Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 190021
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
821 PM EDT Tue Apr 18 2017

.SYNOPSIS...
High pressure moves east over the Atlantic tonight. A cold
front approaches on Wednesday and stalls over the region from
Wednesday night into Thursday. The front returns as a warm front
Thursday night moving through on Friday. A cold front passes
through late Friday. High pressure builds Friday night into
Saturday. Low pressure to the southwest may affect the area
early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.

The axis of a deep layered ridge slides offshore tonight,
allowing for some cirrus to build in behind it. Also monitoring
area of marine stratus to the SE of Long Island, as the SE low
level flow should bring scattered clouds onshore overnight.
Overall, a gradual increase in cloud cover, with areas becoming
partly to maybe even mostly cloudy overnight.

Lows temperatures are forecast close to the slightly cooler GFS
MOS based on a clear sky for a good portion of the night.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Clouds increase through the day on Wednesday. Have kept it dry
through 6 PM. This based on consistency of the short range NWP.
Higher GFS MOS used for highs which is still nearly 10 degrees
cooler than today and actually below seasonable which is around
60. SE flow off the Atlantic persists.

Cold front gradually slides across the region overnight and with
that the likelihood for period or two of light rain. Too stable
to call it showers. Key is for light amounts with QPF only a
few hundredths.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Weak ridge flattens ahead of a shortwave that will pass across the
Great Lakes region Thursday. A sfc warm front remains near or sags
just south of the area Thursday. Light rain is possible, especially
in the morning with the front in the general vicinity. The global
and NWP models suggest drier conditions return during the afternoon.

By Thursday night, the shortwave passes to the north across northern
New England, with a sfc low doing the same. The warm front makes
progress Thursday night tracking from SW to NE late at night and
Friday morning. Rain chances increase during this time, and cannot
rule out thunder due to instability noted aloft. Maintained fog
mention as the warm front approaches. The showers move northeast,
with drier weather to follow as a cold front passes late in the day
Friday, and the warm front lifting well to the northeast. Maybe a
shower with the cold front, but rain chances appear to be low.

Dry conditions are anticipated late Friday night into Saturday,
depending on how far the front passes east. Then attention turns
toward upstream trough, and eventual sfc low that moves across the
TN Valley and off the Mid Atlantic coast during the latter portion
of the weekend and into early next week. Still some questions in
eventual placement of several weak lows riding along a frontal
boundary. This boundary should set up south and east of the area,
but a little too close to not include chance pops for rain.

Temps may rise slightly above normal Thursday, with the usual higher
readings across the interior, and lower further east along the coast
due to onshore winds. The same temps gradient is expected Friday,
although likely warmer as the area sits in the warm sector during
the afternoon. Behind a cold front, temps fall back to near or
slightly below normal for the weekend and into early next week as
the area remains to the north of a frontal boundary.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
High pressure over the Canadian Maritimes will slowly move east
through Wednesday as low pressure tracks across SE Canada while
its attending warm front lifts through New England.

VFR conditions expected through the first part of tonight.
Guidance is indicating the development of MVFR cigs after
06z...although there is uncertainty in when/where and whether
it stays in once it comes in. There is some indication that it
could be patchy and SCTvBKN. It is also the first night of
onshore flow...which also typically isn`t conducive to
widespread stratus. The best chance for MVFR ceilings appears to
be between about 10Z-15Z. VFR conditions then return for the
remainder of the TAF period.

SE winds around 10 kt will diminish to 5-10 kt overnight, then
return at 10-15g15-20kt late Wednesday morning. Any remaining
15-20kt gusts this eve should be ocnl through 02z or so.

     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: Uncertainty in timing and extent of MVFR
cigs during the morning push.

KLGA TAF Comments: Uncertainty in timing and extent of MVFR
cigs during the morning push.

KEWR TAF Comments: Uncertainty in timing and extent of MVFR
cigs during the morning push.

KTEB TAF Comments: Uncertainty in timing and extent of MVFR
cigs Wed morning.

KHPN TAF Comments: Uncertainty in timing and extent of MVFR
cigs Wed morning.

KISP TAF Comments: Uncertainty in timing and extent of MVFR
cigs Wed morning.

.OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
.Wednesday night-Thursday night...MVFR likely, IFR possible with
a chance of rain.
.Friday...IFR possible early, then improvement to at least MVFR.
Chance of showers and thunderstorms.
.Friday night-Saturday...VFR.
.Sunday...MVFR with rain possible.

&&

.MARINE...
Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.

A developing persistent E-SE flow of around 15 KT that increases
seas on the ocean to near 4 ft on Wednesday...still below SCA
levels. These conditions should persist into Wednesday night.

Winds remain rather light as a warm front remains just south of the
waters on Thursday. The warm front lifts to the north by
Friday, as E/SE winds shift to the S. Behind a cold front, winds
shift to the W/NW, and should increase somewhat. However,
believe winds remain below 25 KT, or SCA thresholds. Winds then
shift around to the N, then E/NE over the weekend as low
pressure and a frontal boundary move and setup to the south and
east, with high pressure well to the N.

Seas generally remain under 5 Ft on the ocean waters until possibly
later this weekend as E/NE winds prevail.

&&

.HYDROLOGY...
At this time, no hydrologic concerns are foreseen for the next
7 days.

&&

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

&&

$$

SYNOPSIS...Tongue
NEAR TERM...Maloit/Tongue
SHORT TERM...Tongue
LONG TERM...PW
AVIATION...24
MARINE...Maloit/Tongue/PW
HYDROLOGY...Tongue/PW



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