000
FXUS61 KOKX 241803
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
203 PM EDT Thu Aug 24 2023
.SYNOPSIS...
Low pressure and its associated warm front approach into
tonight. The warm front slowly pushes through Friday, followed
by a cold front Friday night. A slow moving frontal system
slides east early Saturday, followed by a Canadian cold front
moving through late Saturday. Canadian high pressure builds in
for Sunday and east on Monday. A frontal system will approach
Monday Night, slowly crossing through Tuesday into Tuesday
Night. Another Canadian cold front crosses on Wednesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
Scattered showers will continue to develop this afternoon,
mainly across the Lower Hudson Valley, NE NJ, NYC metro and
western Long Island. Some showers may spill further east, but
could end up just being some sprinkles as drier air and surface
ridging hang on there. Noting radar returns moving in two
different directions, from NW to SE within the middle level
flow, and then S to N with the low level warm advection
increasing. This general set up will continue through the rest
of the afternoon with scattered showers gradually shifting
eastward. Max temps will only get into the lower and middle 70s
today.
Shower activity will likely increase for the evening as the
elevated warm front starts to slide in from the west. Therefore
shower activity will become more widespread into the overnight.
A convective complex likely develops off the Great Lakes
tonight and quickly moves south into PA after 4-6z. The complex
should follow the higher instability that will reside further
west. There will also be a 30-40 kt LLJ developing over the
region early Friday which will still support showers over the
region that could become locally heavy at times with PW values
1 3/4 and 2 inches. Also with some elevated instability,
embedded thunder is possible. Forecast soundings continue to
indicate little surface CAPE and a cap/inversion around 700 mb.
Warm rain processes should occur with a deep warm cloud layer
around 13 to 14 kft towards early Fri AM. With warmer and more
humid air on a SSE flow look for temperatures to hold steady
tonight, warmer than previous nights as dew point readings rise
into the upper 60s towards early Fri AM.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
During Friday morning the more widespread shower activity will
likely be pivoting through as the warm front pushes into the area at
and just above the sfc. One thing of note is the 0-1, and 0-3 km
helicity and hodographs on the forecast soundings. However,
surface instability looks to be limited and the cap/inversion
remains aloft. While low level shear and helicity are there, the
instability is not, so not anticipating any severe weather
concerns at this time with any convection with the warm front.
There is still some uncertainty with how much the warm front
actually moves through. It could linger over eastern portions of
the area. Will still need to monitor trends with guidance with
surface instability and proximity of the warm front. Rainfall
rates in the heaviest shower activity will likely be on the
order of three quarters of an inch per hour, with maximum
rainfall rates of up to 1 inch or more per hour not out of the
question.
Into Fri afternoon and evening with lingering instability and the
region in the warm sector, look for scattered shower and
thunderstorm activity. There remains uncertainty if there will be a
dominant focus mechanism for convection, until the cold front slowly
pushes through either Fri evening or later Fri night. Have continued
with a chance of showers and a slight chance of thunderstorms for
this time frame, along with a heavy rain mention further east into
the day Friday. By early Sat AM on the back side the cold front look
for the winds to become more NW. Shower coverage overall should
decrease towards early Sat AM, although some guidance is suggestive
of the front temporarily stalling which would keep shower chances
lingering into Sat AM. QPF Amounts look to be on the order of
mainly 3/4 to 1 inch. Locally higher amounts of 1.5 inches or more
are possible where any locally heavy downpours take place. See the
Hydrology section for more details.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Good model agreement in persistent mean NE troughing continuing
through the period as one trough develops for the weekend and a
second deeper trough approaches for Tue/Wed. Meanwhile, the
anomalously strong Central and Southern US subtropical ridge will
gradually weaken and retrograde to the SW US through the weekend.
The first shortwave, associated with a closed low currently over
Alberta, will track around the northern periphery of the Central US
subtropical ridge Thu Night/Fri and dig through the Great Lakes into
NE US Fri night into Sat. At the surface, this will have a broad
surface wave/cold front pushing through the region Friday night into
early Saturday morning with associated shower/embedded tstm activity
sliding offshore.
Cyclonic flow on Saturday, and lingering weak surface troughing
across northern and eastern areas will likely have considerable
cloud cover lingering, and could spark an isolated instability
shra/tsra Sat aft, or with a cold frontal passage late Sat/Sat eve.
Temps should run near seasonable upper 70s to lower 80s with
offshore flow.
Model in better agreement with the orientation/strength and
progressiveness of the trough axis and associated closed over New
England for the weekend, increasing confidence in a fairly strong
Canadian cold front approaching late Sat and likely crossing Sat
night. Gusty NW winds likely in the wake of the passage with an
early autumn-like airmass advecting into the region for Sun/Mon.
