Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 252341
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
741 PM EDT Sun Sep 25 2016

.SYNOPSIS...
High pressure over the Northeast will slowly drift off the coast
on Monday. A frontal system moves through on Tuesday. The front
will likely linger near or just offshore through the end of the
week...resulting in an unsettled weather.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Clear skies tonight with the high pressure ridge building over the
forecast area. Good radiational cooling conditions overnight with
temps dropping through the 50 and 40s. Some patchy frost possible for
portions of the Long Island Pine Barrens and the interior valley with
reading likely falling into the mid 30s and possibly the lower
30s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
After a sunny start to the day, high clouds will overspread the
area from the west as a 500 millibar trough over the Northern
Plains advances towards the area. Southerly winds will increase,
especially along the south shore of Long Island, as the center of
the high sets up over the Atlantic. The models progress the
associated front eastward at around 20 kt, so the front will
supposedly not delay its arrival. Based on this speed and timing,
rain chances begin after dark, with the best chance for rain
coming during the overnight period. The ribbon of moisture ahead
of the front is progged to translate into about 1.8 inches of
precipitable water, so max rainfall with the steadily moving
system is expected to be capped at around an inch and a half at
this time.

There is a low risk for rip current development Monday
morning from a 2 ft long period se swell; expected to increase to
moderate in the afternoon as southerly wind waves increase.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Models in good agreement with a deep closed low sitting over the
Great Lakes/Southern Ontario on Tuesday. Then models coming into
better agreement with the upper low slowly sinking se into the
Ohio/Tennessee River Valley through the end of the week...and
possibly meandering around through the weekend. This setup is
pointing towards a more unsettled weather pattern for the mid to
late week period.

At the surface...a cold front associated with the stacked Great
Lakes low approaches the region Monday Night...and crosses the
region Tuesday. Continued good agreement in deep layered lift
interacting with southern moisture (1 to 2 std PWAT) bringing a
soaking rain during the late Monday night to Tuesday morning period.
An isolated tstm is not out of the question Tue morning with some
weak elevated instability and strong lift ahead of the cold
front...but prob is quite low. Appears the cold front pushes far
enough east late Tue/Tue eve for rain to taper off.

Confidence is increasing in an unsettled mid to late week period
based on ensemble/operational trend towards a less progressive and
cutoff upper level scenario as described earlier. This will result
in potential for additional waves of low pressure to develop along
the cold front just offshore as well as broad low pressure to sit sw
of the region...affecting the region with periods of rain mid to
late week. Forecast has been further weighted towards the unsettled
scenario.

Temps on Tuesday will likely be above seasonable with offshore flow
in wake of cold front and with any partial clearing.
Thereafter...temps should be nears seasonable under a maritime
airmass.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR as high pressure builds across the area overnight, then
offshore on Monday.

Light NE flow tonight veers around to the SE by late Monday
morning.

.Outlook for 00Z Tuesday through Friday...
.MON NIGHT...VFR...then MVFR w/areas of IFR in showers late at
night.
.TUE...MVFR w/areas of IFR in the morning. Becoming VFR from West to
East midday.
.WED...VFR.
.THU and FRI...Potential IFR/MVFR CIGS with RA. NE Wind 15-20 KT.

&&

.MARINE...
Sub sca conds overnight.

Southerly winds will increase Monday ahead of a cold front, but
speeds will not reach 25 kt until Monday night. A small craft
advisory will likely be required on the ocean as a result, and
possible elsewhere.

SCA conditions likely Tuesday morning on ocean waters...and possibly
eastern nearshore waters...ahead of an approaching frontal system.
Winds will fall below sca behind the front Tue afternoon...with
ocean seas gradually following suit.

Sub sca conditions likely return for Tues night into Wed...then
potential for sca seas to develop once again with persistent
easterly flow for remainder of the week. There is still a great deal
of uncertainty regarding the specifics of the forecast during this
time period.

&&

.HYDROLOGY...
Around an inch of rain is possible Monday night into Tuesday. Some
locally higher amounts are possible. Additional bouts of rain are
possible during the mid to late week. No significant hydrologic
impacts are expected at this time.

&&

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

&&

$$
SYNOPSIS...JMC
NEAR TERM...JMC/NV
SHORT TERM...JMC
LONG TERM...NV
AVIATION...JC/DW
MARINE...JMC/NV
HYDROLOGY...JMC/NV



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