170
FXUS61 KOKX 122338
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
738 PM EDT Fri Jul 12 2024
.SYNOPSIS...
A stationary front along the east coast, from Maine into the
southeastern states, remains into Saturday as a weak wave of low
pressure over the Delmarva tracks slowly northward. The front
moves slowly east and washes out just southeast of the area late
Saturday and Saturday night. High pressure returns Sunday with a
thermal trough setting up over the region Monday and Tuesday. A
cold front then approaches from the west on Wednesday, moving
offshore Thursday. High pressure may return next Friday.
&&
.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --
Forecast remains on track with only minor adjustments. Shower
activity has been fairly limited this evening but should
continue to develop to our south and move into the area into the
overnight period.
The Flood Watch remains in effect for western portions of the
forecast area through Saturday afternoon. While there remains a
chance of flooding this evening, confidence in this occurring is
low as showers remain scattered, and thunderstorms have weakened
as isolated storms to the south weakened as the storms moved
into a more stable airmass. Higher instability was to the east
and offshore, however, there is a lot of convective inhibition
in these areas. So, have used coverage wording for both the
showers and thunderstorms.
A stationary front remains across the region from coastal Maine
into the southeastern states, with a weak wave of low pressure
over the Delmarva. This low and supporting upper energy will be
moving northward tonight into Saturday morning, and another
round of moderate to briefly heavy rain remains possible late
tonight into Saturday morning as precipitable water values
remain at 2 to 2.25 inches. CAMs and even the global models
differ in the placement of the axis of the heavier rain, and the
timing of the heaviest rain, from early Saturday morning into
Saturday afternoon with diffuse and weak lift across the region.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY NIGHT/...
The stationary front will be weakening and drifting east
Saturday and should be nearly dissipated by Saturday evening
with the rain ending. Weak mid and upper level ridging builds to
the west Saturday night with heights slowly rising across the
region.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
The main story in the long term will be another heat wave that
likely begins Sunday and peaks Monday and Tuesday. Some relief
from the heat and humidity is currently expected late next week.
Key points:
* Confidence continues increasing for another heat wave for parts of
the area (NYC, NE NJ, interior) which begins Sunday, but peaks
Monday and Tuesday and most likely ends on Wednesday.
* Afternoon heat indices will reach in the lower 90s for most
locations on Sunday with some isolated spots touching 95 in the
urban NE NJ corridor.
* Afternoon heat indices 95-100F expected Monday and Tuesday. The
usual warmer locations could exceed 100F and it is not out of the
question for the heat index to touch 105F in the urban NE NJ
corridor.
* Chance for PM showers and thunderstorms, mainly north and west of
NYC Monday and Tuesday. More widespread showers and thunderstorms
Wednesday afternoon into Wednesday night.
* Temperatures should end up closer to normal with less humidity to
end next week.
The Tri-State area will lie along the southern edge of the
westerlies aloft with any substantial ridging over the Western
Atlantic and southern US. The deep westerly flow will transport
anomalously warm air into the region, especially early next week.
Sunday will be the beginning of the heat, but dew points are likely
to mix out a bit in the afternoon especially away from the immediate
coast. A consensus of the guidance yields highs in the upper 80s to
lower 90s, warmest away from the immediate coast. Dew points likely
start the day in the 70s, but mix out into the middle and upper 60s
with a predominately west flow. Coastal locations should see a sea
breeze develop in the afternoon, so dew points likely stay closer to
70F. Thinking heat indices peak in the lower 90s for much of the
area with the urban NE NJ corridor touching 95F in a few spots.
Given that this is still 4 periods out and temperatures and dew
points trended down since previous cycles, have held off on a heat
advisory for the warmest spots.
A heat advisory will eventually be needed for Monday and Tuesday for
a large portion of the area. Ensemble means progs continue to show
H85 temps around 20C by Monday, and into the low 20s Tuesday into
Wednesday. In addition, the low-level flow will be more from the SW,
which will lessen the marine influence, especially just inland from
the coast. High temps for much of the area Monday and Tuesday will
be in the low to mid 90s with the exception of immediate coastal
locations. Upper 90s are possible in the urban NE NJ corridor and
potentially the NYC metro, and not out of the question a few of the
warmest spots (KEWR) touch triple digits. Stayed very close to the
deterministic NBM for forecast highs, but continued to blend in
CONSALL for dew points to bring values down a few degrees. This
still results in widespread heat indices of 95 to 100F Monday and
Tuesday with some locations in urban NE NJ to touch 105F.
