000
FXUS61 KOKX 081140
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
740 AM EDT Sat Jul 8 2023
.SYNOPSIS...
A weak cold front stalls nearby this morning before retreating
to the west later today. A stronger cold front approaches
Sunday with a wave of low pressure developing over the Mid
Atlantic states late Sunday into Sunday night. The low pressure
system and cold front head east of the area on Monday. High
pressure will then build behind the system for Tuesday through
Thursday. Another frontal system may approach the area by the
end of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Forecast on track with only minor adjustments to account for the
latest observations of temperature and dew points.
There remains pockets of low stratus in the area along with
patchy fog mainly for some coastal locations. This should burn
off after sunrise and skies should become clearer into the mid-
late morning.
A weak cold front stalled over the western portion of the area
this morning will become a potential focus of convection for
later this morning and into the afternoon as daytime heating
will allow for the development of some instability. The area
remains between weak ridging in the Atlantic and a large upper
trough over the Great Lakes and Plains. As such, there remains a
lack of forcing and shear for convection to organize. Surface
convergence along the stalled boundary and any sea breeze
convergence may be enough to develop some pulse convection
this afternoon and early evening. A weak steering flow and
moist airmass supports locally heavy downpours with potential of
minor flooding. Localized flash flooding is also possible
across NE NJ and the Lower Hudson Valley. It will once again be
warm and humid with temperatures in the middle to upper 80s.
Any convection diminishes this evening with loss of heating.
Mostly cloudy conditions are then expected overnight. There may
be a bit more widespread low cloud development ahead of the
approaching shortwave. Patchy fog is also possible out east.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
A shortwave rounds the base of the large upper trough early
Sunday morning. The lingering stalled out boundary will remain
in the vicinity along with another frontal boundary approaching
the front west. Models are continuing to indicate a frontal wave
developing over the Middle Atlantic Sunday afternoon and Sunday
evening, which will interact with a highly saturated airmass
with PWATs around 2 inches. There are still timing and placement
differences with regards to the axis of heaviest rainfall.
Overall, widespread moderate rainfall with embedded heavy
thunderstorms are expected to develop along the approaching
front during the day on Sunday as it moves into the western
portion of the CWA. Most CAMs are fairly consistent on the
progression of the heaviest precip to remain in the western
portion of the CWA (mainly the Lower Hudson Valley and N NJ)
prior to 8PM on Sunday. This will be the primary concern for any
flooding during the day on Sunday. Moderate to heavy rain will
then continue to move eastward into Sunday evening and overnight
as the intensity is expected to generally lighten as
instability decreases.
The overall synoptic set up is concerning due to the slow
moving front, frontal wave enhancing lift, and high PWAT air.
There continues to be indication convection will develop a train
over areas, increasing the flood potential. The amount of
instability is uncertain and may be maximized further south
across the Middle Atlantic. However, weaker instability may
still be enough to combine with the high PWATs and slow
moving/stalled frontal boundary to bring heavy rainfall.
WPC has continued with a slight risk for excessive rainfall
across the western half of the area and a marginal risk across
the eastern half. The latest collaborated QPF Sunday through
early Monday morning yields 2-2.5 inches of rain across the
interior of the Lower Hudson Valley and NE NJ with 1-2 closer to
the Hudson River corridor and amounts an inch or less further
east. Locally heavy rainfall is possible, especially where the
axis of heaviest rain ultimately sets up. We should begin to
have more confidence in this area as the HREF and CAMs come
into the timeframe of this system. No flood watches have been
issued yet, but may be needed across portions of the area once
confidence increases.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The global guidance continues to be in fairly good agreement
with the synoptic pattern during this period. Global ensemble
means continue to advertise a trough over the eastern CONUS with
a weakening closed upper low over central Ontario slowly
retreating to the northeast through next week.
The low pressure and attendant frontal system then looks to
slowly move out of the area on Monday as the mid level trough
axis follows by 00Z Tuesday. Shortwave ridging aloft and surface
high pressure then looks to build back in by Tuesday and into
Wednesday, with a slight warming trend toward the end of the
week.
A shortwave then approaches the area from the southeast
Thursday into Friday, with the surface low remaining south of
the area. A secondary shortwave associated with the Canadian
upper low then approaches from the Great Lakes by Friday,
bringing another chance of showers and thunderstorms.
Daily high temperates will remain near or slightly above normal
+for the period in the mid to upper 80s. Wednesday looks to be
the warmest day of the week with highs near or just above 90 for
much of the area.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
A weak stationary front in close proximity to the NYC and Lower
Hudson Valley terminals this morning will shift slowly west
today. A frontal wave over the Ohio Valley approaches on Sunday.
Plan to stay close to a persistence type of forecast as there
has been no change in the airmass or the flow regime across the
terminal forecast area. Thus, expect a mainly VFR forecast with
brief MVFR/IFR conditions during early the morning hours with
the exception of KGON and KHPN which could take a bit longer to
improve. Warm season fog/low clouds are often a challenge and
primarily hinge on warm, humid air moving across the cooler
nearshore waters. In addition, there is less radiational cooling
in this type of airmass. Bottom line, don`t see much change
than what we have been dealing with the last several days.
Scattered thunderstorms are possible this afternoon, mainly
inland, but only enough confidence to include TEMPO for KSWF.
Latest CAMs are hinting at convection possibly initiating near
the NYC terminals this afternoon before shifting north and
west. Based on recent days and weak forcing not quite biting
on this yet but will continue to monitor.
Light E-SE winds this morning, become SE-S this afternoon as
5-10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Chance of MVFR this morning. Chance of thunderstorms may need
to be added this afternoon, but confidence is too low at this
time to mention.
OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
Sunday: Mainly VFR. MVFR or lower possible at times. Showers
likely and a chance of thunderstorms, mainly in the afternoon
into the night.
Monday: MVFR or lower possible at times. Chance of showers. A
chance of thunderstorms afternoon into early evening.
Tuesday and Wednesday: Mainly VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
There is potential for some fog, especially for the eastern
nearshore and ocean waters the next few nights and early mornings.
Otherwise, conditions remain below SCA criteria through early next
week with a weak pressure gradient over the area.
&&
.HYDROLOGY...
No widespread hydrologic issues are expected through tonight.
Locally heavy rainfall is possible in any showers/thunderstorms
this afternoon and evening. The main concern is confined to the
interior Lower Hudson Valley and interior NE NJ.
A more significant flood threat is possible Sunday into Sunday
night with the potential for the south to north training of
showers and thunderstorms along a slow moving frontal system.
This could lead to at least isolated to scattered flash
flooding. The main threat for flash flooding appears to be from
NYC and points north and west, but adjustments in this area are
possible. WPC currently has the western half of the area in a
slight risk for excessive rainfall and marginal elsewhere.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a low risk of rip current development for all ocean
beaches.
Water levels are forecast to remain below minor flooding
benchmarks into early next week.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DBR/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...DBR
AVIATION...DW
MARINE...DBR/MW
HYDROLOGY...DBR/MW
TIDES/COASTAL FLOODING...//