000
FXUS61 KOKX 232040 CCA
AFDOKX
Area Forecast Discussion...CORRECTED
National Weather Service New York NY
440 PM EDT Fri Jun 23 2023
.SYNOPSIS...
-- Changed Discussion --
A warm front will eventually move into the region from the
south this evening. The warm front will continue moving
northward late tonight. The warm front is expected to slow down
and become nearly stationary in the vicinity of the forecast
area Saturday with low pressure attached moving in for late
Saturday into Saturday night. Afterwards, a slow moving upper
level disturbance and frontal system will affect the area for
much of the next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Latest update was to increase the showers and chances for
thunderstorms for western sections of the region, near NYC and
to the north and west. A group of showers and embedded
thunderstorms has developed and grown in coverage across the
DelMarva and into SE PA as well as Southern NJ. This convection
is expected to move into NYC, NE NJ, Lower Hudson Valley, SW CT
going into early this evening, mainly before 8 PM. Locally heavy
rain can be expected with this activity.
For tonight, continued height falls in the mid levels with some
added synoptic forcing with an incoming upper level jet streak
overnight. The left front quad of this jet streak moves near the
area. This will enhance synoptic lift. At the surface, the warm
front continues to approach and the boundary itself starts to
move in late this evening into overnight. Overnight, the warm
front will slowly makes its way northward across the area. There
is uncertainty on how far north the warm front gets as models
have recently over estimated the speed of the warm front.
In terms of weather, outside of Northeast NJ and Lower Hudson
Valley into NYC vicinity, where more numerous shower coverage
is forecast this evening, shower coverage this evening will be
mainly scattered. Patchy fog expected to expand across the
coastal sections and further develop especially with any lulls
in shower activity.
Expecting an increase in elevated instability tonight as the
warm front gets more into the region. In combination with the
aforementioned increase in synoptic lift, expecting an increase
in shower coverage overnight and an increase for thunderstorm
chances as well. With higher precipitable waters, some showers
and thunderstorms will result in heavy downpours. Patchy fog is
forecast going into overnight especially across eastern sections
of the region but is expected to break up from west to east
with the more vertical mixing as showers increase and traverse
the area for the latter half of the overnight period.
The lows tonight were taken from MOS consensus which were
relatively warmer compared to NBM and the raw consensus data,
with mainly upper 60s expected.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
For Saturday morning, expecting widespread showers and scattered
embedded thunderstorms. Aloft, still some height lowering and
jet streak still south of the region with its left front quad
enhancing lift. The warm front boundary may become nearly
stationary within the area. An area of low pressure approaches
the area from the west.
The synoptic lift enhancement decreases Saturday afternoon into
Saturday evening with the exit of the upper jet streak and
height tendency becoming more steady. With warm air advection on
a continued southerly flow and much of the area in the warm
sector, there is forecast to be more surfaced based instability
especially across western sections of the region. This will
allow for an increasing likelihood of showers and an increasing
chance of thunderstorms for the afternoon into early evening
Saturday. Again, with high precipitable waters in place (near
1.8 inches), could have heavy downpours with some showers and
thunderstorms. Forecast high temperatures Saturday range from
mid 70s to near 80 using a consensus of MOS.
Models are conveying a decrease in convection Saturday night
with the loss of diurnal instability and without much synoptic
forcing aloft. Trough will be weakening aloft along with low
pressure and frontal boundary at the surface. Forecast lows from
consensus of MOS, mainly upper 60s still without much change in
airmass. Scattered convection will become more isolated and
eventually diminish. Forecast lows again Saturday were from
consensus of MOS and once again mainly in the upper 60s. Fog
will be possible as well for some areas Saturday night.-- End Changed Discussion --
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Unsettled pattern through midweek with gradual improvement possible
for late week. Closed upper low that has been to the southwest of
the region much of the week will open up and swing through the
region late Sunday/Sunday Night, with another closed upper low
trekking from the upper plain this weekend and then into the Great
Lakes/Ohio Valley for early next week, before opening into a deep
trough approaching the coast for the mid to late week.
At the surface, a weak trough will linger across interior portions
of the region, combined with inland moving sea breeze, will act as a
focus for shower/tstm development Sun aft/eve as shortwave trigger
approaches in a marginally unstable and moist airmass. Main threat
is heavy downpours and localized flooding with potential for slow
and training storm movement in a weak shear environment. Warm and
humid conditions on Sunday with distinct potential for heating in
the morning/early afternoon, which should allow for temps to rise
into the lower to mid 80s.
