Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 210901

Area Forecast Discussion
National Weather Service New York NY
401 AM EST Thu Jan 21 2021

A series of cold fronts will move across the region going into the
start of the weekend. Strong high pressure will start to build
in from the west on Saturday. It will continue to build in
across the region for the rest of the weekend and into Monday
while gradually weakening. Low pressure approaches the area
early next week followed by high pressure building back in by


Upper level low moves east within Southeast Canada. Along the
southern periphery of the low, some embedded areas of positive
vorticity advection along weak shortwaves will be moving across.

Noting an increase in forecast reflectivity from the HRRR mostly
north of the region for late this morning into this afternoon,
added in slight chance POPs for rain and snow showers and
chances of rain sprinkles or snow flurries. Much of the time is
expected to remain dry.

Otherwise, expect an increase in clouds late this morning into
the afternoon and boundary layer SW winds increasing. Forecast
highs range from the upper 30s across the interior to lower 40s
along the coast and NYC. There will be a little warm air
advection ahead of the cold front for today, resulting in a
slightly warmer day compared to yesterday.


Synoptic pattern aloft remains nearly constant tonight through
early Saturday with periodic shortwaves and associated positive
vorticity advection. These will be periodically passing through
the region along the southern periphery of an upper level low.
At the surface, a cold front moves across tonight, to be
followed by another cold front for Friday night. High pressure
then strengthens to the west of the region going into this
weekend. The high gets more into the local region for the second
half of this weekend. There will be a tightening pressure
gradient going into this weekend, making for very breezy
conditions especially Friday night into Saturday with some
strong cold air advection set to occur.

The weather will be mainly dry but an occasional snow shower or
snow flurry will be possible Friday into Friday night in
association with the second cold front. Dry conditions are
forecast for the weekend with highs barely making the freezing
mark for Saturday and wind chills mainly in the teens for
Saturday and low to mid 30s for Sunday with wind chills mostly
in the teens to lower 20s.


A shortwave over the Plains forces a surface low pressure to
develop. There is still significant discrepancy in where and
when this low pressure forms and its eventual track as it
approaches the East Coast. Models had been sliding the system
off to the south of our area, but the latest ECMWF shifted
north, developing a surface low pressure over Ohio and then
moving east into the area. As a result, have increased the PoPs
into the late Monday through Tuesday timeframe to denote the
potential for some precipitation to move into the area. If this
is the case, it would likely be mostly snow given how cold the
airmass ahead of it is. This system is still more than 5 days
out so there are still large uncertainties... it`s just the next
thing to keep an eye on.

Thereafter, it looks like another strong and cold high pressure
system moves in after the low pressure moves out of the area to
the east by mid-week.


A warm front moves north of the terminals today, followed by a cold
this evening.

VFR through the TAF period.

Light and variable winds are expected early this morning, but
increase after sunrise and quickly shift to the SW. Speeds will
generally be 10-15 kt. Gusts to near 20 kt are expected late morning
and afternoon. We lose the gusts this evening, with speeds
remaining around 10kt.

     NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

The timing of wind gusts this morning may be off by an hour or two.

.Thursday night...VFR. W winds sustained around 10kt.
.Friday...VFR. W gusts around 20kt.
.Saturday...VFR. NW gusts 25-30kt.
.Sunday...VFR. NW gusts around 20kt.
.MONDAY...Mainly VFR, except MVFR possible in light snow late.

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


Winds and seas will increase to SCA levels this morning and remain
up through the end of the week and into the weekend. As a result, a
small craft advisory is in effect today for the ocean waters. The
SCA will run through Friday.

For the non-ocean waters, gusts to 25 kt will be likely on
the south shore bays, eastern sound and Peconic and Gardiners Bays.
Therefore, small craft advisories are in effect today. Gusts will be
marginal on the western sound and Harbor, and have elected not to
put up SCAs for those areas. Conditions on the non-ocean waters fall
below SCA criteria tonight.

Strong winds continue through the weekend with all waters
firmly in SCA criteria. It`s likely that at least the ocean
waters meet the Gale Warning threshold with more marginal winds
on the sheltered waters from Saturday morning through Sunday
morning. Thereafter, SCA conditions linger on the ocean through
Monday morning. A sub-SCA lull in the winds and waves may occur
early Monday through early Tuesday before winds and waves
increase again to SCA criteria as a low pressure moves by
somewhere near the area.


No hydrologic concerns are anticipated through the beginning of
next week.


MARINE...Small Craft Advisory from 10 AM this morning to 6 PM EST this
     evening for ANZ330-340-345.
     Small Craft Advisory until 6 PM EST Friday for ANZ353-355.
     Small Craft Advisory until 6 PM EST Friday for ANZ350.


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