000
FXUS61 KOKX 151141
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
741 AM EDT Sat Jul 15 2023
.SYNOPSIS...
A frontal system approaches from the west today and impacts the area
on Sunday, followed by weak high pressure on Monday. Unsettled
weather is likely to continue through the rest of the week with
potential for a series of frontal boundaries.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast on track with just a few showers across the far eastern
sections of the CWA. Shortwave ridging should keep conditions
a little more dry than the previous day. However, we are
expecting some shower activity this afternoon. Some of the CAMs
are showing convection developing along the late morning/early
afternoon seabreeze. Overall, coverage should be isolated to
scattered. Once again, with a very warm and humid airmass in
place, any rainfall will be capable of some heavy downpours, but
convection will be short-lived.
Highs today will be in the mid to upper 80s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Flood Watch is in effect for all of Sunday.
The main concern tonight and Sunday will be another heavy rain
event. A closed upper low near the border of the Northern Plains and
southern Canada will slowly push east during the short term period.
A shortwave will round the base of the trough and approach on
Sunday. At the surface, a nearly stationary frontal boundary will
remain over portions of the CWA. With the proximity of the front
nearby, the upper level shortwave and PWATs exceeding 2+ inches,
heavy rain will be the main concern with storms that develop. As a
result, WPC has much of the forecast area in a moderate risk of
Excessive Rainfall. The only locations that remain in the slight
risk of Excessive rainfall will be NYC and Long Island, where the
signal for heavy rain over these area are slightly lower than the
rest of the CWA. That being said, it can not be ruled out that NYC
and parts of Long Island get into the moderate risk later today or
even tonight. A lot will depend on what the 12z CAMs show later this
morning.
The placement of the heaviest rainfall is always difficult in
convective season, but on average around 1-2 inches of rain is
currently forecast. Heavy rainfall is also possible and amounts
could be locally higher. Can not rule out a few locations reaching 3
to as much as 5 inches if any storms train over the same area. As a
result, have gone ahead and issued a flood watch for the entire CWA.
Concerns remain elevated across portions of the Lower Hudson
Valley and southern CT where several rounds of heavy rain occurred
both this past Sunday and early Friday. Some locations in this area
has seen significant flooding over the last week.
SPC has also has the region in a marginal risk for severe
thunderstorms on Sunday. Severe weather concerns are likely
dependent on if there is more significant destabilization. The main
threat with any severe storms will be strong gusty winds and large
hail.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Little to no change in the long term period.
Persistent upper troughing will continue over the northeastern
portion of the CONUS through the long term. The most significant
ridging and heat will likely remain well to the south and west of
the area based on overall good agreement among the latest ensemble
means.
The main forcing and moisture axis is progged to start moving
offshore Sunday night with decreasing chances for convection through
the night.
The model consensus is indicating the front from Sunday will be wash
out or weaken just offshore on Monday. Weak high pressure should
build into the region from the south and west with the region lying
between western Atlantic Ridging and the larger upper trough near
the Great Lakes. The upper trough then sharpens a bit into Tuesday
which will bring the next frontal system towards the area. The
shortwave may make its way across New England late Tuesday or
Tuesday night with another potential round of showers and
thunderstorms. Thereafter, it is a bit uncertain if the trough axis
will remain nearby or Wednesday or shift offshore. If the trough
axis remains closer to the area, then the front may slow down or
stall keeping the possibility of showers/storms at some point
Wednesday or Wednesday night. The guidance then hints at a continued
active pattern overall into the end of the week with weak impulses
moving around the continued upper troughing. Have followed the NBM
closely for the end of the week based on the uncertainty at this
time range. This yields potential of convection at some point
Thursday into Friday, but does not look to be a washout both days at
this point.
Temperatures in the long term overall look to be near seasonable
levels. However, there is chance for highs in the upper 80s to
around 90 degrees on both Monday and Tuesday. Heat indices look to
top out in the low 90s, but how much dew points mix out both days
will ultimately determine these values.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
A frontal boundary will remain in the vicinity of the terminals
today and tonight.
Any remaining MVFR to IFR stratus early this morning expected to
dissipate 13Z to 14Z, then VFR. Scattered showers and
thunderstorms possible mainly inland late this afternoon into
early this evening, with low confidence in timing and coverage.
High confidence for showers and thunderstorms by late tonight,
with heavy rain at times, with MVFR to IFR, and possibly LIFR.
Development may be an hour or two earlier than forecast.
A southerly flow is expected through the forecast period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
MVFR stratus likely at KJFK, KEWR and KTEB until around 13Z,
then VFR.
A few scattered thunderstorms will be possible late afternoon
into early this evening and included PROB30 at KEWR and KTEB,
lower chances that thunder occurs at KJFK and KLGA, and may be
included later.
Timing of MVFR to possibly IFR stratus moving into KJFK this
evening is uncertain, with low confidence in the timing.
Showers and thunderstorms may develop an hour or two earlier
than forecast late tonight.
The afternoon KJFK and KLGA haze potential forecast is YELLOW, which
implies slant range visibility 4-6SM outside of cloud.
The afternoon KEWR haze potential forecast is GREEN, which implies
slant range visibility P6SM outside of cloud.
OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
Sunday: Showers and Thunderstorms with MVFR to IFR, chance LIFR.
Monday: Early morning MVFR possible in cigs/vsby, especially
east of the NYC terminals, becoming VFR.
Tuesday-Wednesday: Chance of showers/thunderstorms with MVFR or
lower especially inland.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA conditions are expected through early next week. However, an
increasing southerly swell Sunday into Monday may allow for ocean
seas to be near 5 feet at times Sunday night into Monday, especially
east of Moriches Inlet. Seas briefly subside Monday night before
potential of 5 ft seas returns on Tuesday.
&&
.HYDROLOGY...
A Flood Watch is in effect for the entire CWA late tonight and
Sunday.
Flooding concerns continue on Sunday with potential for heavy
rainfall. Areas that have received heavy rainfall in the last week
are more prone to more impacts, but flash flooding is possible
anywhere across the region. Flashier small streams and rivers could
also reach bankfull. WPC currently has much of the region in a
moderate risk for excessive rainfall with NYC and Long Island
remaining in a slight risk. On average, widespread rainfall of 1 to
2 inches, with localized amounts of 3 to 5 inches will be possible.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development at all the ocean
beaches today. There is a high risk of rip current development at
all the ocean beaches Sunday as southerly swells increase.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from late tonight through Sunday evening for
CTZ005>012.
NY...Flood Watch from late tonight through Sunday evening for
NYZ067>075-078>081-176>179.
NJ...Flood Watch from late tonight through Sunday evening for
NJZ002-004-006-103>108.
MARINE...None.
&&
$$
SYNOPSIS...BC/DS
NEAR TERM...BC
SHORT TERM...BC
LONG TERM...DS
AVIATION...MET
MARINE...BC/DS
HYDROLOGY...BC
TIDES/COASTAL FLOODING...