Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 181635
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1235 PM EDT Wed Oct 18 2017

.SYNOPSIS...
High pressure will remain in control through the weekend, with a
prolonged period of fair weather. An approaching cold front will
bring a chance of rain for the beginning of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor updates this afternoon to reflect current wind trends with
a slightly slower arrival of the sea breeze. Otherwise forecast
remains on track.

Skies will be sunny as surface high pressure dominates and as an
upper trough passes east, with rising heights aloft. A
subsidence inversion between 875-900 mb will limit mixing, still
with warm air advection temps should reach the upper 60s and
lower 70s this afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
As the upper ridge passes east, WAA aloft ahead of another
transient upper trough should lead to some high clouds late
tonight into Thu morning, with the sky remaining mostly clear
overall. Lows tonight should be mostly in the 40s and 50s, with
only some isold upper 30s well inland.

The subsidence inversion associated with the sfc high as it
sinks to the south will be a little stronger, with mixing only
to 900-925 mb. This despite plenty of sunshine will yield temps
only a little warmer than those expected for today, reaching
70-75, about 10 degrees above average for this time of year.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
High pressure will continue to dominate through Saturday. The
high drifts offshore late Saturday, with return flow developing
for the second half of the weekend. This will produce an
increase in humidity across the area, particularly from Long
Island to Connecticut. Large diurnal spreads of 20-25 degrees
through Saturday are likely due to the dry air mass. High
temperatures will remain several degrees above average.
Southwesterly flow will pick up Monday and Tuesday, as the area
starts to get squeezed from an approaching cold front to the
west, and high pressure over the Atlantic. The potential exists
for the Gulf of Mexico to get tapped with this excess moisture
getting transported into the forecast area. Monday and Tuesday
could be quite humid as a result. As far as actual rain chances,
there are two main shots to contend with. The first is with the
approach of a residual convective boundary racing ahead of the
main system. Both the GFS and ECMWF have this feature. This has
the potential to produce locally heavy showers as it interacts
with the deepening moisture on Monday. As the main upper level
system gets here Tuesday or slightly later, this produces
significant lift and therefore a solid round of moderate to
heavy rain. Both the ECMWF and GFS again are pointing in the
same direction. The only limiting factor would be if the leading
boundary shunts the deeper moisture out to sea. This however in
not what the models are currently signaling.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
High pressure builds southeast of the region through the TAF
period with a high confidence of VFR continuing.

The wind forecast is moderate confidence due some uncertainty
on when W flow becomes more SW-S with sea breeze development
mid-late afternoon and how far north the sea breeze moves. Wind
speeds stay 10 kt or less through the TAF period.

     NY 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: Timing of more S winds could be 1-2 hours
off from forecast.

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

KLGA TAF Comments: Timing of more S winds could be 1-2 hours
off from forecast.

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

KEWR TAF Comments: Timing of more SW winds could be 2-3 hours
off from forecast.

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

KTEB TAF Comments: Timing of more SW winds could be 2-3 hours
off from forecast.

KHPN TAF Comments: Timing of more SW winds could be 2-3 hours
off from forecast.

KISP TAF Comments: Timing of more SW-S winds could be 2-3 hours
off from forecast.

.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.Thursday-Thursday night...VFR. SW-W winds G15-25kt possible
Thursday and Thursday evening.
.Friday-Friday night...VFR. NW-N winds G15-25kt possible
Friday afternoon and evening.
.Saturday-Saturday night...VFR.
.Sunday...VFR. SW winds G15-20kt possible.

&&

.MARINE...
High pressure settling to the south will produce a WSW flow.
Another period of increased WSW flow should bring winds and seas
on the ocean close to advy thresholds Wed night, possibly
briefly ramping to advy levels on Thu. Quiet conditions expected
otherwise.

&&

.HYDROLOGY...
No hydrologic issues expected through the weekend. Locally heavy
rain is possible during the beginning of next week.

&&

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

&&

$$
SYNOPSIS...JMC/Goodman
NEAR TERM...MD/Goodman
SHORT TERM...Goodman
LONG TERM...JMC
AVIATION...Maloit/JM
MARINE...JMC/Goodman
HYDROLOGY...JMC/Goodman


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