000
FXUS61 KOKX 270024
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
724 PM EST Sun Nov 26 2023
.SYNOPSIS...
A developing area of low pressure intensifies as it tracks up the
coast into this evening, passing over the region tonight, before
exiting into New England on Monday. High pressure settles south of
the area Tuesday and Wednesday, as low pressure passes well to
the north Wednesday night. High pressure remains in control
Thursday into Friday. Low pressure may then impact the region
late Friday into Saturday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --
The forecast is on track this evening with only minor updates
made to reflect current conditions. Precipitation has begun to
overspread the area except for southeast and southcentral CT,
where dewpoint depressions remain in the 5-10F degree range.
Expect precip coverage and intensity to increase over the whole
area into the evening as the surface low, currently over
DelMarVa, begins to trek northeast. The short term guidance
(HRRR, NAM) continues to nudge the axis of heaviest rainfall
slightly to the west, into northeast NJ, northward into Rockland
and Westchester Counties. These areas appear to have the
highest likelihood of a period of heavy rainfall over the next
few hours. In collaboration with WPC, will maintain the marginal
risk for excessive rainfall here. Have also maintained the
previous QPF, with 1.0-1.2" total across these areas. Previous
discussion follows.
A large upper trough over the Central US swings east toward the
region into tonight. Southern energy phasing with the trough has
spawned a surface low off the North Carolina coast. This low deepens
and tracks up the Mid-Atlantic coastline tonight as the upper
trough becomes negatively tilted.
Increasing SE flow ahead of this low as the pressure gradient
tightens. With strong isentropic forcing, precipitation chances
will continue to increase from the south. Temperatures well
into the 40s will exclude any frozen precipitation from this
event. The strong lift and an increasing low level jet should
allow the rain to fall moderate to locally heavy for a period
tonight. This appears to occur between 00z to 03Z a period of
moderate to heavy rainfall is expected tonight.
Guidance has shifted a tad west and a smidge deeper with the surface
low track from yesterday`s cycles, placing the axis of heaviest
rainfall along the urban corridor. The 12Z HREF reflects this, with
50% of members now producing at least an inch of rain in the NYC
metro, compared with just 10% in the prior run. Increased QPF here,
in line with WPC guidance, with the highest amounts across NYC, NE
NJ, the lower Hudson Valley, and SW CT where between three quarters
of an inch and an inch and a quarter is expected. WPC has added
a marginal risk for excessive rainfall in this area as well, though
main concern is more urban runoff and nuisance flooding in poor
drainage areas.
Region dries out entirely by sunrise as the deepening low quickly
scoots into New England. Temperatures overnight may not fall more
than a couple of degrees, with morning lows only in the mid 40s
along the coast, and upper 30s across the far interior.-- End Changed Discussion --
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
In the wake of the exiting low, drier conditions await to start the
workweek. The trough axis shifts over the region, and a dry cold
front pushes through in the afternoon, reinforcing strong cold
air advection behind it.
As high pressure gradually builds in from the Plains, the pressure
gradient between the two systems will allow for increased westerly
flow through the day, occasionally gusts between 20 and 30 mph,
especially in the afternoon.
Cyclonic flow around the trough should maintain a fair amount of
stratocu through the day, with breaks of sunshine becoming more
apparent late, particularly along the coast. While highs top
out in the lower 50s, temperatures tumble Monday night, falling
near or below freezing with a colder air mass advecting in.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
There has not been much change to the forecast reasoning in the
extended. The global ensemble guidance remains in general agreement
with the overall pattern. An anomalously deep low centered over
eastern Canada to start the period will head northeast, with a more
zonal pattern in its wake by week`s end. The NBM was followed for
this forecast update.
The highlights for the long term are:
* Below normal temperatures Tuesday and Wednesday with a gradual
warmup thereafter, into next weekend.
* Dry and windy Tuesday and Wednesday, with the next chance of
precipitation late Friday into Saturday.
A strong pressure gradient remains intact as a surface low continues
to deepen as it heads northeast of the region on Tuesday. Behind
this system, cold air advection and thicknesses in the low 500s dam
will result in a blustery, but dry, period. NBM winds have been
adjusted up toward the 90th percentile Tuesday and Tuesday
afternoon, as model soundings continue to indicate deep mixing up to
650-700mb. While we are short of wind advisory criteria, Tuesday
afternoon looks to be the peak of the strongest winds, highest along
coastal areas. It will feel blustery on Tuesday afternoon with the
cold air advection, with highs only in the mid to upper 30s across
the area. In addition, given the cold northwest flow, cannot rule
out a few snow streamers/flurries across the interior, north
and west of NYC, on Tuesday afternoon given the lake effect
activity across upstate NY. Confidence in flurries/snow showers
not high enough at this point to include in the gridded
forecast.
Cold and dry conditions continue Wednesday as the upper flow
deamplifies with a return to southerly flow and surface high
pressure slides offshore. This will allow temperatures to moderate a
bit, with daily highs into the low and mid 40s Wednesday, upper 40s
on Thursday, and upper 40s and lower 50s Friday and Saturday. By
late Friday, guidance continues to advertise a fast moving low
pressure approaching the area from the southwest, as a southern
stream mid/upper shortwave lifts out of the Southern Plains. For
now, given the large uncertainty this far out, have maintained the
NBM chance PoPs starting late Friday. At this point, it looks warm
enough for any precipitation to be all rain, given the
inside/westward track of the system.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Low pressure will impact the terminals this evening into early
Monday morning. The low quickly moves northeast of the area on
Monday with high pressure gradually building into the area from the
west through Monday evening.
