000
FXUS61 KOKX 060546
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1246 AM EST Wed Dec 6 2023
.SYNOPSIS...
Weak high pressure gives way tonight to a developing low that
develops well to the south of the area on Wednesday. High
pressure noses in from the south on Thursday as a warm front
approaches from the west. The warm front will lift north of the
region Friday into Saturday. A strong frontal system approaches
from the west Sunday with its associated cold front moving
across Sunday night. High pressure returns for early next week.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
Radar is showing low reflectivity returns across eastern PA,
and areas just north and west of Orange county. Ground
observations and live cams both confirm snow is falling across
this area as these reflectivities move east. Have raised POPs
to chance for light snow or light rain/snow mix across NE NJ,
the Lower Hudson Valley and NYC metro. Snow or rain will depend
on the temperatures at each location and will likely be light
and brief. As for the forecast through 18Z, have including at
least slight chance for light snow or light rain/snow mix for
all areas that did not have any low-end POPs as the latest CAMs
consistently show isolated coverage later today. The rest of the
forecast remains on track...
Weak mid-level ridging over the area gives way to an incoming
shortwave embedded in a large-scale trough approaching from the
west tonight and into Wednesday. The energy associated with this
shortwave is forcing a weak surface low over the southern Great
Lakes. At this time, this is resulting in very light snowfall
over much of western Pennsylvania. As the moisture associated
with this weak disturbance approaches the area tonight, much of
the weak precipitation is expected to dissipate as it runs into
drier air over the area. That being said, left a slight chance
of snow showers, possibly mixed with rain showers for coastal
areas, for much of the area tonight. Otherwise, overcast skies
are anticipated and lows tonight will be in the middle to upper
20s for outlying areas with low temperatures in the low to
middle 30s for the NYC metro.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
As the shortwave energy approaches the East Coast on Wednesday,
cyclogenesis occurs off of the Carolina coast. The area will
remain well to the north of the low and the most likely sensible
weather from the deepening of the low will be an increase in
winds into the afternoon and evening on Wednesday.
As the energy from the weak surface wave over the Ohio Valley
transfers to the developing coastal low, low level moisture may
increase a bit. Increased moisture combined with cooler
temperatures aloft due to the placement under an upper level
trough, may result in the development of some instability
showers during the day on Wednesday, though much of these should
be confined to the eastern portion of the area. High
temperatures on Wednesday will only be in the upper 30s to near
40 for much of the area so any of these showers that develop
will have a chance of being snow showers. The earlier in the day
they develop, the high the chance at seeing snow, but even if
surface temperatures are above freezing into Wednesday, cool
temperatures aloft may support the occurrence of at least a mix
with snow in any shower that develops.
Any showers end Wednesday afternoon and into Wednesday night
with skies clearing in the wake of the departing low. A brisk NW
wind advects in cold air such that low temperatures Wednesday
night into Thursday morning will be in the 20s for much of the
area. Some outlying spots may drop into the upper teens.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Stayed fairly close to the NBM throughout the period. A quasi-
zonal flow to begin the period on Thursday becomes increasingly
amplified into the weekend. A trough over the Northern Rockies
will amplify as it progresses east. This will be the system that
impacts our sensible weather late in the weekend. Afterwards,
high pressure should return into next week.
A warm front will reside just west of the area and nearby into
Thursday. This will bring more in the way of clouds into the
area, especially further west. A cP air mass will stick around
through Thursday which should keep the area dry despite more in
the way of clouds. Temperatures will average a good 5 degrees or
so below normal before the air mass begins to push off the
coast Thursday night. On Friday the warm front is expected to
progress east and lift north of the area. This will lead to an
increasing southerly component to the wind direction. An
eventual SW flow will get temperatures a few degrees above
normal by Friday afternoon with a fair amount of sun. Towards
Saturday the warm front should get well north of the area, and
thus a mild south to southwest flow will prevail. Warm advection
should promote temperatures at 850 mb to get to around 8 to 10
C. Therefore temperatures should get into the middle 50s, a good
10 degrees above normal to begin the weekend. It is possible
that temperatures could get even warmer than currently progged,
but NBM members were not straying far from the mean, thus did
not get more aggressive with daytime maxes on Saturday but could
easily see it get another 3 degrees or so warmer than currently
progged.
