Area Forecast Discussion
Issued by NWS Upton, NY

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802
FXUS61 KOKX 202231
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
631 PM EDT Fri Oct 20 2017

.SYNOPSIS...
High pressure will be in control through the weekend before
moving offshore Sunday night through Monday night. A strong
cold approaches on Tuesday and moves across by early Wednesday.
The front slows down its eastward progress, staying close to the
region Wednesday into Thursday as weak low pressure develops
along the front. The front moves farther east away from the
region later Thursday into next Friday with weak high pressure
returning to the region.

&&

.NEAR TERM /THROUGH SATURDAY/...
Winds will continue subsiding this evening with loss of deeper
mixing and daytime heating. A dry atmosphere in place with no
clouds in sight amidst high pressure will create favorable
radiational cooling conditions tonight as the winds subside.
Despite radiational cooling, above normal temperatures will
continue with lows in the 40s across most areas and closer to
the low to mid 50s in urban areas and closer to the coast.

&&

.SHORT TERM /SATURDAY NIGHT/...
High pressure continues into Saturday with a subtle return
flow/weak WAA allowing unseasonable warmth. Highs will generally
be in the 70s, and may approach 80 degrees in northern NJ. Skies
will remain clear into the night, once again allowing
radiational cooling as winds relax. Temperatures and moisture
will be slightly higher than Friday night in a light onshore
flow.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
The jet stream will remain well north of the region with upper
level ridging Sunday through Monday. Clouds will be minimal
until Monday when an upper level trough will dig to the west of
the region and become amplified. There will be an increase in
meridional flow across the region. At the surface, high pressure
continues to move offshore during this period, increasing warm
and moist air advection.

Low levels look to become moist enough late Monday night into
early Tuesday for the development of patchy fog. The upper level
trough and jet stream dive toward the Southeast during this
time. The meridional flow increases further across the region.

For Tuesday, rain showers will expand and develop ahead of the
cold front. The southerly flow will increase to near 20 to 25
mph with higher gusts to near 30 to 35 mph possible. The
precipitable waters grow to near 1.8 inches according to the
GFS, which is slightly higher than what this model was showing
yesterday. This would be well above the 90th percentile
according to OKX sounding climatology. With parallel flow from
low to high levels, training of showers and thunderstorms will
be possible with potential for heavy rain. The thunderstorms are
only a slight chance with surface CAPE only a few hundred J/kg
so expecting these to materialize as a few embedded
thunderstorms within the heavy showers.

The cold front moves across Wednesday morning, with a
substantial decrease in precipitable water thereafter to much
below 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 approaching the region Wednesday
into Thursday, with rain shower chances continuing, highest for
Southeast CT and Eastern Long Island.

Chances for rain showers lower Thursday into Friday as the front
pushes farther east of the region. Did not trend down too fast
in case subsequent model runs are stronger with the low along
the front and trend closer to the region with the front. Weak
high pressure moves in Thursday into Friday next week.

Temperatures are expected to be well above normal Sunday through
Tuesday with a little decline thereafter to values closer to
normal. Highs Sunday through Tuesday are forecast to be well
into the 70s with lows trending to be well into the 50s to
lower 60s for some locations along the coast and NYC. The highs
are forecast to be more in the 60s for Wednesday through Friday
next week.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR through the TAF period as high pressure builds in from the
west through tonight, then begins to move offshore Saturday.

NW winds lighten tonight and shift to the N, or become nearly calm.
In the morning, light and variable winds shift to the S/SW under 10
kt in the afternoon.

   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: No unscheduled amendments expected.

KLGA TAF Comments: No unscheduled amendments expected.

KEWR TAF Comments: No unscheduled amendments expected.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
.Saturday night-Sunday...VFR.
.Sunday night-Monday...MVFR possible in stratus and fog.
.Tuesday...MVFR possible in showers. S wind G20-25 KT at coast.
LLWS possible.
.Wednesday...VFR. A chance of showers with areas of MVFR,
especially early.

&&

.MARINE...
NW wind gusts will continue subsiding this evening as high
pressure builds over the waters. The high will remain in control
through the late weekend, maintaining tranquil conditions
across the waters. Conditions stay below SCA Monday into Monday
night. Then southerly flow and fetch increase ahead of the cold
front Tuesday. SCA conditions more probable for all waters
Tuesday into Tuesday night, lingering for the ocean Wednesday
into Wednesday night with non- ocean waters trending below SCA
as cold front lingers offshore.

&&

.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.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...MD/JM
NEAR TERM...MD/DS
SHORT TERM...MD
LONG TERM...JM
AVIATION...MET/PW
MARINE...MD/JM
HYDROLOGY...MD/JM



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