Area Forecast Discussion
Issued by NWS Upton, NY

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406
FXUS61 KOKX 200857
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
357 AM EST Mon Jan 20 2020

.SYNOPSIS...
A Canadian high will builds towards the area today, and set up
over the area for most of the week. The high will begin to
retreat on Friday, with low pressure potentially impacting the
area over the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MSAS centered a 1043 high over nern SD at 8Z. The center of the
high will build to around Omaha by 00Z. The pressure across the
forecast area will build around 10mb today. A gradual decrease
in winds is expected as the gradient weakens. High temperatures
below freezing, with the NBM used. Wind chills in the single
digits and teens.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
Cold with single digits and teens for lows. A blend of the
guidance was used, which was much colder than the NBM. If winds
overperform, the forecast temperatures may be too cold. Most
likely spots for the winds to stay up are the north shore of
Long Island, New York City and close surrounds, and the
remaining immediate shorelines. Areas with snow cover over
CT and the Hudson Valley, along with the Pine Barrens of Long
Island, will be the most likely spots to decouple.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Quiet for much of the period with the influence of high pressure
until next weekend with a high moving farther northward and
approaching low pressure from the south.

For Tuesday and going through Thursday, an air mass from the
North Central US will be building into the region. Strong high
pressure builds in gradually from the west Tuesday through
Wednesday, moving overhead Wednesday night into Thursday. This
will make for light and variable winds with the very weak
pressure gradient. The high weakens Thursday night into Friday
allowing for more clouds to move into the region as subsidence
weakens.

Dry weather is expected through Friday. Next chances for precip
arrive Friday night with increasing chances of precip for next
weekend.

Next weekend, forecast has gusty E-NE flow and some potential heavy
precip. Track of low center moves near region, either directly over
the region or offshore. A lot of uncertainty with this event being a
week away especially with the speed and position of the low
center. Precip type will be highly dependent on track. Overall
looking at the ECMWF, GFS, and Canadian models, the center of
the low could track close enough to have some warming aloft. The
retreating high going farther northward signals some cold air
damming potential so with temperatures at 850mb getting
potentially a few degrees C above freezing, could have a wintry
mix Friday night into early Saturday changing to rain Saturday
from south to north. Depending on how the low evolves next
weekend, could have some wintry precip as well as Saturday night
into Sunday. Have this as a rain and snow mix across the
interior with a forecast of having the low move east of the area
with colder air working into the area on the backside of the
low.

Regarding temperatures, the air mass for Tuesday through
Wednesday will be from the North Central states. Winds will be
northerly but gradually decreasing as the center of the high
moves in closer to the local area. The decrease of northerly
winds will gradually lessen the cold air advection allowing for
the air mass to moderate by midweek. Conveyed a gradual warmup
for daytime highs each day Tuesday through Thursday going from
several degrees below normal to several degrees above normal.
There is more weight towards MOS for all temperatures Tuesday
through Tuesday night as well as Wednesday night and Thursday
night. The nighttime temperature use more MOS to convey
radiational cooling conditions with more vast range of lows
between NYC and rural sections.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
High pressure gradually builds to the west through tonight.

VFR.

NW winds around 15ktg20-25kt through this afternoon for NYC/NJ metro
terminals. Gusts will likely be occasional for outlying terminals
early this morning, but they should become frequent around 20 kt
once again by mid morning. The wind direction should average right
of 310 magnetic through the period. Winds and gusts subside for
the evening push.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.Late Tonight-Friday...VFR.

&&

.MARINE...
Advisory level winds will gradually diminish today. The ocean
will be the last place to fall below Small Craft Advisory levels
tonight. Wavewatch was running a little low on the ocean so was
adjusted up. Winds and seas then remain below advisory levels
for the entire area until Friday, when swell from approaching
low pressure could warrant an advisory on the ocean.

&&

.HYDROLOGY...
There is potential for widespread precip next weekend. Still it
is too soon to tell what exact hydrologic impacts there will be
due to uncertainty with precip types and amounts.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) is still
operating at reduced power.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ338-
     355.
     Small Craft Advisory until 10 AM EST this morning for ANZ330-
     335-340-345.
     Small Craft Advisory until 8 PM EST this evening for ANZ350-
     353.

&&

$$



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