679
FXUS61 KOKX 210224
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
924 PM EST Wed Nov 20 2024
.SYNOPSIS...
Strengthening low pressure moves in from the south tonight and
meanders over the Tri-State area through Friday before shifting
northeast Friday night. The low will move towards the Canadian
Maritimes on Saturday and then tracks slowly northeast through
Monday. At the same time, weak high pressure builds in from the
west. A weak frontal system will then pass through the area
Monday night into Tuesday, followed by high pressure for the
middle of next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
Forecast still on track with a only few adjustments this update
to account for latest observations, and a slight delay for onset
of precipitation.
A warm front ahead of developing low pressure to our south
approaches. Lift and upward forcing increase with the front,
deepening low center, and strengthening low level jet. Most of
the rain tonight will fall after midnight and coincide with the
axis of deepest moisture shifting through as indicated by
modeled PWATs. Moderate to briefly heavy downpours are therefore
anticipated at times, and can`t even rule out a rumble of
thunder across southern zones as upward forcing near the
developing low center interacts with some CAPE. Lows near 50 for
the coastal areas and mid to upper 40s inland. Winds pick up
out of the east late with gusts up to 25 mph possible.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Closed H5 low shifts in from the west Thursday and captures the
surface low Thursday night. This will cause the storm center to
linger over or close to the forecast area through Friday. The
storm then begins to shift NE Friday night. Rain continues
through Thursday, and at least for some areas east of the city,
becomes less steady Thursday night. Cold air wraps in from the
west with the low center continuing to deepen. Areas well NW of
the city, particularly the higher elevations, therefore see a
wintry mix of rain and snow as freezing heights fall in the
range of 750-1250 feet. Snow accumulation forecast here into
Friday morning is tricky as thermal profiles are marginal, and
with the low center nearby, there could be a somewhat sharp
gradient in qpf as well as strong upward frontogenetic forcing
nearby. Heavier precip may overcome marginal thermal profiles
and end up in snow accumulations higher than currently forecast.
Elevations above 1000 feet may see 2-4 inches of snow
accumulation by the end of Friday morning, but this is not
enough to warrant an advisory as this would not be much
coverage. Breezy mainly near the coast with the chance of a lull
in the winds during the afternoon.
Models are in decent agreement that the center of the storm
tracks south through eastern PA during Friday before shifting
east across the forecast area Friday night. Periods of rain with
the higher chances generally near the low center. Thermal
profiles still support a wintry mix well NW of the city, but
since the higher chances of precip overall are during the
daytime hours, any additional snow accumulation would be very
little. Breezy mainly by the coast, but winds may be a little
stronger than currently forecast if the center of the storm
doesn`t track over us. Went a little colder than NBM for
temperatures and dewpoints during the short term.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
* Gusty NW flow and near normal temperatures behind departing storm
system this weekend.
* Weak frontal system to move through the area Monday night into
Tuesday.
Deepening low pressure approaching the Canadian Maritimes on
Saturday will gradually lift northeast through the weekend into
early next week, while weak high pressure builds east from the
Ohio Valley. Except for a chance of showers Saturday, mainly in
the morning, it will be dry during this time with a strong NW
flow. Gusts will approach 30 mph each afternoon, with brief
higher gusts up to 40 mph possible. Leaned toward a cooler model
consensus/MOS forecast as compared to the NBM based on latest
vertical temperature profiles from some of the 12Z guidance.
This will put highs just below normal Saturday in the upper 40s
to around 50. Winds stay up Saturday night keeping temperatures
about 5 degrees above normal. Expect slightly warmer
temperatures on Sunday.
A nearly zonal upper flow to start the week will send a fast
moving low NE across the Ohio Valley and Lower Great Lakes
Monday, to the north of the area on Tuesday. This will send a
weak frontal system through the area Monday night into Tuesday
morning with a low chance for rain. High pressure then builds in
through midweek. Temperatures Monday and Tuesday will be a few
degrees above normal, but then cool back down Tuesday night into
Wednesday at or just below normal.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure along the New England coast continues to move
east and northeast as a frontal system approaches to the west.
Low pressure strengthens just south of Long Island late tonight
into Thursday. There is some uncertainty as to where the low
will be developing which will affect wind direction and
strength, as well as gusts. The low then tracks northward across
Long Island and into the Lower Hudson Valley late Thursday into
Thursday evening.
VFR to MVFR as areas of MVFR strato cu move through the region
early this evening. Conditions then lower to prevailing MVFR by
05z at the NYC terminals, with RA arriving closer to 06z. IFR
should then quickly develop after 08z with moderate to heavy
rain possible through early Thursday morning, especially for NYC
metro and Lower Hudson Valley terminals. A rumble of thunder
cannot be ruled out. The moderate to heavy rain will shift east
of the NYC terminals around 12-13z. A lighter rain overall will
persist through the day Thursday, and into Thursday evening.
