000
FXUS61 KOKX 222014
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
414 PM EDT Sat Apr 22 2023
.SYNOPSIS...
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A warm front meanders near or over the area into this evening
before a cold front and frontal wave push across the region
tonight into Sunday. Another cold front passes through Sunday
night. Weak low pressure slowly moves farther north and east
early into mid next week while high pressure slowly approaches
but its center stays south and west of the area. One area of low
pressure passes offshore Thursday into Thursday night. High
pressure stays north of the area next Friday with potential for
another low to approach for next Saturday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A few widely scattered showers are possible through late this
afternoon, otherwise the region largely remains dry until this
evening just ahead of an advancing cold front. A corridor of
moisture transport ahead of the front via an increasing LLJ, as
well as enhanced lift with a wave of low pressure along the
front, results in a band of showers, and possibly a few embedded
thunderstorms, moving through the area late Saturday evening
and night. With the LLJ strengthening to around 40 to 50 kt
aloft (~1 kft) just ahead of the front, a few strong wind gusts
are possible tonight, especially with any convection.
SPC has a marginal severe risk to the western edge of the CWA, and
this appears reasonable given onshore flow. HRRR soundings do
indicate some lingering instability across New Jersey and the lower
Hudson Valley this evening, up to 500 J/kg of CAPE, above a weak
cap. Kept thunder probs at slight chance coverage for most of
the area for this evening except NE NJ and western Orange County,
with chance wording closer to the warm front and where the
highest instability will lie.
The greatest threat with the convection continues to be damaging
wind gusts, generally between 40 and 50 mph. A brief weak tornado
cannot be entirely ruled out, particularly in NE NJ (in line with
where SPC has a 2% tornado risk outlined). A Severe Tstorm Watch was
hoisted to our west for portions of eastern PA and western NJ,
though with a marginal environment, thinking our region largely
avoids any severe threat.
Timing of the main band looks to arrive between 8 to 10 pm for NE NJ
and the lower Hudson Valley, 10 pm to 12 am for NYC, and between 12
am and 4 am for Long Island and Southern Connecticut. The rain may
fall moderate, to locally heavy, at times as the line advances east.
Total rainfall should largely range between half an inch and an
inch, with a bit higher totals possible (up to 1.5") across
interior Connecticut and the lower Hudson Valley. Fortunately,
with recent dry conditions, the rain should be more beneficial
than anything else.
Maintained a slower progression of the front with blocking over the
North Atlantic and hi-res guidance advancing the boundary eastward
relatively slowly through the region overnight into the daytime on
Sunday. Largely followed a consensus of bias-corrected guidance
for this update.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
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While the bulk of the rain pushes east after daybreak Sunday,
given the slower progression of the front, the wet weather
likely lingers into the day Sunday across eastern Long Island
and SE CT, where enhancement from a frontal wave may allow
additional periods of moderate rain.
Winds lighten and veer westerly behind the first front Sunday
morning, with drying conditions and a bend to the NW expected
behind the secondary frontal wave Sunday evening as the trough
continues to advance east over the region.
In much of the area that dries out, the cyclonic flow will aid
scattered cloud cover development on Sunday. Temps on Sunday
should be similar to Saturday, with highs mainly in the 60s.
Another shortwave trough pivots through the area around an upper
low centered to the west late in the day, which should help
push a cold front through, with a chance of a few additional
showers, mainly for the interior, but cannot be ruled out
anywhere.-- End Changed Discussion --
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
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A mid level low hovering in Southeast Canada will result in a quasi
zonal mid level flow across the region through much of the week.
More of a ridging pattern shown by forecast models for Friday next
week in the mid levels but potential for the ridge to breakdown with
trough development to the south and west for next Saturday.
At the surface, low pressure slowly moves farther north and east of
the area early into midweek. Meanwhile, high pressure will slowly
approach but its center will stay to the south and west. The
pressure gradient will be not be that tight without much change in
the center magnitude of the high and low pressure areas so both the
high and low will not be that strong.
High pressure will weaken across the local area with low pressure
that is forecast to pass well south and east of the area Thursday
into Thursday night.
High pressure stays north of the region Friday with low pressure
possibly impacting the area from the south going into the start of
next weekend.
