864
FXUS61 KOKX 312119
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
419 PM EST Tue Dec 31 2024
.SYNOPSIS...
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Developing low pressure will approach from the southwest this
evening, pass over the area late tonight, then move along the
eastern New England coast Wednesday into Wednesday evening and
into eastern Canada late Wednesday night into Thursday. A series
of disturbances will move across Friday into Saturday. High
pressure will then begin to build from the west on Sunday. Low
pressure could impact the area early next week as it passes
mostly to the south.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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*Two to four hour period of locally heavy rain and embedded
thunderstorms to ring in the New year
A strong, negatively-tilted shortwave trough over the Ohio Valley
this afternoon will pivot into PA/NY tonight. At the surface,
primary low pressure moves ne from Ohio this afternoon through
the eastern Great Lakes region this evening. Shortawve and ulj
energy will induced secondary cyclogenesis along its associated
warm front over the DelMarVa this evening, and the tracking
over or just south of the local Tri- State tonight.
Expect shower activity to increase from SW/NE between 6pm and 8pm
this evening. A 2 to 4 hr period of moderate to locally heavy
rain with embedded thunderstorm activity likely between 8pm and
2am imnediately ahead of and southeast of the developing low.
Rainfall rates of generally 1/4" to 1/2" for a 2 to 4 hr period,
with brief peak rates of 3/4" to 1" possible with any training
convection. Minor urban and poor drainage flooding possible.
12z Fcst soundings have trended slightly higher with elevated
instability (MUCAPE) above a sfc-based inversion, as well as
CAPE in the -10C to -30C region, to strengthen potetnial for
isolated thunderstorms across NE NJ, NYC and western Long
Island. Only slight chance thunder fcst for most areas
north/east of there. Small hail and winds gusts to 40 mph
possible with any isolated stronger thunderstorms.
Severe tstms are not expected based on consensus low pressure
track and with modest low-level inversion, but a further NW jog
of low pressure would introduce less than a 5% risk of damaging
winds gusts and less than a 2% tor risk (within 25 miles of a
point) into southern portions of NYC/NJ metro and LI. Very low
prob of this occurring.
Timing for rain in the NYC metro area still looks to be about 00Z-
07Z, and an hour or two later to the north/east. Peak timing of
thunder from 02z to 06z in the NYC metro area, and an hour or
two later to the north/east
In additon, nose of 35 to 40 kt LLJ slides across coastal areas
this evening, with a few hours of peak SE winds of 15 to 20 mph
gusts 25 to 30 mph ahead of low/occluded front.
Rain tapers to isolated shower activity from west to east
between 5z and 9z in wake of occluded front/low pressure, but
still under deep cylconic flow. Generally light westerly flow in
wake of front overnight and weak CAA, with temps remaining well
abvoe seasonable in the 40s.-- End Changed Discussion --
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
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Deep troughing continues across the northeast US thru the period,
with lead shortwave sliding east Wed AM, and trailing shortwave
appropaching Wed aft and crossing Wed eve. At the surface,
coastal low pressure departs up the New England coast on Wed,
with secondary cold front crossing the region Wed aft.
The pressure gradient tightens in the wake of the deepening and
departing low Wed AM. W winds should pick up beginning Wed AM,
with strongest winds in wake of cold front/trough Wed aft/eve
with 20 to 30 gusts 45 to 55 mph. Gradient remains strong
overnight, with winds 45-50 kt at top of mixed layer, but with
lapse rates weakening a bit overnight, peak wind gusts will
likley remain capped at 45 to 50 mph into Thu AM. Pressure
gradient appears to remain tight into Thu aft as low pressure
deepens over northern Maine/new Brunswick, with winds at top of
mixed layer 45-50 kt in a steeper mixing profile. This should
support resurgence of westerly 45-55 mph wind gust threat into
the afternoon. Wind advisory to address hazard for Wed aft into
Thu eve.
Considerable cloud cover in cyclonic flow, with scattered rain
shower likely Wed aft/eve with shortwave/cold frontal passage. With
cold advection behind front, a few snow showers possible at tail
end across interior, particularly higher elvations.
Mild conditions on Wed with nearly stationary highs in the upper
40s/lower 50s giving way to cold advection late Wed aft into
into Thu. Low temps in the lower/mid 30s Wed night, and high
temps in the upper 30s/lower 40s on Thu. Windchills in the 20s
Wed Night thru Thu.-- End Changed Discussion --
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Will be updated shortly...
