Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 250938
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
538 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/...
Lead shortwave moves through the region this morning with warm front
lifting north through the region. Scattered showers associated with
this feature...across se pa/nj...may translate east across nyc/nj
metro and 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.

Morning convection and cloud cover complicates the temperature and
instability forecast for today. With subsidence in wake of lead
shortwave and warm front lifting north...expecting opportunity for
at least partial clearing late morning into early afternoon. This
should allow for temps to 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 likely across
nyc/NJ metro...with isolated 105 possible. 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 shra/tsra
development along this boundary appears to be late afternoon into
this evening with 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 along
the pre-frontal 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 some 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 /10Z MONDAY THROUGH FRIDAY/...
Some minor tweaks were made to the TAFs for the 09Z AMDs. Area of
convection moving through SE PA and into SW NJ looks to stay
south of the local terminals. Think a few storms could clip KEWR
and KJFK, so will leave the VCTS in the KNYC TAFs. Will remove
VCTS from KSWF, as convection should stay well south. KOKX radar
indicating some light precip passing through KNYC terminals, it is
not reaching the ground.

Primarily a VFR forecast for most terminals. That wave of
convection this morning should pass through the terminals by
13-15Z. Brief MVFR conditions possible.

MVFR VSBYs possible in HZ for KNYC terminals from late morning
through early afternoon. VFR otherwise.

Cold front approaches this afternoon. Convection will fire up west
of the region and looks to impact western terminals from around
20Z-02Z.

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

Gusty winds and heavy rain possible in convection.

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: Potential for convection from 10-13Z. Reduced
VSBYs possible in HZ later this morning as well. Afternoon sea
breezes possible later this afternoon.

KLGA TAF Comments: Potential for convection from 10-13Z. Reduced
VSBYs possible in HZ later this morning as well. Afternoon sea
breezes possible later this afternoon.

KEWR TAF Comments: Potential for convection from 10-13Z. Reduced
VSBYs possible in HZ later this morning as well.

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

KTEB TAF Comments: Potential for convection from 10-13Z.

KHPN TAF Comments: Low confidence on convection from 10-13Z.

KISP TAF Comments: Convection possible from 11-14Z. Afternoon sea
breezes possible this afternoon.

.OUTLOOK FOR 09Z TUESDAY THROUGH FRIDAY...
.Late tonight...MVFR VSBY possible north and east of KNYC in fog.
.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. 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 from noon today to 8 PM EDT this evening for
     CTZ005>007-009-010.
NY...Heat Advisory from noon today to 8 PM EDT this evening for
     NYZ067>075-078-080-176>179.
NJ...Heat Advisory from noon today to 8 PM EDT this evening for
     NJZ002-004-006-103>108.
MARINE...None.

&&

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


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