Some local LIFR is possible.
Light east winds increase and start to become gusty after 05Z.
Gusts 20-25kt, with a few peak gusts at 30kt are possible
overnight into early Thursday morning. Depending on where and
when low pressure deepens south of Long Island late tonight
there may be a brief lowering of wind speeds and a lull in the
gusts. Western terminals will see winds become more N into
Thursday morning, then NW late day Thursday, and W Thursday
evening as deepening low pressure tracks through the region near
or just east of the NYC terminals.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
Amendments likely for timing of lowering flight categories as well
as developing rain late this evening and overnight.
Amendments likely for winds late tonight into Thursday, especially
with magnitude and duration of gusts. There may be a lowering of
winds and a lull in the gusts toward Thursday morning, with some
uncertainty where low pressure develops.
OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
Thursday Night...IFR to MVFR with periods of rain, possibly mixed
with wet snow well NW of NYC metro. SW gusts 15-25kt.
Friday...Mainly MVFR with rain possible. Wet snow may mix in well NW
of the NYC metro. S-SW gusts 15-20kt possible.
Saturday...MVFR possibly becoming VFR late. WNW winds gusting 20-
30kt.
Sunday...VFR. W-NW winds gusting to 20-30kt.
Monday...VFR. Light winds.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
All waters remain under a small craft advisory tonight through
Thursday night. There may be a short period Thursday morning on the
ocean waters where there may be a few gale force gusts. A better
chance of gales for the ocean during Thursday night, however this
will depend on the track of the storm, and with the storm center so
close, not confident enough to upgrade to a Gale Warning. Will let
the night shift get a look at new guidance to see if confidence
increases for gales during Thursday night. Otherwise, SCA will
likely need to be extended into Friday, mainly on the ocean, as seas
remain elevated through the day.
A strong NW flow behind deepening low pressure lifting NE across the
Canadian Maritimes this weekend will at least produce SCA seas and
winds across the waters, with the potential for Gale force gusts.
The best chance for gales at this time will be across the ocean from
Saturday afternoon through Sunday afternoon. Thereafter, high
pressure builds in from the west with decreasing winds and seas
Sunday night into Monday.
&&
.FIRE WEATHER...
A substantial wetting rainfall is then expected tonight night
through Friday which should help mitigate short term concerns
for fire danger, but would not be enough to lift us from long-
term drought.
&&
.HYDROLOGY...
Overall storm total rainfall tonight through Friday night is 2.5-3
inches west of the Hudson, ranging closer to 1.5-2.5 inches to the
east. Most of this, along with any potential impacts, is expected to
occur late tonight into Thursday morning. There could be minor
flooding associated with clogged drains, otherwise no hydrologic
impacts are expected given the recent dry weather and progressive
nature of any heavier rainfall.
No hydrologic impacts are expected this weekend through the middle
of next week.
&&
.TIDES/COASTAL FLOODING...
Astronomical tides will continue to fall through the end of the
week. However, an intensifying low south of Long Island late tonight
into Thursday will bring a surge of 2 to 3 ft, especially across the
coasts of Long Island and Southern CT. The exact location/track of
the low will be important to the magnitude and duration of the surge
along with it coinciding with the timing of high tide.
Confidence remains highest for minor coastal flooding benchmarks
to be exceeded across the south shore back bays of western LI,
Great South Bay, and eastern LI Bays as well as along much of
the north shore. Minor coastal flooding also looks widespread
across southern Fairfield and southern Westchester. Coastal
Flood Advisories remain in effect for these areas for the late
Thursday morning into Thursday afternoon high tide. Much of the
remainder of the area resides under coastal flood statements as
water levels may approach or just exceed minor flood benchmarks.
There is a fine line with the wind shift near high tide across
Lower NY harbor and thought it would be prudent to go with a
statement in case the easterly flow lasts a bit longer than
forecast and piles more water into the NY Bight area.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory from 1 PM to 5 PM EST Thursday for
CTZ009.
NY...Coastal Flood Advisory from 1 PM to 5 PM EST Thursday for
NYZ071.
Coastal Flood Advisory from 11 AM to 5 PM EST Thursday for
NYZ078>081.
Coastal Flood Advisory from 10 AM to 2 PM EST Thursday for
NYZ179.
NJ...None.
MARINE...Small Craft Advisory until 7 AM EST Friday for ANZ331-332-335-
338-340-345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/DW
NEAR TERM...JC/MET/DW
SHORT TERM...JC
LONG TERM...DW
AVIATION...MET
MARINE...JC/DW
FIRE WEATHER...
HYDROLOGY...JC/DW
TIDES/COASTAL FLOODING...