Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 250817

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

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.


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

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 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

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.


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.


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

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


A warm front lifts through the terminals during the pre-dawn
hours as high pressure slides offshore. A cold front approaches
this afternoon and passes through the region this evening. High
pressure returns tonight.

Primarily a VFR forecast for most terminals. Some convection
associated with an approaching warm front developing over SE PA
and W NJ will lift towards the region and could impact western
terminals by 09-10Z. That wave of convection 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

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.

.Tonight...SHRA/TSRA taper off from west to east. 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


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.


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

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


CT...Heat Advisory from noon today to 8 PM EDT this evening for
NY...Heat Advisory from noon today to 8 PM EDT this evening for
NJ...Heat Advisory from noon today to 8 PM EDT this evening for


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