000
FXUS61 KOKX 202212
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
612 PM EDT Sun Aug 20 2017

.SYNOPSIS...
High pressure building into the region through Monday morning
will settle to the south and east Monday afternoon, allowing a
weak warm front to approach Monday night. After a hot and humid
Tuesday, a cold frontal passage on Wednesday will produce a
drastic cooldown for the end of the week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The fcst is on track with no major changes made. Cu continue to
slowly thin out, with a mostly clear night coming up. This
along with diminishing winds should allow temps to trop to the
50s and 60s in most areas, with only NYC remaining above 70
overnight.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Sky cover could be tricky in spots for the partial solar
eclipse, which should run from about 120 PM to 400 PM in NYC
and peak at 244 PM. Do expect some sct high clouds and also some
sct Cu, possibly a narrow band of broken Cu with the sea breeze
closer to the north shore of Long Island and in southern CT.
South facing coastlines may be better viewing locations as any
lower clouds that form inland with the sea breeze.

Temps should rise quickly into early afternoon, and per 15Z run
of the HRRRX which has been modified to incorporate impact on
incoming solar radiation due to the eclipse, may actually drop a
couple of degrees between 2-4 PM, then rebound. Overall temps
should still reach the mid/upper 80s, possibly 90 in parts of
urban NE NJ.

The approaching warm front could spark an isolated shower or
tstm toward sunset well west of NYC, with slight chances
overspreading nearly all the area later Mon night. Lows should
be in the upper 60s/lower 70s, and it will become muggy as
dewpoints also increase into that range.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
A cold front will reach the area on Wednesday per the 12Z suite of
model guidance, which was in good agreement. This means that Tue is
setting up to be hot and humid. Winds progged around 200 degrees
will pump lots of humidity into the area, and across the ern half of
the CWA keep actual temps slightly suppressed despite H85
warming towards 20C. The humidity will compensate for any lack
of heat, with just about all areas likely aoa 90 for a heat
index. Across the normally hottest areas like NJ zones, the
heat index attm looks to reach about 100. There could be a few
aftn and eve tstms, particularly N and W of NYC, but there will
at least be an increase in dense cirrus from upstream
convective debris. As a result the fcst goes mostly cloudy by
Tue eve. Shwrs and tstms ahead of the front Tue ngt and Wed,
then the area dries out for the remainder of the fcst period.
The cold front will be driven by a 100-kt H3 jet, so tstms will
be easier to sustain or initiate at ngt. If the timing ends up
slightly slower, a svr outbreak is possible on Wed as CAPE could
soar to 3000 J/kg or more. Even with the progged faster timing
however, there could still be svr at any time ahead of the front
with the jet acting on MUCAPE around 1500-2000 J/kg. Much cooler
weather will then settle in for Thu-Sun, with temps averaging
blw climo.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
High pressure will build to the south into Monday morning, then
slide to the southeast of the area into Monday afternoon. VFR
through the TAF period.

Mainly occasional gusts this afternoon to 15-20KT at most terminals.
JFK could see winds go W for a few hours late this afternoon. Any
gusts abate by early evening, with winds becoming light and variable
throughout by around midnight. SW winds at under 10kt develop by mid-
late Tuesday morning, with sea breezes at coastal terminals
showing up by late Tuesday morning to early Tuesday afternoon.

.OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
.Monday afternoon-evening...VFR. G15-20KT possible with sea breezes.
.Late Monday night-Tuesday morning...Mainly VFR, with low chance
MVFR or lower at mainly Long Island terminals.
.Tuesday Afternoon-Wednesday...A chance of showers and thunderstorms
with brief periods of MVFR or lower possible. SW winds G15-20KT
possible Tuesday afternoon. LLWS possible Tuesday night. W-NW winds
G15-20kt possible Wednesday afternoon.
.Wednesday Night-Friday...VFR.

&&

.MARINE...
Winds and seas will ramp up on Tue, with SCA conditions
developing on all waters. Winds will decrease after a cold
frontal passage, bringing winds the protected waters blw SCA
lvls by Wed eve. On the ocean, seas should linger around 5 ft
into Wed ngt. Winds and seas are then progged to remain, in the
absence of any increased swell, blw SCA lvls thru the weekend.

&&

.HYDROLOGY...
No widespread hydrologic impacts foreseen attm.

&&

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

&&

$$
SYNOPSIS...JMC/Goodman
NEAR TERM...JMC/Goodman
SHORT TERM...Goodman
LONG TERM...JMC
AVIATION...Maloit
MARINE...JMC/Goodman
HYDROLOGY...JMC/Goodman

NWS OKX Office Area Forecast Discussion