000
FXUS61 KOKX 102150
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
450 PM EST Sun Dec 10 2023
.SYNOPSIS...
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A strengthening frontal system pushes through tonight into Monday
morning. The deepening low pressure along it will move away quickly
into Canada by Monday evening. High pressure will then build from
the southwest on Monday night into Tuesday. A cold front approaches
Tuesday night and pass through late Tuesday night or Wednesday
morning. Another strong high will then build from the west for later
in the week, then shift off the New England coast Saturday
night.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH MONDAY/...
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A very dynamic system will impact our area into tonight, continuing
to advance downstream from Appalachians and into the the eastern
coastal plain. The complex frontal system along with the cold front
is forecast to be progressive across the southern U.S. as the base
of the upper trough becomes negatively tilted as it swings from the
Lower Mississippi Valley to the East Coast through tonight, with a
deepening surface low forecast to track from the Mid Atlantic into
the Northeast late tonight into Monday AM.
The first batch of rain with a few embedded convective elements is
shifting northeast. Even though this batch exits to the north, a
train of heavy rain with a few embedded thunderstorms, or at least
claps of thunder get established from south to north as it gets
later in the evening. This is all due to a conveyor belt of moisture
with anomalous high for this time of the year PWATs and Integrated
Water Vapor Transport. All the ingredients are in place for a
widespread heavy rain event, with a thick warm cloud layer up to 9
to 10 kft, PWATs up to 1.5 inches, and mean RH up around 95 percent.
A very strong LLJ of 60-65 kt providing a classic warm tongue at 850
and 925 mb, along with a trough going negatively tilted is suggestive
of an active night. This saturated deep layer column shown by all
guidance and upstream soundings only increases confidence for a
significant event. To the east of the boundary is lots of high theta
E or low latitude air origin, thus the warm rain processes will be
in place to drive some higher rainfall rates. WPC has put the area
in a rare slight risk of excessive rainfall, with a moderate risk
across portions of Central and Eastern CT. See the hydrology section
for further details.
The period of strongest winds along the east side of the frontal
boundary will be going forward until about 1-2 AM for the eastern
half of the city and Nassau, and until 3 AM for Central LI, and
until 6-7 am for far eastern portions of LI and New London, CT.
Gusts up to 55-60 mph seem like they can happen. The forecast model
soundings do not have the strongest of inversions, and have more of
an isothermal look to them, thus a 2-3 hour window for the strong to
damaging wind gusts is in place. Also, the a wet soil from tonight`s
heavy rain could result in some uprooted trees. Thus the High Wind
Warning continues, with the addition now of Southern New London, CT.
Northern New London, CT is now in a wind advisory until late Mon
morning. The front should begin to pivot through eastern areas
towards 8-10z. The winds will decrease a bit momentarily into the
start of the morning commute for a couple of hours as the winds
switch around to the NW quickly. As this happens, across NW zones,
particularly Orange County look for the precip to end as a brief
period of snow. With surface temps likely still being above freezing
any snow will have difficulty sticking, with perhaps a dusting or so
on the grassy surfaces. The column dries out quickly so any stead
snow would end quickly, with snow showers lingering into the mid
morning hours, especially in the higher elevations.
During Monday morning lingering showers will move away to the
northeast, thus toward mid to late morning day skies will be
clearing from SW to NE. The winds will pick up again, but not get to
the highest levels seen during the night. Gusts of 35 to 40 mph
appear to be a good bet for the mid to late morning as cold
advection is maximized as the upper trough axis pivots through. Late
in the day and into the evening the pressure gradient begins to
decrease somewhat. It will be a good 10 to 15 degrees cooler with
40s across the area into the afternoon.-- End Changed Discussion --
&&
.SHORT TERM /MONDAY NIGHT/...
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As high pressure builds from the southwest look for the winds to
gradually decrease with gusts still around 20 to 25 mph at times
during the evening. After midnight under clear skies any gusts
should end with temperatures falling to seasonably cold levels.
Temperatures should get below freezing in most places with lows in
the middle and upper 20s in the more rural area, to mainly lower 30s
across the city and urban locations.-- End Changed Discussion --
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
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No changes to the long term. Followed the NBM closely.
Quasi-zonal flow aloft in the wake of one departing trough on Tue
will give way to another northern stream trough on Wednesday, which
should drive a cold front through either late Tuesday night or
Wednesday morning. Confluent mid level flow after this trough
passage, followed by ridging aloft Fri, will then maintain strong
sfc high pressure over the area, with perhaps a weak intervening
cold frontal passage Friday night. Guidance has been trending
towards hanging on to high pressure over the area through the
weekend. As high pressure shifts east is where model spread starts
to really increase. There is potential for another low pressure
system to impact the area late Sunday, but large differences remain
in timing, strength and location.
