000
FXUS61 KOKX 061810
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
210 PM EDT Fri Oct 6 2023
.SYNOPSIS...
High pressure offshore continues to shift east today as a
frontal system slowly approaches from the west. This frontal
system will drag a cold front through the area Saturday into
Saturday night while Post-Tropical Cyclone Philippe tracks
north, about 250 to 300 nm east of Montauk Point on Saturday.
The post tropical low pressure tracks into northern New England
and southeastern Canada Saturday night. The low then tracks
through southern Canada early next week allowing weak
disturbances to move through the area during the week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Showers were widely scattered across the region at midday, and
will likely remain scattered until late afternoon or into this
evening as the upper trough moves closer to the region, with
increasing lift. Updated probabilities and converted to areal
wording.
High pressure is currently offshore, well to our north and
east, and will continue to head east today.
Strong shortwave energy digs into the Upper Mississippi Valley,
around a southern Ontario closed low and deep eastern Central US
trough, while a broad upper low off the SE US coast gradually lifts
north, influencing Post-Tropical Cyclone Philippe to accelerate
north towards Bermuda. At the surface, a frontal system
associated with the Ontario Low pushes into the eastern Great
Lakes.
Refer to the National Hurricane Center, https:/www.nhc.noaa.gov
for official forecasts on Philippe.
Scattered showers will be possible through the day with the
approach of lead and southern shortwave energy aiding lift of
the gradually increasing Atlantic and sub-tropical moisture
feed. The heaviest of the shower activity likely stays to the
north and west of the area through the day today with
orographics and in vicinity of weak warm front/pre-frontal
trough. Right now light returns can be seen over northeast NJ
and NYC and also approaching the south fork of Long Island. Have
adjusted PoPs to reflect this in the latest update.
Temperatures will be back to normal today, with highs in the low
70s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
As the upper level trough approaches, it will become negatively
tilted late tonight into early Saturday. Overall confidence
remains low due to the amount of interactions between features,
but the thinking remains the same that there will likely be a
focus for a 6 hour period of moderate to heavy rainfall late
tonight into Saturday. This will be forced by the negatively
tilted trough, and right rear quad of an upper level jet in a
moist airmass with pwats 1.5 - 1.75 inches. These values are
well above the 90% moving average for the OKX 12z 10/7 launch
per SPC`s Sounding Climatology Page.
NBM probabilities for 1 inch of rain over any 6 hr period tonight
continue to be about 5-10%, with the higher values over the Lower
Hudson Valley and southwester CT. The HREF also continues to show a
10% area over the western half of the area for 3 inches in 3 hours
in both the 3 hour periods ending 12z and 15z Saturday. These trends
need to continue to be monitored over the next 12+ hours. Bumped up
totals overall with this update and now have mainly 1.25 - 1.5 for
the Lower Hudson Valley, northeast NJ, NYC and portions of southern
CT.
The aforementioned Ontario low will drag a cold front through the
area late Saturday into Saturday night. Behind the front, showers
taper off and the coldest airmass of the season will filter in.
Gusty northwest winds will peak early Sunday morning with 15-20mph
sustained winds and 25-30mph gusts. Lows Saturday night will be in
the mid 40s to low 50s and highs on Sunday will only reach the upper
50s to low 60s.
Refer to the National Hurricane Center, https:/www.nhc.noaa.gov for
official forecasts on Philippe.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High amplitude trough in association with strong low pressure over
northern New England Sunday will track into southeastern Canada and
retrograde into southern Ontario, north of the Great Lakes by Monday
night. This upper trough will remain over the Northeast and
upper Mid-West through much of next week, with some
weakening/deamplification as the low becomes vertically stacked
and weakens over Ontario. During this time frame, weak
disturbances in association with the cyclonic flow aloft will
move through the region. Where and when is still somewhat
uncertain at this point, but best timing right now look to be
Monday night through Tuesday night. However, it will not be
raining the entire time, with at most about a 30% chance of
showers during this time frame.
As far as temperature is concerned, a cooler air mass will be
advected into the region for much of the week. Temperatures on
Sunday and Monday will only be in the upper 50s to lower 60s. Some
moderation is expected by Tuesday onward as temperature are forecast
to rise into the lower to upper 60s.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure centered well east of the area will gradually
retreat farther offshore today while a frontal system approaches
from the west.
