000
FXUS61 KOKX 260004
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
704 PM EST Mon Dec 25 2023
.SYNOPSIS...
Weak high pressure over the region today slowly weakens through
Tuesday night as the system shifts east. Low pressure approaches
on Wednesday and passes nearby Wednesday night into early Thursday.
Low pressure develops to the north and offshore Friday into Friday
night, and then pushes away Saturday. A clipper low approaches New
Year`s Eve and redevelops offshore New Year`s Day.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Forecast on track this evening as fog and stratus have started
to move back into the region. Otherwise, high pressure over the
region will continue to contribute to a subsidence inversion in
the low levels while a weak onshore flow prevails. With the
strong inversion and little to no turbulent mixing near the top
of the inversion, low stratus and fog can be expected tonight.
Based on what had occurred this morning and support from some
guidance that at least had a general idea of the extent and
density of this fog earlier, have decided to issue a dense fog
advisory for the entire area tonight into mid- Tuesday morning.
It will probably take longer in some areas for the fog to
develop, but with the inherent difficulty in predicting the
timing, density and coverage of fog, decided to err on the side
of the caution and start the advisory a few hours after sunset.
Temperatures overnight will be above normal with the clouds and
fog.-- End Changed Discussion --
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Fog lingers into at least part of the morning, but even as the fog
lifts, we`ll probably be left with plenty of clouds at least
during the morning as an inversion keeps low level moisture
trapped. Tough call on how much sunshine develops for the
afternoon. Wouldn`t be surprised to see mostly sunny conditions
develop in several areas as moisture above the inversion is
lacking, but then broken to overcast cirrus may filter in ahead
of the next system to impact the area. What`s more certain is
that high temperatures will once again be above normal - in the
upper 40s to lower 50s.
Surface high pressure weakens Tuesday night. Weak low pressure
shifts east through the Great Lakes Region, dragging a cold front
with it. At the same time, another area of low pressure in the
vicinity of the Carolinas begins to consolidate with a weakness on
the backside of an upper ridge aloft and upper divergence from the
left-exit region of a jet streak. Looks like most of the area should
be dry through the night, but can`t rule out light rain or showers
over eastern zones as weak isentropic lift pushes in from off the
ocean, and moisture in advance cold front to our west may push into
the western zones. As for the fog potential, thinking that there
should at least be patchy fog across the entire area, but this time
around there should be some marginal turbulent mixing at the top of
the low level inversion. Still some dense fog potential as well, but
probably not as widespread this time around.
The low to our south then approaches on Wednesday, and although some
strengthening should occur with a developing subtropical low level
jet, it appears that this low won`t be particularly strong.
Meanwhile, the approaching cold front weakens as it runs into remnant
ridging aloft, but moisture convergence along the weakening boundary
pushes into the forecast area by the end of the day. Rain therefore
becomes likely generally west to east for the entire forecast area
by the end of the day. The low to our south then passes through late
at night into early Thursday morning, combining with the moisture
convergence along the cold front shifting through. Rain therefore
becomes even more likely Wednesday night. Rain chances then drop off
by the end of Thursday morning behind the departing storm system,
with some areas possibly having an entirely dry day.
Operational NBM probability for 1" of rain in 24 hr remains at 55 to
65%, and 2" of rain remains at 10 to 20% (reasonable worst case
scenario). There has been a very slow upward trend in this over the
last 48 hours, and based on potential lift and moisture, would
expect these amounts to trend upward if stronger low pressure
intensification scenarios verify. See the hydrology section below
for potential rainfall impacts.
Temperatures Wednesday through Thursday remain above normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
*Key Points*
* Pattern shift to mean troughing in the Northeast with
mean ridging out west.
* A turn to more seasonable temperatures Friday into Saturday, and
to begin 2024.
Overall the unseasonably mild pattern gives way to more of a ridge
for the Western CONUS and an overall trough in the Northeast CONUS.
With the preceding low pressure in the short term taking much of the
low level moisture away, look for a good amount of clouds, but dry
conditions most of the time for Thursday night on a NW to N flow in
the wake of the preceding system. Carried low end chance PoPs for
Thu. night. There will still be air of Pacific origin in place, thus
any lingering shower activity will be in the liquid form for Thu.
night and into Friday and much of Friday night. Have slightly higher
PoPs on Friday with mainly 30 to 50 percent shower chances across
the area. Later Friday night as low pressure attempts to get better
organized up to the north and eventually offshore, look for colder
air to get wrapped in from the west. This may lead to some mixing
of some snowflakes across mainly northern and northwestern sections
as the any shower activity ends late Friday night / early Sat.
morning. As the system start to lift out PoPs become minimal with
mainly sprinkle and flurry mention. The weekend will mark the start
of a return to more seasonable temperatures with mainly lower 40s
for daytime maxes, and 20s for night time minimums.
