discussion on 2024-02-22

000
FXUS61 KOKX 221841
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
141 PM EST Thu Feb 22 2024

.SYNOPSIS...
-- Changed Discussion --A frontal system and associated low pressure approaches late
this afternoon into tonight, and will move across the area on
Friday. High pressure builds in for the start of the weekend and
remains in control through Sunday. A warm front passes through
Sunday night, followed by a weak cold front Monday. Another warm
front approaches Tuesday and Tuesday night, then passes through
on Wednesday.-- End Changed Discussion --

&&

.NEAR TERM /THROUGH FRIDAY/...
-- Changed Discussion --Clouds have thinned out across much of the area, but more cloud
cover moves in from aloft and eventually lower down towards
later in the afternoon. Western areas see the lower level clouds
advecting in from Central PA out of the WSW sooner. For this
update only change was to bump up cloud cover slightly for the
late afternoon, especially further west. Also bumped up PoPs
slightly for the very late afternoon and start of the evening
for western / northwestern most areas based on latest trends.
Previous discussion follows.

High pressure that was nosing in from the northeast continues to
weaken into this afternoon as an offshore low nudges the high
pressure centered northeast of the Canadian Maritimes out into
the far north Atlantic. At the same time, a low pressure system
along a front in the Ohio Valley will approach the area,
increasing broken to overcast cloud cover west to east
throughout the day. Ahead of the frontal system, onshore flow
will lead to warmer temperatures with highs in the middle to
lower 40s this afternoon.

This evening the first wave of rain from the frontal system
should arrive, overspreading across the area from west to east.
This frontal system arrives with a mid-level shortwave which
could provide waves of mid-level energy to bring more consistent
rainfall. Despite this, forcing does not look particularly
strong, so it will likely be light precipitation at the onset.
Some light snow or a rain-snow mix is possible Thursday evening
and early Thursday night for areas in the interior portions of
Connecticut and the Lower Hudson Valley. Some brief sleet or
freezing rain may also be possible. The impact from this is
expected to be low as warm air advection from a warm front ahead
to the approaching low will lead to temperatures warming both
at the surface and in the low-mid levels late Thursday night. In
addition, surface temperatures will only briefly reach touch
freezing in interior sections before rising, based on the latest
model guidance.

Based on CAMs, it looks like the main shield of precipitation
ahead of the approaching low late Thursday night into early
Friday will fall along northern portions of the CWA with
intermittent rain for southern portions of the CWA during this
time. Rain will pick up again midday Friday into the afternoon
as the low passes with a frontal boundary by late
afternoon/early evening. The forcing from this boundary should
lead to widespread light rain across the area during midday to
afternoon Friday. Rain will clear west to east with the exit of
the system late Friday afternoon/early evening.

Event QPF is currently forecasted to be between 0.25 to 0.35 inches.
Higher totals are possible for northern and eastern areas. 00Z HREF
shows probabilities for >=0.5" around 50% for Long Island, S CT and
the Lower Hudson Valley. This drops down to 0% for >=0.75" for most
of the area with only a 15-25% probability in the interior sections
of the Lower Hudson Valley. PWATs during the event max out midday
Friday around 0.7-0.8" which lies around the 90th percentile per
SPC`s Sounding Climatology page.

Its also worth noting, highs on Friday with be in the middle to
upper 40s with areas of NE NJ topping off around 50 degrees
thanks to warm air advection from the warm front.-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
A secondary cold front arrives Friday night behind the exiting
system reinforcing cold, dry air in the region. This leads to
decreasing clouds through Friday night with lows in the low-30s to
mid-20s. Following the frontal passage, breezy northwest winds are
expected throughout Friday night and much of Saturday before
gradually easing Saturday evening, becoming light by Sunday morning.

Cold dry air behind the front with high pressure building back into
the area and a deep trough aloft will lead to sunny skies and highs
in the mid/low-30s Saturday afternoon, lows in the mid-teens to low-
20s Saturday night.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
High pressure over the area shifts offshore Sunday afternoon. Winds
shift SW with a warming trend through the rest of the long term
forecast period. Highs on Sunday close to normal at mostly 40-45. A
warm front passes through Sunday night. Moisture is limited, but
combined with isentropic lift, slight chances of a rain/snow mix
north of the city. Thermal profiles are marginally cold enough for
the potential for all snow, but in any case, overall chances for
precip are low with very little liquid equivalent potential. A weak
cold front follows during Monday. High temperatures still manage to
reach the upper 40s to lower 50s in spite of this.

