000
FXUS61 KOKX 071815
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
215 PM EDT Mon Aug 7 2023
.SYNOPSIS...
A frontal system slowly approaches from the west through today.
An associated warm front moves across this evening, followed by
an associated cold front moving through on Tuesday. The front
moves northeast of the region Tuesday night into Wednesday
eventually getting into the Canadian Maritimes. High pressure
gradually builds into the region from the southwest midweek. The
next low pressure system moves through late Thursday into Friday,
with potentially another approaching toward the end of the
weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
The forecast is generally on track. The main area of showers
will exit southeastern Connecticut over the next hour or two,
while showers are starting to pop up across western portions of
the area. While some clearing occurred earlier across the metro
area, it quickly clouded over again. This may delay the onset
of thunder.
Mid level shortwave approaches from the west with a frontal system
approaching at the surface. Isentropic lift increases going
into this morning. First round of showers moves in and will be
across the region going into first half of this morning. There
may be an occasional isolated thunderstorm from time to time.
Layer precipitable waters increase with this area of showers to
around 2 inches. Locally heavy rainfall will be possible at
times.
Then convection will become less frequent with more of a lull in
convective activity going into this afternoon. Chances for showers
and thunderstorms will remain and with some partial clearing in the
sky, more sun will lead to greater daytime heating, thereby
increasing the low level instability. This low level instability
will be highest across most western sections of the region where the
higher end of max temperatures is forecast.
Another initiation mechanism for convection will be the closer
proximity of the shortwave and its associated positive vorticity
advection moving in for tonight. Even greater isentropic lift
moves in from the west for tonight. Upper level jet streak moves
in late tonight with right rear quad of the jet near the area
acting to enhance lift. There will be potential for strong to
severe thunderstorms especially where there is greater
instability. Model forecasts of Bulk Richardson Number indicate
increasing values into the 15 to 35 into the area. The
instability as diagnosed by surface CAPE reaches around 1500 to
potentially near 2000 J/kg in interior places such as interior
NE NJ and into Orange County NY. Main threat with the severe
thunderstorms will be damaging winds. A supercell thunderstorm
with discrete enhanced convection will be possible as well as
indicated by the Bulk Richardson number forecast so therefore a
brief tornado will also be possible. The relatively highest
threat of severe thunderstorms will be across the most western
sections of the region that have the highest instability and
will be relatively closest to the approaching warm front.
In addition, another enhanced higher layer precipitable water area
moves in for tonight near 2 inches, so heavy rainfall potential will
remain. CAMs convey an organized squall line with some potentially
discrete thunderstorm cells ahead and behind the line to start
moving into the western portions of the local region in the evening
hours across NE NJ, Lower Hudson Valley, and NYC. However the CAMs
indicate the convective line weakens as it tracks eastward going
into the late evening across Southern CT and Long Island. CAMs
depict more convection popping up and moving northeastward across
the eastern half of the region overnight. There may be some
additional lulls in convective activity between the evening and
the overnight.
Max temperature forecast today was from consensus of MOS, ranging
from the mid 70s to lower 80s for much of the region, with some mid
80s for parts of NE NJ.
Min temperatures forecast tonight were from a less vast range of
consensus of raw model data mainly in the 60s to lower 70s. While
not specifically stated in the forecast, patchy fog will be possible
for locations that receive more rainfall and have less wind
overnight tonight into very early Tuesday morning, perhaps
across parts of the interior.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Upper level trough axis moves across Tuesday. At the surface, a cold
front moves across on Tuesday. Winds become more westerly and gusty,
advecting in drier air behind the cold front. Layer precipitable
waters drop to near 1.5 inches.
Forecast has some lingering showers especially across parts of
Southern CT Tuesday morning with additional chances for showers and
thunderstorms in the afternoon. All convection diminishes Tuesday
night when more dry air enters the region, resulting in a further
lowering of precipitable waters to less than 1 inch. Temperatures
forecast Tuesday and Tuesday night are near to slightly below
normal values. Forecast highs are in the upper 70s to lower 80s
and forecast lows are in the 60s on average.
Mid level zonal flow in place on Wednesday with high pressure at the
surface and low pressure getting into the Canadian Maritimes. A dry
day with more sun expected. Forecast highs trend a few degrees
warmer compared to the previous day, getting above normal.