Towards New Year`s Eve the ridge start to amplify out west as a
shortwave starts to dig downstream and into the Northern Plains /
Upper Midwest. This energy will need to be monitored heading into
the New Year`s festivities and into New Year` Day. At the present
time it appears that this system will remain separate and distinct
from any southern branch feature and moisture, at least before
getting offshore later New Year`s Day. For the time being the most
likely outcome is that this system will be moisture starved and
should only bring clouds and perhaps a period of flurries or a brief
period light snow. High pressure is expected to build in behind the
system for Tuesday of next week. For now, followed closely the NBM /
consensus guidance for New Year`s Eve and New Year`s Day.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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High pressure over the terminals will slowly weaken.
Low cigs with IFR or lower conditions have returned to most
terminals. MVFR remain at KEWR/KTEB should persist into this
evening. A few VFR spots remain, but conditions everywhere will
lower. Widespread IFR/LIFR conditions expected overnight into
Tuesday morning. Improvement likely after about 15Z Tue, with
VFR expected during the afternoon (19-21z). Conditions will
lower again Tuesday night, for now will only go MVFR with some
uncertainty with just how low conditions get.
Winds will be light and variable.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD likely for changing flight categories. Timing of improvement
Tuesday morning may be off by an hour or two.
OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday night: Chance of showers with MVFR cond, mainly after
midnight.
Wednesday: Rain with MVFR cond.
Wednesday night: Rain with IFR cond. SE winds G20-25kt and
marginal LLWS possible at terminals closer to the coast
(KGON/KBDR/KISP/KLGA/KJFK).
Thursday: MVFR possible with chance of showers.
Friday: MVFR possible with chance of showers. N winds
10-15G20kt.
Saturday: Mainly VFR. NW winds 10-15G20kt.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Expecting more coverage of dense fog across the waters tonight as
compared to last night. Have therefore issued a dense fog advisory
on all waters tonight into the middle of Tuesday morning.
Otherwise, conditions are forecast to remain below SCA thresholds
through Wednesday with a relatively weak pressure gradient in place.
Chances then increase for SCA conditions on the ocean and possibly
for some of the nearshore waters as well Wednesday night ahead of
approaching low pressure. Better overall chances of advisory level
conditions being realized will be on the ocean waters Wednesday night
into Thursday with chance of swell associated with low pressure
passes through helps build waves to 5 ft. Winds otherwise are the
secondary threat.
Mainly sub small craft seas are expected for Thursday night, with
only perhaps lingering 5 ft seas for a portion of the eastern most
ocean waters. By late in the day Friday, and into Friday night and
Saturday marginal small craft winds are likely for the nearshore
waters and ocean waters as low pressure starts to strengthen along
and off the NE coast.
&&
.HYDROLOGY...
A storm total rainfall range of 3/4" to 1 1/2" is likely Wednesday
through Wednesday night, with a reasonable worst case of 2". Highest
amounts across areas W and NW of NYC with orographic enhancement of
SE flow. Most of this likely falls in a 6 to 9 hr period during the
earlier half of Wednesday night. 6hr headwater guidance for flashy
NE NJ rivers is around 1 1/4", and with widespread streamflows still
above 75th to 90th percentile, the threat for minor flood impacts
along a few to several quick responding rivers in NE NJ is
increasing. The threat for minor flood impacts along a few flashy
rivers across Lower Hud and S CT is increasing as well. Soil
moisture anomalies are also running at 99th percentile areawide,
lending to a scattered minor urban/poor drainage flood impact
potential.
More clarity expect on rainfall amounts and hydrologic threat for
Wed/Wed Night in the next 24-36 hrs with increased model consistency
and as high res models resolve this system.
&&
.TIDES/COASTAL FLOODING...
Monitoring the potential for minor coastal flood impacts for
vulnerable coastal communities Thu with a passing low pressure
system. Tidal departures of 1.25-1.50 ft are needed for minor
flooding, and 2.25-2.50 for moderate flooding during the morning
high tides. About 1 ft additional surge is needed for the
evening high tides.
Potential for minor flooding with the Thu morning high tide
cycle, particularly along the south shore of Nassau and Queens,
and possible along the SW CT coastline on the western Sound.
The threat for dune erosion appears to be low and isolated with
this event.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Dense Fog Advisory until 10 AM EST Tuesday for CTZ005>012.
NY...Dense Fog Advisory until 10 AM EST Tuesday for NYZ067>075-
078>081-176>179.
NJ...Dense Fog Advisory until 10 AM EST Tuesday for NJZ002-004-006-
103>108.
MARINE...Dense Fog Advisory until 10 AM EST Tuesday for ANZ331-332-335-
338-340-345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/JE
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...JE
AVIATION...BC
MARINE...JC/JE
HYDROLOGY...JC/JE
TIDES/COASTAL FLOODING...