The modeling has been hinting at some weak shortwaves moving across
the northeast both Monday and Tuesday. Diurnally driven convection
is possible both afternoon and evenings, with the higher
probabilities (still chance category), mainly north and west of the
NYC metro.
A more amplified and deeper trough is likely to approach next
Wednesday. This will send a cold front into the area. Ahead of the
front, temperatures should once again reach the upper 80s and lower
90s. Dew points could end up slightly higher compared to Monday and
Tuesday, so heat indices peak in the middle to upper 90s, especially
away from the immediate coast and far northern interior.
A widespread convective event remains possible Wednesday
afternoon/evening into Wednesday night. Still some spread in global
ensembles, but it continues to look like the front will help usher
in a drier and more seasonable regime behind it late next week.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
A stationary front remains nearby into Saturday.
Mainly VFR with periods MVFR/IFR as showers move north this
evening. MVFR to IFR conditions likely become more widespread
after 06Z as shower coverage increases. Some thunder is possible
around 12-15Z Sat morning, but confidence is low in this
occurrence and so have maintained Prob30s for now.
Southerly with speeds generally increasing to 10-15 kt through
the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence in TSRA coverage and timing tonight.
OUTLOOK FOR 20Z SATURDAY THROUGH WEDNESDAY...
Saturday: MVFR or lower with showers/thunderstorms early in the day.
Improvement to VFR by afternoon.
Sunday: VFR.
Monday through Wednesday: Mainly VFR. A chance of afternoon
into early evening showers and thunderstorms with MVFR possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Ocean seas remain elevated through at least Saturday afternoon
with south to southeast swells, and the SCA was extended
through Saturday. Ocean seas east of Fire Island Inlet do remain
at or above 5 feet Saturday evening, and will be slowly
diminishing through late Saturday night, and the SCA may need to
be extended. With not enough confidence, and the marginal seas
especially late Saturday night, have not extended the advisory
into Saturday night at this time. For the non ocean waters winds
and seas remain below advisory levels tonight through Saturday
night.
Winds and seas will then largely remain below SCA criteria Sunday
into mid next week. Ocean seas may begin to approach 5 ft late
Wednesday ahead of an approaching front.
&&
.HYDROLOGY...
-- Changed Discussion --
Rainfall this evening through Saturday afternoon is expected to
range mostly from 1 to 1 1/2 inches in the areas currently with
a Flood Watch, with locally higher amounts, up to 3 inches,
possible. Timing of the greatest threat may be early this
evening, although confidence is low, and again late tonight into
early Saturday morning. Mostly small stream and minor
urban/poor drainage flooding are anticipated, but isolated to
scattered instances of flash flooding will be possible during
this time.
Given an abundantly moist air mass in place, any thunderstorms that
develop early to mid next week will have the potential to produce
locally heavy downpours that result in nuisance flooding,
particularly in urban and poor drainage areas.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
There is a high rip current risk along all ocean beaches through
Saturday evening. Seas will be around 5 ft with continued S swells
at 7-8s and S-SW winds 10-15 kt. There is a moderate rip current
risk on Sunday with seas and swells subsiding to 3-4 ft and weaker
winds.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch through Saturday afternoon for CTZ005-009.
NY...Flood Watch through Saturday afternoon for NYZ067>075-176>179.
High Risk for Rip Currents through Saturday evening for NYZ075-080-
081-178-179.
NJ...Flood Watch through Saturday afternoon for NJZ002-004-006-
103>108.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ350-353-
355.
&&
$$
SYNOPSIS...DS/MET
NEAR TERM...MET/MW
SHORT TERM...MET
LONG TERM...DS
AVIATION...DBR
MARINE...DS/MET
HYDROLOGY...DS/MET
TIDES/COASTAL FLOODING...