613
FXUS61 KOKX 232304
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
604 PM EST Mon Dec 23 2024
.SYNOPSIS...
High pressure moves offshore tonight as a clipper system
approaches, moving across the area on Tuesday. High pressure
returns Tuesday night and will remain in control through Friday.
A series of frontal systems approach from the west this
weekend, potentially impacting the region into early next
weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
Forecast remains on track early this evening. Not quite as cold
as the previous nights, though temperatures remain in the teens
and 20s everywhere through the overnight ahead of a quick shot
of snow into Tuesday morning. Previous discussion follows.
High pressure will move offshore tonight ahead of an approaching
clipper system, which will bring a quick band of accumulating
light snow Tuesday morning.
Warm advection develops tonight ahead of the system. Some
of the weak flow off the ocean will likely bring in low clouds
across Long Island and southern Connecticut. Some of the CAMs
indicate very light precip developing, which may be in the form
of flurries. While saturation is just in the low levels and
around -5C, past situations have yielded some light flurries
with sea salt as the CCN. PoPs are at 20 percent across eastern
Long Island and southeast CT with the expectation that very
little precip will actually fall tonight. Otherwise,
temperatures will fall this evening into the teens away from the
coast and lower 20s near the coast. Temperatures may rise a few
degrees late tonight ahead of the clipper system, but most
areas will remain in the 20s before any snow reaches the area.
A band of snow will accompany clipper, which usually come in an
hour or two faster than the guidance. Have accounted for this
in the latest forecast. The band of snow reaches the interior of
the Lower Hudson Valley and Northeast New Jersey 4am-7am, NYC
metro and Hudson River Corridor, 7am-10am, and the rest of CT
and Long Island 8am- 12pm. The band will move across any given
location quickly with snow lasting only a few hours. The band of
snow will also weaken as it moves east towards the NYC metro,
Long Island and Southern Connecticut. Some of the east end may
mix with some rain as well mid to late morning.
Snowfall accumulations range from around an inch across the
interior of the Lower Hudson Valley, interior SW CT, and
potential interior NE NJ, down to around a half inch in the NYC
metro and just a few tenths further east across Long Island and
southeast CT. Snow-to- liquid ratios should not be as high as
the previous event based on the latest sounding analysis, but
some interior locations may be able to briefly run just above
10:1. Coastal locations look to be just below 10:1 as snow
growth does not appear as efficient in the dendritic growth
zone.
Have issued an Special Weather Statement to account for
potential slick roads during busy holiday travel as any snow
that falls should be able to accumulate due to the recent cold
air and cold grounds. The only exception is across eastern Long
Island and southeast CT. The band of snow will arrive mid to
late morning and ground temperatures may be able to respond to
some of the warming occurring to prevent impacts. May need to
expand the statement to these zones if the band is faster and/or
able to maintain its intensity longer.
Conditions will quickly improve from west to east mid to late
Tuesday morning. Dry conditions are expected across the area
Tuesday afternoon with partly to mostly cloudy skies.
Temperatures should be able to rise into the middle and upper
30s in the afternoon.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
The shortwave and clipper system continue moving off the New
England coast Tuesday night. Ridging builds aloft behind it
allowing surface high pressure to return across New England
through Wednesday. Temperatures Tuesday night bottom out in the
upper teens inland to lower and middle 20s elsewhere. Highs
Wednesday remain slightly below normal with in the 30s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Upper level ridging builds east from the Great Lakes on
Thursday, and high pressure remains centered over northern New
England and southeast Canada through Friday, maintaining dry,
but cold, conditions locally. The ridge axis shifts overhead
then east into late weekend, with return flow setting up as the
surface high slips offshore.
Behind it, the next shortwave and associated frontal system will
attempt to approach from the west, returning chances for
precipitation this weekend. Guidance continues to offer varying
solutions with the timing and placement with this system in an
advancing trough, so capped PoPs at 50% for now. With the recent
cold air mass likely being scoured out from the developing onshore
flow, profiles appear to support mainly rain, though can`t rule out
the possibility of some ice or wintry mix at the onset on Saturday
depending on the solution. Additional precipitation looks to arrive
early next week with another frontal system quickly moving in behind
the first.
Temperatures gradually increase late this week into early next, with
afternoon highs Thursday and Friday still in the 30s for most with
light northerly flow, getting into the 40s Saturday as easterly
winds develop, and near 50 along the coast Sunday and Monday.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
High pressure over the region will slide off the coast through
tonight. A weak frontal system will pass through Tue morning.
VFR at most sites through most of tonight except out east,
where low clouds currently off the coast may slide back into
KISP/KBDR/KGON for a time overnight.
Have higher than usual confidence in timing of light snow band
with the approaching front, affecting most terminals for a few
hours: KSWF 10Z-14Z, NYC metros and KBDR mostly from 13Z-16Z,
KISP 14Z-17Z, and KGON 14Z-18Z. Prevailing IFR vsby expected in
the snow at KSWF with up to an inch accumulation, and MVFR/tempo
IFR vsby, with a dusting elsewhere.
Winds should become SW 5-10 kt this eve, then veering WSW-W
with onset of snow Tue mrng. Inland winds may remain light/vrb
through most of the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
AMD possible possible toward Tue morning with -SN developing.
OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday night through Saturday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
High pressure will shift east as a weak clipper system passes
across the waters late tonight into Tuesday. High pressure then
returns through the end of the week. A series of frontal systems
approach the first half of next weekend. Winds and seas will
remain below SCA levels through Saturday.
&&
.HYDROLOGY...
There are no hydrologic concerns through next weekend.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DR/DS
NEAR TERM...DR/DS
SHORT TERM...DS
LONG TERM...DR
AVIATION...JMC/BG
MARINE...DR/DS
HYDROLOGY...DR/DS