NWS Forecaster Discussion
OKX
Area Forecast Discussion National Weather Service New York NY.
000
FXUS61 KOKX 101039
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
539 AM EST Sun Dec 10 2023
.SYNOPSIS...
A strengthening frontal system approaches the region today and moves
across the area tonight into Monday morning as low pressure
deepening along it as it tracks into Canada. Strong high pressure
building 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 then build from the
west for later in the week, then shift off the New England coast
Saturday night.
&&
.NEAR TERM /THROUGH MONDAY/...
** Confidence increasing for a significant frontal system to impact
the region through the near term period.
** Flood Watch remains in effect for the entire CWA.
** High Wind Advisories/Warnings in effect for much of the
Coast.
Forecast on track with no significant changes this morning.
A strong cold front approaches the region today and will pass over
the region Sunday night into early Monday morning. In addition, an
area of low pressure is forecast to develop along the front, passing
through or nearby the forecast area before rapidly deepening to our
NE.
Rain chances increase through the day with the entire forecast area
likely seeing rain by the end of the afternoon. The rain is expected
to become moderate to locally heavy at times as early as the
afternoon as per latest CAM reflectivity. The best chances for the
moderate to locally heavy rain is expected tonight. 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. Latest 00z Hi-res guidance seems to be picking up on
this potential, with HREF values now forecasting the potential for
as much as 5-7 inches possible across portions of SE CT. The flood
watch remains up for the entire CWA and has been extended to include
much of Monday morning and early afternoon. See the hydrology
section below for more details.
A high wind warning has been issued for Suffolk County. A wind
advisory is also been issued for Brooklyn, Queens, and Nassau County
in NY. A wind advisory remains in effect for coastal sections of New
Haven, Middlesex and New London in CT.
For several days now, forecast guidance has been progging 925mb
winds reaching 60-80 kt east of NYC tonight. Even by late afternoon,
they`re progged at 50-60 kt. 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 1000 ft, there is an increased threat of
seeing wind gusts reaching high wind warning thresholds in some
areas. For now, thinking the place with the best chance to meet high
wind warnings will be across Suffolk county. While portions of
NYC/Nassau County and part of the CT coast, could see an isolated
gusts to warning or come close to it, felt it was best to keep them
in a Wind Advisory. All the forecast guidance is indicating a
fairly sharp cut off with respect to the strongest winds occur. Can
nor rule out the day shift potentially having to adjust the
headlines a bit based on the newer forecast data that comes in
during the day. The combination of a saturated ground and strong
gusty winds, would expect some wind damage across the advisory and
warning locations.
The front moves east of the area between 12-15z Monday morning.
While some drier conditions are expected, rain chances don`t
completely come to an end as the flow aloft remains cyclonic and
we`ll be within the right entrance region of an upper jet streak.
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.
&&
.SHORT TERM /MONDAY NIGHT/...
Mainly dry conditions expected Monday night as high pressure
continues to gradually build into the region. The gradient will
continue to gradually weaken, but remain tight enough for at least
some gusty conditions possible through the first half of the night.
Lows will fall into the middle and upper 20s to lower 30s.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
No changes to the long term. Followed the NBM closely. The previous
discussion follows:
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 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.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A strengthening frontal system approaches today and crosses
the region tonight.
While the NYC terminals are mainly VFR this AM, MVFR and IFR
conditions are expected to overspread the entire area through 12Z.
SHRA chances increase during the mid morning, with IFR/LIFR in +SHRA
expected this afternoon and into tonight. Isolated TSRA possible,
mainly this afternoon and into tonight. Precipitation may mix with
or briefly change over to snow behind the frontal passage late
tonight into Monday morning at KSWF.
Light southerly flow this morning will steadily increase through the
afternoon, with southerly gusts 35 to 45 kt likely at the coastal
terminals for the late afternoon/evening push. Highest gusts for
KJFK/KISP/KGON. Peak S wind gusts tonight at KISP/KGON may approach
50kt. The front passes through the terminals overnight into early
Monday morning with an abrupt wind shift to the W/NW and gusts
maintaining 20-30 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of lowering cigs/visibilities this morning may be off by and
hour or two. Isolated TSRA in +SHRA possible this afternoon and
evening. LLWS with S winds of 50-60kt at 2kft for coastal terminals
in afternoon/evening.
OUTLOOK FOR 09Z SUNDAY THROUGH THURSDAY...
Late Sunday night: IFR, with +SHRA. Isolated TSRA possible. FROPA to
NW winds 15g25kt btwn 03-05z for western terminals and 9-12z for
eastern terminals
Monday: MVFR or lower for AM push in RA/SN mix for western
terminals. VFR in afternoon. W-WNW winds 20-25G30-40kt.
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
&&
.MARINE...
Gale and storm warnings on the area waters as a strong cold front
pushes across the area tonight.
Winds and seas should ramp up quickly today with SCA conditions
quickly going to gales by late in the day/early evening. 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 the day Monday and possibly linger into Monday
evening. 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 are possible on the ocean
and the open Sound waters into daytime Thu.
&&
.HYDROLOGY...
A flood watch remains in effect for the entire area. Across portions
of Long Island and Southern Connecticut, 3 to 5 inches of rainfall
is likely, with locally 6+ amounts possible. Elsewhere, 2-4 inches
is likely. 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. Heavier downpours will be
possible as early afternoon, but impacts are more likely later
afternoon into the night. WPC has much of the forecast area in a
Slight Risk in their excessive rainfall outlook for today and
tonight.
&&
.TIDES/COASTAL FLOODING...
A strong cold front will bring increasing S flow late today
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.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 4 PM EST this afternoon through Monday
afternoon for CTZ005>012.
Wind Advisory from 6 PM this evening to 11 AM EST Monday for
CTZ010>012.
NY...Flood Watch from 4 PM EST this afternoon through Monday
afternoon for NYZ067>075-078>081-176>179.
Wind Advisory from 4 PM this afternoon to 6 AM EST Monday for
NYZ075-176>179.
High Wind Warning from 4 PM this afternoon to 11 AM EST Monday
for NYZ078>081.
NJ...Flood Watch from 4 PM EST this afternoon through Monday
afternoon for NJZ002-004-006-103>108.
MARINE...Gale Warning from 1 PM this afternoon to 6 PM EST Monday for
ANZ331-335-338-355.
Storm Warning from 1 PM this afternoon to 11 AM EST Monday for
ANZ332-340-345-350-353.
&&
$$
SYNOPSIS...BC/MW
NEAR TERM...BC
SHORT TERM...BC
LONG TERM...MW
AVIATION...MW
MARINE...BC/MW
HYDROLOGY...BC/MW
TIDES/COASTAL FLOODING...