000
FXUS61 KOKX 241111
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
711 AM EDT Thu Aug 24 2023
.SYNOPSIS...
Low pressure and its associated warm front approaches today and
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/...
With high pressure moving further offshore, and a warm front back
over Western PA gradually moving closer, look for a mainly cloudy
day as a mid deck gradually lowers. The chances for showers will be
minimal initially as the lower levels slowly moisten throughout this
morning. On a SE flow and mainly cloudy skies taking shape look for
temperatures to average below normal with max temps only getting
into the lower and middle 70s today. Towards the afternoon the
CAM NWP indicates an increasing chance of shower activity, mainly
from NYC and the Hudson River and points west. This shower
activity will likely increase for the late afternoon and evening
as the elevated warm front starts to slide in from the west.
Therefore shower activity will become more widespread into
Thursday evening / night. PW values later Thursday night will
get to 1 3/4 and 2 inches. Also with some elevated instability
some showers have the potential to become locally heavy with the
potential for some embedded convection, more so after 4-6z.
Look for efficient warm rain processes in any heavier pockets of
rain with warm cloud layer to around 13 to 14 kft towards early
Fri AM. Thus, most of the ingredients for localized heavy
rainfall are in place for the late night and into early Fri
morning. With warmer and more humid air on a SSE flow look for
temperatures to hold steady Thu night, 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 fcst soundings. If convection does
form right along the warm front into Friday morning there may be
some rotation associated with any thunderstorms. There remains
uncertainty among NWP with regard to the degree of instability
closer to the sfc and any lingering convection and the proximity of
the warm front that would provide added helicity to any associated
convection. The guidance will have to be closely monitored getting
closer to Fri AM with regard to any spin up potential with any t-
storms that may develop. 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 /12Z THURSDAY THROUGH MONDAY/...
-- 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.
Isolated showers develop across western terminals this morning. This
activity should become more widespread for western terminals
(including NYC/NJ metro) this afternoon with conditions likely
coming down to MVFR. For the eastern terminals, mainly VFR
conditions are expected today, with brief MVFR possible in late
afternoon/evening shower activity.
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.
S/SE winds at 5-8 kt this morning, increasing to 10-15g20kt by late
morning for coastal terminals, and continuing into tonight.
Peak gusts to 25 kt for NYC and eastern terminals.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
VFR for AM push, MVFR conds w/SHRA likely for PM push. Timing of
onset of gusts may be off by 1 to 2 hrs. Peak gusts to 25 kt
possible.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday: MVFR/IFR conds in widespread showers and embedded tsra
through Friday morning for western terminals, and into Friday
aft/eve for eastern terminals. Isolated shra/tsra threat for
western terminals for Fri PM push. S/SE gusts 20-25 kt into
Friday AM push, diminishing and veering S/SW late morning into
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.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With high pressure moving further east look for a SE wind to slowly
increase 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...
An increasing chance of showers takes shape Thursday through Friday
morning with WPC placing much of the CWA in a marginal risk of
excessive rainfall focused on later today into tonight, and also
into the day on Friday. Locally heavy downpours become a possibility
with the any flash flood risk being associated with minor urban and
poor drainage flooding Thursday evening through Friday AM, and
potentially into Friday afternoon for eastern and northeastern
sections. On a local scale, 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
SHORT TERM...JE
LONG TERM...NV
AVIATION...NV
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...