Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 221913

Area Forecast Discussion
National Weather Service New York NY
313 PM EDT Sun Apr 22 2018

High pressure will be in control through Tuesday. Low pressure
then approaches Tuesday night and passes to the northeast
Wednesday. Another low pressure system may impact the region
Friday or Saturday.


Deep-layered ridging with a surface high axis over us will result in
clear conditions with light to calm winds. Areas of frost will be
likely with these good radiational cooling conditions, mainly across
eastern Long Island and the northernmost suburbs. A MAV/NAM MOS
blend was used for low temps.


High pressure slowly shifts east of the region Monday into Monday
night, but ridging remains aloft. Mostly clear conditions through
the period along with seasonable temperatures, although some areas
west of the Hudson and away from a SE flow will have highs in the
upper 60s. Some frost should return late at night across eastern
Long Island, SE CT, and parts of the Lower Hudson Valley.


Complex pattern this time frame, with several features to watch.

Initial shortwave lifts slowly northeast, with sfc low along the
coast tracking northeast toward the area Tuesday and Tuesday night.
General model agreement noted with this mid week system.

Clouds will be on the increase Tuesday with dry weather through much
of the day. Then rain moves in Tuesday night and continues into
Wednesday as the low draws near, and warm front lifts toward the
area. Northern stream shortwave dives out of Canada, phasing with
the trough over the northeast Wednesday. The sfc low lifts northeast
Wednesday, and drier air should advect east across the area behind
the system as the shortwave and low pulls further to the northeast
Wed night into Thursday.

Then, next southern stream shortwave passes across the southeast
states, with downstream northern stream shortwave moving quickly
east Thursday and into Friday. The question is how these two
features interact late in the week. If they phase, could see a
larger trough developing late in the week and into next weekend. The
sfc low likely will deepen as it lifts northward, dragging a cold
front through. But, not all model/ensemble members show this
scenario, which leads to forecast uncertainty, especially with exact
details during the late week and weekend time frame.

In general, wet weather Tue night/Wednesday, followed by drier
conditions Wed night and Thursday. Unsettled thereafter (except
mainly dry Thu night into Friday), and will maintain slight chance
or chance pops given the uncertainty and timing of strength of the
aforementioned upper features.

Seasonable temperatures are anticipated for much of the period,
except Wednesday. This would be the cooler day due to clouds, rain
and gusty onshore flow ahead of the low.


VFR conditions through the TAF period with high pressure in control.

Sea breeze continues to slowly progress inland this afternoon. Winds
at KLGA will vary under 10 kt this afternoon. Timing of sea breeze
passage at KLGA may be off 1-2 hours. Confidence the sea breeze will
pass across KEWR and KTEB is lower and it may not pass until early
evening when winds diminish.

KSWF will remain with NW flow and this is possible across KHPN as

Winds become light and variable tonight before becoming SE 5-10 kt
Monday morning and early afternoon.

.Monday Afternoon-Tuesday...VFR. SE gusts 20 kt possible near the
coast on Tuesday.
.Tuesday Night-Wednesday...IFR becoming likely with rain. SE gusts
near 20 KT Tuesday night. E gusts 20-25 KT on Wednesday morning.
.Thursday-Friday...Mainly VFR. Shower Possible.


Sub-SCA conditions expected through Tuesday with high pressure in
control and a weak pressure gradient. There is, however, a potential
for 15 to 20 kt gusts in sea breezes across NY Bight and surrounding
nearshore waters early this evening and late day/early evening

Low pressure moves up the eastern seaboard Tuesday into Wednesday.
Strengthening easterly winds and building seas are forecast across
the waters Tuesday night into Wednesday morning.

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


A widespread 1/2 to 1 inch of rain with locally higher amounts, is
expected Tuesday night into Wednesday. No hydrologic issues are
anticipated at this time.


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




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