000
FXUS61 KOKX 291130
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
730 AM EDT Sat Jul 29 2023
.SYNOPSIS...
A cold front will move across the region this afternoon and
evening. High pressure will then slowly build in from the
northwest through the middle of next week. A frontal system
could impact the area late in the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Convectively induced vort continues to work its way east early
this morning. Convection developed as the remnant vort moved in
from the southwest and organized along a weak surface trough
situated across southern CT and the Lower Hudson Valley. The
convection has weakened over the last half hour, but there still
may be some heavier embedded showers and thunderstorm over the
next few hours. The higher chance for this appears to be closer
to the surface trough across the Lower Hudson Valley and
southern CT. The remnant vort will weaken/move NE of the area
later this morning. Have kept a chance PoP in as the environment
will continue to become unstable and the surface trough may
linger nearby.
Attention then turns to the potential of more organized showers
and thunderstorms in the afternoon and early evening. These
will be associated with a cold front that will move across the
area as well as another shortwave/convectively induced vort that
translates out of the Great Lakes region. As has been the case
this summer, the CAMs are still offer differing solutions on
the timing and evolution of the convection. Despite the
potential for some isolated morning convection, the atmosphere
should destabilize rapidly into the afternoon in response to
falling heights aloft and fairly strong heating. Any morning
cloud cover should thin and give way to a period of heating to
yield CAPE values around 2000-2500 J/kg. Bulk shear values look
to be from about 35 to 40 kt. These ingredients support
potential of severe thunderstorms with the main threat damaging
wind gusts. A brief, isolated tornado cannot be ruled out,
especially if there is any low level shear enhancement from
outflow boundary convergence. The greatest severe threat is from
about 3pm to 9pm northwest to southeast. SPC has continued to
place the region in a slight risk.
Locally heavy rainfall is possible with any shower and
thunderstorms. HREF neighborhood probabilities of 3 inches or
more largely reside north and east of the area where there may
be a higher chance of training convection along weak warm
front/surface trough ahead of the main cold front. Think the
middle level flow is strong enough to prevent a more widespread
flash flood risk at this time across the CWA and have held off
on any flood watch. However, localized flash flooding cannot be
ruled out where the stronger convection ends up occurring.
No changes were made to the Heat Advisory. Still expecting high
temperatures to reach the upper 80s to lower 90s. Some parts of
urban NE NJ could hit the middle 90s. Max heat indices should
range from 95 to 99 for much of the area with the exception of
the NYC metro and NE NJ where around 100 is expected. Earlier
development of convection in the afternoon could prevent these
values from being reached. The end time of the Advisory
continues to be 8 pm, but it may be able to be taken down sooner
with the late afternoon/early evening convection.
The cold front will continue pushing south and east of the area
before midnight tonight. There could be some lingering convection
across eastern Long Island and southeast CT around 00z, but most
of the activity should be moving offshore and ending shortly
after sunset. Drier air will begin working in from the north and
west overnight. Skies may remain partly to mostly cloudy, but
temperatures likely will fall into the lower 60s inland to the
middle and upper 60s most elsewhere. The NYC metro should fall
to around 70 degrees.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
Heights aloft will continue falling on Sunday as a longwave
upper trough becomes established over the northeastern US.
Surface high pressure will begin building in from southern
Canada. Models continue to indicate a shortwave rounding the
base of the trough in the afternoon as it moves through the
area. Have elected to keep conditions dry as there is not
overwhelming evidence of organized lift and moisture for any
showers in the afternoon. Highs will be much cooler than recent
days and actually could end up a few degrees below normal in the
lower to middle 80s. Dew points will range from the upper 50s
to low 60s allowing humidity levels to be much lower.
Another shortwave rounds the base of the upper trough Sunday
night. This one may have a bit more consolidated energy which
may be just enough for an isolated shower. The latest model
consensus also has a very low PoP after 06z. Have included a
slight chance for a shower, but most of the area will be dry
late Sunday night into early Monday morning. Sunday night looks
to be one of the cooler nights in recent weeks with lows falling
into the upper 50s and low 60s inland and middle 60s elsewhere.