Temps will be running a few degrees below seasonable (mid to upper
70s) for late August with low humidity levels.
General consensus in the next in a series of shortwaves digging an
upper trough into the upper Mississippi River Valley and Great Lakes
Monday night into Tuesday, with a resultant frontal system sliding
towards the region Monday night and slowly through the region
Tue/Tue Night. This pattern and model consensus points to TC
Franklin staying well offshore. Monitor
https:/www.weather.gov/okx/tropical for the latest NHC forecasts on
this tropical system and others. Signals though, are looking better
for possible enhanced/predecessor rainfall development somewhere
along the front from northern Mid Atlantic to southern New England
during the Mon Night to Tue Night timeframe. A lot of inherent
uncertainty on this type of phenomenon, especially this far out, and
will be dependent on timing/track of Franklin and trough axis/front
particulars.
Higher confidence in energetic swells from Franklin likely building
to the coast late Monday into Tuesday and continuing into mid week,
bringing increasing potential for dangerous rip currents and high
surf.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
A warm front approaches from the west this afternoon into tonight.
An associated low pressure system gradually crosses the region
Friday into Friday Night.
Mainly MVFR/VFR but variable flight categories including pockets
of IFR possible across the region this afternoon. Stratiform
showers are expected across the area making any one condition
temporary.
Widespread shower activity and MVFR conditions develop from w
to e tonight, after 04-06z and continue thru Fri AM push.
Isolated tsra threat, mainly across western terminals, late
tonight into Fri AM (between 08z and 15z) as warm front nears.
By midday Friday, limited improvement in flight categories are
expected with guidance suggesting MVFR ceilings with a chance of
showers continuing throughout much of the day.
S/SE winds increasing to 10-15g20kt this afternoon for coastal
terminals, and continuing into tonight. Peak gusts to 25 kt for
NYC and eastern terminals especially into Friday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of onset of gusts may be off by 1 to 2 hrs. Peak gusts
to 25 kt possible.
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday: MVFR/IFR conds in showers and embedded TSRA. S gusts
20-25 kt afternoon.
Friday Night: Isolated Shra/Tsra threat, mainly east late.
Saturday: VFR, early AM isolated shower/tstm threat across
eastern terminals. Isolated shower threat across northern
terminals in PM.
Sunday and Monday: VFR.
Tuesday: MVFR or lower in SHRA/TSRA especially in the afternoon
and evening.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
SE winds slowly increase today with gusts on the western waters
approaching 20 kt late today. Winds approach small craft
criteria late tonight, especially for the western ocean waters
with ocean seas building to around 4 ft. Small craft conditions
are expected for the majority of the waters Friday, and perhaps
into a portion of Friday evening. Small craft advisories have
been issued for all waters, except for the western most
nearshore waters of the NY Harbor and Western LI Sound. But
small crafts may eventually be needed for these zones as well
with marginal small craft wind gusts currently being forecast.
Any small craft conditions should come to an end Friday night
from west to east with a cold front slowly sliding through.
Residual SCA southerly wind swell on the ocean should gradually
subside below SCA on Saturday, although marginal SCA conds may be
extended into Sat Night with gusty NW flow in wake of cold frontal
passage. Thereafter, sub SCA conditions favored for Sun into Mon
morning on all waters (although ocean seas may run 3-4 ft in long
period SE swell), with high pressure building in.
Energetic SE swells likely build in from tropical cyclone Franklin
late Monday into Tuesday, likely bringing a return of SCA conditions
on the ocean.
&&
.HYDROLOGY...
Showers will become more widespread tonight into Friday morning
with some embedded thunderstorms possible. Locally heavy
rainfall is possible with the main concern from minor urban and
poor drainage flooding late tonight into early Friday morning.
This risk may continue into Friday afternoon for eastern CT and
eastern LI. An isolated flash flood occurrence or two cannot be
ruled out.
No widespread hydrological concerns for Saturday through Monday.
Low predictability on heavy rain threat along a slow moving frontal
system Monday night into Tuesday night of next week.
&&
.TIDES/COASTAL FLOODING...
The risk of rip current development increases from low to moderate
for all beaches this afternoon, with strengthening SE/S winds and
building southerly wind waves this afternoon and this evening.
A high rip current risk is likely Friday into Saturday with 5 ft+
southerly wind waves.
Swells from tropical cyclone Franklin will likely build late Monday
into Tuesday, continuing into midweek, increasing likelihood for
high surf and dangerous rip currents.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 3 AM to 6 PM EDT Friday for ANZ331-
332-340-345-350.
Small Craft Advisory from midnight tonight to 6 PM EDT Friday
for ANZ353-355.
&&
$$
SYNOPSIS...JE/NV
NEAR TERM...JE/DS
SHORT TERM...JE/DS
LONG TERM...NV
AVIATION...IRD
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...