000
FXUS61 KOKX 072127
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
527 PM EDT Thu Sep 7 2023
.SYNOPSIS...
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 /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
The fcst is on track. A Severe Thunderstorm Watch has been
issued for Union, Essex, Passaic and Orange counties primarily
for the risk of damaging winds through this evening. Severe
storms have begun to develop west of the area a little earlier
than originally anticipated and could impact areas west and
northwest of the city by 4-5pm and could persist into the
evening with the threat subsiding overnight. Some of these
storms west of our area have been producing wind gusts in excess
of 60 mph and radar indicates strong updrafts capable of
supporting large hail. Coverage of thunderstorms will be
isolated for this evening with scattered coverage possible for
extreme western portions of the CWA like Orange county.
SPC`s Mesoanalysis RAP forecast is giving areas west and north of
the city 2,500-3,500 SBCAPE with eff. bulk shear around 20 kts this
evening. 0-6km bulk shear from the HRRR is showing similar values,
however, some CAMS such as the NSSL or NAMNEST are giving values of
30-40 kts for 0-6km bulk shear. Overall, the isolated threat
for severe storms today looks to primarily be a damaging wind
risk west and northwest of the city. However, based on some of
the strong updrafts of ongoing storms west of our area, can`t
rule out the risk for large hail. Sufficient moisture that has
fueled heat index values today will also play a part in
providing storms with enough moisture to lead to some areas of
locally heavy rainfall with minor nuisance flooding possible.
Again, this threat will mainly be west and northwest of the city
this evening. Rain chances drop off significantly for eastern
areas of the CWA, expecting to remain dry today and tonight.
Depending on how the rain plays out, some climate sites have the
potential to break their record maximum lows for September 7th
considering the anomalous warmth seen with morning lows this
morning. Refer to the climate section below for a listing of
prior records.
Confidence in patchy fog occurring along coastal areas,
particularly on Long Island is low for overnight and in the morning,
but is possible and has been reflected in the forecast.-- End Changed Discussion --
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
High pressure builds to the east as an upper-level ridge shifts
eastward while a second high sets up over the Great Lakes. We`ll be
in between these two high pressure systems under a surface
trough.
Stronger southerly flow on Friday leads to increasing dewpoints in
the mid-70s. Despite lower temperatures, the increased moisture
should lead to some areas touching the mid/upper-90s heat index
criteria again. Heat advisories will be continuing for NE NJ, NYC,
Rockland county, and Westchester county until 6PM. It is possible
that areas west could see temperatures decreasing sooner than
in recent days as cloud cover increases from possible showers
and thunderstorms.
The hot and humid day will be followed by a round of scattered
showers and thunderstorms developing west to east in the afternoon
and evening, with coverage decreasing as you go east. THe increased
southerly flow and moisture will help aid coverage showers and
thunderstorms. SPC has NYC and areas west and north of the city
under a Slight risk for severe weather. Most CAMS indicated areas of
2,500-3,500 SBCAPE with sufficient bulk shear to lead to concerns
for damaging winds in a few of the thunderstorms. Model
sounding profiles show a decent amount of CAPE in the hail
growth zone. Small hail or marginally severe large hail could be
possible in isolated storms. WPC has a marginal risk for areas
west and northwest of the city with locally heavy rainfall
possible.
Unlike Thursday night, showers and thunderstorms could remain
isolated to scattered for western areas into the night.-- End Changed Discussion --
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
The main story during the long term period will be the unsettled
weather into Monday, then again during mid next 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
Mon as an upper level shortwave approaches from the W. The front
should finally move east of the region sometime late Mon evening or
overnight.
While much of the time frame through daytime Mon carries at least
chance PoP, still thinking that it won`t be a complete washout and
not raining for the entire time frame, as the timing of any
individual piece of energy and associated lift remains uncertain.
Continued with diurnal timing for likely probabilities. Portions of
Long Island and southern Connecticut may not see any convection
until late Sunday or even early Mon.
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 Tue,
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 Tue night into Wed, perhaps lingering into Thu.
High temps on Sat in the lower 80s (still 5-10 deg above avg) will
gradually trend cooler to a more seasonable mid/upper 70s Wed/Thu.
Lows however will remain on the mild side mostly due to nighttime
cloud cover.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
High pressure remains offshore, meanwhile an upper level trough
and cold front slowly approach from the west.
VFR conditions until late tonight, after 08Z, when MVFR fog and
stratus is likely. There is a chance of brief IFR around
sunrise at the coastal terminals. Improving to VFR by mid
morning, late morning at KGON, with timing uncertainty +/- 1
hour.
Showers and thunderstorms more likely at KSWF, with the
potential for severe weather with strong gusty winds. Low
chances at the NYC metro terminals this evening, and not
included at this time.
S to SW winds, with sea breezes, will become light and variable
this evening. Winds become southerly again Friday morning.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Too low chances of showers/thunderstorms early this evening to
include in the forecast, if any occur timing would be around
00Z to 03Z. Chances for MVFR ceilings and visibilities in
stratus and fog have increased for late tonight into Friday
morning, and the is a chance that KJFK could lower to IFR
briefly 10Z to 12Z. Timing of improvement to VFR Friday morning
uncertain by +/- 1 hour.
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday afternoon through Friday night: Chance of showers and
thunderstorms, more likely from NYC and points N&W in the
evening. MVFR to IFR at night along the coast in stratus and
fog.
Saturday through Sunday: Aft/Eve showers and thunderstorms
likely, particularly NYC and points N&W on Sat, more widespread
Sunday Increasing potential for nocturnal/early morning
MVFR/IFR coastal stratus.
Monday: Possible early morning MVFR/IFR coastal stratus. Showers
and thunderstorms, more likely across the northern and western
areas.
Tuesday: Slight chance of showers with MVFR possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.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 Sat, flooding chances increase, but again would be of the minor
type. Flash flooding would again be more likely to occur across the
interior NW of NYC as rain chances increase and slower-
moving/training cells become more likely. This threat should then
spread east to cover more of the area from Sunday into Monday.
&&
.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...
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.
&&
$$