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fxus61 kokx 201136 
afdokx

Area forecast discussion
National Weather Service New York New York
736 am EDT Fri Oct 20 2017

Synopsis...
mild high pressure dominates through Monday. A slow moving
frontal system will then approach the area Tuesday into Tuesday
night with a cold frontal passage by early Wednesday. The front
is slow to depart farther away with a wave of low pressure
developing along it and approaching the area mid into late next
week.

&&

Near term /until 6 PM this evening/...
730 am EDT update - forecast on track no changes as cold front
has pushed offshore and high pressure is building in. Northwest flow
prevails through the day with perhaps some gusts in the upper
teens late this morning and aftn. With no sensible change in
airmass and mostly clear skies, highs will be similar to
yesterday, mainly upper 60s to lower 70s except mid 70s in the
New York/New Jersey Metro area.

&&

Short term /6 PM this evening through 6 PM Saturday/...
ridging continues to build into the region with weak warm air advection through
the short term providing dry and unseasonably warm conditions.
Even though optimal conditions will exist for radiational
cooling tonight, clear skies and light/calm winds, the warm air advection will
limit its impact. 925mb temps at 12z this morning are progged
to be between 10c and 12c, and increase to 15-16c by 12z Sat.

Sunny conditions expected on Sat with just few-sct cirrus. Highs
will remain above normal ranging in the mid to upper 70s except
on the Twin Forks of Li and southeast coastal CT.

&&

Long term /Saturday night through Thursday/...
warm weather continues through Monday as the jet stream remains
north of the region with upper level ridging. At the surface,
the dominant feature will be high pressure eventually moving
offshore and the resulting S-SW flow. Mainly clear sky
conditions are expected to continue through Sunday.

Clouds increase Monday into Monday night ahead of the next
frontal system. The next chance of rain showers arrives late
Monday night into Tuesday, when a deep upper level trough
approaches from the west.

The trough further deepens Tuesday along the eastern Seaboard
with increasing meridional flow. This will give plentiful
moisture to a developing frontal system at the surface. The
frontal system will be approaching the region Tuesday into
Tuesday night with the region being in the warm sector to the
east of the low with strengthening southerly flow, thereby
increasing warm air advection. Precipitable water increases to
near 1.5 inches from the moisture advection. This is much above
normal for this time of year. According to okx sounding
climatology, it would be above the 90th percentile. Some
moderate to heavy rainfall will be possible.

The cold front moves across Wednesday morning, with a
substantial decrease in precipitable water thereafter to less
than 1 inch. The front slows down and is slow to depart away
from the region. The numerical forecast models show weak low
pressure development along it and the low approaching the region
mid into late next week, with rain shower chances continuing.

Temperatures are expected to be well above normal this weekend
through Tuesday with a gradual decline thereafter. Highs this
weekend through Tuesday are forecast to be well into the 70s
with lows trending to be well into the 50s and near 60 for some
locations along the coast and NYC. The highs are forecast to be
more in the 60s for next Wednesday and next Thursday.

&&

Aviation /12z Friday through Tuesday/...
VFR through the taf period as high pressure builds in from the
west.

Good confidence in the wind forecast with the typical 20
degrees of variability either side of forecast through the day.

New York Metro enhanced aviation weather support...

Detailed information, including hourly taf wind component fcsts,
can be found at:
http:/www.Weather.Gov/zny/n90

Kjfk taf comments: gusts in the metar/atis could be more
occasional today. High confidence in the wind direction
forecast, though do expect variablity 20 degrees either side of
the forecast.

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

Klga taf comments: gusts in the metar/atis could be more
occasional today. Good confidence in wind direction averaging
10-30 degrees to the right on 310 magnetic.

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

Kewr taf comments: fairly confident that gust reports will be
occasional in nature this afternoon - less than 50% of the time.

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

Kteb taf comments: no unscheduled amendments expected

Khpn taf comments: no unscheduled amendments expected

Kisp taf comments: no unscheduled amendments expected

Outlook for 06z Saturday through Tuesday...
Saturday-Monday...VFR.
Tuesday...MVFR possible in showers. S wind g20-25 knots at coast.
Low level wind shear possible.

&&

Marine...
northwest flow today as high pressure builds in with some near shore gusts
to 20 knots. Otherwise, tranquil conditions are forecast through
Monday.

Winds, as well as seas on the ocean, increase on Tuesday ahead of a
cold front with Small Craft Advisory conditions likely.

&&

Fire weather...
the Special Weather Statement will be continued for today for
the entire region due to enhanced fire danger. Min relative humidity values
are expected to drop to 30 to 35 percent, except in the New York/New Jersey
Metro area where they could drop into the upper 20s. Wind gusts
of 20 to 25 mph are also expected, especially late this morning
into the afternoon.

&&

Hydrology...
no hydrologic problems are expected through Monday night. For
Tuesday through early Wednesday, heavy rain will be possible at
times with potential areas of 1 inch or higher. There is much
uncertainty with exact rainfall amounts. Urban and poor drainage
flooding will be possible.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.

&&

$$
Synopsis...BC/jm
near term...24/ds
short term...British Columbia

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