Area Forecast Discussion
Issued by NWS Upton, NY-- Remove Highlighting --
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FXUS61 KOKX 301540
Area Forecast Discussion
National Weather Service New York NY
1140 AM EDT Sun Apr 30 2017
High pressure building into New England slowly moves east of the
area through tonight. A warm front moves northward through the
area tomorrow morning, followed by a cold front moving in from
the west Monday night and passing through the area by Tuesday
morning. High pressure builds in briefly for the middle of the
week. An area of low pressure will bring unsettled weather for
the end of the week into the weekend.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Warm advection coupled with instability above 850 mb has
resulted in a few showers this morning across the Lower Hudson
Valley. Will keep mention through early this afternoon until
drier air aloft stabilizes the airmass. Isolated thunder is also
a possibility. Anything that does develop should be brief.
Temperatures have also been adjusted up several degrees based
on latest obs/trends. This is due to the cold air filtering in
slower behind the cold frontal passage this morning. Highs will
be around 60 and should level off late this morning, if not
begin to fall with the ongoing low-level cold advection.
A surface high will continue to build into New England beneath
a building upper high. Onshore flow gradually develops by
afternoon, with a strengthening low-level inversion and
increasing cloud cover through the day.
Highs will be much cooler than yesterday, even a few
degrees below climatological normals, follow this morning`s cold
frontal passage and with the afternoon/evening onshore flow and
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Continued onshore flow will lead to low-level saturation, with
increasing chances for light drizzle through the evening and
into Monday night, particularly as warm advection strengthens
ahead of the returning/modified cold front. Low temperatures
will be closer to climatological normals. The warm front is
expected to move north of the area by morning/early afternoon
with brief clearing possible behind the front. Meanwhile, the
upper high off the southeast coast will gradually shift eastward
ahead of a closed upper low. At this time, there is no clear
signal for a pre- frontal trough, though there is a possibility
of a convectively induced vorticity maximum moving through the
area ahead of the main upper trough that may be sufficient
enough to produce isolated afternoon thunderstorms, primarily
north and west of the city. Afternoon highs largely depend on
how quickly the warm front moves through and how much clearing
can occur following its departure, though highs will likely be
much warmer than Sunday.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The cold front moves through from west to east Monday night,
with rain and isolated thunderstorms clearing the area by
Tuesday morning. Low temperatures will be mild amidst cloud
cover and south flow, generally 5 to 10 degrees above
climatological normals. Flow becomes more westerly following the
frontal passage for Tuesday, and despite cold advection the
westerly component will be favorable for downslope warming which
may keep high temperatures a few degrees above guidance. Expect
above normal highs for Tuesday. By Wednesday, a subtle upper
trough and attendant cold front pass through the area by
afternoon/evening, with a reinforcement of cold advection and
temperatures closer to or slightly below normal. By late week,
upper difluence ahead of a developing system across the central
US will support moisture advection along the east coast and the
intensification of a surface low across the Southeast that will
gradually traverse northeastward into the region, leading to a
period of unsettled weather into the weekend.
.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
High pressure centered off the New England coast and extending into
the terminals will remain nearly stationary into this afternoon,
then begin to drift offshore late this afternoon and tonight. A warm
front will approach from the southwest tonight.
VFR until around 23Z then MVFR conditions develop. IFR conditions
are likely by late evening, 04Z, at all but KSWF and KGON, where
they should develop after midnight. Airport minimums for ceiling
and/or visibility could possibly be reached late tonight/early
Winds continue to veer around to the E this morning, with speeds
generally around 10 KT up to 13 KT. Winds veer to the E-ESE this
afternoon. Occasional gusts 15 to 20 KT are possible late this
morning and this afternoon. Winds become light and variable late
.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday...IFR or lower likely through morning, with a chance
for improvement to MVFR or VFR in the afternoon.
.Monday night...IFR or lower conditions, LLWS and scattered
thunderstorms are possible.
.Tuesday-Wednesday night...VFR. SW-WSW winds G15-20KT possible
Tuesday. W-NW winds G15-25KT possible Wednesday/Wednesday
.Thursday...MVFR or lower conditions developing is possible.
A moderate pressure gradient over the waters through Monday
morning will result in winds of 15 to 20 KT. The pressure
gradient increases Monday afternoon with gusts up to 25 KT.
A persistent onshore flow will build seas to 5-6 ft over
southern portions of the coastal ocean zones on Monday as well.
The winds increase on Monday night, with solid Small Craft
conditions on the coastal ocean waters. As a result, have issued an
SCA for the coastal ocean waters for Monday and Monday night. On the
non-ocean waters Monday night, gusts to small craft levels possible,
but given limited mixing, confidence is not high enough to warrant
headlines at this time.
From Tuesday into Tuesday night, all waters likely will experience
SCA conditions with gusts of 25-30 KT.
The pressure gradient relaxes to light to moderate again by
Wednesday, and remains so through Thursday, limiting winds to 15 kt
or less. SCA level seas should linger on the coastal ocean waters
into Wednesday, then possibly return again by late Thursday ahead of
the next storm system.
No hydrologic impacts are expected through the forecast period.
MARINE...Small Craft Advisory from 6 AM Monday to 6 AM EDT Tuesday for