Key points include cold/blustery/mainly dry conditions until
potentially early next week, with chances of snow. Uncertainty
is high for early next week with resulting wide variances of
snowfall forecasts. Temperatures forecast to become more below
normal through the weekend. The gusty winds will make it feel
about ten degrees colder than the actual temperatures regarding
the forecast high temperatures.
Mid level quasi-zonal flow Thursday night into Friday will
transition to more trough Friday night. The trough stays
across the region through the weekend and then shifts east
offshore early next week. Any ridging appears brief with more
troughing for next Tuesday.
At the surface, strong low pressure in SE Canada starts the long
term forecast period Thursday night. Then, a disturbance
approaches the region Friday from the west, eventually going
offshore Friday night into early Saturday. High pressure
gradually makes a return, as it slowly builds in from the west
Sunday. However, magnitude of high pressure will not be too
strong.
Low pressure developing south and west moves south of local
region early next week.-- End Changed Discussion --
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
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A developing area of low pressure crosses over the terminals tonight
before exiting to the northeast during the day on Wednesday.
VFR conditions will prevail through 00Z, then quickly deteriorate to
MVFR/IFR after 02Z in rain. A few thunderstorms are possible as
well, generally between 02-05Z. A period of LLWS is also expected
late this evening with SE winds near 40-45 kt at 2kft. Conditions
then gradually begin to improve during the day on Wednesday.
SE winds at 5-10 kt will continue to back to the E this evening
while increasing to 10-15 kt at coastal terminals. Wind direction
will vary significantly between 06-12Z as low pressure passes
overhead. Winds then return out of the W Wednesday morning and
increase in speed through the day, with gusts 25 kt or greater by
18Z at most terminals.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely tonight with the onset of rain and lowering
cigs/vsbys. Wind direction will become highly variable overnight as
low pressure moves across the area.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday afternoon: Improving to VFR. Chance of -SHRA at KSWF in
the afternoon. Increasing W winds G25-35kt, occasionally up to 40
kt, by afternoon.
Thursday: VFR. W winds G25-35kt with occasional gusts up to 40 kt.
Gusts decrease Thursday night.
Friday through Sunday: Mainly VFR. W winds G20-25kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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As low pressure approaches tonight, expect SE-S gusts to 25-30 kt
developing on the ocean this evening and then translating eastward
across southern bays and eastern LI Sound. A few gusts up to 35 kt
may be possible on the eastern ocean waters, but appears too
inverted for any more than brief and infrequent.
Winds should subside below SCA briefly on all waters late tonight in
wake of developing low pressure. Westerly winds then quickly
increasing thru SCA to Gale Wed AM into early afternoon for the
ocean waters, and then all water Wed aft. Sustained W winds 25-35 kt
and gusts 40-45 kt expected to continue into Thu eve, before
gradually diminishing to SCA Thu night. Gales should linger on most
of the waters Thu evening.-- End Changed Discussion --
&&
.HYDROLOGY...
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Rainfall rates of 1/4 to 1/2" likely with heaviest precip, briefly
3/4-1" with any heavier convection this evening. Basinwide
rainfall totals of 1/2 to 3/4", with locally 1 1/2" possible
if/where there is more persistent heavy rain shower/tstm
banding. Most of this falls in a 3 to 4 hr time period, which
may cause some minor urban and poor drainage flood issues.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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Per bias corrected ETSS/ESTOFS and NYHOPS central forecast blend,
water levels may touch minor flood thresholds along the south shore
bays of LI (including eastern Great South Bay, Moriches Bay,
and Shinnecock Bay), Jamaica Bay and along the most vulnerable
portions along NY Harbor with the Wed AM high tide. Statement
issued to address this.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Wind Advisory from 3 PM Wednesday to 10 PM EST Thursday for
CTZ005>012.
NY...Wind Advisory from 3 PM Wednesday to 10 PM EST Thursday for
NYZ067>075-078>081-176>179.
NJ...Wind Advisory from 3 PM Wednesday to 10 PM EST Thursday for
NJZ002-004-006-103>108.
MARINE...Small Craft Advisory from 7 PM this evening to 6 AM EST
Wednesday for ANZ331-332-340-345.
Gale Warning from 1 PM Wednesday to 10 PM EST Thursday for
ANZ331-332-335-338-340-345.
Small Craft Advisory until 6 AM EST Wednesday for ANZ350-353-
355.
Gale Warning from 6 AM Wednesday to 1 AM EST Friday for ANZ350-
353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JP/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...JP
AVIATION...FEB
MARINE...JP/NV
HYDROLOGY...JP/NV
TIDES/COASTAL FLOODING...NV