000
FXUS61 KOKX 202343
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
743 PM EDT Wed Mar 20 2024

.SYNOPSIS...
-- Changed Discussion --
A cold front to the east tonight. Low pressure moves from
Northern New England into the Canadian Maritimes tonight into
Thursday. High pressure will be in control Thursday night into
Friday. High pressure pushes offshore late Friday with low
pressure and its inverted trough impacting the area Saturday
into Saturday night. High pressure ridges down from the north
Sunday into Monday as low pressure slowly pushes further
offshore. A frontal system approaches from the west midweek.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
The mid level trough and vort max exit late this evening. The
increase in negative vorticity advection will shut off rain and
snow shower activity.

Central low pressure will stay north of the region and deepen
as it is expected to move into Northern New England overnight.
The increase and steepening of the pressure gradient will drive
an increasing NW flow, increasing cold and dry air advection. A
noticeable temperature drop has occurred across the area already.
Get used to the wind and the blustery conditions as wind chill
readings fall through tonight.

Slowed down the decrease of clouds initially for the evening
compared to what the models are conveying as there will be
cyclonic flow aloft which tends to have more clouds on average
via frictional converge / Ekman spiral, etc. Used a blend of
NBM and MOS consensus for lows tonight, ranging from the upper
teens and low 20s across parts of the interior to upper 20s to
near 30 for much of the coastal areas.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Mid level ridging and negative vorticity advection on Thursday will
allow for more subsidence. Expect dry conditions with lessening
cloud coverage. The airmass over the area for Thursday and
Thursday night will be very cold for this time of year so below
normal temperatures are expected. Forecast highs and lows will
be near 5 to 10 degrees below normal.

At the surface, central low pressure will be nearly the same
strength as it moves towards and eventually into the Canadian
Maritimes Thursday into Thursday evening. High pressure will
gradually build in from the north and west but its center will be
staying more within the Great Lakes region.

Gusty NW winds will continue during the day Thursday and then
subside Thursday night with high pressure having more influence
across the area.

High temperatures forecast Thursday followed closely with the
combination of consensus of MOS and NBM, ranging from upper 30s
to near 40 across much of the interior to lower 40s along the
coastline. However, with the wind, the wind chills will be at
most in the upper 20s to mid 30s Thursday afternoon.

The lows forecast Thursday followed closely to the same blend
of guidance, with the whole area expected to be below freezing.
The range of lows is from upper teens to near 20 across much of
the interior to mid to upper 20s along much of the coast.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Dry conditions take place to begin the period on Friday with a
strong confluence zone beginning to push out. High pressure settles
over and just north of the area early in the day. The high will then
get further east later in the day and for the evening. This is when
clouds begin to streak in from the west at first from a primary low
which starts to weaken as it moves east. Another area of low
pressure gets organized along the southeastern US coast. This will
very slowly lift northeast Friday night into Saturday. More
importantly an trough will emanate from the low in a south to north
fashion. The eastern edge of this feature will serve as the moisture
track per say for the low down to the south. The winds aloft will be
more out of the south and that should pool moisture along the trough
and lift the lower latitude air and rain into the CWA. Figure the
rain will start after 06z Friday night, and probably closer to 9z or
so for most areas, and closer to 12z Saturday for far eastern
sections. The likelihood of northern sections beginning as a mix or
wet snow has decreased a bit with the last couple of runs. By mid
morning Saturday the steadiest / heaviest rain should get into the
region, from NYC and points east. There appears to be fairly good
agreement now that the trough leans east going through the day which
should get the axis of heavier rain further east. Such that by late
in the day and into the evening much of the rain will be light for
western sections (mainly west of the Hudson River and the city),
with the steadier rain shifting into far eastern sections during
Saturday evening. From 6Z to 12z Sunday there is a chance that the
rain shuts off, or at least tapers significantly across eastern
sections as the moisture axis shifts offshore. The new ECMWF
supports this thinking. The German ICON appears to be the model that
is an outlier as it closes the low off closer to the coast, and thus
keeps significant rain across much of the CWA through much of
Saturday night. If this solution occurred then there would likely be
flooding concerns into NE NJ, the lower Hudson Valley, and NYC where
flash flood guidance is lower, compared to the higher flash flood
guidance and sandier soils across eastern most sections. WPC
maintains the Marginal risk of excessive rainfall for the majority
of the CWA (with the exception being portions of Orange and Putnam
counties) and a Slight risk to the immediate south for Central and
Southern NJ. Collaborated with WPC and thought it prudent to
maintain the current excessive rainfall outlook. However, if things
shift just a little bit west with NWP guidance and that axis of
heavier rainfall then the excessive rainfall / river flood risk
would increase where the lower FFG is. Thinking a 1 to 2 inch
rainfall, with amounts generally increasing from west-northwest to
east-southeast. See Hydrology sections for further details.