Weather conditions are forecast to be mainly dry but there could be
an isolated rain shower from time to time, mainly daytime into
evening, in response to periodic shortwave positive vorticity
advection early into midweek. The forcing towards late week will be
with one low pressure passing offshore and with another low at the
surface approaching towards next weekend. By next weekend, the
synoptic flow becomes more southerly ahead of a larger trough.
The forecast has higher chances of rain showers Thursday into
Thursday early evening and Friday afternoon into Friday early
evening as well as next Saturday.
There is a lot of model uncertainty, including significant
differences between the 12Z ECMWF deterministic and its previous run
with regards to the MSLP field for late next week.
Temperatures in the long term forecast do not exhibit much deviation
from normal values. Airmass appears to transition from more of a
continental airmass early in the week to more of a maritime one from
mid to late week. This will be as low level winds transition from
more westerly early in the week to more easterly thereafter.-- End Changed Discussion --
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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A warm front was located south of the NYC terminals at 20Z. A wave
of low pressure and cold front will then move across the area
tonight and into early Sunday morning.
Cigs have improved to VFR at most terminals though MVFR cigs have
now returned to KSWF and KISP. As the afternoon progresses, expect
conditions to lower back briefly to MVFR then IFR/IFR with showers
into this evening. A thunderstorm remains possible, but with low
confidence and isolated coverage especially north and west of NYC,
have kept it out of the TAFs except at EWR and TEB from 01-04Z.
Conditions begin to improve at the western/city terminals toward 10-
12Z Sunday with a cold front passage and at the coastal terminals
after 15Z.
E/SE winds have been occasionally gusting this afternoon for the
western terminals but have been more persistent at the coastal
terminals. Gusts will continue through early evening. As low
pressure moves into the region winds become light and variable late
tonight, and then become westerly 10kt or less. LLWS likely 00Z to
around 05Z, and as late as 09Z at KGON.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments for timing of flight category changes to IFR by 00Z
Sunday are possible. An isolated thunderstorm will be possible 00Z
to 05Z Sunday, and mainly at KEWR and KTEB.
LLWS, 15045kt, mainly from 00Z to 05Z may continue an hour or two
later.
OUTLOOK FOR 12Z SUNDAY THROUGH THURSDAY...
Sunday: MVFR to IFR with showers early, improving to VFR around 15Z
at the NYC metros, remaining IFR to MVFR to the east until midday,
then improving to VFR.
Monday and Tuesday: VFR. W-NW winds G15-20 kt.
Wednesday: VFR.
Thursday: MVFR or lower in showers.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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A few gusts on the LI Sound may exceed 25 kt into early this
evening before lowering below SCA criteria.
Meanwhile, SCA conds expand to all ocean waters and continue on
the eastern LI Sound this evening ahead of an approaching cold
front and wave of low pressure. Seas come up to around 5 ft on
the ocean waters during this time.
Patchy fog, possibly locally dense, may develop on the waters
tonight ahead of a period of rain along a frontal boundary.
Winds subside behind the frontal passage overnight, but ocean
seas remain elevated near 5 feet into the daytime Sunday and
possibly Sunday night.
With the pressure gradient forecast to remain weak overall Monday
through Thursday night next week, conditions on all waters are
expected to remain below small craft advisory thresholds.-- End Changed Discussion --
&&
.HYDROLOGY...
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No hydrologic impacts are expected through the weekend. A frontal
system could bring 0.75" to 1.25" rainfall tonight into Sunday
morning, with locally higher amounts of up to 1.50" possible
across parts of S CT. Nuisance flooding of urban and poor
drainage areas is the most likely outcome due to antecedent dry
conditions.
No hydrologic problems are expected in the long term period
(Monday through Saturday) at this time.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
Minor coastal flooding may be possible with tonight`s high tide
cycle tonight along the south shore bays of Nassau County. A
statement or advy will be issued to address this.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...Coastal Flood Advisory from 9 PM this evening to 1 AM EDT
Sunday for NYZ179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ331-
335.
Small Craft Advisory until 6 AM EDT Sunday for ANZ332.
Small Craft Advisory until midnight EDT Sunday night for
ANZ350.
Small Craft Advisory until midnight EDT Sunday night for
ANZ353.
Small Craft Advisory until 6 AM EDT Sunday for ANZ355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JM/DR
NEAR TERM...DR
SHORT TERM...DR
LONG TERM...JM
AVIATION...DBR
MARINE...DBR/DR
HYDROLOGY...DBR/DR
TIDES/COASTAL FLOODING...