Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 050905

Area Forecast Discussion
National Weather Service New York NY
405 AM EST Mon Dec 5 2016

An upper level disturbance will pass through the Tri-State Region
today. High pressure will build in on Tuesday. Low pressure
developing off the Mid Atlantic coast Tuesday evening passes to
the south of the region through Wednesday. A series of cold fronts
will then move across the area Thursday into Friday. High pressure
builds in for the first half of the weekend followed by a warm
front passing to the north on Sunday.


A weakening 300 millibar jet stream will pass through the region
this morning. At 00Z, the jet was at 160 kt over Illinois,
however it is progged to only be in the 130s range when it
reaches the forecast area.

The radar composite indicates that precipitation will continue to
overspread the region through sunrise. Snow across the north,
trending towards rain as you move southward through the forecast

It appears the heaviest precipitation will remain south of Long
Island per the infrared satellite and radar depictions. This
should keep snowfall accumulations at a minimum, as snowfall rates
will make accumulations difficult under marginal thermal

Special weather statements have been continued for this event.

The back edge of the precipitation was moving along at about 42
kt per the radar, so if this momentum holds, the band of snow and
rain will be gone by 10-13Z from west to east across the forecast

A second round of more showery weather, such as what is happening
over central Pennsylvania, is possible thereafter as the upper
level trough moves through and lapse rates steepen above 600
millibars. Dry air pouring in a 700 millibars and downslope flow
will be limiting factors for this activity.


High pressure builds in from the west this afternoon, and over
the region late tonight into Tuesday morning. This will provide
dry weather and clearing skies. By Tuesday afternoon, low pressure
will be deepening near Cape Hatteras. It is possible that the
northern fringe of the precipitation shield reaches the forecast
area by dark. Low chances have been maintained in the forecast,
although the timing has been slowed from the previous forecast
based on the model consensus.

A blend of the guidance, which was in good agreement, was used
for temperatures through the period.


A progressive upper flow across the Lower 48 will feature a
southern branch short wave trough ejecting out ahead of an
amplifying upper low over the upper Midwest and south central
Canada at the onset of the period. This will allow for surface low
pressure to pass off the Mid Atlantic coast Tuesday night into
Wednesday, with a mainly rain event for the forecast area. The 00z
GFS continues to be warmer aloft versus the ECMWF and NAM. A
compromise of the two solutions results in some snow across far
northern sections of the Lower Hudson Valley and interior SW
Connecticut, with the potential for 1-2 inches. This will depend
on how quickly the cold air erodes Tuesday night with high
pressure retreating to the NE. Elsewhere, it will be a rain event
with the up to half an inch possible.

A building upper ridge along the west coast of North America
Wednesday into Thursday will allow the upper trough/low to dig SE
across the Great Lakes and into the Northeast states Thursday
into Friday. This will result in a series of cold fronts passing
through the area and an unseasonably cold airmass moving in for
Friday and the weekend. This will also be accompanied by strong
NW winds Friday into early Saturday. Outside of some snow flurries
or sprinkles it will be primarily dry with scattered clouds,
mainly north and west of NYC. Warm advection on Sunday ahead of
low pressure moving into the Great Lakes may result in scatted
rain/snow showers.


A frontal system moves through during the morning, and is followed
by high pressure late in the day.

Conditions will lower to MVFR by 10Z as light precipitation
overspreads the area. Expecting primarily rain across the city and
coastal terminals of LI. Farther inland, precipitation at KSWF will
fall predominately as snow, possibly tapering to light rain or
drizzle. Precipitation at KHPN/KBDR and KGON may start as a
rain/snow mix before transitioning to all rain.

IFR conditions are possible a few hours on either side of 12Z (10-
15Z). VFR returns during the afternoon and through the evening as
skies clear.

Light E/SE winds shift to the S, then SW by late morning and
afternoon at around 10 kt as the system approaches and crosses the
area. W/NW winds then prevail late in the day. A gust or two to 15
to 20 kt is possible briefly with the wind shift to the W.

NW winds lighten during the evening.

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

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

KJFK TAF Comments: Chance conditions could fall to IFR this morning.
An occasional higher gust is possible this afternoon.

KLGA TAF Comments: Chance conditions could fall to IFR this
morning. An occasional higher gust is possible this afternoon.

KEWR TAF Comments: Chance conditions could fall to IFR this
morning. An occasional higher gust is possible this afternoon.

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

KTEB TAF Comments: Chance conditions could fall to IFR this
morning. An occasional higher gust is possible this afternoon.

KHPN TAF Comments: There remains a chance conditions remain MVFR
this morning. An occasional higher gust is possible this afternoon.

KISP TAF Comments: Chance conditions could fall to IFR this
morning. An occasional higher gust is possible this afternoon.

.Late tonight...VFR.
.Tuesday...VFR early, then MVFR possible with a chance of light
rain or drizzle.
.Tuesday night-Wednesday...IFR in drizzle and light rain.
.Thursday...MVFR possible with a chance of rain.


Northwest flow will pick up this afternoon and evening behind a
passing trough. A small craft advisory has been issued for the
ocean and eastern Sound as a result. Elsewhere, winds are too
marginal to issue an advisory at this time. Conditions improve lat
tonight and Tuesday as high pressure builds over the waters.

Low pressure passes to the south of the waters Tuesday night into
Friday. Marginal SCA conditions are possible across the waters
with east winds on the ocean waters approaching 20 kt with seas
around 5 ft.

Thursday into Thursday night another frontal system will move
through the forecast waters with a strong cold passing through
Thursday night. Strong and gusty northwest winds will develop
behind the front with the potential for gale conditions Friday
into saturday morning across all the forecast waters.


About a tenth of an inch of liquid is possible today. No
hydrologic impacts are anticipated the next 7 days.


MARINE...Small Craft Advisory from 4 PM this afternoon to 6 AM EST
     Tuesday for ANZ330-350-353-355.


HYDROLOGY...JMC/DW is the U.S. government's official web portal to all federal, state and local government web resources and services.