000
FXUS61 KOKX 092126
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
426 PM EST Sat Dec 9 2023
.SYNOPSIS...
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High pressure over the western Atlantic will continue to gradually
move eastward, while a strengthening frontal system over the mid
section of the country tracks east. A strong cold frontal passage
will occur late Sunday night into Monday morning, with low pressure
deepening along it as it tracks into Canada on Monday. Strong high
pressure to the south on Tuesday will flatten out, allowing a
cold front to approach Tuesday night and pass through late
Tuesday night or Wednesday morning. Another strong high will
them build from the west for later in the week, then shift off
the New England coast Saturday night.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A warm front will be nearby this evening and shift north through the
night. Increasing clouds with patchy fog developing. Isentropic lift
with increasing low level moisture may result in some light rain
forming in a few spots during the overnight hours. Lows above normal
due to the cloud cover and weak warm advection.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
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A 500mb trough digs in to our west on Sunday, then lifts during the
day Monday with its axis shifting through the forecast area Monday
evening. At the surface, a strong cold front approaches us on Sunday
and passes through during Sunday night. While it`s passing through,
an area of low pressure develops along the front, passing through or
nearby the forecast area before rapidly deepening to our NE.
Rain chances ramp up through the day with the entire forecast area
likely seeing rain by the end of the afternoon. The rain could be
heavy at times as early as the afternoon as per latest CAMs
reflectivity, with this potential lasting into the night. The heavy
rain potential comes from a developing strong low level jet
combining with deep synoptic lift aloft and an anomalously moist air
mass. Some models continue to show some elevated instability, so
with deep lift, will keep in an isolated thunderstorm in the
forecast. Models continue to favor eastern areas for the higher
total rain amounts, as the llj will be stronger here, and
forcing/convergence near the deepening low center will be passing
through or nearby. Further enhancement may occur in parts of CT due
to speed convergence on a southerly flow. The flood watch has been
extended to include eastern Suffolk County as the trend for heavier
rain totals remains focused more over eastern sections. See the
hydrology section below for more details.
Regarding winds for this event, for several days now, 925mb winds
continue to be progged reach 60-80kt over roughly the eastern half
of the forecast area Sunday night. Even by late afternoon, they`re
progged at 50-60kt. There will be a low level inversion, but not
particularly strong. Especially with the threat of convectively
enhanced downpours and models showing 50-60kt winds below the
inversion at 1000ft, there is an increased threat of seeing wind
gusts reaching high wind warning thresholds in some areas. Thinking
about 60-70% of the 925mb jet could mix down. Complicating this is
that there could be a couple hours of a lull in the winds as low
pressure takes shape along the developing low nearby or just off to
our south. There could be a pretty sharp east to west gradient where
winds could get to at least wind advisory criteria. There also could
be a timing offset on when the potential convective downpours could
occur with the strongest winds aloft. Therefore do not have the
confidence at this time to upgrade to a high wind warning for the
zones currently under a watch. There is a possibility that the
threat will be more focused over Long Island, and not so much for
Brooklyn and Queens. Will however maintain the watch for the time
being. However, after collaboration with WFO BOX, have enough
confidence to go with a wind advisory along portions of the CT Coast.
Rain chances continue into Monday even behind the front as the flow
aloft remains cyclonic and we`ll be within the right entrance region
of an upper jet streak. Some cold air wraps in behind the front, and
may cause a mix of rain and snow well NW of the city in the morning.
Little to no snow accumulation expected. Remaining breezy through
the day as we dry out for the afternoon. Highs generally in the
40s.-- End Changed Discussion --
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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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-Sat, will then maintain
strong sfc high pressure over the area, with perhaps a weak
intervening cold frontal passage Friday night. A storm system to the
west should hold off until just after the forecast period, with some
increase in high/mid cloud cover Sat into Sat night.
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 (20%) PoP for late Sat night. 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 SATURDAY THROUGH THURSDAY/...
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High pressure moves offshore and away from the area tonight, while a
strengthening frontal system over the Ohio and Tennessee valleys
tracks east during the course of the weekend.
