000
FXUS61 KOKX 041126
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
626 AM EST Thu Jan 4 2024
.SYNOPSIS...
A cold front passes through today with high pressure building in
through Saturday. Low pressure passes to the south and east of the
area Saturday night through Sunday night, bringing rain and
snow. High pressure builds in on Monday and shifts east of the
area early Tuesday. Another strong low pressure system is then
expected to impact the area Tuesday through Wednesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Forecast remains on track with only minor adjustments to
temperatures, dew points, and PoPs to account for the latest
observations.
A mid level trough is pushing a cold front into the area from the
west this morning with a weak surface low pressure to the south of
the area. This is allowing for low to mid-level cloud cover with the
potential of some flurries or light snow showers this morning for
portions of the Lower Hudson Valley to the coast. The cold front
pushes through later this morning and into the afternoon, where a
few isolated rain or snow showers may develop, but be fairly
inconsequential. Highs today will be in the low to middle 40s.
Strong high pressure quickly builds in tonight behind the departing
low to the east. The increasing pressure gradient this afternoon
will allow winds to increase becoming NW 10-15 mph with gusts
upwards of 30 mph along the coast. This brisk wind advects cold air
from the north allowing temperatures tonight to drop into the upper
teens and 20s. Winds gradually decrease during the overnight
and into Friday morning.-- End Changed Discussion --
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
High pressure then moves over the area and dominates the weather
over the Northeast for Friday and through the beginning of the day
on Saturday. Temperatures Friday and Friday night will be below
average with highs Friday afternoon only in the middle to upper 30s
and lows Friday night in the 20s.
Attention then turns to a developing coastal low pressure that looks
to pass by the 40N/70W benchmark Saturday night and into early
Sunday. At this time, consensus is that a shield of precipitation
begins to overtake the area from southwest to northeast late
Saturday afternoon and evening, eventually overspreading the area
Saturday night and through early Sunday. Antecedent cold air may
allow for the initial light precipitation to begin as snow for the
interior and a rain/mix along the coast.
As the low pressure strengthens and shifts south of the area, a
strengthening easterly flow will set up over the area. With ocean
temperatures in the low to middle 40s, this will likely result in
the boundary layer remaining above freezing for much of the coastal
areas which will likely allow for a predominantly rain event for
Long Island and the NYC metro. Areas to the north and west of NYC
and Southern Connecticut should be more encompassed in a low level
cold airmass to allow for mainly snow for the Lower Hudson Valley
and interior Southern Connecticut with more of a mix of rain and
snow for the immediate Southern Connecticut coastline and near the
immediate NYC metro.
Winds with the system will be of concern for eastern coastal areas
as well with a strengthening E/NE flow of 15-25 mph with gusts
upwards of 35-40 mph possible along the immediate coastline, mainly
Long Island, for Saturday night and through early Sunday afternoon.
As the low pressure system pulls away on Sunday, a more northerly
flow will cool the boundary layer along the coast with any residual
precipitation on the backside of the low ending in light snowfall
for much of the area before coming to an end Sunday
afternoon/evening.
WPC now has probability of warning level snowfall for portions of
the interior at 50% or greater with percentages rapidly dropping off
near the coastline. Snowfall amounts of 4-8 inches appear likely for
interior areas of Southern Connecticut and the Lower Hudson Valley,
namely Orange and Putnam Counties. A sharp gradient of snowfall will
likely develop with immediate coastal areas seeing only 1-3
inches or less. The NYC metro and Long Island at this time are
expecting less than an inch of snow.
It is worth noting, however, that there remains a fair amount of
uncertainty in the exact strength and track of the low and if any
banding on the NW side of the cyclone develops. Given marginal BL
and low level temperatures, much of the snow accumulations will be
dependent on any mesoscale banding and heavier snowfall rates that
develop. Heavier precipitation may also allow for dynamic cooling of
the lower atmosphere which may provide for a changeover from rain to
snow for more coastal areas, but once again this depends on the
exact strength and positioning of the low and its respective
mesoscale precipitation banding.
High pressure then builds into the area with dry conditions Sunday
night.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
*Key Points*
* Another strong low pressure system will impact the area in the
middle of next week, with the potential for wind and flooding
impacts.
