410
FXUS61 KOKX 191142
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
642 AM EST Tue Nov 19 2024
.SYNOPSIS...
High pressure will remain in control through Wednesday. Low
pressure strengthens south of Long Island Wednesday night into
Thursday and will linger nearby through Friday. The low exits
this weekend followed by high pressure early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Forecast on track. The CWA will be situated between two closed
upper lows today, one just south of the Maritimes and another
over the Northern Plains. Ridging will build both at the surface
and aloft between the two lows, leading to dry and mostly sunny
conditions across the region. Temperatures will be cooler
compared to the last two days, but still above normal for this
time of year. Highs will be in the middle to upper 50s.
A sheared out shortwave energy ahead of the upper low over
the Northern Rockies will approach tonight. The energy will
encounter the ridging axis and weaken/diminish over the area.
The result will be mostly cloudy skies tonight. A sprinkle
cannot be completely ruled out west of the NYC metro. Lows will
range from the upper 30s inland and lower to middle 40s
elsewhere.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The ridge axis will remain overhead to start Wednesday, but
should slowly begin moving east in the afternoon and evening.
The daytime hours will remain dry as the main frontal system
will still be located well to our west. Clouds will likely be
thickest across the western half of the area for much of the
day with some high level clouds across the eastern half. This
will yield mostly cloudy conditions west and partly cloudy
conditions east. Highs will reach the upper 50s to around 60
degrees.
There is high confidence in a widespread rainfall Wednesday
night into Thursday. A deep, closed upper low pressure will
spin across the Great Lakes region Wednesday night. Jet energy
rounding the base of the low will help develop a new low surface
low along the Middle Atlantic coast Wednesday night. The low
will then quickly deepen into Thursday over the region before
shifting towards the west or northwest as the large upper low
captures it. While the latest 00z global deterministic guidance
are occluding the low nearly over the region, the ensembles are
indicating more spread to this process leading to lower
confidence in where any lingering bands of precip will occur
Thursday night.
Widespread rain will develop and move across the area from west
to east Wednesday night. The rain quickly becomes moderate to
locally heavy at times, especially after midnight into the
morning commute. The rain should then continue through Thursday
afternoon, but become light to occasionally moderate as the
surface low begins to retrograde towards the NW. There is a
chance that a steady light rain will persist even outside of
areas with more organized banding into Thursday night, so have
kept PoPs no lower than 50 percent and this may need to be
raised further. As for Thursday night, have confined the highest
PoPs NW of the NYC metro where there is a bit of a signal for
wrap around banding here, but this may need to be adjusted in
subsequent forecasts as confidence increases and model spread is
reduced.
Much colder air will move in Thursday night as the surface low
gets captured by the closed upper low. This will introduce
potential for wet snow across the Lower Hudson Valley and
potentially into SW CT, especially the higher elevations.
However, the timing and location of the aforementioned
occlusion process will ultimately determine the extent of the
colder air and where the most organized forcing sets up.
Rainfall amounts Wednesday night through Thursday afternoon
average around 1 to 1.25 inches across much of the area with
locally higher amounts possible. Additional precipitation
Thursday night will vary, but an additional few tenths are
possible.
The strengthening low pressure will bring gusty winds,
especially near the coast. Gusts 30 to 35 mph are possible
Wednesday night into Thursday. If the low were to remain just
south of Long Island longer, winds could be a bit higher.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
The models remain in good agreement that the upr low will spin
over the region on Fri, then gradually lift out to the NE Sat
and Sun. While the precise details still need to be ironed out,
in general it looks to be cloudy and cool with periods of pcpn
Fri and Fri ngt, then lessening chances Sat and most likely dry
to perhaps an isold shwr on Sun.