Low confidence forecast as vsby and cigs vary from IFR (metro
terminals) to VFR (KGON) across the area. Therefore, metro
terminals are most likely to remain IFR to MVFR through the
day, with some brief improvement possible before IFR conditions
return tonight. Brief LIFR or MVFR conditions are possible at
these locations. Better conditions expected for eastern
terminals through the day, but these areas area also expected to
deteriorate overnight, just how much is the question.
Scattered showers are moving through the metro terminals, with
gradually increasing coverage through the day and night. A
period of heavy rain is expected Saturday morning into the early
afternoon. Isolated thunderstorms are also possible during this
time frame.
ESE-E winds around 10 kt today and into tonight. Wind shift to
SW then W expected Saturday toward 18Z. Sea breeze has moved
through KJFK, so expected a S wind to continue there. The sea
breeze will is expected to move through KISP, but there is a
medium chance it remains to the south.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of improving flight categories could be off by a couple
of hours this morning.
OUTLOOK FOR 18Z SATURDAY THROUGH TUESDAY...
Saturday: MVFR or lower in rain showers. Improving late with a cold
frontal passage and NW winds 10-15kt G20-25kt. An isolated
thunderstorm is possible during the afternoon.
Sunday: VFR. W winds 15-20kt G25-30kt.
Monday: Mainly VFR. Chance of showers late. SW G15-20kt
Tuesday...Manly VFR. Chance of showers. S-SW G15-20kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Ocean seas near the lower New York Harbor were running about a
foot higher than forecast, and were increased to around 4 feet.
Sub SCA winds are expected to continue through Saturday
morning, but ocean seas build to 5 ft tonight as swells increase
from Post-Tropical Cyclone Phillipe. By Saturday night, ocean
seas are expected to be 9-10 ft. SCA winds likely behind a
strong cold frontal passage late Saturday, continuing into
Sunday.
SCA conditions look to continue for Sunday and into the first
part of Sunday night on all waters, though winds and waves will
be diminishing starting late Sunday afternoon. Waves peak on
the ocean to 6 to 10 ft, while 4 to 6 ft are expected on the
central and eastern sound waters by Sunday afternoon. A strong
WSW to W flow is expected, with sustained winds of 20 to 30 kt
on all waters, and gusts 30 to 35 kt. Gales are possible on the
ocean for Sunday, so will continue to monitor for this
possibility.
By late Sunday night, only the ocean waters are expected to remain
in SCA as wave heights above 5 ft. From Monday through Tuesday, sub
SCA conditions are expected on all waters.
Refer to the National Hurricane Center, https:/www.nhc.noaa.gov for
official forecasts on Philippe.
&&
.HYDROLOGY...
A basin wide average of 1 1/4 to 1 1/2" is likely from NYC and
points N&W, tapering to 1/4 to 1/2" along the coast from today
thru Sat evening. 00z HREF is indicating a 10% probability of
3"/3hr early Saturday morning into Saturday afternoon in
vicinity of NYC/NJ metro, which does pose some concerns for
isolated flash flooding across NYC/NJ metro and the quick
reacting river basins across NE NJ, Lower Hud and SW CT due to
saturated soils and streamflows at 75th percentile or greater.
Some CAMs also indicating potential for some very localized
swaths of 1-2"/hr rainfall rates in this area, which supports a
localized flash flood threat from any training
downpours/embedded tstms. Higher probability appears to be for
minor urban and poor drainage and small river/stream flooding.
Given the low confidence in the forecast overall with multiple
features interacting, decided to hold off on a Flood Watch. If
high res guidance becomes more bullish on coverage/duration of
these enhanced rainfall rates aver the next 12 hrs, a watch may
be needed.
&&
.TIDES/COASTAL FLOODING...
Long period SE swells from Phillipe will build to 6 to 8 ft
tonight into Sat Night, presenting likelihood of additional
beach erosion/escarpment from an east to west sweep of 5 to 9 ft
breaking surf. Because water levels are not astronomically
high, the dune erosion threat during times of high tide is
isolated.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 8 PM EDT Sunday
for ANZ350-353-355.
&&
$$
SYNOPSIS...MET/JT
NEAR TERM...MET/JT
SHORT TERM...JT/NV
LONG TERM...JP
AVIATION...JP/MW
MARINE...MET/JT
HYDROLOGY...JT/NV
TIDES/COASTAL FLOODING...