600 pm for the eastern
ocean waters, and will be replaced with a small craft advisory. A
small craft advisory remains on Long Island Sound, the bays, and
New York Harbor until 600 pm, and on the remainder of the ocean
waters through Monday night.

There will be a lull in the winds later this evening and tonight
as the surface low and front move through and the surface pressure
gradient weakens. However seas on the ocean waters remain at small
craft levels.

Small craft conditions across all the waters will be likely Monday
and possibly into Monday night as a strong and gusty northwest
flow develops behind the cold front.

SCA conditions likely to continue on all waters into Tue evening,
with gusts 25-30 kt. These conditions should continue into Tue night
and on the ocean and the eastern Sound late Tue night, and possibly
into Wed morning.

SW flow increasing to 15-20 kt Thu night ahead of a frontal system
could push ocean seas up to 5 ft Thu night. Post-frontal WNW flow
could gust up to 25 kt on the ocean on Fri as well.


One to two tenths of an inch of precipitation are possible late
tonight. Otherwise dry through Wednesday night.

Most likely QPF with a passing frontal system Thu afternoon into
early Fri morning ranges from 1/2 to 3/4 inch. Local amounts over an
inch are possible. No hydrologic impacts expected attm.


MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ330-
     Small Craft Advisory until 6 AM EDT Tuesday for ANZ353-355.
     Gale Warning until 6 PM EDT this evening for ANZ350.


LONG TERM...Goodman
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