000
FXUS61 KOKX 222353
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
653 PM EST Fri Dec 22 2023
.SYNOPSIS...
High pressure over the area will move east late tonight into
Saturday. A weakening warm front approaching Saturday night
will lift north on Sunday and away from the area Sunday night.
High pressure will reestablish itself on Christmas Day, then
move farther out into the Atlantic through the first half of
next week. Meanwhile, a frontal system will begin to approach,
moving nearby Wednesday night and then away from the area
Thursday into Friday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
Adjusted slightly with cloud coverage and slightly lowered
temperatures. Clouds are starting to move in from the west, but
will take their time moving in, with Southern CT and Long
Island having mostly clear sky conditions much of the night.
With calm winds at quite a few locations, radiational cooling
thus far has been pretty efficient with temperatures running a
few degrees colder than forecast.
A band of lower clouds moving into central NJ and E PA should
also expand NE, and per RAP/HRRR fcst soundings could make it
into the NYC metro area as early as late this evening, but more
likely after midnight, with bkn skies.
With areas to NE of there experiencing a mostly clear to partly
cloudy night with light winds, temps across interior S CT and
eastern Long Island should fall to the teens to near 20. West
of there lows should range from near 30 in NYC to near 20 in
the outlying suburbs with some localized upper teens.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
The sfc high will move off the New England coast, with mid level
shortwave energy approaching as a mid level ridge axis also
slides east. That will allow for a continued gradually increase
in clouds daytime Sat, with daytime highs a few degrees warmer
than those of today, with mid/upper 30s inland and lower 40s for
NYC metro and the coast.
Combo of a mid level shortwave trough approaching from the west
Sat night and low level WAA on the back side of the high off
the New England coast will bring overcast skies and the chance
for some light precip from late Sat night into Sunday. With
combo of warming aloft and sfc temps falling to the upper
20s/lower 30s well inland (and models also showing some in-situ
cold air damming with sfc winds backing to the NE), a period of
light snow/sleet/freezing rain is looking more likely for areas
well NW of NYC (mostly Orange/W Passaic/Putnam/N Fairfield)
late Sat night into Sunday morning. Rain expected elsewhere with
lows from the mid 30s to near 40. With this being a late 3rd
period/early 4th period event, and the possibility that precip
could be spotty and temps remain just above freezing Sat night
especially outside of Orange County, it is still too
early/uncertain for any winter wx headlines.
Light rain/showers should continue spreading eastward across the
rest of the CWA into Sat morning, and then shift more to the
east across ern Long Island and SE CT by afternoon, with skies
remaining cloudy. As low level WAA continues, temps should reach
the lower 40s inland and mid 40s for the metro/coastal sections
by afternoon.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Main takeaways:
* Warmer than normal overall
* Mainly dry conditions continue through Christmas
* Midweek frontal system: Widespread rain, potentially heavy at
times, bulk of rain Wednesday and Wednesday night, minor
flooding possible due to recent heavy rains and above normal
soil moisture
* Possible lingering rain showers late next week
Overall, synoptic pattern transitions from a ridging pattern
Sunday night through Monday night to more of a troughing
pattern Tuesday night through Friday.
A departing mid level vorticity maximum with a weakening surface
trough may present a few rain showers across the region Sunday
night. Otherwise, surface high pressure will reestablish itself
across the region Sunday night but will be based southeast of
the Canadian Maritimes. This high pressure area will gradually
move farther out into the Atlantic early into the middle of next
week. Dry weather conditions are expected late Sunday night
through Monday night.
The local area will have an increase in moisture in the
atmosphere on the backside of this high pressure area and as a
frontal system approaches Tuesday, the moisture will increase.
Low level warm air advection will also increase. These positive
temperature and moisture advection continue into mid week. There
will be chances for rain on Tuesday afternoon, with rainfall
becoming likely Tuesday night.
A deepening trough to the west will increase the southerly
atmospheric flow going through midweek. Meanwhile, a wave of
surface low pressure in the Southeast US Tuesday night moves
towards the mid- Atlantic for early Wednesday. The low continues
to approach from the south Wednesday and then traverses nearby
Wednesday night into early Thursday morning. There are large
scale numerical weather prediction models differences with the
location of the center of the low and how strong it is.
The focus of this event seems to be on the Wednesday into
Wednesday night timeframe, when precipitable achieve their
relative maximum of near 1 inch and when the low will be
relatively closer to the area. Some upper level features to note
are a general positive tilt to the mid and upper level trough
and a strengthening subtropical SW jet that moves in for
midweek. As it moves in, the local area gets in the left front
quadrant of the jet, which enhances vertical lift. ECMWF
deterministic was showing a hint of elevated instability with a
decrease in Showalter indices to near to just below zero. So, an
embedded rumble of thunder is possible but probabilities for
this are just slight chance. Otherwise, the bulk of the rain is
expected Wednesday through Wednesday night.
The positive tilt of the mid and upper level trough remains for
Thursday and the jet streak shifts mostly east of the region. At
the surface, this will allow for the wave of low pressure and
its frontal system to shift east of the area. However, there
will still be a cutoff upper level low to the west that will be
moving in towards the end of next week. This will keep
relatively colder air aloft and this cyclonic flow will keep a
chance of showers in the forecast.
Temperatures overall are forecast to be warmer than normal in
the long term. Christmas Day forecast highs mostly near 50, a
relatively cooler day within the long term and also for next
Friday with highs more in the lower/mid 40s. Otherwise, daytime
highs mostly in the lower 50s except for Wednesday when highs
are forecast to be more in the lower/mid 50s.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure remains in control through Saturday. A weak trough of
low pressure will then be nearby Saturday night.
VFR. Light and variable winds through tonight. Light S-SE winds
developing near noon Saturday with speeds at or under 5 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments are expected.
OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY...
Saturday night: Chance of MVFR and RA or -FZRA for KSWF late,
otherwise VFR.
Sunday: MVFR possible, with sct rain showers. Low prob of -FZRA for
KSWF early.
Christmas Day: VFR.
Tuesday: Becoming MVFR or lower late, increasing likelihood for
rain.
Wednesday: MVFR or lower with rain.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA cond prevail with winds less than 10 kt, and ocean seas
lowering to 2-3 ft late tonight, and around 2 ft Sat afternoon
through Sunday.
Conditions on the forecast waters should continue below SCA
criteria into Tuesday night with a weak pressure gradient in
place. For Wednesday and Wednesday night, winds and seas
increase with the potential for SCA conditions on at least the
ocean waters.
&&
.HYDROLOGY...
River flood warnings are still in effect along the CT and
Pawcatuck Rivers (handled by WFO BOX) and parts of the Passaic
River basin (handled by WFO PHI). Otherwise, no hydrologic
impacts are expected through Tuesday.
For the midweek system Tuesday night through Wednesday night,
heavy rain will be possible and possibly some minor flooding.
Very low confidence for any other hydrologic problems and low
confidence on forecast rainfall amounts.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BG/JM
NEAR TERM...BG/JM
SHORT TERM...BG
LONG TERM...JM
AVIATION...DR
MARINE...BG/JM
HYDROLOGY...JM