499
FXUS61 KOKX 162250
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
550 PM EST Thu Jan 16 2025
.SYNOPSIS...
A weak frontal system passes across the region tonight. High
pressure briefly returns on Friday ahead of another frontal
system Saturday into Saturday night. A coastal low then likely
impacts the region Sunday into Sunday night, followed by high
pressure through the middle of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
The forecast is mainly on track. Only bumped up PoPs by about
10% across some coastal and eastern sections for this evening.
Also changed the wording to scattered snow showers instead of
"chance" of snow showers as snow is falling in some areas where
radar returns appear, but not everywhere due to a lack of low
level moisture. In any case, accumulations will remain very
light.
An upper level trough will continue moving across the region
tonight. A weak frontal system will accompany the upper trough,
with both systems offshore by daybreak Friday. Moisture is a
limiting factor along with overall weak lift heading this evening.
The expectation is for at least some snow showers continuing to
make it to the ground amidst the virga. The CAMs continue to
hint at a slight increase in simulated reflectivity and
organization of snow showers across central and eastern Long
Island. This appears tied to a weak wave of low pressure on the
frontal boundary helping to increase moisture and convergence.
These snow showers will quickly pass through over the next few
hours. A few lingering flurries are possible towards midnight,
but dry conditions are forecast overnight into early Friday
morning.
A coating to a few tenths of an inch of snow accumulation are
possible. Snow amounts could be slightly higher across eastern
Long Island where one half up to an inch cannot be ruled out.
Overall this is a light event with liquid equivalent amounts
averaging around a few hundredths of an inch or less.
The upper trough passing to the east late tonight will allow
clouds to begin clearing early Friday morning. There will only
be a slight increase in NW flow behind the system with lows
ranging from the teens inland and lower to middle 20s elsewhere.-- End Changed Discussion --
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A ridge of high pressure both aloft and at the surface will
move across the region on Friday. The air mass is not as cold
as recent days, which will allow temperatures to approach normal
highs in the upper 30s to around 40 degrees. The ridging is
quite progressive and will move offshore Friday night in
response to the next upper trough/shortwave approaching from the
Great Lakes region. Clouds begin increasing from west to east
Friday night with temperatures in the 20s inland and lower 30s
near the coast.
The shortwave will send the next frontal system into the area
on Saturday. A warm front lifts north of the area early on
Saturday helping to bring in warmer temperatures. Most of the
region will have high temperatures in the middle to upper 40s
except for the interior of the Lower Hudson Valley where highs
may just reach 40 degrees. The approaching front and lift from
the shortwave will yield increasing chances for rain, especially
the eastern half of the area where moisture return is greatest.
The forcing will be quick to move across the area in the
afternoon and evening with rain amounts up several hundredths
to a few tenths, highest across Long Island and southeast
Connecticut. This will largely be an all liquid event, but some
colder air Saturday evening across the interior could bring a
brief rain/snow shower as the shortwave energy passes through
the area. Otherwise, mostly cloudy conditions prevail overnight
Saturday with some clearing late. Lows will be in the 20s inland
and around 30 at the coast.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The trend among deterministic models and their ensemble
means continues for low pressure passing close enough to bring
us a good chance of precipitation Sunday into Sunday night with
an overall wetter solution. A 500mb shortwave rotates around the
periphery of a large polar vortex over Canada and passes either
through or nearby the area during Sunday night. Although most
of the guidance tracks the surface near or SE of the 40N/70W
benchmark, the positioning of a strong upper jet or coupled jet
streaks may create enough large scale upper divergence over the
region such that even inland areas could have a likelihood of
precipitation. PoPs have been raised from the previous forecast,
however likely PoPs have been limited to LI and SE CT for the
time being.
Too early to have high confidence in snow the accumulation
potential with trends not yet firmly established and with the
potential for some mixed precip at the coast. A lack of
downstream blocking resulting in a progressive system also
factors into accumulations as they would be mitigated by the
forward speed of the storm. With all of this said, the chances
of getting an advisory-level snowfall here Sunday into Sunday
night are at least increasing.
An arctic airmass filters into the region and lingers through
the middle of next week. Dry weather anticipated as another
storm system gets suppressed by high pressure, but well-below
temperatures are expected. After highs only in the 20s on
Monday, highs only in the teens for most spots Tuesday and
Wednesday. Adding to the chill will be gusty winds which may
lead to advisory-level wind chills for both Monday and Tuesday
nights. Given the tightness of the pressure gradient progged by
the models, NBM winds may be too low through Wednesday thus wind
chills may end up lower than currently forecast. Didn`t stray
too far from NBM for sustained winds, but bumped up the gusts
more noticeably due to the strong cold advection.
Winds on Thursday should be lighter as a high pressure ridge
reaches the east coast, centered to our south. This would begin
to bring us some relief with a W to SW flow helping high
temperatures reach mostly 25-30.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A frontal system, approaching from the west, moves offshore
tonight, passing south and east late tonight. High pressure
builds back in for Friday.
Becoming MVFR with light snow showers late afternoon into this
evening, and continue with PROB30. There is a low chance of
brief IFR conditions with the snow. Little to no accumulation
expected, one to two tenths of an inch. Light snow and lowered
conditions may be an hour earlier than forecast. Also, better
chances of IFR will be at KISP and KGON this evening as low
pressure develops south of Long Island.
Winds SW to W 10-14 kt become westerly later this evening, and
then NW around 10 kt after the snow ends.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments possible with lowering conditions in snow showers into
this evening. Low chance of IFR 00Z to 03Z.
.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday afternoon: VFR.
Saturday: MVFR or lower at times with rain likely during the
afternoon, possible snow at night before ending. S wind gusts around
20 kt during the day.
Sunday: Chance for MVFR or lower at times with increasing chances of
snow, with rain/snow mix for coastal terminals late day into the
evening.
Monday: Mainly VFR, MVFR possible early morning. NW wind gusts near
20 kt.
Tuesday: VFR. W wind gusts around 20 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Conditions will remain below SCA levels on the waters through
Friday as the pressure gradient will be weak. An approaching
frontal system on Saturday will help increase southerly winds
and bring a chance of SCA conditions for at least the ocean. The
front pushes offshore Saturday evening with winds falling below
SCA levels into Sunday morning.
Waves on the ocean may build up to 5 feet starting during the
day Sunday ahead of low pressure passing SE of the waters
Sunday night into Monday. A better chance for advisory
conditions across all waters arrives Sunday night into Monday
with the closest approach of the storm. The current wind
forecast for Monday through at least Monday night, particularly
for wind gusts, might be too conservative at this point, but
there`s too much uncertainty to go significantly higher than
NBM. The combination of the pressure gradient on the backside of
the low and strong cold advection could bring gales across all
waters during this period. Winds diminish on Tuesday, but at
least SCA conds appear to be likely.
&&
.HYDROLOGY...
No hydrologic impacts are expected into the middle of next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JC/DS
NEAR TERM...JC/DS
SHORT TERM...DS
LONG TERM...JC
AVIATION...MET
MARINE...JC/DS
HYDROLOGY...JC/DS