263
FXUS61 KOKX 280042
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
742 PM EST Fri Dec 27 2024
.SYNOPSIS...
-- Changed Discussion --
Multiple frontal systems will affect the area over the weekend.
Low pressure will track north across western Great Lakes
tonight and into Canada on Saturday. The associated warm front
will approach from the southwest tonight, moving across the area
on Saturday before dissipating. A second low deepening over the
Ohio Valley on Sunday will track north across the Great Lakes
Sunday night into Monday. This system will send another warm
front through the area Sunday, followed by cold frontal passage
late Sunday night into Monday. High pressure will then briefly
move in for Tuesday followed by another low pressure system
moving over the area on Wednesday.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH SATURDAY/...
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*Icy conditions expected across Interior after midnight into
Saturday morning
Forecast on track with temperatures across advisory area already
radiating into the upper 20s with light flow and scattered
cirrus. Increasing cloud cover should have temps stabilizing
through midnight. Road temps (per MesoWest) already at or working
towards freezing across much of S CT and would expect similar
for remainder of advisory area, particularly elevated roadways.
Leading edge of liquid precip is currently across west PA/MD
with nose of developing llj. This is initializing fairly well
with high-res CAMs and previous forecast with increasing
likelihood of light rain developing west of the Hudson R btwn
05 and 07z, and then translating east thru around daybreak. TD
in the 20s and weak/calm low-level flow should help reinforce
in- situ cold air damming and fzra rain across advisory area
threat through daybreak.
Across Suffolk County LI and coastal CT cant rule out some
brief and patchy icing issues. Will monitor T and precip
trends, as temps have radiated at or below freezing in these
areas this evening. Expectation that with increasing cloud
cover and light onshore flow that temps should slowly rise
overnight and above freezing before precip onset, but some
brief patchy icing is possible at onset if precip comes in on
faster end.
For NYC/NJ metro air and ground temps expected to be safely
above freezing to preclude any icing issue.
Previous Forecast....
Multiple streams of the polar jet will interact over the
weekend sending a series of frontal systems across the area. The
first will be an approaching warm front thats move out of the
Ohio Valley tonight and into the area late Saturday morning or
early afternoon. This front is associated with an occluded low
that lifts north across the western Great Lakes tonight and into
Canada on Saturday. This boundary more or less dissipates near
of just north of the area Saturday afternoon/night as a southern
branch storm system takes shape over the lower Mississippi
Valley.
Overrunning rains will work into the area late tonight working
in from SW to NE. Far eastern areas of SE CT and LI may not see
rain until just before daybreak. While high pressure continues
to retreat out into the Atlantic, which is not ideal for cold
air damming, the return flow on the backside of the high is very
weak. As a result, any low-level sub-freezing air will be slow
to mix out, especially across interior valley locations. The
greatest threat at this time looks to be across the Lower
Hudson Valley and NE interior NJ, specifically Orange and Putnam
Counties in NY, and western Passaic in NJ. These locations
could see up to a tenth of an inch of ice before changing to all
rain by mid to late morning. Farther east, across interior
southern CT and portions of NJ outside the NYC metro, the cold
air will erode quicker and the transition to all rain will occur
earlier. These locations will see anywhere from a glaze to a
few hundredths of an inch. The immediate CT coast could see a
real brief period of patchy freezing rain. Elsewhere, across NYC
and LI, expecting all rain. Rainfall amounts late tonight
through Saturday night will average about a quarter inch. The
best thermal forcing ahead of the warm front will be late
tonight into the morning, with the axis shifting southward
across LI Saturday afternoon. The rain may become more drizzly
late in the day and at night due to drier air in the mid levels
and weak lift.
Highs on Saturday will get into the 40s for most locations,
possibly even around 50 across LI.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY NIGHT/...
The combination of weak lift and dry mid levels will result in
occasional light rain and drizzle Saturday night. Temperatures
will drop little from the highs on Saturday, with lows in the
upper 30s inland, and the lower to mid 40s along the coast.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
A very unsettled pattern is expected for the long term with multiple
systems moving through. The NBM was closely followed with some
subtle adjustments.
