000
FXUS61 KOKX 071146
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
746 AM EDT Thu Sep 7 2023
.SYNOPSIS...
Weak high pressure will be over the region today. A slow moving
frontal system will impact the area tonight through the weekend.
The associated cold front eventually moves east of the region
late Monday, followed by another frontal system for the middle
of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Minor changes made with this update - mainly for hourly
temperatures and dewpoints over the next few hours. Some record
high minimum temperatures could occur for today provided
temperatures later this evening do not cool more quickly than
anticipated. Biggest reason for a quicker cooldown would be
rain. See the climate section below for the records.
The region will be on the western side of a mid level ridge today.
After a mostly sunny start, more in the way of clouds this afternoon
mainly W and NW of NYC as convective debris clouds may drift into
the area by day`s end. CAPES will be sufficient to support
convective development over the region - again mainly W and NW of
the city, however low to mid-level capping probably limits this to
scattered activity. Not much mechanical lift to tap into CAPE until
this evening when a shortwave aloft is progged to pass by not too
far to our NW. CAPES will be lower by this time, but still plenty
enough to continue the threat of showers and thunderstorms well into
the night.
Regarding the severe weather potential, shear isn`t particularly
ideal, but a little stronger this evening with the shortwave nearby.
It`s enough however to support strong to severe wind gusts. Large
hail cannot be completely ruled out with sufficient cape in the -10
to -30C region through this evening, however directional shear
appears to be lacking and wet-bulb zero heights will be on the high
side. SPC continues to highlight areas W and NW of the city with a
slight risk for severe weather today with a marginal risk for the
rest of the area except eastern LI and SE CT.
It will be another hot and humid day. Although temps at the top of
the mixed layer rise slightly from yesterday, an earlier onshore
flow probably keeps temps from reaching as high as they did
yesterday for most coastal areas. Farther inland, it may even be
hotter than yesterday in some areas, especially if convection can
hold off until late in the day and/or convection to the west doesn`t
send a significant amount of debris clouds our way. Surface
dewpoints will have a tough time mixing out this afternoon - whether
it be because of seabreezes at the coast or SW flow with high
dewpoints (14-17C) at 850mb inland. Heat advisories pertaining to
today remain unchanged from the previous forecast with the exception
of adding Western Passaic County based on yesterday`s observations
and today`s forecast. The heat advisory has been extended to include
Friday for some areas. See the short term section for more details.
While max heat indices probably end up even higher than yesterday in
most areas, they are expected to remain within the advisory
threshold.
Warm and muggy conditions continue tonight with a chance of record
high minimum temperatures being set.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Surface high pressure builds to our east while under a ridge aloft.
To our NW, confluence aloft will promote high pressure building over
the Great Lakes. We`ll be in between with surface troughing over us.
Moisture convergence along and near this trough will promote
primarily diurnal showers with a chance of thunderstorms. Once
again, thunderstorms can be strong to severe with the main threat
being gusty winds as 0-6km bulk shear will be 25-30 kt. SPC has most
of the city and areas N and W of the city with a slight risk for
severe weather, and a marginal risk for the rest of the area.
More clouds and cooler temperatures aloft will promote high
temperatures cooler than the past few days, however dewpoints will
be in the mid 70s. This should manage to produce heat indices of at
least 95 degrees for NE NJ, NYC, as well as Rockland and Westchester
Counties. As such, heat advisories have been extended in time to
cover through Friday afternoon.
The pattern doesn`t change much on Saturday with a trough and
enhanced moisture convergence over the region. Showers will be more
likely in the afternoon and night along with the threat of a
thunderstorm. Overall higher chances will be from around the city to
points N and W where moisture convergence will be greater in the
vicinity of the surface trough. The flash flooding threat through
Saturday remains low. See the hydrology section for more details.
Mostly cloudy conditions should hold high temperatures in the 80s
across the area, but dewpoints will still be in the low to mid 70s.
If this holds, then heat advisories wouldn`t need to be extended
into Saturday.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The main story during the long term period will be the unsettled
weather Sunday into Monday, then again during the middle of the
week.
The long term period starts off with a nearly stalled cold front
over the far western portion of the CWA. This front won`t move much
during the day, with a wave of low pressure traveling along its
boundary. The front finally starts to move eastward during the day
Monday as an upper level shortwave approaches from the west. The
front should finally move east of the region sometime late Monday
evening or overnight.
