Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 240554

Area Forecast Discussion
National Weather Service New York NY
154 AM EDT Mon Oct 24 2016

Fast moving low pressure and an associated cold front will move
through overnight. High pressure will build across from 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.


A weakening pressure gradient as a clipper low approaches the
region will result in continued light winds with radiational
cooling already resulting in lower temperatures across some
outlying locations where clouds were minimal in coverage.
Temperatures and dewpoints were adjusted accordingly. Still
expecting some moderation of temperatures as expansive cloud deck
traverses forecast region as showers move across during the
overnight period. Outside of the rural locations, most lows will
be in the mid 40s to low 50s.

Convective indices still show total totals and Showalter indices
near 50 and 0 respectively, and with MUCAPE also increasing to
near 500 J/kg over Eastern Long Island and the coastal waters
late tonight, there could be a few isolated thunderstorms. SPC
has the local area under a marginal threat for thunderstorms for
the overnight period.


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.


A cold front moves through during the pre-dawn hours.

Mainly VFR, but brief MVFR vsbys/cigs possible north of the city
in pre-dawn showers. For the city terminals/KTEB/KISP, a brief
shower or two possible, but not likely enough to include as
prevailing or tempo in the forecast. Any thunder would be isolated
and is not included in the forecast.

SW winds shift NW by 10-12z. Winds are more likely to prevail
north of 310 magnetic for most of the day. Occasional gusts to 30
KT possible in the city terminals this afternoon.

.Outlook for 06Z Tuesday through Friday...
.Monday night...VFR with NW winds. Occasional gusts possible.
.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.


For the non ocean waters, winds should remain below 25 Kts
overnight as the pressure gradient relaxes ahead of low pressure.
For the ocean waters, winds should diminish somewhat, but will
remains gusty, and seas remain 5 ft or higher.

SCA conditions should redevelop on all waters from Monday into Tue
evening as a strong/gusty NW flow develops behind the cold front.
As such, a new SCA has been posted through Monday night for now.

These conditions should continue 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.


QPF from 1/10 to 1/4 inch likely overnight, with the higher
amounts inland and across eastern Long Island.

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 from 6 AM this morning to 6 AM EDT
     Tuesday for ANZ330-335-338-340-345.
     Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355.



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