Sunday through Monday remains a difficult forecast. The models
continue to handle the mid / upper level feature differently in terms
of the details. The difficulty lies in forecasting PoPs and how much
shower activity will be left over with the low as it attempts to
close off and be more of a drifter and non-progressive. It could
remain predominantly dry and mostly cloudy. Maintained a good deal
of clouds through Sunday with a chance to slight chance of showers.
Some guidance also hints at showers attempting to linger for a
portion of Sunday night into early Mon AM, more so for eastern
sections. This is where low end chance to slight chance PoPs are
maintained for now. Due to the pressure gradient remaining tight
with high pressure building across Southern Canada and offshore low
pressure look for brisk conditions, and windy conditions for eastern
coastal sections.

The upper level ridge axis draws closer Monday into Tuesday. This
should lead to a decrease in clouds and more in the way of sun
potentially by Monday afternoon. This will depend on how far west
any influence of the offshore / upper low low gets. The northeast
wind will continue to be felt. The winds decrease gradually over
time and should be noticeably less into Tue PM. The next frontal
system will approach late Tue night or Wed. With the upper level
height field increasing into Tue this may delay the next system from
getting any closer until Wed as differences in timing show up in the
various NWP suites. Night time temperatures through the period
should average close to normal, with daytime temperatures likely
remaining a few degrees below normal.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure builds in from the northwest tonight through
Thursday as deep low pressure tracks through northern New
England and into southeastern Canada.

VFR.

A few rain and snow showers possible through 03Z with brief
MVFR conditions, manly outside of the NYC metro area.

Gusty W/NW winds overnight with the highest winds and gusts
through 06Z. Winds and gusts then diminish, and then increase
again during the day Thursday, 13Z to 14Z, and a few peak gusts
may be around 40 kt during the morning. Winds and gusts will be
diminishing after 18Z Thursday.


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

Gusts 30kt+ may end a few hours before 06z, and a chance that
gusts from approx 23-06z are more frequently around 5kt lower
than forecast.

OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...

Thursday night: VFR. WNW gusts 25-30kt, diminishing and ending
around 02Z Friday.

Friday: VFR.

Friday night: MVFR or lower developing after midnight with rain near
the coast and rain/snow inland.

Saturday: IFR and rain. SE wind gusts 20-25kt during the day with
LLWS possible city east, becoming N all areas with gusts 30-35kt at
night.

Sunday: VFR. A slight chance of rain. N-NE wind gusts around 25kt.

Monday: VFR. NE gusts 20-25kt.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
The pressure gradient tightens tonight with gales hoisted for
all waters. Associated low pressure will strengthen as it heads
into Northern New England overnight and then will remain nearly
the same strength as it moves into the Canadian Maritimes
Thursday. The gales continue into Thursday morning for most of
the waters before winds decrease more into SCA range Thursday
afternoon into Thursday night.

A relaxed pressure gradient will result in quieter conditions to
begin Friday, however an onshore flow increases late in the day and
into Friday night. Small craft conditions will develop by Saturday
morning out on the ocean, and by the afternoon for the eastern
nearshore waters. A prolonged period of gales is looking likely late
Saturday night and through at least the first half of Monday for
much of the coastal waters. This period of gales may last longer and
into Monday night, especially out on the ocean and eastern most near
shore waters.
-- End Changed Discussion --

&&

.HYDROLOGY...
Total precipitation of less than a quarter inch through tonight
(mostly in the form of rain) will not present any hydrologic
issues.

Rain on the order of 1 to 2 inches on average is expected late
Friday night through Saturday, and into a portion of Saturday night
mainly for eastern sections. Some minor nuisance urban flooding is
expected where the axis of heavier rain sets up. Flash flood
guidance has recovered some over the past week from previous rain
events, but there remains some elevated pockets of soil moisture.
However, the coverage of elevated soil moisture has decreased. As of
now the axis of steadier, heavier rainfall would be over the eastern
half of the area where flash flood guidance is relatively higher,
but if this axis shifts further west where flash flood guidance is
lower then at least minor river flooding would be brought into play
for NE NJ and perhaps even the Lower Hudson Valley. WPC maintains
the Marginal risk of excessive rainfall across the majority of the
CWA, but overall the flood risk remains limited at this time.
However confidence remains lower than ideal, thus this could change
in subsequent forecast releases.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Gale Warning until 10 AM EDT Thursday for ANZ331-332-335-340-
     345.
     Gale Warning until 6 AM EDT Thursday for ANZ338.
     Gale Warning until noon EDT Thursday for ANZ350-353-355.
-- End Changed Discussion --

&&

$$

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