Forecast highs reach into the mid 80s for much of the area with
some upper 80s for Northeast NJ and NYC. It will not be that humid
though with the gusty westerly flow continuing to advect in drier
air so heat indices will not be a factor. Apparent temperatures
will be nearly the same as actual temperatures.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The weak high pressure pushes offshore Thursday and surface
flow backs SW as another shortwave trough swings east into the
Great Lakes region. This will send a frontal system through late
Thursday into Friday, and bring another round of showers and
perhaps a few thunderstorms. At this time, the bulk of Friday
and Saturday may remain mostly dry, before another shortwave
approaches late in the weekend increase PoPs once again.
Temperatures will remain relatively seasonable through the
period, with highs generally in the low to mid 80s. Dew pts drop
behind the frontal passage Tuesday, allowing for a bit lower
humidity on Wednesday, before increasing once again late week.
Primarily followed the national blend of model guidance for this
update.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A warm front slowly approaches from the SW today, likely
lifting across the terminals tonight. A cold front then follows
late Tuesday morning.
Mainly VFR and MVFR this afternoon, with some lingering IFR.
Slight improvement should continue through the afternoon. The
first round of showers has moved through most terminals and
should be east of KGON by 18z. Lingering isolated showers are
possible throughout the rest of the afternoon and have covered
this with a VCSH.
Another round of showers and thunderstorms is expected tonight.
Have kept a TEMPO for TSRA for the NYC and Lower Hudson Valley
terminals, mainly after 00Z. There is quite a bit of uncertainty
with the strength of these showers and thunderstorms and
amendments are likely. Otherwise, back down to MVFR-IFR cigs is
forecast tonight. Showers then linger early Tuesday. There is
some potential for thunderstorms again in the 05-10z time frame,
but confidence too low to add in the TAF and have kept -SHRA.
SE winds increase to 10-15 kt with gusts 18-25 kt this afternoon,
strongest along the immediate coast. The highest wind speeds
and gusts should begin to subside this evening. Winds will then
veer to the SW late tonight at 10kt or less. Winds pick up again
early Tuesday out of the SW-W, with gusts 20-25 kt possible.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence in ceiling forecast this afternoon, but a return
to MVFR is likely by early evening. Brief IFR is possible
after midnight. Improvement to VFR may happen a few hours
earlier on Tuesday afternoon.
Timing and strength of showers/thunderstorms tonight will
likely be refined in subsequent forecasts. Potential is there
for strong to severe thunderstorms.
OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday Afternoon: Improvement to VFR likely by early
afternoon. Showers and an isolated thunderstorm possible in the
afternoon and evening with MVFR conditions. SW wind gusts 20-25
kt possible.
Tuesday night through Wednesday: VFR. W wind gusts around 20
kt.
Thursday: VFR.
Thursday Night-Friday: Mainly VFR. Chance of showers and MVFR.
A slight chance of thunderstorms Friday afternoon.
Saturday: Mainly VFR. Slight chance of afternoon showers and
thunderstorms mainly for NYC north and west.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Mainly sub-SCA conditions today but occasional 25 kt gusts
for some waters. Tonight, more consistent and frequent 25 kt
gusts on the ocean and ocean seas get to near 5 ft. SCA in
effect for the ocean tonight into Tuesday with SCA conditions
continuing into Tuesday. Mainly sub-SCA conditions remain
elsewhere tonight going into Tuesday but some waters will have
occasional gusts to 25 kt. Potential for more widespread SCA
conditions Tuesday night into Wednesday.
Thereafter, largely sub-SCA conds expected on all waters into
late week.
&&
.HYDROLOGY...
Multiple rounds of showers and thunderstorms through Tuesday
morning could result in flooding, including isolated to scattered
areas of flash flooding. The best chance for isolated to
scattered flash flooding will be tonight into early Tuesday
morning. Rainfall amounts of near 1 to 2 inches are forecast
across the area with the potential for localized higher amounts,
possibly as much as near 3 inches. The Weather Prediction
Center has placed most of the area in a slight risk for
excessive rainfall today through tonight.
Heavy rain is possible late Thursday into Friday, but at this
time there remains too much uncertainty to determine any
potential hydro risk.
&&
.TIDES/COASTAL FLOODING...
There is a high rip current risk for all Atlantic-facing
beaches on today due to a strengthening southerly flow of 10 to
20 kt and building seas. This rip current threat remains high
for all beaches on Tuesday as seas build to around 5 ft with
gusty 10 to 20 kt winds.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075-
080-081-178-179.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EDT
Tuesday for ANZ350-353-355.
&&
$$
SYNOPSIS...JM/DR
NEAR TERM...JM/JP
SHORT TERM...JM
LONG TERM...DR
AVIATION...JT
MARINE...JM/DR
HYDROLOGY...JM/DR
TIDES/COASTAL FLOODING...