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Area forecast discussion 
National Weather Service New York New York
456 am EDT Fri Sep 30 2016

Synopsis...
high pressure over southern Quebec will maintain a moist northeast
flow off the Atlantic Ocean into the weekend as low pressure
spins over the Ohio Valley. The unsettled weather may continue
into early next week before high pressure begins to exert its
influence from the north for mid week.

&&

Near term /until 6 PM this evening/...
unsettled weather will continue through this evening as a cut off
low meanders over the mid-west while at the same time, a frontal
boundary slowly moves north toward the area. Models continue to
differ significantly with rainfall amounts. Given that much of
what is on the radar as of 0830z remains either west or east of
the area, decided to lower quantitative precipitation forecast amounts quite a bit from previous
forecast package. Only expecting about half an inch or slightly
more through this afternoon for Long Island and the New York City
Metro area with lesser amounts for the lower Hudson Valley and
inland southern Connecticut.

It will be breezy today as a tight pressure gradient between the
high pressure to our north over southern Quebec and the low over
the mid-west continues. Winds could gust to 35-40 mph, mainly
along the coast.

With the blocking pattern in place, persistence will be the
forecast. Continued cloudy today. Highs will be a few degrees
lower than yesterday, with portions of the lower Hudson Valley and
inland southern Connecticut not even reaching 60. Generally, upper
50s to lower 60s for high temperatures for the entire area.

&&

Short term /6 PM this evening through 6 PM Saturday/...
chances for rain continue into the short term with the cut off
low remaining to the west and the frontal boundary to our south.
Again, models differ on exact placement of the heaviest rain.
Expecting anywhere from 3/4 to 1 1/3 inches of rain, with the
heavies falling across eastern Long Island, from Friday morning
through the day Saturday.

Winds diminish Friday night as the high pressure retreats farther
north into Canada. Temperatures will be a bit warmer on Saturday,
but still a bit below normal for this time of year, generally
lower to middle 60s.

&&

Long term /Saturday night through Thursday/...
no significant changes made to the long term period as a stagnant
and unsettled weather pattern continues for the weekend and into
early next week as a stacked cutoff low remains over the Ohio
Valley as a ridge over the western Atlantic remains in place. Models
continue to show the upper ridge gradually weakening and shifting
south enough early next week to allow the upper low to finally start
moving northeast early next week.

At the surface, stacked low pressure sits over the Ohio
Valley, with a stationary front running northeast from the mid
Atlantic and southeast of Long Island through the weekend. A
series of weak waves running along this front will produce periods
of rain this weekend. Then as the stacked low finally begins to
lift northeast early next week, expect the the main moisture/lift
axis to also weaken and lift NE. Lingering scattered showers could
continue through early next week via cold pool instability
interacting with the maritime air mass.

Thereafter, potential for deep layered ridging developing for mid
week as the region lies under ridging of an Omega blocked pattern.
The dry ridged pattern may continue into late week, but will have
to monitor the evolution of Hurricane Matthew. Please refer to
the National Hurricane Center forecasts for further information.

Temperatures will be at or slightly below normal on Sunday,
then return to near seasonable for early next week.

&&

Aviation /09z Friday through Tuesday/...
terminal area will be in between high pressure to the northeast
and low pressure to the southwest today.

MVFR this morning, bcmg IFR this aftn. Tempo IFR vsbys in rain
possible this morning.

NE-east winds gusting to 25-35 knots at city/coastal terminals and
20-25 knots at inland terminals.

..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: gusts before 12z might be only occasional. Timing
of IFR may be off by a couple of hours.

Klga taf comments: timing of IFR may be off by a couple of hours.

Kewr taf comments: gusts before 12z might be only occasional. Timing
of IFR may be off by a couple of hours.

The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.

Kteb taf comments: gusts before 12z-13z might be only occasional.
Timing of IFR may be off by a couple of hours.

Khpn taf comments: gusts before 12z-13z might be only occasional.
Timing of IFR may be off by a couple of hours.

Kisp taf comments: gusts before 12z might be only occasional.
Timing of IFR may be off by a couple of hours.

Outlook for 06z Saturday through Tuesday...
Friday night-Saturday...IFR/MVFR in rain. NE gusts around 20 knots
Friday night.
Saturday night-Sunday night...MVFR or lower possible with showers.
Monday-Tuesday...VFR with isolated to scattered showers possible.

&&

Marine...
gale winds are expected to continue today as the tight pressure
gradient with the high over southern Canada and low over the mid-
west continues. The gale warnings were extended into early
tonight, but the winds should gradually diminish tonight as the
high retreats farther north into Canada. Winds should come down
below Gale Warning criteria after 8 PM tonight, with Small Craft Advisory winds
expected through the remainder of the night. Seas on the ocean
will range from 8-13 ft, while 5-7 ft are expected on the sound.

Small Craft Advisory criteria should continue into mid Saturday morning for the
ocean waters, while everywhere else, winds will come down below 25
kt around sun rise. Waves over the sound will also come down below
5 ft by around sun rise on Saturday. Waves will diminish on the
ocean waters as well, but they will remain at or above 5 ft
through the day Saturday.

Conditions fall below Small Craft Advisory levels Sat night into early Sunday as
easterly flow weakens and seas subside. These sub-Small Craft Advisory conditions
will remain likely for early next week under a weak pressure
gradient.

Seas on the ocean waters start to increase mid week with small craft
conditions returning.



&&

Hydrology...
there is a high degree of uncertainty on the amount of rainfall
through Saturday. 1-1 1/2 inches of quantitative precipitation forecast possible through Saturday
night. The prolonged nature of the rain event should preclude any
hydrologic issues.

No significant rainfall for early to mid next week.

&&

Tides/coastal flooding...
with slight strengthening of east-northeast gales this morning's high tide
cycle, would expect surge to at least match or even slightly
exceed that of last night's. With a slightly higher astronomical
high tide, this should result in widespread minor coastal flooding
for the above mentioned areas.

Along western Long Island Sound and the eastern bays of Long
Island, wind fields will be slightly weaker the next 12 hours,
and may be falling off by high tide times Fri late morning, but
can't rule out localized minor coastal flooding or wave splashover
in the most vulnerable northeast and east facing spots during high
tide.

Although wind fields weaken for Fri evening high tide, widespread
minor flooding continues to be a concern for the South Shore of
Long Island and thus a coastal Flood Advisory was issued for this
time frame for southern Nassau County.

Additionally, a persistent easterly sweep of 6 to 10 ft surf
through Friday will likely result in minor to moderate beach
erosion issues at the the ocean beachfront.

&&

Okx watches/warnings/advisories...
CT...none.
New York...coastal Flood Advisory until 11 am EDT this morning for nyz074-
075-080-178-179.
Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for
nyz179.
New Jersey...coastal Flood Advisory until 11 am EDT this morning for njz006-
106-108.
Marine...Small Craft Advisory until 8 am EDT Saturday for anz338.
Gale Warning until 8 PM EDT this evening for anz330-335-340-
345-350-353-355.

&&

$$
Synopsis...BC/jp
near term...jp
short term...jp
long term...British Columbia
aviation...jc
marine...BC/jp
hydrology...BC/jp
tides/coastal flooding...

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