-- Discussion containing changed information from previous version are highlighted. --
291
FXUS61 KOKX 130254
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1054 PM EDT Mon Apr 12 2021

.SYNOPSIS...
Low pressure weakens as it tracks along a stalled boundary to our
south and west tonight. High pressure then builds over the region
Tuesday and then offshore Tuesday night into Wednesday. Ridge axis
shifts to the east Wednesday into Thursday followed by a trough
and coastal low pressure system. System impacts southern New
York through the end of the work week. Another low pressure
system could impact our area early next week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Convergence running NW to SE has been evident for the past few
hours on radar as well as surface wind analysis. This trough of
convergence is expected to shift S and W over the next few
hours, bringing and end to rain by daybreak across the entire
forecast area. SE CT and eastern LI should be dry for the rest
of the night as high pressure ridges in and dries things out.
PoPs have been changed with this update to reflect this thinking
and the latest radar trends. Additional rainfall amounts
should be light with generally up to around a tenth of an inch.

Lows temperatures tonight will be near normal in the lower to
middle 40s.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Middle and upper level ridging builds over the northeast on
Tuesday. Surface high pressure will also build over the area in
the afternoon and evening. The main forecast challenge for
Tuesday revolves around the degree of stratocu, especially
across the eastern half of the region. Moisture looks to move
around the larger upper level low near the Canadian Maritimes
and could settle over eastern Connecticut and eastern Long
Island in the morning. Subsidence from the ridging aloft and
surface high building overhead should allow for some clearing in
the afternoon. Partly cloudy skies are expected for the western
half of the area through the day. While the latest forecast is
more on the optimistic side with clearing in the afternoon, it
is possible mostly cloudy skies persist through the day across
the eastern half of the area.

Near normal high temperatures in the upper 50s are forecast for
most locations with low 60s in the NYC metro, NE NJ, and Lower
Hudson Valley.

The ridge axis likely moves overhead Tuesday night with the
surface high settling to the south of the area. Skies should be
partly cloudy with some increasing high clouds from the west
late. Lows will be in the 40s for most locations.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Ridge axis shifts east Wednesday into Thursday. Main focus for
the long term is a developing shortwave trough over the
Southeast states as it interacts with the deep mid level low
north of the Great Lakes. As the low enters northern New York
Gulf moisture is pulled into the forecast area Thursday into
Friday. Complex dynamics begin as a southern low off the
DelMarVa coast deepens in response to a 100kt jet over the Mid-
Atlantic coast. This southern low drifts north into the waters
south of Long Island as it does isentropic showers begin as
early as Thursday morning. East winds during the day Thursday
should take on a more northeasterly component late Thursday into
Friday. This cold air advection works to enhance the upper
level jet to 130kts possible. This will allow the coastal low
located in the left exit region of the jet to deepen further and
possibly retrograde Friday as it interacts with the upper level
trough above the Tri-state area.

We`ll have to be mindful of possible heavy rain bands forming along
a secondary frontal zone across the forecast area Friday morning.
Precipitable water values around one inch support steady rain for a
36 hour period beginning Thursday night through early Saturday
morning. Rainfall totals between 1 to 2 inches can be expected.
Can not rule out the possibility of mixed precipitation for our
northern counties early Friday morning. Rain will be falling
through sub- freezing temperatures aloft until the last 50mb.
Surface temperatures are anticipated to be between 38-40 degrees
at that time so accumulations are not expected.

The low heads northeast off shore as winds die down throughout the
day on Saturday. Guidance is in good agreement with keeping most of
the day dry. Brief ridging then builds in aloft ahead of the next
feature. There are some model differences with this next feature as
the Canadian and Euro bring a shortwave on a more southerly track
than the GFS. In turn the Canadian and Euro bring a stronger surface
low to our southeast while the GFS brings a weaker low just
overhead. Went with slight chance PoPs starting Sunday afternoon as
both solutions bring precip to the area.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A trough of low pressure over the region shifts south this evening.

Mostly IFR/MVFR this evening, improving to VFR overnight.
Improvement to VFR occurs generally NE to SW. Showers this
evening end overnight near the time of VFR improvement. VFR on
Tuesday.

NE winds around 10kt back toward N overnight. Late day/early evening
synoptic flow/sea breeze hybrid shifts winds SE-S for the coastal
terminals.

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

Timing for flight category changes could be off by 1-2 hours,
particularly IFR conditions, which may prevail longer than
currently forecast.

.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY....
.Tuesday Night...VFR.
.Wednesday...VFR. A chance of MVFR late in the day with
showers.
.Thursday-Friday...MVFR to IFR with a chance of rain.
.Saturday...Improving to VFR through the day.

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

&&

.MARINE...
SCA conditions will continue on the ocean waters through
tonight. Wind gusts to around 25 kt are possible for the first
half of the night with winds generally around 20 kt during the
early Tuesday morning hours. Ocean seas will remain elevated due
to latest obs into Tuesday morning with 5 to 6 ft tonight and
then around 5 ft during the morning hours. Have extended the SCA
until 15z Tuesday. It appears seas should subside during the
remainder of Tuesday and Tuesday night with high pressure moving
over the waters. Otherwise, sub-SCA conditions are expected
through Tuesday night.

South east winds Wednesday increase to near SCA criteria
Thursday afternoon as a low pressure system nears the ocean
waters. Winds increase to 20 kts with gusts up to 30 kts
Thursday afternoon. Front passes Thursday night as winds become
more northerly to begin the weekend with wind gusts up to 25 kts
possible.

Winds may reach SCA criteria through Saturday afternoon. Winds and
waves are then expected to remain below SCA criteria through Monday.

&&

.HYDROLOGY...
Steady rain Thursday morning through late Friday night may bring
instances of heavy rain and nuisance flooding. Rainfall totals
between 1 to 2 inches are possible.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 11 AM EDT Tuesday for ANZ350-353-
     355.

&&

$$
SYNOPSIS...DJ/DS/JT
NEAR TERM...JC/DS
SHORT TERM...DS
LONG TERM...DJ/JT
AVIATION...JC
MARINE...DJ/DS/JT
HYDROLOGY...TM/DS/JT