Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 251350
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
950 AM EDT MON JUL 25 2016

.SYNOPSIS...
A cold front approaches today and moves through the region tonight.
High pressure builds to the west Tuesday and moves off the southeast
coast Wednesday into Thursday. A weak cold front approaches the
region Friday and may linger into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Back edge of clouds moving across the NYC metro, coastal CT, and
Long Island the next couple of hours. Mostly sunny skies will
develop from west to east with rapidly warming temps. Upstream
convection over the western NY state will be closely watched as
outflow boundaries and mid level short wave arrive this afternoon.
Decaying convective complex passes about 40 miles south of LI
this morning.

Shearing northern stream shortwave then approaches late today
with pre-frontal trough approaching the region late this afternoon
crossing the region this evening. Trailing cold front crosses
tonight.

Temps rapidly heat up late this morning into early afternoon.
Temperatures away from the south coasts should be able to climb
into the lower to mid 90s...with dewpoints rising into the lower
70s. Heat indices of 100 to 104 expected across nyc/NJ metro...with
potential for 105+ if dewpoints advecting NE from southern NJ/se
PA don`t mix out. For most of the remainder of the region...heat
indices peaking around 100 degrees. The exception will be southern
and eastern coastal areas limited to the mid to upper 80s due to
morning cloud cover and onshore flow. Despite this...heat indices
could still peak in the mid to upper 90s as dewpoints should surge
into the lower to mid 70s.

In terms of convection...would expect subsidence in wake of lead
shortwave to limit convective potential late morning into early
afternoon. Can`t rule out an isolated storm developing along
the developing pre-frontal/lee trough and tracking eastward into
NE NJ /Lower Hud during this time. Better chance for organized
shra/tsra development will be late afternoon into this evening as
shra/tsra likely develop/maintain across central NY/PA along
early morning convective outflow/pre-frontal trough and approach
the region...supported by lift from approaching shortwave energy
and right rear quad of jet streak. This forcing in combination
with marginal to locally moderate instability...thanks to a subtle
elevated mixed layer...in a very moist environment should support
scattered to numerous showers and thunderstorms developing/maintaining
W/NW of NYC metro late this afternoon and then translating
eastward through Lower Hud/NE NJ/SW CT and NYC metro and towards
the western coastal areas late today into this evening.

Strengthening uni-directional deep layer shear and tstm coverage
should support storm organization into strong to severe storms
line segments affecting NYC/NJ/LI metro and points N/NW/W.
Damaging winds from wet micro/macro bursts looks like the main
threat based on uni-directional wind fields...deep moisture...and
inverted V soundings. Relatively quick storm motions should
localize flash flood threat to areas with training tstms.

Convection should become elevated and weaken this evening as it
translates farther east across LI/Southern CT as it runs into a
deeper marine stable layer. Convection should push offshore by
around midnight as shortwave axis moves across.

Drier air slowly advects in late tonight with weak cold frontal
passage. Areas of fog possible across outlying areas in warm and
muggy airmass.

There is a low risk of rip current development this
morning...becoming moderate late this afternoon into evening as
southerly wind waves increase to around 3 ft.

&&

.SHORT TERM /TUESDAY/...
Shortwave axis slides offshore Tuesday...with deep WNW flow on
Tuesday. With 850 hpa temps still running in the high
teens...deep mixing...downslope flow and full sunshine...expect
temps to quickly rise into the mid 90s for much of the coastal
plain. Lower 90s for nw hills...and potential for a few upper 90s
for NYC/NJ metro. Noticeably lower dewpoints should keep heat
indices close to air temps...but close to heat advisory criteria
for NYC metro. Sea breezes should be limited to late day and
immediate south coasts...if at all.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
High pressure builds across the area on Tuesday night then moves
offshore on Thursday. A stalled frontal boundary south of the area
will remain through the weekend.  Showers and thunderstorms are
possible during the afternoon and evenings Thursday and through the
weekend, as waves of low pressure begin to ride along this frontal
boundary.

Temperatures on Wednesday and Thursday will be above normal with
highs in the upper 80s to lower 90s and returning to normal levels
on Friday and through the weekend with highs in the low to mid
80s.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
A warm front moves across the terminals this morning followed by a
cold front passage tonight.

VFR forecast through this afternoon. Showers and thunderstorms are
expected to move across late this afternoon and evening with brief
MVFR or lower visibilities. Gusty winds and heavy rain possible in
any storms. Some uncertainty in timing and how far east these
storms will be able to move.

SSW-SW flow 5-10 KT will give way to afternoon sea breezes at
coastal terminals 10-15 KT.

VFR conditions expected tonight, but it is possible that outlying
terminals, such as KHPN and KGON could have MVFR or lower VSBYs in
fog late tonight.

     ...NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: Brief MVFR CIG through 15z. Some variability
in wind direction between 200-220 true this morning with winds
backing to around 180 true this afternoon. Amendments for TSRA
timing this afternoon/evening likely.

KLGA TAF Comments: Winds should veer to the SW late this morning
with sea breeze passage possible this afternoon. Amendments for
TSRA timing this afternoon/evening likely.

KEWR TAF Comments: Winds should veer to the SW late this morning
with sea breeze passage possible this afternoon. Amendments for
TSRA timing this afternoon/evening likely.

The afternoon KEWR haze potential forecast is YELLOW...which
implies slant range visibility 4-6SM outside of cloud.

KTEB TAF Comments: Winds should veer to the SW late this morning
with sea breeze passage possible this afternoon. Amendments for
TSRA timing this afternoon/evening likely.

KHPN TAF Comments: Winds should veer to the SW late this morning
with sea breeze passage unlikely this afternoon. Amendments for
TSRA timing this afternoon/evening likely.

KISP TAF Comments: Southerly winds continue through the day.
Amendments for TSRA timing this afternoon/evening likely.

.OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
.Tuesday-Wednesday Night...VFR.
.Thursday-Thursday Night...Mainly VFR, except MVFR or lower
possible in isolated to scattered showers and thunderstorms,
mainly late in the day and at night.
.Friday...Chance of MVFR or lower in scattered showers and
thunderstorms.

&&

.MARINE...
Sub sca conditions expected through Tuesday. S/SW winds gusts to
20 kt possible for most waters this afternoon...with nearshore NW
winds gusts to 20 kt possible Tuesday afternoon. Occasional
nearshore gusts to 25 kt possible. Ocean seas should remain in the
2 to 4 ft range.

Slight tstm threat on the water this morning with greater chance late
today through this evening.

Below small advisory conditions expected across the area waters from
Tuesday through Friday.

&&

.HYDROLOGY...
There is the potential for 1/4 to 1/2 inch of rainfall, with locally
higher amounts, possibly 2+ inches, as numerous showers and
thunderstorms track across the region late this afternoon into
this evening. This presents a localized flash flood
threat...mainly across nyc/nj metro and interior with any training
cells.

There is the potential for scattered showers and thunderstorms,
across the area during the afternoons and evenings Thursday through
next weekend.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT this evening for CTZ005>007-009-
     010.
NY...Heat Advisory until 8 PM EDT this evening for NYZ067>075-078-
     080-176>179.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ002-004-006-
     103>108.
MARINE...None.

&&

$$

SYNOPSIS...FIG/NV
NEAR TERM...NV/DW
SHORT TERM...NV
LONG TERM...FIG
AVIATION...MPS/DS
MARINE...FIG/NV
HYDROLOGY...FIG/NV



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