Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 161130 CCA
AFDOKX

Area Forecast Discussion...CORRECTED
National Weather Service New York NY
630 AM EST Mon Jan 16 2017

.SYNOPSIS...
A warm front approaches Tuesday night and then moves offshore
Wednesday morning as low pressure develops near the Tri-State. This
low gradually moves offshore late Wednesday into Thursday.
Weak high pressure builds into the Thursday into Friday, before
retreating north of the region Saturday. A wave of low pressure may
pass just south Saturday before a more significant low approaches
the end of the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Only minor adjustments needed to lower current temperatures across
eastern Long Island. Otherwise forecast remains on track.

Clear skies and calm winds will allow temperatures to fall further
this morning bringing a cool start to the day. Temperatures will
rebound fairly quickly after sunrise with dry and sunny
conditions expected for today under high pressure. Temperatures
will rise close to or slightly above climatological normals, with
most sites around 40 degrees. Winds will generally remain light.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Warm/moist advection will allow for the gradual development of
light precipitation late ahead of an approaching short wave. With
the area starting off initially very dry, moisture increase will
be very slow. Temperatures outside of the NYC metro and
surrounding suburbs will most likely be below freezing at the
onset of any precipitation, so there is a short period in the
morning where freezing rain will be possible, particularly to the
northwest of NYC. Very little accumulation is expected. Rain will
increase in coverage and intensity through the day, but after
temperatures have risen above freezing.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Warm advection ahead of an approaching warm front will bring a
steady rainfall Tuesday night. Parent low pressure moving across the
Great Lakes early will gradually transfer to a secondary low along
the warm front. It does not appear the warm front will fully move
across the region rather will move offshore as the secondary low
develops. Rainfall amounts should average around a half inch with
this system.

Coverage of rain should become much lower by Wednesday morning.
However, a potent piece of energy within a positively tilted 500 mb
shortwave is progged to approach Wednesday morning and then move
offshore in the afternoon. Deterministic models differ in the
amplitude of the shortwave as well as positioning of the energy with
the 00z GFS furthest south and less amplified. The 00z NAM, ECMWF,
and CMC are more amplified and further north. Most of the 21 members
of the GFS ensemble are dry Wednesday morning. Have continued with
chance pops in the morning to reflect the potential for some showers
with this shortwave, and then as it moves offshore PoPs lower to
slight chance. High temperatures are above normal in the middle and
upper 40s.

Models are in good agreement on ridging building Wednesday night
through Thursday across the eastern states as the trough moves
offshore. As ridging continues to build into Friday, another upper
trough will dig towards the north Atlantic from SE Canada. With this
pattern aloft, high pressure will build over the region Thursday
into Friday. Above normal temperatures continue in the middle and
upper 40s. Some readings near 50 are possible in the NYC metro. The
warmest air in this pattern appears to stay well to the south of the
Tri-State as we will be under the influence of NW flow aloft and
light N to NE flow at the surface.

Energy from slow moving upper trough across the SW US and Plains is
progged to eject out towards the Ohio Valley on Friday and then get
caught underneath strengthening ridging aloft. This energy may
approach Friday night and bring enough moisture for precipitation.
However there is a large amount of spread on the amount of lift
available as well as the strength of the energy as it gets to the
coast. Despite this potential energy bringing a brief chance of
precipitation Friday night, anomalous ridging continues to build
aloft. The ridge axis may move offshore Sunday as a more significant
upper trough and low pressure approach from the west. Temperatures 5-
10 degrees above normal continue this weekend.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
High pressure over the terminals moves east of the DELMARVA
late this afternoon and then southeast tonight. A warm front
approaches from the southwest late tonight, toward 12Z.

VFR through the TAF period.

Light and variable wind will become WSW-SW 13Z to 16Z, less than
10KT. Winds become light and variable again this evening and into
the overnight.


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

Detailed information...including hourly TAF wind component fcsts
can be found at:
http://www.weather.gov/zny/n90

KJFK TAF Comments: no unscheduled amendments expected

KLGA TAF Comments: no unscheduled amendments expected

KEWR TAF Comments: no unscheduled amendments expected

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

KTEB TAF Comments: no unscheduled amendments expected

KHPN TAF Comments: no unscheduled amendments expected

KISP TAF Comments: no unscheduled amendments expected


.OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
.Tuesday...MVFR early in the morning, then becoming IFR with LIFR at
times. There is a chance of freezing rain across the Lower Hudson
Valley and into interior southwestern Connecticut from around 12Z
to around 15Z. A light coating of glaze is possible. Freezing
rain transitions to plain rain and continues through the day.
.Tuesday night-Wednesday...IFR or lower in rain. Conditions
improving late Wednesday.
.Wednesday night-Friday...VFR.

&&

.MARINE...
Forecast remains on track with light winds and seas generally 1-2
ft.

Winds and seas will remain below Small Craft Advisory criteria
through Monday night due to a relaxed pressure gradient over the
area.

Sub-SCA conditions are likely on the waters Tuesday into Tuesday
night with a weak pressure gradient. Winds on the ocean may
approach 20 kt on the ocean late Wednesday into Wednesday night as
low pressure gradually intensifies offshore. The low will slowly
move to the east Thursday into Friday. Ocean seas should stay
below SCA levels, but could approach 4 ft the end of the week.
Otherwise, a weak pressure gradient continues to bring Sub-SCA
winds on all waters for the end of the week.

&&

.HYDROLOGY...
No hydrologic impacts are anticipated with around a half inch of
precipitation late Tuesday through early Wednesday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...JMC/JM
NEAR TERM...MD
SHORT TERM...MD
LONG TERM...DS
AVIATION...MET
MARINE...MD/DS
HYDROLOGY...DS


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