000
FXUS61 KOKX 261130
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
630 AM EST Tue Dec 26 2023
.SYNOPSIS...
High pressure over the region slowly weakens through tonight.
Low pressure and its associated frontal system approach on
Wednesday and pass nearby Wednesday night into Thursday.
&&
.NEAR TERM /THROUGH TONIGHT/...
Latest observations have shown a general improvement with
visibilities. Confidence is low that this will continue and
still anticipating visibilities to drop again around sunrise.
Some areas may not see the fog become dense, but will leave the
Dense Fog Advisory up for now since visibilities could drop
rapidly given the weak flow and moist low levels.
Visibilities should start to improve after 9-10 am, but there
will likely be plenty of low clouds for the remainder of the
morning, potentially into the afternoon. There are conflicting
signals with the degree of clouds in the afternoon. The fog this
morning is shallow and should improve, but there are hints at a
low level inversion around 2 kft. This may help keep low clouds
in place. If the inversion is weaker and moisture can mix out,
some places could see sunny conditions for a time this
afternoon. Broken cirrus should begin to move overhead ahead of
approaching low pressure. Another day of above normal
temperatures are forecast with highs in the upper 40s to lower
50s.
The surface high weakens tonight as it begins to move offshore.
A large closed low over the central states will send low pressure
and its associated frontal system towards the region. A general
model consensus keeps the region dry tonight with just a chance
at some light rain late across the western half of the area.
Model soundings also indicate stronger winds compared to Monday
night. This turbulent mixing should prevent any fog from
becoming dense or widespread. Will continue with patchy fog for
the entire area, but it appears more likely that low stratus
will be dominant. There will also be increasing middle and high
level moisture limiting radiation fog potential. Lows will be
mild and generally in the 40s.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The frontal system slowly moves into the area on Wednesday.
The system will initially struggle as it moves closer to the area
as it encounters lingering ridging aloft just offshore.
However, guidance has started to come into more agreement on a
wave of low pressure developing along the front over the Middle
Atlantic on Wednesday. This should help reinvigorate rainfall as
the system moves over the area Wednesday night. The new low
does not look particularly strong, but will have some enhanced
lift from the left exit region of a subtropical jet over the
southeast. Rain will start to enter the area during the late
morning and afternoon, but become widespread Wednesday night.
The majority of the rain with this system will fall in about
a 12 hour period late Wednesday into early Thursday morning.
The latest NBM probabilities for greater than 1 inch in 12 hours
late Wednesday during this time period are generally 20 to 30
percent. NBM probabilities for seeing greater than 2 inches in
12 hours during the same time period are generally less than 5
percent. These probabilities continue to signal limited rainfall
impacts.
The rain could become moderate to locally heavy, especially
where any enhanced moisture convergence occurs with the low
pressure. Ensemble means and global deterministic models signal
this potential exists north and west of the NYC metro across NE
NJ and the Lower Hudson Valley. Wednesday night falls beyond the
timeframe of most of the HREF members, so there is limited
higher resolution model data available at this time. Where this
axis of briefly heavier rain occurs should begin to come into
focus in the next 24 hours.
Forecast rain totals from late Wednesday through Wednesday
night range from 3/4" to 1 1/4". Due to recent heavy rain and
high streamflows, some of the flashier rivers and streams in NE
NJ could come close to minor flooding benchmarks if reasonable
worst case scenario solutions verify with rainfall 1.5" to 2"
Otherwise, just minor urban and poor drainage flooding is
possible.
The rain will taper off from west to east early Thursday morning.
A consensus of the modeling puts the steadiest rain offshore by
12z Thursday. The main closed low will still be well to our
west on Thursday. Low pressure will likely linger near or just
south and east of the area. The pattern does not change too much
Thursday night with low pressure nearby. Not expecting a
washout Thursday into Thursday night, but a few showers cannot
be ruled out with any organized areas of lift from weak energy
rotating around the upper low.
