000
FXUS61 KOKX 161102
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
702 AM EDT Fri Jun 16 2023
.SYNOPSIS...
A frontal system and associated low pressure pivots through today
and tonight, then stalls just to the northeast for the first half of
the weekend. Low pressure heads east Sunday as high pressure
builds in from the northwest through Monday night. Weak low
pressure remains south of the area Tuesday through Thursday with
high pressure anchored north of the region.
&&
.NEAR TERM /THROUGH TONIGHT/...
Forecast remains on track, no revisions on this update.
An upper level trough with digging shortwave energy approaches this
morning. As an area of height falls approaches look for cloud cover
to overspread the region quickly from west to east as any sunshine
across eastern sections gives way to increasing cloud cover. The
latest CAMs have better agreement with respect to developing shower
and embedded t-storm activity for later in the day and the evening
as the center of the height fall max gets into No Central PA and the
Southern tier of NY. With respect to the timing of organized shower
/ t-storm activity the consensus from the CAMs is suggestive of
closer to 17-18z for the city and western portions of the CWA,
through about 02-03z. This may come from multiple line segments.
Much of the more organized and heavier shower activity should get
east of the area towards and after midnight. The current thinking is
that the majority of thunderstorm activity will be sub severe.
However, SPC has placed the marginal and slight risks of severe
weather just south of the CWA with the placement nudged slightly
further north in their last overnight update. It appears that
the best instability will be displaced just south of the area.
If the northern edge of this higher instability can get further
north then the southern portions of the area at the very least
will have more of a chance to see a few storms approach severe
levels as shear appears to be present with 30 to 40 kt of bulk
shear towards late in the day and evening. Overall CAPE looks to
be below a few hundred joules across much of the area, but the
northern edge of higher instability with 500 to 1000 j/kg on
some guidance gets into portions of NE NJ and NYC, and into
possibly western portions of LI. If this scenario works out then
a cluster of stronger storms could get into southern and
southwestern portions of the CWA. For now, the consensus is the
better combination of CAPE and shear remain just south over
Central and Southern NJ. The mesoscale analysis will need
watching throughout the day. As far as the potential for heavy
rain, at this time it appears that any flooding would be more on
the minor side and be more of the urban nuisance and poor
drainage type. With an upper level low synoptic scenario this is
not the typical set up that would yield flooding from heavy
rain for our area. It looks like the rain would be briefly heavy
in association with any stronger t-storms, but the duration and
the potential for training over the same areas, and with a lack
of back building should preclude a flooding rain threat. This
risk therefore is low at this time and would only pertain to
urban areas. For more details on this see the Hydrology section.
The 500 mb height minimum then positions itself over the area
tonight into early Sat am. Although there will be the loss of
diurnal heating into tonight, there will likely still be enough
forcing to drive continuous scattered shower activity as the
upper level low gets directly overhead with a few lingering
t-storms or some rumbles of thunder remaining possible.
Temperatures should be below normal today with highs mainly in the
middle and upper 70s due mainly to more pronounced cloud cover. Lows
tonight will be more of the same with lows primarily in the upper
50s across the interior and more rural locations, and lower 60s for
the NYC metro and along coastal communities.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
The upper level low will then pause and set up just to the northeast
off the area on Saturday. With a cold pool aloft along with cyclonic
curvature in the lower to mid levels the risk of showers and a few
thunderstorms will remain in place. The best forcing will lift just
north and northeast of the area. Thus look for a mostly cloudy and
unsettled day with periodic showers and a thunderstorm or two
rotating through. A few storms may bring heavy rainfall as WPC
has place the eastern 2/3rds of the area in a marginal risk of
excessive rainfall. Temperatures will continue to run below
average due to lots of cloud cover and a developing cooler NW
flow. Most daytime max temperatures will run in the upper 60s to
middle 70s.
