Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 160943
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
543 AM EDT Mon Jul 16 2018

.SYNOPSIS...
High pressure remains offshore today and tonight. A cold front
will approach from the west on Tuesday and move through Tuesday
night. A weak surface trough will linger on Wednesday, then high
pressure will build across on Thursday, and pass east on Friday.
Low pressure and an attendant warm front will slowly approach
from the south this weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast is on track with only minor changes made.

A typical summer time Bermuda high pressure type system will be
in place off the East Coast for Monday, which will continue to
pump in heat and humidity on a southerly flow. Temperatures will
rise into the upper 80s to lower 90s while dew points rise into
the lower 70s. This will produce heat index values of 95-99
today.

Upper level ridge will move in from the west today. This will
help to limit the development of showers and thunderstorms in
the morning. POPs have been cut back to only a slight chance
starting at 9 am, mainly across northeast New Jersey, the Lower
Hudson Valley and southwestern Connecticut. It is possible that
any showers and thunderstorms may hold off until after 11 am or
thereafter. As the ridge progresses east, the chances for
showers and thunderstorms increases for wester areas such as
northeast New Jersey, the Lower Hudson Valley, and southwest
Connecticut. Sea breeze development may stabilize coastal
areas, and therefore, only chance of showers are possible here
from late morning onward.

There is a moderate risk of rip currents for the ocean beaches
today.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A warm and humid air mass will remain in place as the high
pressure remains off shore. With clouds increasing, temperatures
will not drop much, 70s region-wide. Some upper 70s are possible
in the New York City metro area.

The chances for precipitation will decrease somewhat overnight,
especially for northeast New Jersey, the Lower Hudson Valley,
and southwest Connecticut as the sun sets and those areas lose
diurnal heating.

Tuesday will see POPs continue to increase as the cold front
slowly moves through. There will be a chance for heavy rain
associated with the frontal passage. PWATs are near 2.50", which
is very high for this time of year given climatology. So
although storm total precipitation is around an inch, some
isolated areas may receive upwards of two inches. This could
lead to some urban and small stream flooding. Widespread flash
flooding looks unlikely as much of the tri-state has been
relatively dry lately. In fact, New London County is in a DO in
the US Drought Monitor.

Associated upper level trough will approach Tuesday. With dew
points in the 70s region-wide, instability will increase despite
clouds cover. Most unstable CAPE values in the NAM are showing
2000 J/kg. The cold front could produce enough of a lifting
mechanism to produce some strong to severe storms. 0-6 km shear
will be 25-35 kt. This has prompted the Storm Prediction Center
to put much of our CWA in a marginal risk for severe storms
where the primary threat would be strong winds.

Temperatures will not be as warm on Tuesday as Monday, given
clouds and precipitation, but it will remain very humid. Heat
indices of 95-99 are still possible for the New York metro area,
and Heat Advisories will continue here based on 2 consecutive
days. However, for Nassau and the Lower Hudson Valley, heat
indices are forecast to remain below 95-99 on Tuesday.
Therefore, the Heat Advisory for those areas have been
cancelled.

The cold front will move through Tuesday night and winds will
shift to the northwest. Dew points will drop into the lower to
middle 60s by sunrise Wednesday for much of the area, with some
lingering showers and thunderstorms for eastern areas.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
After the sfc cold front moves east on Wed, a sfc trough will linger
mainly over Long Island and CT, while a wave of low pressure along
the front passes well to the SE. With low level convergence/moisture
pooling and the upper trough still off to the west to provide
forcing, think SE CT and E Long Island could still see isolated to
scattered tstms through the day on Wed, and perhaps into Wed
evening. High pressure should then build in and remain into at least
Friday. possibly Saturday per slower 00Z ECMWF.

For later this weekend, an upper trough will dig into the OH Valley,
with downstream ridging amplifying in response over the western
Atlantic and up into the Canadian Maritimes. Some phasing with
leftover mid level vort maxima from an old frontal zone over the NE
Gulf of Mexico and SE coast may take place, which would draw a weak
sfc low and attendant warm front up the coast. Ignored entertaining
but very unlikely 00Z GFS solution showing a compact low of
subtropical origin riding up the coast on Sunday. Still, warm fronts
at this time of year can have their surprises in terms of heavy rain
and severe weather, so this could bear some watching as we go into
early next week.

Temps through the period should be right around seasonal averages.
Humidity levels remaining relatively comfortable through at least
Fri and possibly Sat, then conditions become muggy by Sunday as
dewpoints increase to near 70.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
High pressure will drift offshore today.

Mainly VFR, with local MVFR or IFR visibility in fog early this
morning outside NYC metro. By afternoon, local MVFR conditions are
possible in isolated thunderstorms, mainly NW of NYC metro.

The isolated thunderstorms diminish this evening.

Winds will be light SW/W in the NYC metro area early this morning,
and light and variable to calm at the outlying terminals. A south
flow develops this morning, increasing to 10-15 KT in the afternoon.
S/SW winds persist this evening and lighten somewhat.

     NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: Light W/SW winds will become south, and timing of
wind shift and wind speed increase could be off an hour or two.

The afternoon KJFK haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KLGA TAF Comments: Light W/SW winds will become south, and timing of
wind shift and wind speed increase could be off an hour or two.

The afternoon KLGA haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KEWR TAF Comments: Light W/SW winds will become south, and timing of
wind shift and wind speed increase could be off an hour or two.
Low chance for a thunderstorm late this afternoon.

The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Light W/SW winds will become south, and timing of
wind shift and wind speed increase could be off an hour or two. Low
chance for a thunderstorm late this afternoon.

KHPN TAF Comments: Low chance for a thunderstorm late this afternoon.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.Late tonight...Mainly VFR, although patchy fog possible.
.Tuesday...Afternoon and evening showers/tstms likely with MVFR
or lower conditions. S winds G20-25KT into early evening.
.Wednesday...VFR. A slight chance of showers in the morning east
of the NYC terminals, with MVFR possible.
.Thursday-Friday...VFR.

&&

.MARINE...
Waves build to 4 ft on the ocean waters tonight and to near 5 ft
on Tuesday on a southerly flow out ahead of an approaching cold
front. Waves diminish on Tuesday night. Winds may approach 25 kt
on the ocean waters Tuesday ahead of the cold front, but right
now it looks marginal and will hold off on issuing a Small Craft
Advisory.

No long term issues foreseen as high pressure builds across later
this week.

&&

.HYDROLOGY...
Showers an thunderstorms may be capable of producing locally
heavy rain, with potential for minor localized flooding, mainly
late tonight into Tuesday. Urban and poor drainage flooding will
be possible. Storm total rainfall of around an inch is forecast
with two inches possible in isolated spots.

&&

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

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from noon today to 6 PM EDT Tuesday for
     NYZ072>075-176-178.
NJ...Heat Advisory from noon today to 6 PM EDT Tuesday for NJZ004-
     006-103>108.
MARINE...None.

&&

$$
SYNOPSIS...Goodman/JP
NEAR TERM...JP
SHORT TERM...JP
LONG TERM...Goodman
AVIATION...PW
MARINE...Goodman/JP
HYDROLOGY...Goodman/JP
EQUIPMENT...



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