000
FXUS61 KOKX 252028
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
428 PM EDT Tue Jul 25 2023
.SYNOPSIS...
High pressure will remain offshore this week. An upper level
disturbance will move across this evening and tonight, followed
by another disturbance on Thursday, as a hot and humid airmass
builds into the region through Saturday. A cold front passes
through the region Saturday into Saturday night. Canadian high
pressure will build in Sunday and Monday, and move off shore
Tuesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A Severe Thunderstorm Watch remains in effect across the whole area
through 8 PM this evening.
A shortwave can be seen approaching from the west on water vapor
satellite imagery. Out ahead of it, MLCAPE values have been able to
rise to 1000-1500 J/kg per SPC Mesoscale Analysis Page. The OKX 18z
special sounding recorded 3138 J/kg of SBCAPE. A few discrete storms
were able to fire up ahead of a more broken line of storms moving
through western portions of our area, but now the broken line has
mainly taken over. It is currently stretching from Putnam down
through Queens. Given the CAPE and modest shear, some storms
have been severe, with damaging winds being the main threat.
This threat continues across the whole area through 8 PM this
evening, but lowers across the western half of the area after
about 6 PM.
Although the line storms have been moving fairly quickly, about 25-
30kt, some have been able to put down a quick 1-2 inches of rainfall
locally. Some training is possible and in turn isolated to scattered
flash flooding is possible.
Chances of showers and thunderstorms continue until about
midnight, with skies clearing thereafter. Lows will be in the
lower 60s to lower 70s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As the aforementioned shortwave trough exits the area to the east,
the flow aloft becomes zonal through Wednesday. High pressure at the
surface remains offshore and will continue to aid in a moist S/SW
flow. Dry conditions are expected with broad subsidence throughout
the profile. High temperatures will be in the mid 80s to low 90s,
with plenty of sunshine.
The zonal flow will be short-lived as the next shortwave approaches
Wednesday night. Clouds will increase and lows are expected to be
several degrees warmer, in the upper 60s to mid 70s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A hot and humid airmass builds into the region for Thursday and
remains into Saturday. A shortwave and surface low will be tracking
north of the region Thursday and have lowered probabilities during
the afternoon. With higher confidence of reaching heat advisory
criteria across much of the region, have issued a heat advisory for
all but southern New London county, and the south fork of Long
Island. There are a few locations that may briefly reach heat
indices near 105. Friday remains the warmest and most humid day, and
heat indices across much of the region are expected to reach at
least 105, and with the possibility of reaching excessive heat
warning criteria held off on extending the advisory into Friday. The
Weather Prediction Center continues to show a 10-40% chance of heat
index values exceeding 110 on Friday.
A cold front will be approaching Saturday and while dew points will
remain in the 70s temperatures are a little more uncertain with
cloud cover and the chance of precipitation. However, several
locations may once again reach heat advisory criteria.
Once the cold front passes through the region Saturday night and
cooler and drier Canadian airmass moves into the area.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
Offshore high pressure remains during the TAF period.
An upper level disturbance will move through the area and produce
showers and thunderstorms into this evening. Some weakening of the
tstms is possible as they track east of the NYC arpts.
VFR conditions are expected to prevail for much of the TAF period.
MVFR or lower is expected in any thunderstorms. MVFR to IFR
fog/stratus is possible overnight, but mainly for outlying terminals.
Outside of thunderstorms, winds will be mainly S to SW around 10 kt
for the city terminals today. There may be an occasional gust to 15
to 20 kt into this eve. Speeds of 5 to 10 kt expected outside the
city terminals. Winds diminish overnight, becoming light and
variable for most terminals, including the city, then become SSW to
around 10 kt aft 16Z Wed.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Any tstms behind the main line thru this eve are expected to be
weaker. Some updated to the end timing possible. Periods of MVFR
possible thru 23-00Z despite whether tstms develop.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday: VFR.
Thursday: Possible showers and thunderstorms at times afternoon into
evening with brief MVFR to IFR possible. Higher chances of showers
and thunderstorms near KSWF. If tstms develop, they could become
severe. Otherwise, VFR. SW wind gusts along coast 15-20 kt.
Friday: Possible showers and thunderstorms at times afternoon into
evening with brief MVFR to IFR possible. Otherwise, VFR. SW wind
gusts along coast 15-20 kt.
Saturday: Chance of showers and thunderstorms afternoon into evening
with brief MVFR to IFR possible. Otherwise, VFR.
Sunday: VFR.
Detailed information. including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
There is a Severe Thunderstorm Watch across all waters through 8 PM
this evening.
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 criteria is expected tonight through Wednesday night.
However, damaging winds and large hail are possible in any
thunderstorms this afternoon and evening.
A persistent southwest flow increases Thursday with gusts reaching
SCA levels on the ocean waters, and possibly into the the Long
Island south shore bays. There is also a chance that gusts reach
near 25 kt across eastern Long Island Sound and the Long Island
eastern bays. Ocean seas will also build to SCA levels during
Thursday. Conditions slowly improve Thursday night into early Friday
as a surface trough weakens across the ocean waters. Ocean seas may
build back to 5 feet Friday night into Saturday ahead of a cold
front, and then fall below Saturday night with the passage of the
front, as winds become northwest.
&&
.HYDROLOGY...
Isolated to scattered flash flooding is possible this afternoon
as some training may take place. A broken line of storms
currently moving through the western half of the area has been
able to put a quick 1 to 2 inches of rainfall locally.
Locally heavy rain is possible Thursday which may produce minor
nuisance and poor drainage flooding.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
A moderate risk of rip current development remains for the Nassau
and Suffolk ocean beaches through this evening.
There is a low risk for the development of rip currents at the
ocean beaches Wednesday and a high risk, especially in the
afternoon, Thursday.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from 11 AM to 9 PM EDT Thursday for CTZ005>011.
NY...Heat Advisory from 11 AM to 9 PM EDT Thursday for NYZ067>075-
078>080-176>179.
NJ...Heat Advisory from 11 AM to 9 PM EDT Thursday for NJZ002-004-
006-103>108.
MARINE...None.
&&
$$
SYNOPSIS...MET/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...MET
AVIATION...JMC
MARINE...MET/JT
HYDROLOGY...MET/JT
TIDES/COASTAL FLOODING...