discussion on 2023-12-24

000
FXUS61 KOKX 250300
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1000 PM EST Sun Dec 24 2023

.SYNOPSIS...
A weak surface trough will linger near eastern Long Island
tonight into early Christmas Day, then weaken as high pressure
to the east becomes reestablished. The high will then slowly
weaken on Tuesday. Low pressure approaching Tuesday night
through Wednesday will move near the area Wednesday night, then
pass to the northeast on Thursday. Another low will approach on
Friday, pass southeast of Long Island Friday night into
Saturday, then move farther out into the Atlantic on Sunday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --Special weather statement has been issued for Middlesex and New
London counties in SE Connecticut for patchy dense fog. This is
in effect until 1AM Monday. The fog is expected to develop
across other parts of the region and expand going into
overnight. Unsure how dense the fog becomes though, so not
enough confidence to go with dense fog advisory overnight but
situation will have to be monitored through tonight to see if
any dense fog becomes greater in coverage.

Patchy fog remains in the forecast tonight into early Monday
morning. Maintained the POPs for rain showers out east across
Eastern Long Island and SE Connecticut as previous forecast for
overnight, as they seem to be in line with the HRW ARW, HRW
FV3, and NAM Nest reflectivity forecasts.

Some fog remains across parts of SE Connecticut with some of
this being locally dense and some mesoscale models and some
forecast BUFKIT soundings indicate some further development of
fog across parts of the region throughout the night. Due to
uncertainty on extent and depth of this fog, left as patchy
coverage. Also with some slight lowering of temperatures
overnight, many locations are expected to achieve low level
saturation but with the overcast cloud coverage this will limit
the coverage spatially of the fog.

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 continue across the forks of Long Island and SE CT
overnight. Forecast carries chance PoP in these areas as this
weak forcing continues, as the upper trough cuts off aloft
beneath a building longwave ridge and moves toward S New
England.

Temps will cool off to near 40 in NYC, and into the 30s
elsewhere, remaining above freezing throughout.-- End Changed Discussion --

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
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.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
-- Changed Discussion --* Midweek rain event, around a half to 1 inch of rain expected.
  Locally higher amounts possible. No more than localized minor
  flooding is expected.

* Forecast has above normal temperatures midweek transition to near
  normal temperatures going into next weekend.

The models have decreased in rain amounts and pushed later the
timing of the bulk of the rainfall, later in the day Wednesday
and into Wednesday night. Also to start this long term period,
patchy fog is in the forecast for the region Tuesday night into
Wednesday.

Troughing synoptic pattern mid to late week will have a corresponding
surface pattern depicting a developing and approaching low from the
Southeast US Tuesday night into Wednesday. Despite an increasing
subtropical upper level jet, the mid and upper level pattern
remains positive tilting, allowing for this system to remain
pretty progressive. This will limit the total rainfall as the
vertical lift will not be as enhanced.

The large scale numerical models do not depict too much deepening
with this low pressure system as it approaches and eventually moves
near the area Wednesday night.

Then, the low moves north to northeast of the area Thursday. Another
low develops and moves near the area Friday but is shown to pass
southeast of Long Island Friday night.

The pattern for Thursday through Friday night of next week depicts
the more unsettled pattern where there will be periodic chances for
rain and/or snow showers depending on the timing of when the mid
level vorticity maxima move in.

It appears the troughing pattern aloft amongst the different large
scale numerical weather prediction models lingers into next
weekend. This will also point to a transition to a relatively colder
airmass for Friday and into the start of next weekend. POPs for
rain and/or snow showers could trend higher in subsequent
forecasts.-- End Changed Discussion --

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --High pressure remains over the area through the TAF period.

Low clouds will linger thru the TAF period. MVFR to IFR cigs
expected at times, especially tonight and Monday morning.
Visibilities may drop at times tonight, but confidence is low.
Thinking its more of a stratus night vs a fog night.

Winds will once again be light and variable thru the TAF
period.

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

Timing of lower cigs may may be off by an hour or two. Periods
of IFR possible thru 16Z Mon.

OUTLOOK FOR 00z TUESDAY THROUGH FRIDAY...

Christmas night: Chance of MVFR or lower.

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...
Conditions are forecast to remain below SCA thresholds through
Wed night with a relatively weak pressure gradient in place.
Chances then increase for SCA conditions on the ocean for
Thursday into Thursday night, mainly for seas. All waters
potentially could see 25-kt wind gusts Friday into Friday night,
with 5+ ft seas remaining on the ocean, as stronger westerly
flow develops.

&&

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

QPF with the mid week system ranges from 1/2 to 3/4 inch.
Impacts appear limited to localized minor/nuisance poor drainage
flooding in areas of relatively heavier rainfall.

&&

.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 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.

Blend of bias-corrected surge guidance keeps water levels below
minor thresholds, while a reasonable worst case blend of bias-
corrected Stevens Tech NYHOPS central and 95th percentile
forecasts indicates potential for minor flooding with the Wed
morning high tide cycle along the south shore of Nassau and for
Jamaica Bays, with water levels nearing minor benchmarks along
the SW CT coastline on the western Sound.

&&

.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...BC
MARINE...BG/JM
HYDROLOGY...BG/JM
TIDES/COASTAL FLOODING...