Although not an arctic airmass, the cold pool will be deep over
the cwa. Any warming temps at the sfc should hit convective
resulting in extensive low cloudiness, this is aside from any
areas of forcing from both the sfc and aloft. This forcing
should focus areas of pcpn Fri and Fri ngt, yet some uncertainty
exists, particularly with the behavior of the sfc low. Areas
that end up in the nwrn quad of the occluded low should be
better positioned for some focused pcpn and wet snow with bl
flow off the warm waters cut off. Favored areas for snow are
interior spots with elevation where there are the best chances
for any accums. Some mixing at least expected for most of the
interior otherwise. The coasts, especially LI, will have a
difficult time with snow unless there is some deep vertical
motion at times to overcome the warm bl in the marine influence
zone.
For temps on Fri, went blw the NBM closer to a blend of the
raw model 2m data based on the expected cloud cover and pcpn.
The upr low begins to pull away on Sat, but model time heights
still indicate extensive moisture with any significant surge of
dry air not coming in until Sat ngt. As a result, the NBM cloud
cover looked too low and was increased significantly. In
addition, temps were lowered blw the NBM essentially close to
what mixing the GFS down from h85 would yield. Maintained 30
percent chcs for pcpn, mainly rain with the intensity lgt, even
across the interior.
The fcst goes dry on Sun with the sys over Canada. Cannot rule
out some sprinkles or isold shwrs per the ECMWF, but the flow
will have to align perfectly with nly flow from the Taconics and
NW hills of CT to get pcpn into the cwa. Have kept the fcst dry
attm as a result. The NBM was used for temps.
A frontal sys approaches from the SW on Mon. The modeling
indicates waa aloft, with a potential warm front Mon ngt. Not
much moisture to work with so the fcst has been kept dry for
now, although there could be a chc of rain particularly invof
the front.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
High pressure remains in control today and weakens tngt. VFR
thru the TAF period with NW/VRB winds blw 10kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
No unscheduled amendments expected.
OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
Wednesday...Lowering CIGS with MVFR possible late Wednesday
along the coast.
Wednesday Night...MVFR/IFR with rain developing and E-SE gusts up to
35kt.
Thursday...MVFR/IFR with rain in the morning, then mostly MVFR in
the afternoon with a chance of rain. Gusts up to 35kt possible with
direction becoming W in the afternoon.
Friday...Mainly MVFR with periods of rain, rain/snow inland. Winds
15 to 25 kt.
Saturday...MVFR possibly becoming VFR late. NW winds gusting 20 to
25 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
High pressure over the waters through Wednesday will lead to
winds and seas below SCA levels. Low pressure develops and
strengthens over the waters Wednesday night into Thursday. This
will lead to increasing winds and building seas. Wind gusts
25-30 kt are likely Wednesday night through Thursday night.
There is also potential of gale force gusts. Per collaboration
with PHI and BOX, have held off a Gale Watch with this update.
Will continue mention gale potential in the HWO.
The low will be slow moving and will continue producing SCA
conditions Friday-Sunday. There is a chance for occasional
gales, especially on the ocean Friday and Saturday.
&&
.FIRE WEATHER...
A Special Weather Statement remains for southern CT per collab
with CT fire wx partners. Otherwise, winds should be lighter
today and generally under 15 mph. Minimum RH values will range
from 35 to 45 percent. Light winds are expected Wednesday along
with minimum RH values 50 to 60 percent. A wetting rain is then
expected Wednesday night and Thursday.
&&
.HYDROLOGY...
Dry conditions will continue through Wednesday afternoon. A
widespread 1 to 1.5 inches of rain is forecast from Wednesday
night through Thursday night. Locally higher amounts are
possible. The heaviest rain is most likely to occur Wednesday
night into Thursday morning. No hydrologic impacts are expected
given the recent dry weather and progressive nature of any
heavier rainfall.
No hydrologic impacts are expected Friday into early next week.
&&
.TIDES/COASTAL FLOODING...
Minor coastal flooding is possible with the daytime high tide
cycles Thursday. The extent of any minor coastal flooding will
be dependent on the magnitude and duration of E flow as well as
fetch and surge.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JMC/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...JMC
AVIATION...JMC
MARINE...JMC/DS
FIRE WEATHER...
HYDROLOGY...JMC/DS
TIDES/COASTAL FLOODING...