000
FXUS61 KOKX 241936
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
236 PM EST Sun Dec 24 2023

.SYNOPSIS...
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A weak warm front will dissipate to the northwest today, while a
weak trough develops near Long Island tonight. This trough will
weaken on Christmas day, as high pressure becomes reestablished.
The high will then slowly move east into the Atlantic Tuesday
into Tuesday night. Low pressure and its associated frontal
system will approach Tuesday night and move across from
Wednesday into Wednesday night. Low pressure or a series of
troughs may linger from Thursday into Saturday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
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Cloudy skies continue with moisture trapped beneath a mid level
inversion, also with low clouds mostly across Long Island/S CT
with low level moisture trapped beneath a marine inversion.
Some spotty light showers associated with a weak sfc trough and
mid level forcing from an upper trough just to the NW across
upstate NY were across the forks of Long Island and the nearby
ocean waters. Forecast carries isolated PoP there this
afternoon, then chance PoP across E Long Island and SE CT for
tonight as this forcing continues, as the trough cuts off aloft
and moving toward S New England.

After daytime highs mostly in the mid/upper 40s, with some
lower 50s across Long Island, temps tonight will cool off to
near 40 in NYC, and into the 30s elsewhere. Temps well inland NW
of NYC should remain just above freezing.
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&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
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Weak cutoff upper low will slowly sink SE across Long Island and
CT on Christmas Day, with continued chance for AM showers out
east. Otherwise, mostly cloudy skies should continue through the
period as the combo of moisture trapped beneath mid level and
marine inversions remains stubborn. With not much change in air
mass temps through Mon night should be similar to or only a
touch milder than those of today. Highs will be in the lower
50s for the NYC metro area and Long Island, and mid/upper 40s
inland and for the CT coast, with lows ranging from the lower
40s in NYC to the mid 30s well inland. Fog should also develop
over most of the area late Mon night into Tue AM as low levels
moisten up on a light onshore flow.

Model guidance has trended slower with the mid week system, so
have cut back PoP daytime Tue to slight chance west of the
Hudson for the late afternoon. WAA ahead of this system should
lead to a touch milder temps, with highs mostly in the lower
50s throughout.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The forecast thinking for the extended has not changed too much
over the last 24 hours. A period of unsettled weather is
expected Wednesday into the end of the upcoming week.

*Key Points*

* Confidence continues to increase on widespread rain Wednesday into
  Wednesday night. Any impacts look limited due to the progressive
  nature and overall weaker system compared to recent events.

* Unsettled weather likely persists Thursday and Friday, but
  uncertainty remains with timing of any potential lingering
  showers.

* Temperatures will start out above normal on Wednesday and Thursday
  before gradually trending below normal by next weekend.

A closed upper low will continue spinning over the central states on
Wednesday, sending a frontal system towards the east coast. Global
deterministic models and ensembles are starting to come into better
agreement on the evolution of this system. Model differences that
continue to exist revolve around where/when secondary low pressure
development occurs over the Middle Atlantic and northeast. Despite
these differences, rain will overspread the region Wednesday morning
and continue into Wednesday evening. The system will be progressive,
which should help limit impacts. The rain could become moderate at
times, but not anticipating a heavy rainfall event like the previous
system. NBM probabilities for greater than 1 inch in any 12 hour
period Wednesday into Wednesday night have come up slightly, but
still largely 15-20 percent. NBM probabilities for greater than
0.50 inches in any 12 hour period have increased over the last 24
hours and are 40-50 percent late Wednesday. This signals an
increasing potential for a half to one inch of rain. Locally higher
amounts are possible, but uncertainty remains where these higher
amounts could occur. Given recent heavy rains, higher streamflows
and soil moisture, some minor flooding cannot be completely ruled
out. Overall, probabilities for a significant event remain low.

The axis of deepest moisture and strongest lift shift to our north
and east Wednesday night allowing the rain to taper off.
The closed upper low will track towards the Great Lakes/Ohio Valley
Wednesday night into Thursday. Deterministic and ensemble mean
differences increase for the end of the week with the handling of
the upper low. GEFS/GFS keep the upper low more consolidated with
several pieces of energy interacting with the the main low into
Friday. ECMWF/ECMWF-EPS/CMC/GEPS weaken the upper low on Thursday
and then have pieces of energy interact with the leftover trough
forming a larger upper low into the weekend. These differences give
a lower forecast confidence for Thursday into Friday with regards to
timing/locations of additional low pressure/surface troughs and
potential precip. The end of the week will remain unsettled and have
followed a low chance PoP in the NBM given the aforementioned
uncertainties. The upper trough/lingering closed low could linger
over New England into Saturday.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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High pres remains over the area thru Christmas Day.

Low clouds will linger over the region thru the TAF period.
MVFR to IFR cigs can be expected at times, especially tngt and
Mon mrng. VIS may drop at times in BR tngt, but confidence is
low so fcst only indicates 5SM.

Winds lgt and vrb thru the TAF period.

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

Periods of IFR possible thru 16Z Mon. Timing and coverage too
uncertain so not mentioned attm, although the best chances are
00Z-14Z. Variability in wind direction possible at LGA where a
general NE flow is fcst.

OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...

Christmas Day: Becoming VFR. Chance of MVFR or lower again aft
00Z Tue.

Tue: MVFR or lower at times.

Wed-Thu: MVFR or lower with rain.

Fri: Mainly MVFR. NE winds G20-30kt possible.

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 expected through Wednesday under weak pressure
regime.

Chances for SCA cond then increase, especially on the ocean,
from late Wed into Thu night. Wind gusts of 25 kt are forecast,
with a higher chance of seeing elevated ocean seas above 5 ft.

&&

.HYDROLOGY...
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Minor flooding along the CT River (warning handled by WFO BOX)
should subside late tonight.

Hydrologic impacts, if any, appear limited to localized minor
flooding from rain Wednesday into Wednesday night.
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&&

.TIDES/COASTAL FLOODING...
Monitoring potential for minor coastal flood impacts for
vulnerable coastal communities Wed/Thu with a passing frontal
system. Tidal departures of 1.25-1.50 ft 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. Low predictability on details attm.

&&

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

&&

$$

SYNOPSIS...BG/DS
NEAR TERM...BG
SHORT TERM...BG
LONG TERM...DS
AVIATION...JMC
MARINE...BG/DS
HYDROLOGY...BG/DS
TIDES/COASTAL FLOODING...