-- Discussion containing changed information from previous version are highlighted. --
498
FXUS61 KOKX 291951
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
351 PM EDT Mon Apr 29 2024

.SYNOPSIS...
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A back door cold front moves through the region this evening,
and becomes nearly stationary into Tuesday. A couple of frontal
waves then move through the area Tuesday night and Wednesday.
Weak high pressure settles across Thursday, followed potentially
by a back door cold front on Friday. A weakening frontal system
approaches for the second half of the weekend, followed by high
pressure building early next week.
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&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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A back door cold front was moving through Cape Cod and into
Rhode Island and into portions of southeastern Connecticut late
this afternoon, and will push through the region by this
evening. Meanwhile sea breeze boundaries were moving northward
across Long Island Sound, southern Connecticut and into
northeastern New Jersey. A few showers have developed across
the lower Hudson Valley and into northeastern New Jersey where
surface based CAPE was up to 1000 J/kg, and mixed layer was
around 500 J/kg, and also where surface based instability has
become maximized. CAMs continue to show scattered showers and
thunderstorms into this evening. Then will keep chance/slight
chance probabilities tonight as some shortwave energy moves into
the upper ridge. Chances of precipitation will be limited by
the upper ridge in the vicinity with dry upper levels and
subsidence. Also, with an east to southeast flow a low level
inversion will set up. Low level clouds develop in the wake of
the back door cold front under the low level inversion.
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&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
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A nearly stationary boundary is expected to remain to the west
and southwest of the region, possibly moving slightly northward
as a warm front later Tuesday, and then shift northward as
developing wave along the boundary track through the coastal
areas Tuesday night and Wednesday. An east to southeast flow
behind the back door front will persist Tuesday through
Wednesday, keeping a maritime airmass across the region. After
well above normal temperatures Monday, temperatures will be
closer to seasonal normals Tuesday through Wednesday. The area
will be capped, and there is little to no elevated CAPE so will
not mention any chances of thunder.
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&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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An uncertain long term period in terms of the details, especially
with respect to the behavior of a back door cold front late this
week, along with the timing of a weakening frontal system towards
the second half of the weekend.

With respect to the beginning of the period for Thursday and Friday
look for mainly dry conditions. A warm front lifts north of the area
Wed night into Thursday. After seasonable temperatures Wednesday
night, temperatures should be able to get above normal once again
during Thursday as 850 mb temps attempt to climb above 10 C once
again as heights build. With a weak pressure gradient in place an
onshore flow will attempt to develop during the day. This will make
the temperatures forecast difficult, especially closer to the coast.
Went above NBM for the most part with respect to temps, especially
further inland where the effects of any light onshore flow out of
the SE would be minimized. Towards Friday much of the guidance is
now pointing towards the warm front that lift north of the area to
become stationary, then settle south as a cold front from the north
and northeast as high pressure along the Eastern Canadian coast
attempts to build south. This will likely aid in the cold front
getting driven further south and into the area Friday. For now have
kept PoPs minimal across northeastern portions of the CWA late
Thursday and into Friday, although a few sprinkles or light showers
cannot be ruled out but any moisture from the boundary should be
rather shallow. Temperatures overall into Friday should average a
bit closer to normal, with warmer temperatures further south and
west and cooler temperatures further north and east.

For the weekend the global guidance has gradually slowed the
progression of a weakening frontal boundary. This is mainly because
heights attempt to rise again across the area and this will make any
eastward progression of showers ahead of the cold front more
difficult. Have introduced slight chance and chance showers for the
day Saturday, but model trends and latest consensus pointing to
Saturday remaining predominantly dry. Thus, Saturday night into
Sunday appears to be the time frame for relatively higher chance
PoPs as the boundary slowly pushes into the region. Look for more in
the way of clouds, but a washout of the second half of the weekend
is looking less likely at this time as the upper level ridge over
the areas doesn`t really break down until the day on Sunday. Will
continue the shower chances through Sunday night, with PoPs
decreasing into Monday AM. High pressure should build behind the
weakened boundary later Monday and into Tuesday of next week. Warmer
temperatures may return on Monday as 850 mb temps warm once again.
This far out sfc winds are always in question this time of year, but
the guidance consensus is suggestive of a SW flow which would get a
large majority of the area above NBM guidance. For now have went
warmer than the NBM guidance for Monday as clouds should begin to
break.
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&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
A back door cold front approaches this afternoon and moves
through this evening.

VFR through at least 01-03z for most spots before lowering to IFR
soon thereafter. A few showers are possible late this afternoon and
early this evening and an isolated shower or thunderstorm cannot be
ruled out. Have VCSH in the TAFs to reflect this potential, mainly
for NYC metro and Lower Hudson Valley terminals. IFR conditions will
prevail early Tuesday morning with conditions to improving to MVFR
mid to late Tuesday morning.

SE-S winds this afternoon around 10kt or less. Winds then begin to
back to the ESE-E this evening and then E overnight. E-ENE winds for
Tuesday.

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

A shower, possibly a thunderstorm, may occur approx 20-01z.

OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...

Tuesday aftn: MVFR, possibly VFR at times.

Tuesday night: Lowering to IFR with showers possible.

Wednesday: IFR early, improving to MVFR with showers possible.

Thursday-Saturday: VFR.

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

&&

.MARINE...
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A weak pressure gradient remains in place over the coastal waters
leading to an extended period of sub small craft conditions. Ocean
seas are expected to be at 2 to 3 feet through the remainder of the
week. Small craft conditions are not expected to potentially return
until late in the weekend.
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&&

.HYDROLOGY...
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There are no hydrologic concerns through the beginning of next
week.
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&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

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