Low pressure over the Northern Plains on Tuesday shifts east,
reaching the Great Lakes Region on Wednesday as it gains some
strength. An associated warm front will approach us on Tuesday.
Overrunning light rainfall may occur during the day. PoPs capped at
chance for this period. Given the progged position and strength of
the parent low center and low level jet development/strength, not
expecting this warm front to move through the area during Tuesday
night as it is not climatologically favored this time of the year.
Isentropic lift and moisture will both increase however, and rain
becomes likely across the area Tuesday night. Better chances for the
warm front to push north through the forecast area during Wednesday,
but this is still not a given. Would like to see better agreement of
the low in the Great Lakes being progged stronger and farther east
to have more confidence. For now, will go with the idea that it
shifts through during the day with a transition of rain to a chance
of showers. Temperatures above normal for both Tuesday and
Wednesday.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
High pressure weakens into tonight as low pressure approaches.
The low passes through during Friday.

MVFR ceilings remain early this afternoon, and timing of
improvement to VFR may be later than forecast, with low
confidence. Once VFR conditions develop VFR remains into early
evening before flight categories lower with rain. Mostly MVFR
late evening and overnight with a chance of IFR developing
toward Friday morning. IFR is more likely north of the city this
evening and overnight.

Southerly winds around 10kt or less, become light and variable
this evening outside of the NYC metro terminals. As low pressure
moves through the terminals winds will switch to the SW and W
Friday morning, before becoming NW late in the forecast.

Timing of wind shifts is low confidence and dependent on the
track of low pressure across the terminals.


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

Lingering MVFR ceilings are expected to improve early this
afternoon, however, timing is uncertain, as MVFR may continue an
hour or two longer.

MVFR may redevelop earlier this evening than forecast.

OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday afternoon: VFR at the NYC terminals and west. IFR/MVFR
in rain east of the NYC terminals with rain ending and
improving to VFR late in the day.

Friday night - Saturday: VFR. NW winds G15-20kt.

Sunday - Monday: VFR.

Tuesday: VFR in the morning, becoming MVFR with a chance of
rain in the afternoon.

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

&&

.MARINE...
-- Changed Discussion --Small craft conditions are now in place on the ocean waters due
to increasing seas as a SE swell increases to around 10-11
second period this afternoon. Small craft seas are likely to
last through the remainder of the week. The winds will be mainly
out of the SE and S late today and tonight as high pressure
departs and low pressure approaches the waters. The winds will
switch around to the NW by Friday evening falling short of small
craft gusts until Friday night.

5-6 foot seas from a southeasterly swell will likely be ongoing at
the start of Friday night. At the same time, low pressure will be
exiting the area and a northwest wind will be increasing, likely
reaching 25 kt gusts late Friday night and dropping below SCA
criteria gusts midday Saturday.

With the exception of seas lingering above 5 ft at times on the
eastern ocean waters, Sunday will feature sub-advisory conditions.
Winds pick up Sunday night and subside on Monday, but will be strong
enough with some swell to build ocean seas to advisory levels Sunday
night and maintain elevated seas through at least during the daytime
Monday.-- End Changed Discussion --

&&

.HYDROLOGY...
No hydrologic impacts are expected throughout the entire forecast
period.

&&

.TIDES/COASTAL FLOODING...
With the approach of a full moon tides with be running high with the
astronomical component increasing, particularly for Friday morning.
However, at this time total water levels are expected to fall short
of minor coastal flood benchmarks. Minor benchmarks will be
approached for the south shore back bays of Nassau County for the
Friday morning high tide cycle, but at this time coastal flood
advisories / statements do not appear to be needed.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 7 PM EST Friday for ANZ350-353-355.

&&

$$

SYNOPSIS...JC/BR
NEAR TERM...JE/BR
SHORT TERM...BR
LONG TERM...JC
AVIATION...MET
MARINE...JC/JE/BR
HYDROLOGY...JC/BR
TIDES/COASTAL FLOODING...