Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 260230

Area Forecast Discussion
National Weather Service New York NY
1030 PM EDT Fri May 25 2018

High pressure remains off the southeastern coast into Saturday
morning. A back door cold front moves through late Saturday
afternoon into Saturday night, then becomes nearly stationary
south of the waters through Memorial Day. Another cold front will
move through from the north on Tuesday, followed by high pressure
building in through the middle of next week. A storm system
should then impact the region for the end of next week.


Minor changes were made with this update to reflect the latest
trends in observations and guidance. The forecast appears on

The region remains on the NW periphery of the sub-tropical ridge
overnight. Early Saturday morning, a northern shortwave moves
out of the upper midwest, and an eastern Canada trough begins to
dig into northern New England. This will only bring an increase
in high clouds to mainly western zones late.

An unseasonably mild airmass will remain in place overnight,
with lows possibly not falling below the 70 degree mark in parts
of NYC.

There is a moderate risk for rip currents tonight at area
Atlantic Beaches.


During Saturday the flow will remain nearly zonal as the
northern stream shortwave moves through the flow, and into the
region by late Saturday afternoon. Meanwhile, the eastern
trough and building high pressure over Hudson Bay will push a
back door cold front into the region by late SAturday. The
combination of the shortwave and cold front will bring a chance
of showers and thunderstorms by late in the day. Mixed layer
CAPE and surface instability increases and remains into Saturday
evening, AS a warm and increasingly humid airmass remains, so
will have thunder into the evening. Instability and CAPE quickly
decrease toward 04Z and will have showers with a chance of
thunder. Then by late Saturday night, with the cold front
through the region will mention just showers.

There is a moderate risk for the meteorological enhancement of
rip current beaches at Atlantic Beaches from Saturday into
Saturday evening.


Sunday remains a question mark at this time. Both the NAM and
ECMWF allow high pressure over the Maritimes to erode
precipitation chances from N to S through the day
substantially. The GFS output indicates essentially a rainy day,
at least through 2pm or so. Pops were unchanged, ranging from
likely in the morning to chance in the afternoon. If the drying
trend continues in the data however, these will be pulled back
in subsequent forecasts. The high looks to produce dry weather
on Monday. The guidance has trended up with temperatures as a
result. A warmup on Tuesday as upper level ridging builds in,
but a backdoor cold front comes through in the afternoon or
evening. The GFS is the wet model yet again, but the weather
has been kept dry until a model consensus builds. High pressure
and dry weather on Wednesday, then a warm front and possible
low pressure system for late Thursday and Friday. Chances for
showers and thunderstorms have been included in the forecast.
There could be a connection to Alberto moisture, so if this does
occur, locally heavy rain will be possible.


High pressure will move further offshore tonight into Saturday. A
back door cold front approaches late Saturday and moves through
Saturday night.

Mainly VFR through the TAF period. SW winds will continue to
diminish below 10 kt tonight and become light and variable
outside of city terminals. SW winds will increase in the morning
and afternoon to around 10 kt on Saturday.

There is a chance of thunderstorms late Saturday afternoon into
Saturday evening, mainly from NYC terminals on north and west.
Showers become more likely after 00z with possible MVFR.

.Saturday Night...Showers likely with a chance of thunderstorms.
MVFR developing late.
.Sunday...IFR in the morning, becoming MVFR in the afternoon.
Showers likely through early afternoon.
.Monday...MVFR possible.


Minor changes were made with this update to reflect the latest
trends in observations and guidance. The forecast appears on

Sub-Small Craft Advisory (SCA) conditions are expected on all
waters around Long Island overnight, with winds generally 10 kt
or less on the non-ocean zones and 15 kt or less on the coastal
ocean waters (with gusts up to around 20 kt).

Saturday and Saturday night winds and seas will remain below
small craft levels with a weak surface pressure gradient force.

Winds are expected to remain below SCA levels Sunday-Wednesday.
5 ft seas are possible from Sunday into Monday on the ocean
with NE flow.


Dry through Saturday morning.

From 3/4 to 1 inch of rainfall is likely from late Saturday
afternoon through Sunday night. Heavy rainfall is a possibility
Saturday night with locally higher amounts possible. Minor urban
and poor drainage flooding will be possible Saturday night.

No significant hydrologic impacts are anticipated Sunday-
Thursday. There is a low potential for locally heavy rain from
Thursday night through Friday.


Water levels may be near minor flood thresholds along the south
shore back bays of Nassau County and in western Long Island
Sound with the Sunday afternoon and evening high tide cycle.
Forcing for increased water levels will be increasing E-NE flow
as a front stalls to the south and strong high pressure sets up
E of New England, along with increasing astronomical high tides
with the full moon on Tue the 29th.


NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.




NEAR TERM...Maloit/19
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