Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 250311

Area Forecast Discussion
National Weather Service New York NY
1111 PM EDT Sat Mar 24 2018

An upper level disturbance moves through the region overnight
into Sunday with a back door cold front moving across. High
pressure builds down from southeastern Canada Sunday night
through Monday night, and remains over the area through Tuesday.
A slow moving cold front then approaches from the west through
Thursday night and crosses the area on Friday.


Forecast is mainly on track with only minor changes made to
reflect current trends.

An upper level low will rotate down from Western Quebec over
the region tonight, while joining with a lingering shortwave
trough east of new England. At the surface, a back door cold
front moves across with flow becoming more NE overnight into
early Sunday. The NE flow will further increase and become

Increasing cloud cover expected across the entire region tonight as
the upper low sinks se. Possible snow flurries will transition,
as low level boundary layer gains moisture, to isolated to scattered
snow showers across E CT and E LI overnight into Sunday
morning. The shortwave forcing will be interacting with deeper
Canadian maritime moisture in low-mid level NE flow. A dusting
of snow possible across E LI/SE CT, with locally an inch of snow
possible across the hills of central and eastern CT. To the
west across NYC metro, NE NJ, and Lower Hud moisture will be
more limited, limiting coverage of snow showers to isolated.

With cloud cover and mixed low-level temps will likely run in the
upper 20s interior, to lower to mid 30s city/coast. This is
near to slightly below seasonable.


Axis of upper low slides southeast of the region Sunday morning,
with weaker backside shortwave passing through the region Sunday
evening. This entire low then should slowly slide east Sunday night.

Morning snow showers should taper off by midday. Otherwise, Sct to
Bkn instability cu likely remain through the day under troughing and
cold pool instability, highest coverage LI/CT. Potential for
isolated snow showers or flurries across E CT/E LI in the
afternoon ahead of next shortwave, with just a few
flurries/sprinkles possible elsewhere.

Gusty NE winds, caa, and cloud cover will make for an unseasonably
chilly Sunday. Highs will likely struggle into the upper 30s and
lower 40s, a good 10 degrees below seasonable levels.

Drying conds Sunday night in wake of shortwave and with rising
heights. Temps will continue to run well below seasonable though,
with potential for temps to drop well down into the lower 20s across
outlying areas with decoupling.


Omega block pattern set up over the CONUS during the beginning of
the long term period, with a trough and cut off low over the open
waters off the East Coast and a trough over the Rockies, with deep
layered ridging over the Eastern Great Lakes Region slowly building
into the Eastern US. This will provide dry weather through at least
Tuesday night with surface high pressure over southeastern Canada
building south into the Northeast.

Our region will be between this coastal storm well off shore that is
forecast to meander and weaken over the open ocean waters through
the middle of the week as a surface cold front slowly approaches
from the west. A piece of this high gets pushed south of the area
and a warm front lifts well north Wednesday night. As the cold front
approaches it will also weaken, with very little moisture to work
with. So, just a slight chance to chance of precipitation is
possible from mid to late week.

Temperature forecast later in the week may be difficult as
there are some differences in how the models handle the warm
front. 12Z GFS is very progressive in lifting the front north,
while the 12Z ECMWF keeps it south of the area or in the
vicinity through the end of the week. If the GFS is right, then
warmer temperatures are in store for the end of the week,
possibly breaking 60 in the New York City metro area on Thursday
and Friday, while cooler temperatures would prevail in the
ECMWF solution. Outside of that, temperatures will be cooler
than normal to start off the week, then warm to slightly above
normal for the middle of the week.


A back door cold front will move across tonight into Sunday.

VFR initially but clouds increase and lower overnight into
early Sunday with MVFR ceilings expected. Some snow showers are
also forecast which will bring MVFR to possibly IFR visibilities
for brief periods of time in a general timeframe of 11Z-17Z
Sunday. IFR will be more probable if there is a light snow
accumulation of a few tenths of an inch. This time window could
vary 1-2 hours from forecast. The chances for these snow showers
are higher outside the city terminals.

N-NE flow tonight 5-10 kt will become gusty for coastal
terminals starting early Sunday. Flow will become NE 10-15 kt
with gusts in the 20-25 kt range for these coastal terminals
Sunday. Gusts are still possible farther inland but may not be
as frequent.

.Sunday Night...Mainly VFR. NE winds G20KT.
.Monday...VFR. NE winds G15-20KT.
.Wednesday...Mainly VFR, chance MVFR in -SHRA, mainly at night.
.Thursday...Mainly VFR, chance MVFR in -SHRA late at night.


Sub SCA conditions continue overnight but winds will
be strengthening out of the NE behind a back door cold front.
SCA conds expected to develop on the ocean waters and possibly
eastern nearshore waters Sunday morning, continuing into Mon. In
response, ocean seas will build to SCA levels on the ocean
Sunday, and likely continuing at these levels through midweek as
NE swells affect the waters in response to a large, strong and
stubborn Atlantic low.

Waves will range from 5 to 9 ft through Tuesday, with waves
slowly diminishing Tuesday night into Wednesday night as the
flow weakens. Waves fall below 5 ft by Wednesday morning and
remain below SCA criteria through the end of the week.

Wind gusts of 25 to 30 kt possible on the ocean waters Monday
through the first half of Monday night as the flow slowly weakens.
Winds remain below SCA criteria through the end of the week with
weak pressure gradient.


Rapid snow melt will continue into the weekend as high temps climb
into the 40s. Although gradual rises are expected on areas stream
and rivers, no hydrologic problems are anticipated through


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


MARINE...Small Craft Advisory from 6 AM Sunday to 11 AM EDT Monday for


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