Temperatures continue above normal Wednesday and Thursday with highs
in the upper 40s to lower 50s.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
No significant changes made to the long term and stuck close to
the NBM for this update.
*Key Points*
* Rain chances continue Friday with a dry period to follow into New
Year`s Day.
* A slight cooldown to more seasonable temperatures Friday into
Saturday, and to begin 2024.
A closed upper low over the Central Plains slowly works to the
east to begin the period, as a weak surface low develops and
heads northeast of the are during the day on Friday. Have
maintained the chance PoPs for much of the day on Friday, and
given the Pacific origin of the air mass associated with this
system, expect ptype to be all rain. The low and attendant
moisture head northeast by Friday evening. Some weak CAA behind
the system results in lower thicknesses across the interior, so
cannot rule out a few snowflakes mixing in late Friday or early
on Saturday as the system pulls away. Highs on Saturday will be
in the low 40s; more seasonable than the days prior.
Thereafter, weak ridging and mainly dry conditions look to prevail
through New Year`s Day. The aforementioned closed upper low finally
shears out to our south and heads east on Saturday. A weak surface
low associated with this upper feature then develops offshore and to
our south on Sunday. At this time, the area remains on the north
side of its precip shield as it heads to the northeast on
Monday.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Visibilities and cigs are improving somewhat over the western
terminals as of 11Z with mainly IFR reported now except at
KEWR. Mainly IFR/LIFR conditions through late morning. These
widespread IFR/LIFR conditions are expected to begin improving
after about 15Z, with VFR expected during the afternoon
(19-21z). Conditions will then lower again tonight; MVFR with
possible IFR overnight, especially for the coastal terminals.
Biggest challenge with the TAFs will be any timing of changing
flight categories conditions may vary through the morning and
even into the early afternoon.
Winds will be light and variable through the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD likely for changing flight categories. Timing of improvement
this morning may be off by an hour or two.
OUTLOOK FOR 08Z WEDNESDAY THROUGH SATURDAY...
Tuesday night: MVFR or lower conditions in stratus and possible fog.
Low chance of rain.
Wednesday: Rain with MVFR conditions, mainly in the afternoon and
evening.
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...
Dense fog advisory remains in effect on all waters through 10
am.
Otherwise, conditions are forecast to remain below SCA thresholds
through Wednesday with a relatively weak pressure gradient in
place. A frontal system and low pressure pass over the waters
Wednesday night into Thursday night. Winds will increase a bit,
but should remain below 25 kt. Ocean seas will likely build
close to 5 ft Wednesday night through Thursday night.
Sub SCA conditions are expected on all waters on Friday. By late
Friday and into Saturday, SCA conditions are possible over the
eastern ocean zones with developing low pressure to the south.
&&
.HYDROLOGY...
A storm total rainfall range of 3/4" to 1 1/4" is likely late
Wednesday through Wednesday night, with a reasonable worst case
of 1 1/2" to 2". The highest amounts are most likely to occur W
and NW of NYC. Due to recent heavy rainfall and continued high
streamflows, there is a threat for minor flooding along a few
quick responding rivers in NE NJ and potentially the Lower
Hudson Valley. Otherwise, minor urban and poor drainage flooding
is the main threat with this rainfall.
&&
.TIDES/COASTAL FLOODING...
The potential remains for minor coastal flood impacts for
vulnerable coastal communities Thu with a passing low pressure
system. The threat exists for mainly the morning high tide,
particularly along the south shore of Nassau and Queens, and
possibly along the SW CT coastline on the Western Sound. 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.
The threat for dune erosion appears to be low and isolated with
this event.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Dense Fog Advisory until 10 AM EST this morning for CTZ005>012.
NY...Dense Fog Advisory until 10 AM EST this morning for NYZ067>075-
078>081-176>179.
NJ...Dense Fog Advisory until 10 AM EST this morning for NJZ002-004-
006-103>108.
MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ331-332-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...DBR/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...DBR
AVIATION...DBR
MARINE...DBR/DS
HYDROLOGY...DBR/DS
TIDES/COASTAL FLOODING...