000
FXUS61 KOKX 231240
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
740 AM EST Sat Jan 23 2021

.SYNOPSIS...
High pressure builds in from the west today. This high
weakens on Sunday night and Monday and moves offshore as low
pressure approaches. The low passes south of the area Monday night
into Tuesday night. High pressure returns Wednesday through Friday.
Another low may move south of the region Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast is on track this morning with some minor edits to
dewpoints and cloud cover to better reflect current
observational trends. Added in chance of snow flurries across
parts of Southern Connecticut after noting latest Doppler radar
reflectivity trends.

A weak surface trough has passed through the area this morning with
cold high pressure building in from the OH Valley.  Cold, dry air
advection has commenced, with temperatures in the lower 20s and
dewpoints in the single digits entering the northwest portions of
the CWA. Cloud cover via latest GOES-16 nighttime microphysics
product is moving out of the interior, Long Island and southern
CT at this hour.

An upper trough axis rotates through later this afternoon,
associated with an upper low centered over southern Quebec. This
feature, combined with the approaching high pressure, will result in
a decent pressure gradient across the area through this afternoon.
Gusty NW winds are expected through the day and into the evening,
gusting 30-35 mph.

For this morning, there is mostly scattered cloud coverage with
some broken cloud coverage across portions of the region. There
are some snow flurries across parts of Southern Connecticut.

Otherwise, skies should remain mostly sunny through the day
save for any midlevel stratocumulus during the afternoon that
advects in from the northwest. High temperatures will struggle
to get into the upper 20s to low 30s, with wind chills in the
upper teens today under the brisk northwest flow.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
High pressure continues to build in from the west Saturday night
into Sunday morning with dry conditions in store.  Low temperatures
Sunday morning will be quite cold, in the low teens to near 20
across NYC and western Long Island, under mostly clear skies. Winds
should stay up into Sunday morning, which may temper lows a bit.
Wind chills will be in the single digits to the low teens. For now
went with NBM temperatures, and adjusted toward lower MOS
values, especially across the interior and SW CT.

The gusty NW winds will continue overnight Saturday and into the day
on Sunday, though less so than on Saturday, 20-25 mph and finally
beginning to taper by Sunday evening. Highs on Sunday will moderate
somewhat into the lower and middle 30s, closer to normal for this
time of year.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Progressive flow will dominate across the country with near
zonal flow. A shortwave moves into the ridge through Monday,
reaching the Ohio Valley by 00Z Tuesday. This shortwave passes
through the area during Tuesday. Guidance has come into better
consensus with the track of the upper ridge and the track and
depth of the surface low. There still is some uncertainty with
the track and how the system will interact with the northern
stream broad longwave trough. The trend has been for a more
northern track. At this time the column will remain cold enough
for an all light snow event. However, if the northern stream is
weaker the storm may track farther north and mixing will be
possible along the coast. And if the blocking remains in place
with a stronger northern stream, the low will track farther to
the south. At this time the precipitation begins Monday evening
and continues into early Tuesday evening, with a prolonged
period of light snow. Another low does begin to develop off the
mid Atlantic coast early Tuesday, and with the progressive flow
moves quickly east into the Atlantic. Again, on the current
track the potential for higher impacts will be across areas
north and west, with lower impacts to areas east of New York
City, and portions of southeastern Connecticut, as high pressure
remains to the north.

High pressure and a building upper ridge return for Wednesday.
Then another southern system quickly moves into the ridge
Wednesday night into Thursday, with the potential for another
surface low tracking south of the area. Then high pressure
returns for Friday.

&&

.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
High pressure will gradually build in from the west while
strong low pressure remains in the Canadian Maritimes through
the TAF period.

This will set up a steep pressure gradient with gusty NW winds.
Conditions are expected to remain VFR through the TAF period.

NW winds will be 15-20 kt this morning with gusts reaching near
25-30 kt late this morning into this afternoon. Some peak gusts
between 30 and 35 kt can be expected this afternoon into early
this evening. Gusts will lower to more within the 20-25 kt
range late this evening and overnight. These gusts will persist
into early Sunday.

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

Timing of 30 kt gusts could be off by a few hours.

.OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
.Sunday...VFR. WNW gusts 20-25 kt during the day, near 20kt for
Sunday evening, gradually diminishing late evening into overnight.
.Monday...Mainly VFR, but MVFR/IFR developing by Monday evening into
Monday night with increasing chances of snow. NW-N under 10 kt.
.Tuesday...IFR, at times possibly lower, in snow, mainly during the
day, with NE winds 10-12 kt with gusts up to near 20 kt. Improving
conditions at night with gusts diminishing.
.Wednesday...VFR. N winds 5-10 kt.

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

&&

.MARINE...
High pressure is in control with strong NW flow through Sunday.
Gales will persist across the ocean waters, the Eastern Sound
and Peconic and Gardiners Bays today into Sunday. Elsewhere, SCA
are forecast through Sunday. There is a chance of light
freezing spray across the ocean waters and western LI Sound for
a period late Saturday night into early Sunday, given the
combination of subfreezing air temperatures, strong winds and
wave action over these areas. Warm sea surface temperatures may
mitigate this to be more scattered in nature across the waters.

Winds and ocean seas will be gradually diminishing below SCA levels
by Monday morning as the pressure gradient weakens.

Sub SCA conditions are expected Monday through Tuesday. Ocean seas 5
to 6 feet will be possible Tuesday night into Wednesday, with
marginal wind gusts, as northerly winds increase behind departing
low pressure.

Small craft conditions will once again be possible on the ocean
waters Thursday as winds and seas increase with a low that is
expected to pass south of the waters.

&&

.HYDROLOGY...
Mainly dry conditions are expected through the weekend. No
hydrologic concerns are anticipated through next week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 11 AM EST Sunday for ANZ335-338-345.
     Gale Warning until 7 AM EST Sunday for ANZ330-340-350-353-355.

&&

$$
SYNOPSIS...DBR/MET
NEAR TERM...JM/DBR
SHORT TERM...DBR
LONG TERM...DBR/MET
AVIATION...JM
MARINE...DBR/MET
HYDROLOGY...DBR/MET

NWS OKX Office Area Forecast Discussion