Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 291344

Area Forecast Discussion
National Weather Service New York NY
944 AM EDT Sat Apr 29 2017

A weak front moves through the area this evening, with high
pressure briefly returning for Sunday. A warm front will then
move northward through the area on Monday, followed by a cold
front from the west Monday night into early Tuesday morning.
Weak high pressure will return for the remainder of Tuesday into
Wednesday. A frontal system approaches from the southwest
Thursday and moves along the coast through late week.


The thunderstorm complex has moved east of the area early this
morning, and no additional convection is expected as a weak
frontal boundary remains in the vicinity. Best forcing and
instability will be to the south of the region. So will keep
balance of the morning and through much of the afternoon dry.

By afternoon, a few gusty winds will be possible, along with a
steady increase in mid-upper level clouds. West downslope flow
with little marine influence will aid in well above normal
temperatures. A few record highs will be possible outside of
the NYC metro.


A few showers and thunderstorms may approach portions of
southeastern NY and northern NJ late in the evening, but
otherwise dry conditions are expected. As the cold front
gradually moves south of the area, flow will turn more north-
northeasterly leading to a low-level inversion and the potential
for more cloud development keeping low temperatures slightly
above climatological normals. The upper ridge centered off the
southeast coast will build northward through the Sunday, and in
combination with the onshore flow should act to strengthen the
low-level inversion. A general lack of overall forcing for
ascent along with the inversion should limit
precipitation/thunderstorm chances, though if low-level cloud
cover thickens sooner than forecast some light drizzle will be
possible. Daytime temperatures will be cooler than Saturday,
with highs closer to climatological normals.


Onshore flow will continue into Monday morning, with increasing
chances of light rain and/or drizzle with a developing stratus
deck. By afternoon, a warm front will move through the area with
skies briefly clearing from south to north ahead of an
approaching cold front. The front moves through Monday night
with rain and a chance of thunderstorms giving way to clearing
skies, gusty west winds and seasonable temperatures by Tuesday
afternoon. The gusty west flow and cooler temperatures will
continue into Wednesday as a secondary trough of low pressure
moves through. By Thursday, divergence aloft associated with an
elongated mid-upper low across the central US will aid in the
development of an attendant surface low across the Southeast
that will gradually move northeastward through Friday. The
prolonged period of south-southwest flow will advect moisture
into the region, with increasing chances for precipitation
through the weekend.


A weak front pushes through the area today, followed by high
pressure building down from Southeastern Canada through tonight.

Mainly VFR through the TAF period, with a short period of
MVFR/IFR conditions at the coastal terminals this morning.

Winds become SW-WSW around 10kt by mid morning. The winds
continue to veer to the W-WNW with gusts around 15-20kt by
around midday. By late afternoon/early evening the winds become
NW. Wind gusts should abate by around 00z, with wind speeds
falling to under 10kt. Winds continue to veer to the N then NE
tonight with speeds under 10 kt. Most terminals will become
light and variable for at least a few hours overnight.

.Sunday morning...VFR.
.Sunday afternoon-Monday....MVFR or lower possible. SW winds
G15-20kt possible Sunday afternoon. LLWS possible Sunday night
mainly at southern terminals.
.Monday night...IFR or lower conditions, LLWS and scattered
thunderstorms are possible.
.Tuesday-Wednesday...VFR. SW-WSW winds G15-20KT possible
Tuesday. W-NW winds G20-25KT possible Wednesday.


Forecast remains on track with winds and seas.

A weak to moderate pressure gradient force over the region
through Monday will limit winds to 15 kt or less, with gusts of
20 kt or less. One of those periods of 15G20KT winds this
afternoon and evening will bring seas on the coastal ocean
waters east of Fire Island Inlet to around 5 ft (mainly 10 or
more miles from shore). A small craft advisory for hazardous
seas remains in effect for the coastal ocean waters east of Fire
Island Inlet from noon today through midnight tonight.

The pressure gradient increases Monday night, with 25-30kt
gusts possible. These winds will build ocean seas to 4-8 ft
Monday night. However, even with 40-50kt of winds at 950 hPa
Monday night/early Tuesday morning, will have to strong of a
marine inversion for much if any of that to mix down, so gales
are not expected then.

Winds should be 15 kt or less Tuesday and Wednesday, with a light to
moderate pressure gradient over the waters. However, seas on the
coastal ocean waters should be slow to come down, and could remain
at or above 5 ft into Wednesday, especially over the southern
portions of the coastal ocean zones.


No hydrologic impacts are expected through Thursday.

A low pressure system approaching from the southwest may lead to
periods of heavy rain and the potential for hydrologic impacts late
next week into the weekend.


MARINE...Small Craft Advisory for hazardous seas until midnight EDT
     tonight for ANZ350-353.


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