For Saturday night as the upper level low begins to slowly progress
further northeast some clearing looks to gradually work in from the
southwest. Therefore closer to and after midnight some clearing may
set in from the SW. A brisk NW flow on the backside of the low
should keep it brisk with minimum temperatures mainly in the middle
and upper 50s across the interior, and lower 60s along much of the
coast and the NYC metro.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Ensemble means continue to depict mean troughing over the eastern
CONUS with a departing closed low to begin the period. Weak ridging
then builds in from the northern plains by the middle of next week
while another upper low meanders over the southeast through the end
of the week. The forecast has trended a bit drier, overall.
Continued near to below normal temperatures to start, but highs will
be on the increase by week`s end. The NBM was followed closely for
this update.
Sprawling high pressure begins to build over the northeast behind
the departing low pressure on Sunday. This high looks to remain
anchored over the region through midweek sliding offshore by the end
of the week. After any lingering clouds/showers across eastern
sections of the area head east early Sunday, drier air advects in
behind the system through the day, and with weak ridging aloft, the
day should be mostly dry. Monday looks to be mostly dry and
seasonable, as well, though a shortwave to the northeast will
provide the chance of an afternoon shower/thunderstorm, mainly for
CT and the Lower Hudson Valley.
The Tuesday - Thursday period looks mainly dry, with a chance of
scattered showers each day. The is region caught between the western
side of the upper low over eastern Canada and the eastern side of
the ridging to the northwest, allowing for some weak shortwaves to
move through the area under the northerly flow. So while widespread
rain/thunder is not expected in this timeframe, diurnally driven
precipitation is possible each afternoon.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
High pressure gives way to a low pressure that approaches and
passes near the terminals this afternoon into Saturday.
VFR through late this morning. Showers and thunderstorms then
develop this afternoon, 17-23Z from west to east, with MVFR or
lower at times. Timing of storms may be off by an hour or two.
Light and vrb winds to start today become southerly towards
midday. Late this afternoon, wind directions could get tricky in
areas of showers and storms before turning northeast into
Saturday am and eventually NW by midday Saturday.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Wind direction will be challenging today, especially at LGA
where sound breeze flow may be NE off the Sound as opposed to S.
Timing of showers and thunderstorms may be off by an hour or
two. Low confidence in developing fog/low stratus this evening
into the overnight.
OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
Friday night: continued threat of MVFR or lower with showers and
tstms.
Sat: VFR to start, then chcs for MVFR or lower in sct aftn shwrs and
tstms.
Sun: Mainly VFR. A slight chc for shwrs and isold tstms.
Mon-Tue: Slight chc of MVFR at times in shwrs. Otherwise VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
A south to southeast flow takes shape today in advance of an
approaching frontal system and low pressure. The pressure gradient
will remain relatively weak with all wind gusts remaining below 20 kt
and seas only up to about 3 ft on the ocean today and heading into
the start of the weekend. The winds will switch to the NW during
Saturday and will increase slightly, but will still remain below
small craft criteria.
From Sunday through Tuesday, sub SCA levels are forecast with weak
departing low pressure Sunday, and weak high pressure building in
for Monday into Tuesday.
&&
.HYDROLOGY...
WPC has placed the area in a marginal risk of excessive rainfall
for today, and primarily the eastern 2/3rds of the area on
Saturday. At this time a flooding threat from heavy rain
appears to be minimal, with a low threat primarily only for
urban locations. The threat would increase if thunderstorm
coverage is more widespread than anticipated over the next 36
hours.
No hydrologic impacts are expected from Sunday through Thursday.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip currents today and a low risk on
Saturday.
Minor coastal flood benchmarks are likely to be reached for the
western south shore back bays of Queens and Nassau for this
evening`s high tide, and potentially for Saturday evening as well.
Tidal departures will run around 1 to 1 1/2 ft, with some locations
having departures closer to 2 ft.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JE/DBR
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...DBR
AVIATION...DBR
MARINE...JE/DBR
HYDROLOGY...JE/DBR
TIDES/COASTAL FLOODING...