Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 201113
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
713 AM EDT Sun May 20 2018

.SYNOPSIS...
A cold front slowly crosses the area today. High pressure will
briefly build into the region tonight and Monday, before a weak
frontal system affects the area from late Monday night into
Wednesday. High pressure returns to close out the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Weak shortwave axis crosses the region this morning, with
another weak shortwave approaching late in the day. Meanwhile a
stronger northern stream shortwave passes through Quebec today.
At the surface, a weak cold front slowly passes through the
region this aft/eve.

Areas of fog, locally dense, should gradually improve through
the morning hours as SW winds begin to pick up. The fog will
likely linger longest across coastal SE CT and Eastern LI.

A few showers expected as the vort axis moves through this
morning, then subsidence in wake of the morning vort axis should
allow for some breaks of sun from w to e late this morning into
the afternoon.

Sct showers and iso tstms are expected to develop along the
cold front, to the NW of the NYC metro, in a marginally unstable
airmass early this afternoon. This activity should traverse
eastward through through the afternoon. Some uncertainty on
extent of convective coverage with subsidence in wake of morning
convection and late approach of next piece of shortwave energy.
With marginally strong deep layer shear, a conditional isolated
strong thunderstorm with strong wind gust is possible with if
pockets of higher instability develop. Expectation is for
convection to weaken as it moves eastward towards the coast in
the late aft/eve due to maritime influence.

Temperatures today will be above seasonable, well into the 70s,
except lower 80s for NYC/NJ metro.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
A couple of shortwaves move east through Quebec tonight, with
zonal upper flow developing across the region into Monday. At
the surface, high pressure builds into the region through
Monday.

Clearing conditions expected tonight, with mostly sunny
conditions on Sunday. Temps tonight will be near seasonable,
with highs on Monday a few degrees above seasonable levels.
Highs generally in the mid to upper 70s, except lower 70s across
south coasts with afternoon seabreeze development.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The upcoming week looks to be relatively benign with a weak
frontal system impacting the area late Monday night into early
Wednesday. There are some small timing differences with the
global models with both the onset of warm advection rain Monday
night and the possibility of scattered convection lingering
into Wednesday as the airmass change behind a cold front is
subtle. This does not look to be a significant rainfall event.
Additionally, while the westerlies and an upper trough will
remain across the area through midweek, the instability at this
time looks to be only marginal.

The second half of the week will feature building heights aloft
as the trough works offshore, resulting in dry weather and
above normal temperatures.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A cold front passes late this aftn.

Cigs and vis improve to vfr today, however some lifr can be
expected mainly n and e of the nyc arpts thru 13-14z. Sct shwrs
and tstms are possible in the aftn invof the cold front. Vfr
tngt.

Sw flow today becomes nw behind the front. Speeds will increase
aft 14z, with speeds then diminishing aft 00z.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday...Vfr with light s winds.
.Tuesday-Wednesday...Most likely VFR with low chance of MVFR in
any shower. S winds G15-20kt possible Tuesday afternoon.
.Wednesday night-Thursday...VFR. N-NW winds G15-20KT possible.

&&

.MARINE...
Dense fog should improve across western nearshore waters
through daybreak, but may take until mid to late morning across
the ocean waters and eastern nearshore waters with moist sw flow
over cool waters.

Marginal SCA conditions are expected across the coastal ocean waters
into tonight, with sub small craft conditions expected elsewhere.

A weak gradient is expected Monday through Wednesday, keeping all
waters below Small Craft Advisory levels.

&&

.HYDROLOGY...
No widespread significant hydrologic issues are anticipated
through early next week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Dense Fog Advisory until 11 AM EDT this morning for ANZ330-340-
     345-350-353-355.
     Dense Fog Advisory until 8 AM EDT this morning for ANZ335.
     Small Craft Advisory until 11 PM EDT this evening for ANZ350-
     353-355.

&&

$$
SYNOPSIS...NV/DW
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...DW
AVIATION...12
MARINE...NV/DW
HYDROLOGY...Fig/NV/DW



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