The trough then swings into the east for Sunday and Sunday
night. There is some spread among the ensembles with the timing,
but confidence remains high for a strong frontal system to work
through later in the day Sunday into early Monday AM. Other
than a few showers Sunday morning, most of the morning may
remain dry. For Sunday afternoon look for rain to develop from
W-SW to E-NE as a good conveyor belt of moisture begins to work
up along the coastal plain. Despite cloud cover and rain look
for temperatures to top out close to 60. The steadiest rain
based on the latest consensus guidance looks to take place
Sunday night, with much of the rain falling the first half of
Sunday night. Standardized anomalies for mean IVT from the ECMWF
and the NAEFS run at +3 to +4, with PWATs standardized
anomalies at around +3. NBM probabilities of greater than 2
inches of rain get to around 30 percent for NW portions of the
area, and probabilities of greater than 1 inch get to around 70
percent for NW sections. Therefore rainfall amounts of 1 to 1.5
inches has a good chance for late Sunday / early Mon AM. Winds
should get rather gusty late in the day Sunday through Monday
morning. Winds out of the south with gusts of around 40 to 45
mph are possible, with the strongest winds likely Sunday evening
/ night. The cold front should clear the area towards daybreak
on Monday with the winds switching to the W. The pressure
gradient should weaken gradually during the day Monday. Look for
Monday to dry out with blustery and cooler conditions.
Seasonable temperatures and dry conditions will be in place for
the remainder of the period.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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High pressure remains in control. Meanwhile, a deepening offshore
low will pass to the south and east during Wednesday into Wednesday
night.
Mainly VFR during the TAF period. Overnight, low chances of
snow showers at KSWF and a low chance of rain/snow mix for NYC
terminals. MVFR would be more probable for KSWF with their snow
showers. Relatively higher chances of snow showers and MVFR at
KGON this morning. Otherwise, other precipitation during the TAF
period too low probability to include in TAF.
Light north northeast winds at the metro terminals, with winds light
and variable at the outlying terminals. Winds at the metro terminals
and east will increase from the north around 09Z, and into Wednesday
morning. NNW gusts around 20kt develop during the afternoon.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments possible for brief rain or snow with possible MVFR.
OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
Late Wednesday night: VFR. NNW gusts near 20kt, mainly at coastal
terminals. Gusts ending late.
Thursday-Saturday: VFR.
Sunday: Mainly VFR in the morning with chc S gusts 20-25kt.
Rain/MVFR/IFR/LLWS mainly in the afternoon and night with a chance
of S-SW gusts 35-45kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA conditions are expected on all waters through Wednesday
morning. By Wednesday afternoon, winds increase to marginal SCA
criteria with gusts to 25 kt on the ocean zones as the pressure
gradient tightens over the area with the development of a coastal low
well to the south. SCA gusts on the ocean zones likely continues
into the first half of Wednesday night before falling below 25 kt by
Thursday morning.
Sub-SCA conditions are expected Thursday through Saturday night with
ocean seas averaging close to 3 ft. Winds and seas should ramp up
quickly during Sunday with small craft conditions quickly going to
Gales in all likelihood by later in the day. Solid gales are
expected across all waters Sunday night, with gales likely
lingering into Monday morning for the eastern waters.
&&
.HYDROLOGY...
An inch to an inch and a half of rain is possible Sunday and Sunday
night. At this time only minor and localized hydrologic impacts
appear possible, though confidence remains low this far out.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 1 PM this afternoon to 4 AM EST
Thursday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JE/MW
NEAR TERM...JE/BR/MET/MW
SHORT TERM...MW
LONG TERM...JE
AVIATION...MET/JM
MARINE...JE/MET/MW
HYDROLOGY...JE/MW