VFR at most terminals, with the exception of KGON at times this
evening. Then by late tonight after 6z MVFR/IFR conditions are
expected to return with the approach of the frontal system. SHRA
chances start to increase towards and just after 10z Sunday.
Light flow mainly out of the southeast and south this evening with
wind speeds below 10 kt. The light southerly flow will begin to
gradually increase throughout Sunday morning, especially at the
coastal terminals.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Sub VFR conditions may return earlier than indicated in TAFs tonight.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Sunday afternoon: IFR as steady rain moves in west to east. S winds
15-20 kt with gusts 25-30 kt in the afternoon, with gusts up to 35
kt late at coastal terminals. LLWS likely late in the afternoon for
city and coastal terminals.
Sunday night: IFR, with rain heavy at times. Isolated thunderstorms
possible. S winds 20-30 kt with gusts 25-45 kt, strongest near the
coast. A few gusts up to 50 kt possible near the coast. LLWS likely
early at eastern coastal terminals.
Monday: MVFR or lower early in showers, then VFR. W-WNW winds 15-20
kt with gusts 25-35 kt.
Tuesday: VFR. SW gusts 15-20 kt in the afternoon.
Wednesday: VFR. W to NW gusts 15-25 kt in the afternoon.
Thursday: 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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Winds and seas should ramp up quickly during Sunday with small craft
conditions quickly going to gales in all likelihood by late in the
day/early evening. After collaboration with the surrounding offices,
have maintained a Storm Watch where it has existed, but was
confident enough to convert the Gale Watches to Gale Warnings. Gales
are expected to continue through Monday, and possibly linger into
Monday evening for these zones. Gales would also prevail elsewhere
Monday into Monday night. Ocean seas are likely build to 10-16 feet
during this time with waves over 5 ft across portions of eastern
Long Island Sound.
Longer term, SCA cond expected for the most part. Hazardous ocean
seas 5-8 ft Tue AM should subside to 4-6 ft by afternoon, then
remain at those levels into at least Wed night. 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 possible on the ocean and
the open Sound waters into Thu.-- End Changed Discussion --
&&
.HYDROLOGY...
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There are no hydrologic concerns through tonight.
Between 2 and 3 inches of rain is likely Sunday into Monday morning.
Locally higher amounts in excess of 3 inches are possible -
potentially up to 4 inches in parts of southern Connecticut. A flood
watch is in effect for the entire area. Widespread urban and poor
drainage flooding is likely, with some areas of more significant
flooding possible, including the flooding of some rivers and
streams. Heavier downpours will be possible as early afternoon, but
impacts are more likely later afternoon into the night.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
A strong cold front will bring increasing southerly flow late
Sunday into Sunday night. The system brings potential for minor
coastal flooding with the Monday morning high tide cycle.
However, the strongest southerly flow is most likely to occur
between high tide cycles. Winds will quickly shift to the west
early Monday morning, which will help keep water levels down
during times of high tide.
Surge guidance has come to more of a consensus that much of the area
should remain below minor flooding thresholds, but any changes in
the forecast timing of the developing low may result in
significant changes to the coastal flooding forecast.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Flood Watch from Sunday afternoon through late Sunday night
for CTZ005>012.
Wind Advisory from 6 PM Sunday to 6 AM EST Monday for
CTZ010>012.
NY...Flood Watch from Sunday afternoon through late Sunday night
for NYZ067>075-078>081-176>179.
High Wind Watch from Sunday afternoon through late Sunday
night for NYZ075-078>081-176>179.
NJ...Flood Watch from Sunday afternoon through late Sunday night
for NJZ002-004-006-103>108.
MARINE...Gale Warning from 4 PM Sunday to 6 PM EST Monday for ANZ331-
335-338.
Storm Watch from Sunday afternoon through late Sunday night
for ANZ332-340-345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/BG
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...BG
AVIATION...JE
MARINE...JC/BG
HYDROLOGY...JC/BG
TIDES/COASTAL FLOODING...