032
FXUS61 KOKX 091635
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1135 AM EST Mon Dec 9 2024
.SYNOPSIS...
-- Changed Discussion --
A warm front moves over the region into this evening and then
will remain nearly stationary into Tuesday. The warm front lifts
north of the area Tuesday night. Strong cold front and
intensifying low then approach for Wednesday, eventually moving
across the area Wednesday night. High pressure then returns for
the end of the week into Saturday before moving offshore on
Sunday.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Forecast on track into this evening. A warm front will continue
approaching ahead of a middle level shortwave. Warm
advection/isentropic lift will lead to stratiform rain this
afternoon and early evening. The rain will mainly be light,
but brief moderate rain is possible. The rain will quickly taper
off from west to east 6 pm to 8 pm with the passage of the
shortwave.
Ridging will build aloft behind the shortwave, but the warm
front likely stalls over the area tonight. Low clouds and some
patchy fog are possible overnight. Locally dense fog is
possible.
Highs today will be in the lower 40s inland to potentially low 50s
near the coast. Low should be in the upper 30s to mid 40s.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Key Points with Potential Impacts
* Widespread rain Tuesday night through Wednesday evening. Potential
for mostly minor flooding with a marginal to slight risk for flash
flooding, particular, more coastal areas.
* Potential for strong wind gusts along the coast Wednesday into
Wednesday evening near 45 to 55 mph.
For the upper levels, after initial ridging in the area
Tuesday, a strong upper level low moves from South Central
Canada into the Great Lakes Tuesday night through Wednesday
night. This is part of a deep upper level trough that will be
developing with phasing and tapping into the Gulf of Mexico as
it digs southward Tuesday night and then as it moves east it
will access the Western Atlantic waters for Wednesday. The
associated strong vort max moves across the local region
Wednesday night.
For Tuesday, the warm front does not make much progress, remaining
within the region. Exact position of this front is uncertain.
However, so more northward progress is expected by the afternoon and
more so for Tuesday night. Boundary layer remains moist with fog
expected to become greater in coverage. Dense fog will be
possible. Chances for rain will be forecast as well as with
some increase in low level convergence. Forecast highs actually
will likely be set late in the evening as southerly flow
increases, bringing increasing low level warm air advection and
temperatures getting into upper 40s to lower 50s.
For late Tuesday night, temperature further rise with low level warm
air advection increasing. Vertical forcing will be increasing as
well with rain developing and moving into the region.
For Wednesday, a strong cold front approaches and rain will be
heavy at times. Right rear quad of upper level jet gets near the
region by late day into early Wednesday evening which will
provide more synoptic lift. Elevated instability forecast as
well for much of the coastal areas, so have a slight chance of
thunderstorms. The strong cold front moves across Wednesday
night. The rain continues into Wednesday evening especially
across Southern CT and Long Island. Precipitation becomes more
showers late Wednesday night and with strong cold air advection,
rain expected to mix and eventually change over to snow
showers. With drier air advecting in late Wednesday night, not
expected much in the way of any snow accumulations.
Low pressure develops and approaches for Wednesday along the
cold front moving into the coastal sections of the area. This
low more rapidly intensifies for Wednesday night into early
Thursday morning, with models indicating around a 15 to 20 mb
drop in 12 hours, traveling from near the region to New England
vicinity to Quebec.
Pressure gradient becomes very tight Wednesday into Wednesday
night in advance of deepening low pressure. Low level jet
intensifies Wednesday into Wednesday evening. Gusty winds expected
in the range of 25 to 40 mph for much of the region with some strong
wind gusts possible up to near 45 to 55 mph Wednesday into Wednesday
night. These potentially strong gusts would be for coastal CT and
Long Island.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A secondary cold front will be exiting the forecast area during
Thursday morning. The only chances of any showers appear to be
associated with the potential of ocean and sound effect rainfall
as cold air filters in on a strong westerly flow with water
surface temperatures still near 50. It`ll probably be gusty much
of the day, but sustained winds and gusts should lower during
the afternoon hours. Gusts in the morning still potentially
35-40 mph. High temperatures on Thursday could very well occur
during the pre-dawn hours for most spots. Strong
downsloping/compressional heating will offset the strong cold
air advection to some extent, but afternoon temps probably only
reach 35-40.
High pressure will be building into the region through at least
Friday night with the high moving offshore most likely during
Saturday. Global models agree that low pressure of some sort
potentially impacts the forecast area Saturday night into Sunday,
but differ on the details. Will go with slight chance to chance PoPs
for the time being. Kept precip types simplified due to the low
confidence on the evolution and track of this potential system 7
days out. Some moderation through the weekend after below normal
high temperatures on Friday.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A weak low pressure center along with a warm front approach this
afternoon, passing through some of the terminals by evening.
The warm front remains in the vicinity through Tuesday.
Rain with lowering flight categories start early this
afternoon. IFR likely by around 21z. The rain ends by 00z for
most terminals, but IFR remains likely with some terminals
lowering to LIFR overnight.
Easterly winds will increase to around 10kt. A relatively quick
veering to the SW occurs for the city terminals at approx
21-00z with the weak low center passing nearby. Winds bcmg light
and variable overnight.
NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
Amendments possible for timing of lowering flight categories this
afternoon. Still a chance of improvement to MVFR for a few hours
late this afternoon into early evening, but confidence in this is
low. Chance of fog reducing vsbys below 3/4SM overnight.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
Tuesday: IFR with potential improvement to MVFR at times. Light rain
or drizzle possible.
Tuesday night: IFR and rain. SE-S gusts around 20kt with LLWS late.
Wednesday: IFR and rain, possibly heavy at times. Chance of thunder.
S-SW gusts increase through the day, potentially up to 40-45 kt
afternoon and evening. VFR returns late Wednesday night with west
winds gusting 30-35kt.
Thursday: VFR with W winds G30-35kt in the morning, then 25-30kt in
the afternoon.
Friday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
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Below SCA conditions expected on the waters for today through
Tuesday evening. SCA conditions then expected to develop on the
ocean late Tuesday night. The seas and winds increase on
Wednesday and Wednesday night. SCA conditions likely for all
waters Wednesday and Wednesday night with potential for gales on
most if not all of the forecast waters as well. There is even
potential for storm force winds on the ocean east of Fire Island
Inlet and potentially the eastern LI Sound.
Gales will be possible, especially on the ocean waters, for a part
of the day Thursday with cold air advection behind a cold front
moving through the waters during the morning. Advisory conditions
otherwise would prevail through the day and last in to Thursday
night. Winds probably below thresholds by Friday morning everywhere,
but seas remain elevated on Friday on the ocean - perhaps falling
below 5 ft by the afternoon.-- End Changed Discussion --
&&
.HYDROLOGY...
No hydrologic issues expected with the mainly light rain this
afternoon and early evening.
Heavy rain is possible at times late Tuesday night through
Wednesday evening with the potential for flooding in at least
low lying and poor drainage areas. A localized flash flood
threat exists, especially across eastern half of the area where
WPC has highlighted a slight risk for excessive rainfall.
Total rainfall Tuesday night through Wednesday night ranges
from about 2 to 3 inches, lowest across NYC, interior NE NJ and
the Lower Hudson Valley and highest across parts of Southern CT
and Long Island. There could be locally higher amounts,
dependent on the heavy rain axis setup. There remains some
uncertainty and these rainfall amounts could shift some in
subsequent forecasts.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JC/JM
NEAR TERM...JM/DS
SHORT TERM...JM
LONG TERM...JC
AVIATION...JC/IRD
MARINE...JC/JM
HYDROLOGY...JC/JM