For Mon thru Wed, a broad surface low (stacked under the closed low)
will slowly move east into NY/PA, with a series of warm
fronts/surface trough moving through the region. This setup will
remain fairly persistent, as weak shortwaves act as a trigger for
torrential downpours and tstm activity in a high PWAT, deep warm
cloud depth, and marginally unstable airmass. WPC marginal excessive
rainfall threat, particularly for areas from NYC metro and N&W and
during diurnal hours, is reasonable with potential for localized
flash flooding with training convection and locally increasing soil
moisture/stream flow. In addition, a conditional localized strong to
severe tstm threat is possible as well each afternoon (mainly NYC
and interior) if peak instability coincides with increased shear
ahead of shortwave/warm front features.
Models in general agreement with the closed upper low opening and
broad surface low/trough moving overhead in the late week period,
but spread in depth and location of trough. Potential that the main
WCB of subtropical moisture flow may have pushed east of the region,
which would transition shower/tstm activity to more of a diurnal
pulse strong to marginally severe cold pool convection threat.
Convection/flash flood details will of course be refined as the week
progresses.
Seasonably warm and humid conditions through the period with sub-
tropical environment. Highs generally in the upper 70s to lower
80s.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
A warm front will approach this evening into tonight. Weak low
pressure then meanders nearby this weekend.
Mainly IFR conditions this evening with LIFR developing and
continuing overnight into early Saturday morning as the warm front
passes through.
Patchy fog with scattered showers and thunderstorms possible into
early evening. Best chance of TSRA is west of NYC terminals. Heavy
rain is possible in any thunderstorm. There may be a brief lull in
showers later tonight followed by increasing showers and possible
thunderstorms again early Saturday morning. Included a prob30 to
reflect the increased chance. Isolated thunder is possible again
Saturday afternoon across the interior west of NYC and Lower Hudson
Valley.
Light E-ESE winds will become SE this evening and the S 10 kt
or less tonight. The wind direction should remain S tonight
into Saturday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely for changing flight categories. Overall...a
low confidence forecast with regard to timing of flight
categories at any particular terminal.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
18Z Saturday: MVFR or lower. Showers likely with possible
thunderstorms.
Sunday: Chance of MVFR and showers. Thunderstorms possible in
the afternoon and evening.
Monday: Showers likely with thunderstorms possible, especially
in the afternoon and evening. MVFR or lower possible at times.
S-SE wind gusts 15-20 kt.
Tuesday and Wednesday. Showers likely. Slight chance of
thunderstorms. MVFR or lower possible at times. S-SE wind gusts
near 20-25 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
With a relatively weak pressure gradient, expecting winds and
seas to remain below SCA thresholds through Saturday night
across the forecast waters. Patchy fog across the waters tonight
make get dense at times. Fog will be possible Saturday night as
well.
Winds and seas look to remain below SCA levels into Sunday night.
SCA wind gusts could develop on the ocean waters as early as late
Monday into Monday night, but more likely on Tuesday into Wednesday
as southerly flow increases ahead of a slow moving frontal system.
Similarly, marginal SCA ocean seas may develop late Monday into
Monday Night, with higher likelihood Tue into Wed with persistent
and increasing southerly flow.
&&
.HYDROLOGY...
Locally heavy rainfall is possible through Saturday, and minor
flooding could occur especially in poor drainage and low lying
areas. Particularly through early Saturday, precipitable waters
will be increasing from near 1.75 inches to near 2 inches,
allowing for heavy downpours with showers and thunderstorms.
For Sun thru Wed, a scattered low lying/poor drainage flood
threat and localized flash flood threat exists, particularly for
areas from NYC metro and N&W and during diurnal hours. The
flash flooding threat will be coincident with any training
convection and areas where soil moisture and stream flow is
elevated due to antecedent rainfall activity.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development for all ocean
beaches for today through Sunday with a continuation of 3 ft
southerly swells affecting the shore.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM/NV
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...NV
AVIATION...IRD
MARINE...JM/NV
HYDROLOGY...JM/NV
TIDES/COASTAL FLOODING...NV