Still thinking that Sunday and Monday wont be a complete washout and
it will not be raining the whole period. The timing of any
individual piece of energy and associated lift is uncertain, but
have gone with the more usual diurnal timing for higher
probabilities. Portions of Long Island and southern Connecticut may
not see any convection until late Sunday or even early Monday.
Localized heavy rainfall is possible in any of the
shower/thunderstorm activity with any flash flood potential
remaining localized.
Some drier air will finally move back into the region on Tuesday,
however there is a second frontal system on its heels with an
amplifying upper trough digging south and east across the Great
Lakes. Chances for convection will be on the increase ahead of this
system late Tuesday into Wednesday, perhaps lingering into Thursday.
Highs on Sunday through Tuesday will be in the Upper 70s and lower
80s, with cooler conditions on Wednesday and Thursday as highs only
reach the 70s.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure remains offshore, meanwhile an upper level trough
and cold front slowly approach from the west.
Generally looking at VFR conditions for much of the TAF period.
Only place sub-VFR right now is out at KGON which has some
MVFR fog. Expect VFR conditions in the next hour.
Later this afternoon, there will be a chance of thunderstorms.
At KSWF, only looking at a 30-40% during the mid afternoon into
evening. Further east, for NYC/NJ/KHPN metro terminals we are
looking at less than a 20%, and not expected for eastern
terminals.
There a chance of fog/stratus once again tonight, however
confidence is low.
Light and variable winds become S/SW 5-7kt this morning, then
S/SE sea breeze 8-12kt for all coastal terminals in the
afternoon and evening. Winds become light once again tonight
night.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Winds could be slightly higher than forecast this afternoon and
evening at JFK/LGA with coastal jet development. Very low prob
(less than 20%) of an aft/eve tstm.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday: Chance of aft/eve showers and thunderstorms,
particularly NYC and points N&W. MVFR/IFR coastal stratus
possible Friday Night.
Saturday through Sunday: Aft/Eve showers and thunderstorms
likely, particularly NYC and points N&W on Sat and Sun.
Increasing potential for nocturnal/early morning MVFR/IFR
coastal stratus.
Monday: Possible early morning MVFR/IFR coastal stratus. Chance
of showers and thunderstorms.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
A weak pressure gradient will lead to sub SCA conditions for the
rest of the week. Winds and seas will remain below SCA levels
for the weekend despite the approach of a slow moving cold
front.
Ocean seas are forecast to build to 5 ft early next week and may
continue for much of the week. For the non-ocean waters, sub SCA
conditions will continue.
&&
.HYDROLOGY...
Locally heavy rain is possible today with isolated/scattered
thunderstorms. Should any flooding occur, it would likely be
limited to minor/nuisance/poor drainage flooding. Can`t
completely rule out flash flooding west of the Hudson River, but
this would likely be isolated.
For Friday and more so Saturday, flooding chances increase, but
again would be of the minor type. Flash flooding would again be more
likely to occur along and west of the Hudson River corridor as rain
chances increase and slower-moving cells/training cells become more
likely. This threat then spreads east to cover more the Tri-State
Area on Sunday.
&&
.TIDES/COASTAL FLOODING...
A moderate risk of rip currents exists today with lingering ESE
swells and a stronger S flow developing in the afternoon. The strong
south flow continues on Friday which likely builds seas to 3 ft.
Swells may still linger, so have gone with a moderate risk of rip
currents on Friday.
&&
.CLIMATE...
Some daily record highs and record high minimums could be tied or
broken early this morning, today and tonight. The records are below.
Daily Record High Temperatures...
Sep 7
Central Park..101(1881)
LaGuardia.....90 (2015)
JFK...........93 (1983)
Islip.........92 (1998)
Newark........95 (2015)
Bridgeport....91 (1983)
Daily Record High Minimum Temperatures...
Sep 7 Sep 8
Central Park..79 (1881)..76(2015)
LaGuardia.....74 (2012)..76(2015)
JFK...........76 (1985)..73(1983)
Islip.........74 (2012)..76(2015)
Newark........74 (1999)..73(1999)
Bridgeport....72 (2016)..74(2015)
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT this evening for CTZ005>010.
NY...Heat Advisory until 8 PM EDT this evening for NYZ067-068-078-
080-177-179.
Heat Advisory until 6 PM EDT Friday for NYZ069>075-176-178.
NJ...Heat Advisory until 6 PM EDT Friday for NJZ002-004-006-103>108.
MARINE...None.
&&
$$
SYNOPSIS...BC/JC
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...BC
AVIATION...BC
MARINE...JC
HYDROLOGY...BC/JC
TIDES/COASTAL FLOODING...
CLIMATE...