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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 262018
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
418 PM EDT Mon Sep 26 2016

.SYNOPSIS...
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High pressure moves farther out into the Atlantic as a frontal
system approaches from the west this afternoon into this evening.
This moves across Tuesday morning but its associated cold front will
become stationary and linger not too far off the coast for the rest
of Tuesday through Wednesday. Then low pressure over the Ohio
Valley and Mid Atlantic states will move slowly up the coast from
late Wednesday night through Saturday night, bringing an extended
period of unsettled weather. The low will gradually move clear of
the area early next week.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
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The upper level ridge moves east of the region out into the
Atlantic, making the way for an approaching large upper level
cutoff low tonight. The associated upper level jet moves into the
region tonight, with the right rear quad of enhanced lift moving
in by Tuesday Morning.

At the surface, a frontal system will be approaching from the west
this evening. The warm front will move across late this evening to
the beginning of the overnight period. This will be followed by the
cold front, which will approach for the rest of the overnight from
the west.

Expect increasing chances for rain showers overnight into daybreak
Tuesday along with increasing winds with developing low level jet. A
few gusts up to 30 mph could very well occur especially with mixing
down of momentum via the rain showers.

Used warmer blend of NAM12/GMOS tonight with abundant clouds,
increasing south to southwest winds and incoming rain showers to
keep less differences spatially between lows.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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The upper level low remains nearly stationary Tuesday and Tuesday
Night. The associated jet remains across the Northeast with the
local region staying in the right rear quadrant where lift will be
enhanced.

At the surface, the cold front will move across from west to east
Tuesday morning. However, it appears to slow down on its trek
through the region, lingering out east during the day and then
slowly moving offshore. The front will be weakening at the same
time. The front looks to remain stationary offshore from the model
guidance and with approaching weak low along it, may bring a return
of rain showers for Tuesday night.

Rain showers continue across the region early and then will be slow
to diminish across the coast. Favorable setup for synoptic lift is
evident within the models so do not totally trust model QPF fields
verbatim. A chance of rain showers will remain along the coastline
going into the afternoon and the evening.

Went with middle of guidance using a combination of GMOS and ECS for
max temperatures Tuesday. For min temperatures Tuesday night, used a
combination of MET and ECS.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
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There is high confidence in the large scale idea of a cutoff low
digging south from the Great Lakes and upper Ohio Valley Wed
morning, meandering about the Central Appalachians and Ohio Valley
from Thu into Sat night, then slowly weakening and lifting out
toward the Great Lakes and interior Northeast Sunday into Monday.
This should lead to an extended period of unsettled weather and
more much needed rainfall, but details on the timing of any
heavier rain are sketchy. GFS may be took quick to kick an
offshore frontal wave out to the NE and weak offshore ridging,
which would allow heavier rain to arrive late Wed night into Thu.
The idea of a slower offshore low helping to reinforce surface
ridging/cool air damming on its rear flank over New England and
into our area should lead to diminishing PoP or even a dry but
cloudy interval Wed afternoon and much of Wed night, with heavier
rain off to the west. This setup should also lead to a gusty ENE
flow from Wed night into Thu evening. Then as onshore low level
flow increases and flow aloft becomes more difluent, one favorable
time frame for heavier rain to take place may be Thu night.
Another may come Fri night into Sat morning as a mid level
shortwave and upper jet streak lift northward along the coast.

After these features pass, still expect unsettled wx to continue
into Sat night and possibly Sunday, and do not have a completely
dry forecast in terms of PoP until Monday as the upper low
finally weakens and lifts NE to the Great Lakes and interior
Northeast.

Temps should be near to slightly below average in this
unsettled regime.
-- End Changed Discussion --

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
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Wind has shifted to N-NW at all NYC terminals. Wind will shift to
the NW across eastern areas later this afternoon. A few gusts to
25kt are possible. Winds will then continue to veer around to the N-
NE tonight at less than 10 kt at all terminal locations. There is a
good chance of a sea breeze developing for KJFK, KISP, KBDR and KGON
after 16z on Saturday.

     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: No unscheduled amendments are expected.

KLGA TAF Comments: No unscheduled amendments are expected.

KEWR TAF Comments: No unscheduled amendments are expected.

KTEB TAF Comments: No unscheduled amendments are expected.

KHPN TAF Comments: No unscheduled amendments are expected.

KISP TAF Comments: No unscheduled amendments are expected.

.Outlook for 18Z Saturday through Wednesday...
.Saturday through Sunday...VFR.
.Monday into Monday Night...VFR. Potential cold frontal passage
with a few showers and thunderstorms.
.Tuesday and Wednesday...VFR.
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&&

.MARINE...
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Expecting winds to increase tonight ahead of the frontal system. SCA
conditions are expected for all waters after 00Z, lasting until 12Z
Tuesday. Then, SCA conditions will be more probable across the
ocean. The ocean seas are also expected to build to 5-6 ft late
tonight into early Tuesday, but SWAN guidance has been recently
overestimating by a foot with ocean seas, so have reduced seas
accordingly.

SCA conditions should REdevelop on the eastern waters on Wed,
then spread westward to all waters Wed night into Thu night via
an increasing pressure gradient between high pressure to the north
and broad/weak low pressure to the southwest, with ENE flow
gusting to 25-30 kt. GFS is alone in advertising a period of
possible gales and think this is overdone, but will keep mention
of low potential in HWO for sake of continuity. Hazardous ocean
seas should linger Fri into Fri night.
-- End Changed Discussion --

&&

.HYDROLOGY...
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Between 1/4 to 3/4 inch of rain expected from midnight into
Tuesday morning. No hydrologic impacts are expected at this time
other than typical urban ponding.

Periods of heavier rain with a slow moving low pressure system
pose urban flood issues later this week, with the potential for a
couple of inches of rain.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
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A persistent moderate easterly flow during mid to late week may
combine with increasing astronomical high tides associated with
the new moon on Friday to cause minor to locally moderate coastal
flooding late this week.
-- End Changed Discussion --

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT
     Tuesday for ANZ330-335-338-340-345.
     Small Craft Advisory from 8 PM this evening to 8 PM EDT
     Tuesday for ANZ353.
     Small Craft Advisory from 8 PM this evening to noon EDT
     Tuesday for ANZ355.
     Small Craft Advisory from 8 PM this evening to 10 PM EDT
     Tuesday for ANZ350.
-- End Changed Discussion --

&&

$$
SYNOPSIS...Goodman/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...Goodman
AVIATION...IRD
MARINE...Goodman/JM
HYDROLOGY...Goodman/JM
TIDES/COASTAL FLOODING...Goodman