844
FXUS61 KOKX 201817
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
117 PM EST Thu Feb 20 2025
.SYNOPSIS...
Low pressure well off the Carolina coast will continue to deepen
as it moves east through tonight. Thereafter, sprawling high
pressure over the mid section of the country will builds in
through the weekend, remaining in control through Monday. Weak low
pressure will pass to the north Monday night into Tuesday,
followed by building high pressure on Wednesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
A 999 mb surface low well E of Cape Hatteras will continue to
deepen as it pulls off to the and east through tonight.
Meanwhile, an upper low will swing across into this evening,
with a weak inverted surface trough extending back toward the
region from the exiting low.
Temperatures this afternoon should remain below freezing,
ranging from the mid 20s inland, to around 30 at the coast.
A high cloud canopy will thicken and lowers into late day.
As the upper low swings through, steepening lapse rates and a
moistening column down to the sub cloud layer should instigate
snow shower development late this afternoon and evening. QPF is
light, locally up to 1/10 inch across Long Island, and less than
that elsewhere especially north/west of NYC. Still, with the
cold air mass entrenched, and SLR progged around 15:1, snow
could stick and accumulate relatively efficiently if/where it
does fall. With such little liquid equivalent to work with
though, amounts should be limited, likely at or under an inch.
Localized amounts could be in the 1-2 inch range as some hi res
guidance is hinting. While not a particularly notable event
based on amounts, the expected timing of this activity, in the
late afternoon and early evening, could pose some travel impacts
and slick spots to the PM rush. Still, some locales may not see
any snow whatsoever, or just a few flurries, largely staying
mainly dry and overcast instead, especially into interior
southern CT.
Clouds begin to thin out regardless overnight as the upper low
shifts offshore and drier air works in. Flow increases as the
exiting surface low deepens and tightens the pressure gradient
locally, which should preclude decoupling. Low temps range from
the teens inland, to lower 20s along the coast.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A sprawling 1040 mb high across the mid section of the country
will build in on Friday. Blustery NW flow persists with the
pressure gradient between the building high and exited offshore
low, and gusts toward 30 mph are expected much of the day,
adding a chill to the already below normal temperatures. Some
coastal locales may sneak above the freezing mark by a degree or
two in the afternoon, otherwise, upper 20s to around 30.
Flow relaxes into Friday night as the high builds closer, and
mostly clear skies prevail as temperatures fall into the teens
overnight.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The upper flow will be mainly zonal Saturday into Sunday night,
with a very weak, low amplitude, trough moving through Saturday
night with surface low pressure passing well to the north, as
high pressure remains in control, centered to the south. With
little upper support and little moisture no precipitation is
expected.
A more amplified trough, accompanied with a vort max, passes
mainly to the north Monday night, quickly followed by another
trough and vort max for Tuesday. With some uncertainty with the
timing and strength of this trough, have only slight chance
probabilities Monday night through Tuesday. Zonal flow returns
for Wednesday. With mild air in the area, with temperatures 5 to
10 degrees above normal Monday night through Wednesday, the
precipitation will be mainly light rain showers, with light snow
showers inland.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
An upper level low, and surface trough, will cross the area
tonight. High pressure builds in Friday.
VFR with a period of MVFR and possibly IFR in light snow
showers this evening. Tempo groups included for the lower
conditions in snow especially for city terminals. There is some
timing uncertainty with the onset and northeast extent given
drier air across CT. Up to a half inch of snow is possible.
NW flow 10-15G20 kt is expected through the remainder of the
forecast. More gusts develop later this evening, and may be
more occasional until toward 00Z. Winds and gusts increase
overnight, with occasional gusts 30-35 kt and continue into
Friday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments for timing of snow and lowering conditions this
evening. Occasional gusts late this evening into tonight may
gust in excess of 30 kt.
.OUTLOOK FOR 12Z FRIDAY THROUGH TUESDAY...
Friday: VFR. NW winds G25 kt.
Saturday and Sunday: VFR.
Monday and Tuesday...Mainly VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Lighter winds and seas maintain sub Small Craft Advisory (SCA)
conditions on all waters today. By this evening, increasing flow
behind passing low pressure well offshore returns SCA conditions
to all waters as NW gusts 25-30 kt develop tonight and persist
thru Friday. Seas on the ocean build toward 5-7 ft during this
time as well. Winds should lighten below advisory criteria
Friday evening on non ocean waters, and by Friday night on the
ocean.
Sub advisory conditions then prevail Saturday through Monday,
however, Saturday night gusts on the ocean waters may briefly
near SCA levels as low pressure passes well to the north and W
to SW winds increase. Persistent WSW flow Sunday night into
Monday night will allow ocean seas to build and by late Monday
night into Tuesday seas may reach 5-6 ft.
&&
.HYDROLOGY...
No hydrologic impacts expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EST Friday
for ANZ331-332-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...BG/DR/MET
NEAR TERM...BG/DR
SHORT TERM...DR
LONG TERM...MET
AVIATION...IRD
MARINE...BG/DR/MET
HYDROLOGY...DR/MET