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000
FXUS61 KOKX 180542 CCA
AFDOKX

Area Forecast Discussion...CORRECTED
National Weather Service New York NY
142 AM EDT Fri Aug 18 2017

.SYNOPSIS...
A warm front will approach tonight and move north through Friday
morning. A cold front approaches Friday, moving across the
region late Friday night. A frontal system will slowly pass
offshore on Saturday. High pressure will then build in through
the beginning of next week, followed by a midweek cold frontal
passage.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
Main showers still located where higher sfc Theta-E is situated
across central PA and farther north into Western Central NY
State. This environment along with the showers approaches closer
to the region towards daybreak. As showers enter, heavy downpours
will be possible due to high precipitable waters of approximately
2 inches that will be moving in which goes with the higher
Theta-E.

An area of low pressure will track east across the northern
Great Lakes tonight. A warm front associated with the system is
expected lift north through the local area overnight and into
Friday morning. Showers and possible thunderstorms will spread
across the area overnight and into Friday morning. Temperatures
tonight will be in the upper 60s to lower 70s.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
-- Changed Discussion --
As a warm front moves north a strong southerly flow will usher
in behind, bringing an influx of moisture across the area.
Latest HRRR indicates some heavier shower activity in the
11-15Z timeframe Friday. This would certainly be possible as
precipitable waters are forecast to increase to between 2 and 2.3
inches. Dewpoints will rise back into the 70s across the region
along with instability resulting in thunderstorms and heavy rain
to develop. There may be a break in the precipitation for a brief
time once the warm front lifts north, and until the cold front
nears later in the day. Storms will weaken and move into Long
Island and southern Connecticut by Friday night.

Temperatures on Friday will be in the upper 70s to lower 80s
with lows in the upper 60s to lower 70s.

There is a moderate risk of rip currents at NYC and Nassau
County ocean beaches.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
The frontal boundary/sfc trof will slowly slide offshore on Sat.
Trends will need to be monitored for a slowing of this feature, as
the main upr trof which will force it ewd is still progged to be
over OH at 18Z Sat. The slower the boundary exits, the slower shwrs
and especially clouds will exit. Based on the 12Z data, areas along
and w of the Hudson dry, with the rest of the area low chances for
pcpn. Dry weather Sat ngt thru Mon ngt with high pres progged to
move in.

12Z GFS timeheights indicate sunny skies on Mon with perhaps some
fair wx cu, particularly along the sea breeze front.

Chances for shwrs and tstms Tue thru Wed ahead of a cold frontal
passage. Best chances are Wed closest to the front attm, so as the
event draws closer pops may be eliminated for Tue.

A blend of the guidance and 2m data was used for temps thru the
period. The numbers will generally be abv average until the fropa
next week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A warm front approaches from the southwest tonight. A cold front
will approach from late Friday.

Stratus deck that developed along the south shore of Long Island
near KJFK has now spread to KISP and the other city terminals.
Uncertainly remains as to whether it remains through the night,
however keeping an optimistic forecast. Otherwise...VFR with
deteriorating conditions around daybreak.

Friday will be very unsettled with the threat of showers and
scattered thunderstorms in the morning and then again with the
approaching cold front late in the afternoon. There is uncertainty
with improving conds in the warm sector after the warm front
passes in the morning, may be too optimistic in the NYC metro.
Gusty winds and MVFR/IFR are possible with any heavier shower or
thunderstorm.

Light southerly winds overnight before increasing again 10 to
15 kt Friday. Gusts to 25 kt possible Friday afternoon across
much the region but especially along the coast.

Higher gusts possible with any thunderstorm.

.OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
.Saturday night...MVFR or lower flight cat possible in
showers/tstms with gusty winds possible during the evening.
Fog/stratus with MVFR or lower conds may linger through the
overnight.
.Sunday and Monday...VFR. light NW wind becoming SW by Late
Sunday and Monday.
.Tuesday...Iso shra/tstms possible with MVFR or lower
conds...otherwise VFR.

&&

.MARINE...
A warm front approaches tonight and moves across the area
waters Friday morning. Southerly winds will increase ahead of an
approaching cold front Friday, resulting in 15 to 20 kt winds.
Seas may briefly build close to 5 feet Friday afternoon and into
Friday evening. Will hold off on a SCA for Friday afternoon and
evening given low confidence in widespread SCA conditions
developing.

There may be some lingering 5 ft seas on the ocean Sat as a
front passes e of the waters, but all areas are fcst to be blw
sca lvls by Sat ngt. Winds and seas are then progged to remain
blw sca lvls on all waters thru next Wed.

&&

.HYDROLOGY...
Heavy rainfall is possible by morning as a warm front moves
northward through the region. Another round of heavy showers and
thunderstorms will be possible by evening with the cold frontal
passage. Rainfall accumulations are expected to be around a half
an inch to an inch, with locally higher amounts possible in
thunderstorms. At this time it remains difficult to pinpoint
where heavier showers and thunderstorms will develop. No
significant hydrologic impacts are expected, but some minor
urban flooding is possible.

Impacts from potential showers and thunderstorms Tuesday into
Wednesday are uncertain at this point, however at least minor
nuisance flooding will remain a possibility.

&&

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

&&

$$
SYNOPSIS...JMC/Fig
NEAR TERM...MD/Fig
SHORT TERM...Fig
LONG TERM...JMC
AVIATION...CB
MARINE...JMC/Fig
HYDROLOGY...JMC/MD/Fig