Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 131451
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1051 AM EDT Thu May 13 2021

.SYNOPSIS...
High pressure continues to build in from the west today, and
will dominate the weather pattern through the middle of next
week. A weak trough of low pressure moves through the region
Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
For this update, made some changes to cloud cover based on the
latest satellite obs. Minor changes made to hourly temperatures
and dewpoints as well. The forecast is otherwise on track.

An upper trough remains today with surface high pressure over
the upper midwest and Ohio Valley building slowly east through
the day. With weak subsidence and a rather dry atmospheric
column only some fair weather cumulus are expected. Temperatures
will be near seasonal levels.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Tonight the high remains in place as the upper trough begins to
weaken as heights slowly rise. Winds will decouple and with
nearly clear conditions good radiational cooling will set up.

Friday weak upper ridging builds into the area as the surface
high remains in place. An afternoon and early evening surface
trough develops. With weak lift and some surface based CAPE
isolated showers and thunderstorms will be possible.
Temperatures will again be near seasonal levels.

Friday night the upper ridge remains in place along with the
surface high. Some mid and upper level cloudiness may remain
through the night from any showers that do develop Friday
afternoon. Winds do decouple again, and a wide range of
overnight lows is expected as inland areas radiate well and the
urban areas remain rather warm.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
No significant changes in the long term forecast. Mainly
followed NBM guidance. Zonal flow or a weak ridge aloft and high
pressure at the surface is expected on Saturday to start the
long term. It should be mostly dry, however can not rule out a
few shower/TSTM in the afternoon/early evening.

For Sunday, high pressure remains in control, but models show
more of a weak cyclonic flow aloft. Moisture is still somewhat
limited, so will continue with primarily a dry forecast outside
of an isolated shower or thunderstorm in the afternoon or
evening.

For Monday and Tuesday, there`s at least agreement among the
global models that high pressure sits offshore over the western
Atlantic and promotes dry weather over here, but differences in
the pattern aloft bring some uncertainty of rain chances and
timing. Both days look dry for the most part, but will include
low chances of showers both days. Monday appears to have a
better combination of moisture and lift, so perhaps the better
chance of a shower will be then. High pressure then brings the
likelihood of dry weather for Wednesday.

High temperatures through the long term generally in the 70s
with south-facing shores in the upper 60s.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
High pressure expected through the TAF period. A daytime trough
is expected to develop later today.

VFR conditions will prevail through the TAF period. NW flow
continues today with sea breezes expected to develop during the
afternoon along the Atlantic coastline. Coastal CT terminals
could see seabreezes develop shortly at or around 15Z. Winds
become light and variable once again tonight.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of sea breeze Thursday could be 1-3 hours off from TAF.

.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.Friday-Sunday...Mainly VFR. Isolated showers and/or
thunderstorms each afternoon into early evening, mainly north
and west of the NYC terminals.
.Monday...Mainly VFR. Isolated showers. Isolated thunderstorms
for the afternoon into early evening.

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

&&

.MARINE...
With high pressure remaining over the forecast waters today
through Friday night winds and seas will remain below SCA
levels.

For this weekend into the first part of next week, the lack of
a tight pressure gradient will lead to relatively light winds
and with a lack of a significant swell, sub-advisory conditions
are expected on all waters.

&&

.HYDROLOGY...
No hydrologic impacts are expected through the forecast period.

&&

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

&&

$$
SYNOPSIS...BC/MET
NEAR TERM...JC/MET
SHORT TERM...MET
LONG TERM...BC
AVIATION...DJ
MARINE...BC/MET
HYDROLOGY...BC/MET


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