The upper trough axis remains overhead on Monday and high
pressure will continue building into the region. High
temperatures should end up a bit cooler than Sunday with
readings ranging from the upper 70s to lower 80s. Other than an
isolated early morning shower, no precipitation is currently
anticipated.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Next week continues to look like the most comfortable airmass
we have seen in several weeks. High pressure will slide down
from Canada Monday night through Wednesday as an upper level
trough sits over the eastern CONUS. Embedded shortwaves will
assist in reinforcing shots of cooler, drier air. High
temperatures will be in the upper 70s to lower 80s each day,
which is about 5 degrees cooler than normal for early August.
Stuck close to the NBM with temperatures. Blended in some of
the MEX guidance for Tuesday night as radiational cooling
conditions look decent. This may be more for the interior as
winds may stay up too much down in the Pine Barrens of Long
Island. There is potential for temps to drop into the upper 40s
in far northwestern Orange.
The trough axis shifts east of the area on Wednesday and heights
rise briefly ahead of an approaching frontal system. Strong low
pressure will track well to our north, but could drag a cold
front through the area late in the week. There are some hints of
a decent rainfall. The NBM currently has about a 20-25% chance
across the lower Hudson Valley and southern CT for 1 inch of
rain in the 24 hr period ending 00z Saturday. Of course, this
far out there are timing and strength differences among the
guidance.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
A cold front will approach from the northwest and pass through
the area this evening.
Mainly a VFR forecast outside of any showers a thunderstorms
associated with the cold front this afternoon/evening. A few
of these storms may be accompanied by heavy rain and strong
gusty winds. Have fine tuned timing to be between 20z and 00z
for most of the area, with KSWF on the earlier side and KGON on
the later side. Prior to this, there could be some spotty
activity this morning, but confidence of this happening remains
low.
S-SW winds increase to around 10-15 kt this afternoon. A few
gusts of 20-25kt possible. There is some uncertainty as to how
much the flow backs at the coastal terminals due to the
seabreeze influence. Expect more of a hybrid seabreeze with more
of a westerly component. Behind the cold front Saturday
evening, winds will become NW-N around 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low chance for MVFR cigs early this AM as well as spotty showers.
Winds Saturday afternoon likely vary +/- 20 degrees at coastal
terminals due to some seabreeze influence.
Chance of strong to severe thunderstorms Sat afternoon/early
evening.
OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
Sunday: VFR.
Sunday Night-Monday Morning: Mainly VFR. Slight chance of showers.
Monday Afternoon-Wednesday: VFR.
Detailed information. including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
A Marine Weather Statement continues for Long Island Sound. The
US Coast Guard still indicates a large debris field caused by
recent flooding across New England.
Sub-SCA conditions are expected on all waters through tonight.
Winds are likely to increase this afternoon ahead of a cold
front, but should remain around 20 kt. Ocean seas are also
likely to build through the afternoon and may come close to 5 ft
east of Moriches Inlet. However, it looks marginal and brief
and have held off on the issuance of an SCA. Winds weaken
tonight and become northerly behind the front and seas will
slowly subside. Sub-SCA conditions are expected Sunday.
Winds and waves will remain below SCA criteria Monday through
at least Wednesday night as high pressure remains in control. A
frontal system late in the week could bring SCA conditions with
a strengthening southerly flow and building seas.
&&
.HYDROLOGY...
Showers and thunderstorms this afternoon and evening will bring
locally heavy rainfall which could lead to localized flash
flooding.
No hydrologic concerns are expected Sunday through next week.
&&
.TIDES/COASTAL FLOODING...
With an increasing SW flow and building waves, there is a high rip
current risk for Suffolk beaches today, with a moderate risk west
towards Nassau and NYC beaches. With a weakening flow on Sunday,
there is a moderate rip current risk at all beaches.
With a full moon on August 1st, some minor coastal flooding is
possible. The main concern is for the South Shore Back Bays of
southern Nassau and southern Queens and the western Long Island
Sound during the Sunday night, Monday night and Tuesday night
high tide cycles. Coastal flood statements and/or advisories may
needed.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT this evening for CTZ005>012.
NY...Heat Advisory until 8 PM EDT this evening for NYZ067>075-
078>081-176>179.
High Rip Current Risk through this evening for NYZ080-081.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ002-004-006-
103>108.
MARINE...None.
&&
$$
SYNOPSIS...DS/JT
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...JT
AVIATION...JT
MARINE...DS/JT
HYDROLOGY...DS/JT
TIDES/COASTAL FLOODING...