121
FXUS61 KOKX 171728
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1228 PM EST Fri Jan 17 2025
.SYNOPSIS...
Dry and mostly fair weather this afternoon will give way to a
series of systems over the weekend. Low pressure departs to the
northeast on Monday with a strong arctic high pressure system
building into the area through the middle of next week. Another
frontal system may move past the area toward the middle to end
of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
The fcst is mostly on track. For this update only added some
cloud cover across NW portions of the CWA with a warm front
which is undergoing frontolysis / weakening. Kept temp forecast
the same. Otherwise, an upr ridge will translate across the cwa
today and tngt. This will result in dry wx due to strong
subsidence and a lack of moisture. Time heights indicate a deep,
albeit not strong, NW flow promoting mixing. Model h85 temps
lined up well with the NBM output for highs. At ngt,
strengthening onshore sly component flow should keep lows more
uniform across the area. The NBM seemed to handle this as well,
so it was followed with a few adjustments.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A strong subtropical jet over Baja will quickly traverse the
country and reach the Southeast on Sat. This will help transport
a bit of moisture into the local area as a deep trof digs into
the Midwest. This should set up a round of rain, mainly light,
perhaps mixed with some snow extreme nwrn areas, particularly
where there is some elevation. Timing is Sat aftn and eve attm.
By the time the colder air filters in, the pcpn is expected to
be over. There could be some residual icy spots however as lows
drop into the 20s most of the cwa.
As the colder airmass builds in on Sun, the upr trof spins up a
low and tracks it somewhere E of the cwa Sun ngt per the latest
model consensus. The NAM appears to be an outlier - even all of
the ECMWF AI runs are in good agreement. Because of this, went
with the likely pops from the NBM. Now it appears to be the
typical exact track game to determine the heaviest snow band and
whether ern/cstl areas get into a mix. For now, will fcst about
4 inches of snow for the entire area, leaving room for
adjustment. It does appear that wrng lvl snow is a possibility
with this sys. Will include a mention in the HWO.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Key Points:
** A frigid airmass is expected to take hold by Monday night and
linger through the middle of the week.
** High temperatures Tuesday and Wednesday will be in the teens to
near 20. Lows in the single digits Monday night through Wednesday
night.
The low pressure departs to the northeast of the area as an arctic
high pressure builds into the area on Monday. A tightening pressure
gradient over the area between these two systems will bring a
persistent NW flow for much of the period. This will also filter in
an arctic airmass that will begin to be felt Monday but firmly
take hold by Monday night.
High temperatures on Monday will be in the 20s with the upper 20s
along the coast to low 20s for the interior areas to the NW. By
Tuesday and Wednesday, the arctic airmass is firmly in place
preventing high temperatures each day form rising out of the upper
teens to near 20 degrees. Low temperatures will be even colder,
despite persistent NW flow. Lows Monday night will be in the single
digits to possibly near 0 for portions of the Lower Hudson Valley.
These frigid low temperatures will persist for Tuesday night and
Wednesday night as well with lows in the single digits or lower each
night. The peak of the frigid temperatures will be on Tuesday night
into early Wednesday morning with even coastal areas dropping into
the middle single digits. A brisk flow will also allow for wind
chill values to drop below 0 for the entire area during each night
with the coldest feels like temperatures on Tuesday night into
Wednesday morning with wind chill values anywhere from 0 to -5 along
the coast and -5 to -10 or lower for interior areas.
Guidance remains inconsistent with regards to the potential
development of the next system where the CMC brings a developing
coastal low pressure system to the area by Wednesday with the GFS
and ECMWF suppressing it to the southeast. Left Slight chance PoPs
for now to account for the possibility of being impacted on the
northern periphery of this system.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure builds in today from the south. Another frontal system
approaches from the west tonight and into Saturday.
VFR expected today and tonight. Ceilings begin to lower Saturday
late morning with MVFR or lower possible after 18Z Saturday.
5-10 kt westerly flow this morning. Wind becomes more SW/SSW by late
afternoon as high pressure builds to the south, then S tonight.
Speeds remain mainly at or under 10 kt through this time. WInds may
begin to gust 20 kt around midday tomorrow.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Onset timing of MVFR ceilings and rain is around 17Z, but subject to
change by a few hours.
Potential for gusts tomorrow morning have been included in TAFs, but
its possible they could be more occasional.
.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
Sunday: MVFR or lower at times with increasing chances of snow in
the afternoon and into the evening.
Monday: Mainly VFR, MVFR possible in the morning. NW wind gusts near
20 kt.
Tuesday: VFR. W wind gusts around 20 kt.
Wednesday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds and seas will be blw sca lvls today. The ocean may
approach sca on Sat, and will likely hit sca criteria by Sun
ngt. The protected waters will have mrgnl winds Sun and Sun ngt.
SCA conditions persist on the ocean waters on Monday with waves
greater than 5 feet and gusts 25-30 kt. The non-ocean waters may be
more marginal as wind gusts may just fall short of 25 kt. Near SCA
gusts then persist mainly for the ocean into Tuesday but the non-
ocean waters may fall short.
Persistent winds above 15 kt with a frigid airmass in place may
result in the potential for freezing spray, especially on the ocean
where wave heights will be more elevated on Monday and into
Tuesday.
&&
.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...JMC/MW
NEAR TERM...JMC/JE
SHORT TERM...JMC
LONG TERM...MW
AVIATION...BR/MW
MARINE...JMC/MW
HYDROLOGY...JMC/MW