Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 221124
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
724 AM EDT Sun Apr 22 2018

.SYNOPSIS...
High pressure will be in control through Tuesday, then give way to a
coastal low pressure Tuesday Night into Wednesday Night. Another low
pressure systems may affect the region Friday or Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Mean upper troughing lingers today, with trough axis crossing
the region this evening. At the surface, a surface trough
develops across the region this afternoon, pushing southeast
through the region this evening.

Mostly sunny, tranquil and seasonable Spring conditions today. With
airmass moderating about 1 to 2 degrees from yesterday, and
continued deep mixing, expect temps to be a degree or two
higher than yesterday. Highs generally in the lower 60s along
the coast and interior, although temps will likely drop back
into the 50s along the south coasts late this afternoon with sea
breeze development. While for NE NJ, NYC metro and surrounding
suburbs, temps should be able to rise into the mid 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
Trough axis slides offshore tonight, with shortwave ridging building
into the region through Monday Night and then offshore on Tuesday.
Meanwhile, an upper low over the southern Mississippi River Valley
today will slowly works northeast towards the Central Appalachians
through Tuesday. At the surface, high pressure will build overhead
tonight, and then gradually slide offshore Monday into Tuesday.
Meanwhile, southern low pressure begins to lift NE towards the
Mid Atlantic on Tuesday.

A clear and chilly night once again tonight. Areas of frost likely
across outlying areas with good radiational cooling to around
freezing. Elsewhere lows generally in lower 40s to mid 40s. A
continued moderation in airmass and moisture Monday Night,
should have temps slightly warmer, with a more patchy threat
for frost across far outlying areas.

Mostly sunny, tranquil and seasonable Spring conditions continue
Monday. With continued moderation of airmass and developing return
flow, temps across the interior should continue to moderate into the
mid to upper 60s. Meanwhile, along the coast, temps will likely hold
in the lower 60s with onshore flow and early sea breeze development.
Even NYC/NJ metro will sea breeze in this flow regime, which should
hold temps in the lower to mid 60s.

The influence of offshore high pressure should maintain another dry
day Tuesday. NAM is likely too aggressive with stratus
development during the day, but increasing late
afternoon/evening cloud cover seems likely. Despite mostly sunny
conditions to start, greater influence of a Canadian Maritime
airmass on Tuesday and continued onshore flow should have temps
dropping back to near or slightly below seasonable levels for
much of the region. Lower to mid 60s NW Interior, lower 60s
NYC/NJ metro to upper 50s across coastal areas.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Models continue in good agreement with the southern closed
upper low over the Tennessee River Valley Tuesday, opening and
lifting into the NE US through Wednesday in response to northern
stream shortwave energy moving into the upper Midwest/Great
Lakes. At the surface, resultant low pressure lifts towards the
region Tuesday Night into Wednesday, and then into New England
Wed Night. A soaking rain with breezy E/SE winds is expected to
develop across the area Tuesday night and continue into
Wednesday morning. Can`t rule out an isolated thunderstorm Wed
morning into early afternoon along/ahead of warm front with
weak elevated instability and forcing from approaching
shortwave energy and 50-60 kt llj. Best forcing/moisture move
NE Wed afternoon, with lingering showers late Wed into Wed Eve.

Thereafter, models still have some spread in the evolution of the
above mentioned Upper Midwest/Great Lakes trough, as its energy
splits N/S during the late week period. This is further complicated
by differences in evolution of the next northern stream shortwave
diving into the Great Lakes and Mississippi River Valley for late
week. The interaction between these two energies will determine
sensible weather for Fri into the weekend. At this point, it appears
there is potential for one or two progressive low pressure systems
to affect the region during this time, but predictability on details
is low. Will continue with low chance of showers in the forecast
during this time to denote the potential.

As for temperatures, much of the period will feature seasonable
temperatures with the exception of Wednesday, where onshore flow
will keep highs several degrees below normal.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VFR conditions continue as high pressure continues to build across
the region through the TAF period.

Winds will be initially NW-N at 5-10 kt this morning with sea
breezes developing late morning into the afternoon. Some
afternoon to early evening gusts to near 15 kt are forecast but
expecting these to be occasional. Another daytime trough within
the region will make the wind direction forecast uncertain this
afternoon into this evening along with the timing of the sea
breeze.

Higher confidence of sea breezes and their forecast timing at KJFK,
KLGA, KBDR, KGON, and KISP but less confident with KEWR, KTEB, KHPN.
KSWF will remain with NW flow. Expecting the sea breeze to form
late this morning along CT terminals, then KJFK, and then KLGA,
KEWR, KTEB, KHPN.

Winds become light and variable tonight with wind speeds of near 5
kt or less.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday through Tuesday...VFR. Local enhancement to winds late
Monday afternoon at KJFK with SE winds 10-15KT gusts near 20KT.
More SE winds 10-15KT gusts near 20KT for Tuesday afternoon.
.Tuesday night through Wednesday...MVFR or lower increasingly likely
with rain. SE winds 10-15KT gusts near 20KT Tuesday evening. E winds
near 10-15KT, with gusts near 20KT on Wednesday. Gusts subside
by late Wednesday afternoon.
.Thursday...Chance of showers with MVFR possible. SW-W gusts to 20KT
possible.

&&

.MARINE...
Sub-SCA conditions expected through Tuesday with high pressure in
control and a weak pressure gradient. Although there is
potential for 15 to 20 kt gusts in late day sea breezes across
NY Bight and surrounding nearshore waters late this afternoon
and perhaps late Monday afternoon.

Low pressure moving up the eastern seaboard Tuesday into Wednesday
will result in strengthening easterly winds and building seas
Tuesday Night, with SCA conditions likely to returning late
Tuesday Night into Wednesday morning.

Winds likely subside below SCA late Wed into Wed Eve as low
pressure moves over and then NE of the region, but ocean seas
may remain elevated a SCA levels into late week from residual
SE swells.

&&

.HYDROLOGY...
Dry conditions are expected through Tuesday.

A widespread 1/2 to 1 inch of rain is expected Tuesday Night
into Wednesday, but no hydrologic issues are anticipated at this
time.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off
the air.

&&

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

&&

$$
SYNOPSIS...NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...NV
AVIATION...JM
MARINE...NV
HYDROLOGY...NV
EQUIPMENT...



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