Quiet weather is expected Monday and Monday night as high pressure
shifts through the area.
Attention then turns to another strong low pressure system that will
bring the potential for wind and flooding impacts. There continues
to be very good agreement across the guidance with this system,
impressive for how far out it is. An upper level low and associated
surface low will lift out of the southern CONUS, with the surface
low tracking west of the area. With high pressure retreating to the
east, the area will be in between roughly a 975mb low and a 1030mb
high. This very tight pressure gradient could bring strong winds to
the area. Stuck close to the NBM and CONSALL, but given the great
agreement across the guidance, also blended in a bit of the NBM 90th
percentile. The other concern with this system is the rain and
potential for flooding impacts. Also stuck close to NBM with PoPs,
which given the great agreement already has 90%+ Tuesday night. Too
far out to talk specific amounts, but the NBM currently has a 60 to
70% chance across the whole area of seeing 2 inches of QPF over a 24
hour period. This will likely fall mostly as rain given the track of
the storm, but there could be a snow or rain/snow mix at the start
of the event. Freezing rain across the interior at the onset late
Tuesday into Tuesday evening may also be possible. The models may be
having a difficult time handling any CAD with the system. Kept the
thinking of previous forecast and went lower than NBM with the highs
on Tuesday.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
A cold front passes through late this morning into early afternoon.
VFR. There is a slight chance of flurries this morning across
the whole area, but vsby is expected to remain VFR. Brief MVFR
vsby possible at HPN early this morning.
Winds become more NW and gusty late this morning. Stronger NW
winds in the afternoon into the early evening. A few gusts may
exceed 30 kt. The flow weakens, but remains NW Friday morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Peak occasional gusts at or just above 30 kt possible after
around 19Z.
Uncertainty in frequency of gusts overnight tonight.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday: VFR. Occasional NW G20kt possible for the AM push.
Saturday: VFR becoming IFR or lower Sat ngt in snow and/or rain.
Increasing E/NE winds with gusts 25-35kt at night.
Sunday: Rain/snow ending as snow. IFR or lower possible. Winds
becoming N with gusts up to 25kt possible in the morning.
Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Conditions remain below SCA this morning. Winds increase behind a
cold frontal passage this afternoon with SCA gusts of 25-30 kt
likely for all waters this afternoon and through much of the
overnight period. The ocean waters may have some near gale force
gusts of 35 kt overnight but will be infrequent enough to leave a
SCA. SCA gusts and waves on the ocean may linger a bit into Friday
morning where SCA may need to be extended by a few hours.
Otherwise, high pressure building in allows conditions to drop below
SCA for all waters Friday afternoon.
Gales then remain possible for all waters this weekend as a coastal
system is expected to impact the area. Eastern and ocean waters are
more likely to be impacted by gale-force wind gusts. The best window
for gales will be Saturday night through Sunday early afternoon.
Waves on the ocean likely remain elevated through Sunday night.
With high pressure in control, sub-SCA conditions are expected on
all waters Monday through early Tuesday. Another strong low pressure
system will then impact the area Tuesday through Wednesday. This
system will likely bring gale force gusts to all waters, with the
potential for storm force gusts on the ocean waters. Confidence is
high enough in gales to mention in the HWO, but confidence is too
low and too far out in time to mention storm force.
&&
.HYDROLOGY...
There is the potential for flooding (especially rivers) with a
strong low pressure system Tuesday through Wednesday. This will
partially depend on what materializes this weekend. Regardless,
soils will remain nearly saturated leading up to the event. The NBM
currently has a 60 to 70% chance across the whole area of seeing 2
inches of rain over a 24 hour period.
&&
.TIDES/COASTAL FLOODING...
Minor coastal flooding is possible, mainly for the Western LI Sound
and South Shore Bays, during the Sunday morning high tide cycle.
There is also potential for scattered dune erosion.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 AM EST
Friday for ANZ331-332-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...JT/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...JT
AVIATION...JT
MARINE...JT/MW
HYDROLOGY...JT/MW
TIDES/COASTAL FLOODING...