A warm front pushes north of the area on Sunday allowing for a
chance of rain showers through the day. As the area becomes
entrenched in the warm sector of the intensifying cyclone over the
Ohio Valley, overcast skies may actually begin to break with dry
conditions possible, especially for southern and eastern areas.
Intensifying southerly flow ahead of the cold front will bring in
unseasonably warm air with high temperatures on Sunday in the middle
to possibly upper 50s.
The cold front approaches from the west Sunday night and brings
periods of light to moderate rainfall. THe cold front likely pushes
through during the first half of Monday allowing for rainfall to
come to an end by the afternoon with skies becoming clearer and the
wind shifting out of the W/SW. 1 to 2 inches of rainfall are
expected with the frontal passage. WPC has western portions of the
area in a marginal risk of excessive rainfall, but generally dry
antecedent conditions and moderate rainfall intensity should result
in minimal if any hydrologic or flooding concerns.
The low exits the area to the north as subtle mid-level ridging
builds over the Western Atlantic allowing for surface high pressure
to nose into the area from the southeast. Meanwhile, another strong
shortwave rounds the base of a mid-level trough over the Central US
allowing for another surface low pressure to develop over the Ohio
Valley and Mid-Atlantic by midweek. Global models differ on details
of this system but the low looks to pass either overhead or nearby
on Wednesday and may occlude northeast of the area as it rapidly
intensifies through the end of the week. This would lead to a period
of rainfall on Wednesday with a strong persistent NW flow for the
remainder of the week with generally dry conditions.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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High pressure remains over the area early this evening, before
sliding offshore later tonight with a warm front approaching into
Saturday.
VFR this evening, with only a low probability of MVFR cigs
developing for S coastal terminals late this evening. MVFR to IFR
conditions expected to arrive late tonight, followed by IFR and LIFR
conditions Saturday.
Light S/SE to variable winds through Saturday morning, with
coastal terminals possibly increasing to S 5-7 kt Saturday
afternoon, and then light SE Sat Night. Light precipitation
moves in for western terminals by around 06Z tonight, with
steadier precipitation aft 09z.
At KSWF temps will be cold enough for several hours of FZRA and
potentially up to 1/10th" ice accretion on untreated surfaces.
A brief period of-FZRA is possible for KHPN, KTEB and have
maintained a tempo group for these terminals. Plain rain is
expected after 08-09Z for these terminals.
There is a low chance for brief -FZRA at KBDR and KGON, if
precip comes in earlier than forecast.
NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
No unscheduled amendments expected through this evening. Low prob
for MVFR cig development for just after the eve push. A brief period
of -FZRA is possible at KTEB between 06-08Z tonight, with plain rain
expected after 08Z.
OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
Tonight: IFR and LIFR in -DZ and - RA.
Sunday: Period of -RA & DZ likely with IFR and LIFR conds.
Sunday night into Mon Morning: -RA/RA and IFR conds. Chance of LLWS.
S winds with gusts up to around 30kt.
Monday afternoon: Becoming VFR with W winds.
Tuesday: Mainly VFR, possible MVFR late or at night in -RA.
Wednesday: MVFR or lower in -RA likely, improvement to VFR possible
late.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With high pressure departing and a weak frontal system moving
across the area late tonight into Saturday, winds and waves are
forecast to remain below SCA criteria through Saturday.
A frontal system will move across the area waters Sunday and Monday,
with SCA conditions returning Sunday night and Monday as winds
increase to near 25 kt and ocean waves build to 5-7 ft. Sheltered
waters may have SCA conditions as well. Conditions fall below SCA
levels on Tuesday for all waters, however this may be short lived as
another frontal system approaches for Tuesday night and Wednesday,
possibly allowing for additional SCA conditions on the ocean.
&&
.HYDROLOGY...
There are no hydrologic concerns through next week at this time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Winter Weather Advisory from 11 PM this evening to 9 AM EST
Saturday for CTZ005>008.
NY...Winter Weather Advisory until 9 AM EST Saturday for NYZ069-070.
Winter Weather Advisory until 11 AM EST Saturday for NYZ067-
068.
NJ...Winter Weather Advisory until 9 AM EST Saturday for NJZ002-004-
103>105-107.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...DW/MW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...MW
AVIATION...NV
MARINE...DW/MW
HYDROLOGY...DW/MW