Light rain and MVFR ceilings will continue to develop tonight
with ceilings quickly deteriorating to IFR between 00-03z with
the rain becoming moderate. There is also a chance of brief,
locally heavy rainfall. The rain will quickly end from southwest
to northeast from 06z to 09z with ceilings improving to MVFR.
VFR conditions quickly follow and prevail through Monday
afternoon. There is a very low potential for thunder for eastern
terminals such as KISP and KGON.
E-ESE 10-15 kt at most terminals with gusts to around 20 kt for
all terminals except KSWF. Winds will likely be stronger for a
brief time at KJFK, KISP, KBDR, and KGON and there is potential
for gusts 20-30 kt, strongest at KGON. Once the low pressure
begins lifting northeast, winds will shift to the NW and then
back to the W-WSW by day break Monday. LLWS is likely at KISP,
KBDR, and KGON from 03-08z, latest at KGON. However, there is a
lower potential for LLWS at the metro terminals as well, but not
enough confidence to include in TAFs, with the highest chances
for KJFK. The LLWS in the metro terminals, if it does occur, is
not expected to be as strong as for eastern terminals.
WNW-W winds increase to around 15 kt with gusts 25-30 kt Monday
afternoon
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely due to changing flight categories.
IFR ceilings could come in 1-2 hours earlier than forecast.
Wind shifts overnight with passage of low pressure may be off by 1-2
hours.
OUTLOOK FOR 00Z SUNDAY THROUGH FRIDAY...
Mon night: VFR. WNW-W wind 15-20kt, G25-30kt.
Tue: VFR. W wind 15-20kt, G25-35kt.
Wed: VFR. SW wind 10-15kt, G20kt.
Thu: VFR. W wind 10-15kt, G20kt.
Fri: Mainly VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
A deepening area of low pressure tracks through the waters tonight,
bringing increased wind and seas. Small craft conditions develop on
most waters, with the exception of the NY Harbor, late this evening
as SE flow increases ahead of the low. Hoisted a Gale Warning
overnight into early Monday morning for ocean waters east of
Moriches Inlet where a period of 35 to 40 kt SE gusts appears
likely. Wind gusts gradually lower here to 25 to 30 kt through
the morning hours. Small craft conditions continue everywhere,
and expand into the Harbor, in the wake of the low on Monday. West
winds will gust 25 to 30 kt through Monday night.
SCA conditions remain on the forecast waters Tuesday and
Tuesday night, and there is a chance that gusts reach gale force
on the ocean waters Tuesday afternoon into Tuesday evening.
Gales may also be on the Long Island bays and Long Island Sound
for a few hours Tuesday evening, as well.
SCA conditions continue Wednesday through at least Thursday, with
elevated seas of 5-6ft on the eastern ocean waters tapering by
Friday morning. Sub SCA conditions are then expected through
Saturday.
&&
.HYDROLOGY...
A period of locally heavy rainfall is possible late this evening
and tonight, particularly for the NYC metro, NE NJ, the lower
Hudson Valley, and SW CT. The Weather Prediction Center has a
marginal risk for excessive rainfall outlined in these areas.
While the risk for flash flooding is low, nuisance flooding of
urban and poor drainage areas is a possibility. Total rainfall
into early Monday morning generally ranges from a half inch to
an inch and a quarter.
There are no hydrologic concerns from Tuesday onward.
&&
.TIDES/COASTAL FLOODING...
Astronomical tides continue to increase with a full moon early
Monday morning. A fast moving low pressure will also pass across the
region late tonight into early Monday. A few vulnerable locations
across the south shore back bays and coastal Fairfield could come
close to minor benchmarks with high tide this evening/tonight.
Minor coastal flooding is more likely for the south shore back bays
of Nassau and Queens with high tide on Monday morning. The highest
surge associated with the low pressure occurs between high tides.
The flow also quickly becomes offshore ahead the morning high tide.
However, only 0.50 to 0.75 ft is needed to reach minor benchmarks
for the south shore back bays. Have issued a Coastal Flood Advisory
for these areas as confidence is highest that minor benchmarks will
be exceeded. Water levels will remain below minor coastal flooding
benchmarks for the lower NY Harbor, Wester Long Island Sound, and
bays along SE Suffolk County.
A strong offshore flow Monday afternoon through Tuesday will keep
water levels below minor benchmarks.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Coastal Flood Advisory from 6 AM to 10 AM EST Monday for
NYZ178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ331-332-335-
340-345-353-355.
Small Craft Advisory from 6 AM Monday to 6 AM EST Tuesday for
ANZ338.
Gale Warning until 7 AM EST Monday for ANZ350.
&&
$$
SYNOPSIS...DBR/DR
NEAR TERM...DBR/DR
SHORT TERM...DR
LONG TERM...DBR
AVIATION...JP/DS
MARINE...DBR/DR
HYDROLOGY...DBR/DR
TIDES/COASTAL FLOODING...