discussion on 2023-12-07

000
FXUS61 KOKX 072251
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
551 PM EST Thu Dec 7 2023

.SYNOPSIS...
High pressure moves across the area tonight and then moves offshore
Friday, remaining in control through Saturday. A strong cold
front approaches on Sunday and passes through during Sunday night.
High pressure then builds in on Monday and remains in control
through the middle of next week.

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Dewpoint depressions over SE CT are starting to lower, but even
so, thinking at most there`s only the potential of a few
flurries here over the next couple of hours. This has been added
to the forecast with this update along with minor changes to
hourly temperatures, dewpoints and cloud cover.

An upper level shortwave pulls away from the area tonight and
heights start to rise as a ridge builds into the area. At the
surface, high pressure starts to build in. With the high
moving overhead tonight, the pressure gradient weakens. Although
winds will be light, there will be some clouds around tonight
so conditions are not optimal for radiational cooling. Because
of this, used mainly the NBM, but blended in some CONSMOS for
the lows.-- End Changed Discussion --

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
Heights continue to rise aloft through Saturday, with the ridge axis
passing overhead Saturday morning. At the surface, high pressure
slowly shifts east, moving offshore Friday but remaining in control
through Saturday. This period will feature dry conditions with a
warming trend.

Highs on Friday will be back to normal, mid 40s. The flow at the
surface becomes southerly on Friday afternoon as high pressure
shifts east and that will allow lows Friday night to be a few
degrees warmer in a moist onshore flow. By early Saturday, the
flow through of much of the column will be W/SW as the upper
level ridge axis shifts east. This will help temperatures reach
the upper 40s to mid 50s on Saturday.

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --A 500mb trough digs in to our west on Sunday, then lifts during the
day Monday with its axis shifting through the forecast area Monday
evening. At the surface, a strong cold front approaches us on Sunday
and passes through during Sunday night. While it`s passing through,
an area of low pressure develops along the front and passes to our
north.

Rain chances ramp up through the day with the entire forecast area
likely seeing rain by the end of the afternoon. The rain could be
heavy at times mainly during Sunday night as a strong low level jet
develops over us and combines with deep synoptic lift aloft and an
anomalously moist air mass. Some models continue to show some
elevated instability, so with deep lift, will keep in an isolated
thunderstorm in the forecast. Rain chances continue into Monday even
behind the front as the flow aloft remains cyclonic and we`ll be
within the right entrance region of an upper jet streak. Should
precipitation actually occur Monday morning over the higher
elevations well NW of the city, some snowflakes may mix in with
showers. Total rain amounts now appear a little higher. See the
hydrology section below for more details.

Regarding winds for this event, 925mb winds continue to be
progged to reach 60-80kt over roughly the eastern half of the
forecast area Sunday night. Even if a relatively stronger low
level inversion were to be in place during the time that the llj
moves through, about half of that speed could potentially reach
the surface. NBM probabilities of a greater than 50% chance of
at least advisory- criteria gusts (46+ mph) have trended a
little lower over the past day, however still think there is a
decent chance of a peak wind gust reaching criteria for mainly
coastal sections east of Manhattan given the setup and potential
help from heavy downpours. The current forecast has gusts
40-50mph for coastal areas and 30-40mph for most inland areas
during Sunday night.

High pressure then builds in through the rest of Monday and remains
in control through Thursday with an extended period of dry weather
and highs generally in the 40s.-- End Changed Discussion --

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A weakening low pressure moves through into early this evening.
High pressure then moves across the area later tonight and then
moves offshore Friday.

MVFR conditions expected through around 00Z as mainly scattered
snow showers move through in association with weak low pressure.
Conditions improve to VFR thereafter, though exact end time is
uncertain and may be off by an hour or two.

W winds 10-15 kt with gusts 15-20 kt into the evening. Gusts
subside this evening with winds lowering back to near 10 kt and
further lowering overnight into Friday. The wind direction
becomes light and variable on Friday.

...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Timing of return to VFR may be an hour or two later than
forecast. Gusts up to 20 kt may be more occasional this
afternoon.

OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday-Saturday: VFR.

Sunday: MVFR or lower in developing rain from west to east
during the day. Slight chance of thunderstorms at night. S
winds increasing with gusts 30 to 40 kt, mainly late day into
night. Highest winds will be at the coastal terminals. LLWS
likely.

Monday: Chance of rain showers earl with MVFR possible.
Otherwise, becoming VFR. W-WSW wind gusts 30-40 kt early,
becoming more WNW with wind gusts 20-30 kt late.

Tuesday: VFR

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

.MARINE...
With high pressure building in tonight and remaining in control
through Saturday, winds and waves will remain below SCA criteria
through Saturday night.

Winds and seas should ramp up quickly during Sunday with small craft
conditions quickly going to gales in all likelihood by late in the
day/early evening. Solid gales are expected across all waters Sunday
night, with gales likely lingering into Monday morning for most of
the waters. Gales may continue well in the afternoon on the ocean.
Ocean seas are likely build to 10-16 feet during this time with
waves over 5 ft across portions of eastern Long Island Sound. SCA
conds on the ocean for Tuesday as seas remain elevated.

.HYDROLOGY...
There are no hydrologic concerns through Saturday night.

1.50 to 2.50 inches of rain are expected from Sunday afternoon
through Monday morning. It appears that the heaviest rainfall is
most likely to occur during Sunday night. Minor urban/small stream
flooding will be possible, mainly Sunday night - confidence in this
is moderate. Cannot completely rule out flash flooding either, but
this is a lower confidence forecast as chances are low given flash
flood guidance and the progressive nature of the storm system.

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

SYNOPSIS...JC/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...JC
AVIATION...JP
MARINE...JC/JT
HYDROLOGY...JC/JT