Forecast follows the NBM for the most part given close enough NWP
model guidance agreement during this time frame, with only minor
adjustments. Fair wx should prevail through the period, with only
slight chance to chance PoP for next Sunday. Near normal temps Tue-
Wed, and a little below normal Wed night-Thu after the cold frontal
passage, should moderate to a few degrees above normal Fri-Sat via
ridging sfc and aloft.-- End Changed Discussion --
&&
.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
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** HIGH AVIATION IMPACTS EXPECTED THROUGH MOST OF THE TAF PERIOD **
A strong cold front moves through tonight.
Mostly IFR through the night with rain, heavy at times, and iso
TSTM. Precipitation may mix with or briefly change over to snow
Monday morning at KSWF. Not enough confidence to include in the TAF
at this time.
Strengthening southerly flow into this evening, more so from approx
KJFK/KLGA eastward. LLWS for all but KSWF until the cold front
passage. 2kft winds 60kt+ at KISP and KGON, and 45-55kt for the
other terminals.
FROPA timing is 1-4Z for western and NYC terminals and 6-10Z for
eastern coastal terminals as the cold front slows down. Behind the
FROPA, winds shift to the NW-WNW with gusts 25-35kt lasting well
into the day Monday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Isolated TSRA possible before around 03-05z, but somewhat less
likely before 01z. Forecast winds and gusts may be too strong by at
least 5 kt this evening ahead of the cold front.
OUTLOOK FOR 18Z SUNDAY THROUGH FRIDAY...
Monday: VFR in afternoon. NW-WNW winds G25-35kt
Tuesday: VFR. SW gusts 15-20 kt in the afternoon.
Wednesday: VFR. W to NW gusts 15-20 kt in the afternoon.
Thursday and Friday: VFR.
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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Continuing with Gale and Storm warnings on the area waters as a
strong cold front pushes across the waters tonight. Storm warnings
are in effect for the central and eastern ocean zones as well as the
south shore bays, Peconic and Garners Bays and the eastern part of
Long Island Sound. These locations have the best chances to see wind
gusts reach 50 kt, especially from about midnight tonight through
early Monday morning. The Storm warnings are up until 11am, however
its possible they will be able to be dropped down to a Gale warning
earlier. Gales are then expected on all waters through much, if not
all of the day Monday, with small craft conditions likely into at
least the first of Monday night.
Sub small craft conditions may prevail for a good portion of Tuesday
across the waters in all likelihood, with small craft conditions
returning through the remainder of the period. Meanwhile W flow
gusting up to 25 kt on all waters Tue night, should shift NW by Wed
morning after a cold frontal passage. Gusts could peak at 30 kt on
the ocean Wed night. Lingering 25 kt gusts are possible, especially
on the eastern ocean and the open Sound waters into daytime
Thursday.-- End Changed Discussion --
&&
.HYDROLOGY...
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A flood watch remains in effect through Monday morning for the
entire area. Across portions Central and Eastern Southern
Connecticut, 3 to 5 inches of rainfall is likely, with locally
6+ amounts possible. For Long Island 2 to 4 inches is likely,
with locally 4+ inch amounts possible. Most of this rain will
fall in a 12 hour period.
As a result, widespread urban and poor drainage flooding is likely,
with some areas of more significant flooding possible, including the
flooding of some rivers and streams. WPC has much of the forecast
area in a Slight Risk in their excessive rainfall outlook for today
and tonight, with a rare Moderate Risk for Central and Eastern
portions of Southern CT. Based on the current rainfall forecast main
stem rivers across CT are forecast to reach minor and moderate flood
stage.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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A strong cold front will bring increasing S flow into tonight. The
system brings potential for minor coastal flooding with the Monday
morning high tide cycle. Winds quickly shift to the W-NW late
tonight/early Monday morning, which will help keep water levels down
during times of high tide. That said, latest Stevens NYHOPS 95th
percentile numbers and taking into account wave runup on south
facing coastlines suggest some potential for the CT coastline and
the forks of Long Island to touch minor thresholds.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Flood Watch through Monday afternoon for CTZ005>012.
Wind Advisory until 11 AM EST Monday for CTZ008-010-011.
High Wind Warning until 11 AM EST Monday for CTZ012.
NY...Flood Watch through Monday afternoon for NYZ067>075-078>081-
176>179.
High Wind Warning until 11 AM EST Monday for NYZ078>081.
Wind Advisory until 6 AM EST Monday for NYZ075-176>179.
NJ...Flood Watch through Monday afternoon for NJZ002-004-006-
103>108.
MARINE...Gale Warning until 6 PM EST Monday for ANZ331-335-338-355.
Storm Warning until 11 AM EST Monday for ANZ332-340-345-350-
353.-- End Changed Discussion --
&&
$$
SYNOPSIS...JE/JT
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...JT
AVIATION...JC
MARINE...JE/JT
HYDROLOGY...JE
TIDES/COASTAL FLOODING...