000
FXUS61 KOKX 262153
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
553 PM EDT Mon Jul 26 2021

.SYNOPSIS...
High pressure builds in from the west through tonight. High
pressure will weaken Tuesday with a cold front from the north
then approaching the region. The cold front moves across Tuesday
night. Weak high pressure builds in Wednesday. A cold front
approaches on Thursday and passes through Thursday night into
Friday. High pressure then builds in through Saturday before
another frontal system approaches late on Sunday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Mostly clear skies with some residual haze potentially causing a
reduction in visibility for northern areas through the early
evening. This updates reflects the current observations and
trends, mainly for temperature, through this evening.

Otherwise, with high pressure at the surface building in from
the west, expecting mostly clear sky conditions tonight. Along
with decreasing winds, radiational cooling will be optimized.
Mid and upper level westerly flow will keep a dry airmass in
place. Dewpoints that have lowered well into 60s and even upper
50s previously during the day will stay in the low to mid 60s
for tonight. A MAV/MET MOS blend was used for low temperatures
to convey a more vast range of temperatures between the urban
heat island and outlying rural sections. Lows range from the
upper 50s to near 60 for outlying rural sections to low to mid
70s within NYC.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
High pressure at the surface will gradually weaken on Tuesday. A
cold front will approach from the north and move across Tuesday
night. Drier air at the surface will still be present with
lowering dewpoints going into the morning and early afternoon.
Forecast 850mb temperatures are expected to reach 17 to 18
degrees C. Highs were a blend of NBM and MOS consensus in the
upper 80s to lower 90s. Dewpoints staying mostly in the lower
60s will keep heat indices close to actual temperatures.

Showers and thunderstorms will become probable for interior
areas late in the afternoon, but across the whole region Tuesday
night as the cold front moves closer to the region. Thunder
chances highest for the first half of the night between 8PM
Tuesday and 2AM Wednesday. Instability will be limited and will
decrease more late at night so after 2AM, thunder chances become
slight with a continued chance of showers.

Vertical forcing increases most Tuesday night with positive
vorticity advection in the mid levels. Bulk shear will be
increasing 0-6km to 30-40 kt so some thunderstorms could be
strong with gusty winds. Highest instability at the surface will
be in the southern half of the region with around 1000 to 1500
J/kg of CAPE and less to the north. Most of the upper level
energy seems to be focused to the north of the region where the
height falls will be more and omega will be higher. There is a
marginal risk of severe thunderstorms across parts of the Lower
Hudson Valley and Southern Connecticut.

Lows Tuesday night were taken from a consensus of all guidance
with temperatures ranging from the lower 60s across the interior
to upper 60s and lower 70s along and near the coast as well as
NYC.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term continues to be dominated by a large mid-level trough
that is reinforced by shortwaves in the flow through the weekend
and into next week.

Weak high pressure over the area on Wednesday may result in a few
showers or thunderstorms though coverage should be rather isolated
if they occur at all. The weak high shifts offshore into Wednesday
night providing for an increasing southerly flow advecting moisture
back into the area. An intensifying low pressure system to the north
tightens the pressure gradient over the area ahead of the
approaching cold front. Showers become likely much of the day
Thursday with an isolated thunderstorm possible late in the day.
Though there is some uncertainty in the timing of the frontal
passage, showers looks to continue into Thursday night and
early Friday.

A brisk NW flow behind the front on Friday gradually weakens into
Saturday as a high pressure tries to build in from the southwest,
but Friday and Saturday will be mostly, if not entirely, dry. High
pressure quickly gets pushed offshore by Sunday as another frontal
system brings another cold front into the area for late on Sunday.
The strongest forcing appears to be toward the north of the area,
but the GFS brings in a surge of moisture just ahead of the front
resulting a significant difference in precipitation and rainfall
amounts. Capped the PoPs at a chance for now. Thereafter, models
diverge in the pattern but look to show a generally dry Monday and
Tuesday.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
Weak high pressure remains over the region into Tuesday. A cold
front approaches from the north late in the afternoon.

VFR, except MVFR in haze at KSWF through the afternoon.

Light NW to N winds outside of sea breezes. Winds become light and
variable across the region this evening, and then SW less than 10 kt
Tuesday morning.


  ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

There is a chance that a sea breeze will move through KLGA late this
afternoon, 22Z or later. However, looking more likely that winds
will remain NW around 10kt.


.OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
.Tuesday afternoon...VFR. Slight chance of late day TSTM at KSWF.
Sea breezes likely.
.Tuesday night...Chance of brief MVFR/local IFR cond with any
showers/isolated tstms.
.Wednesday and Wednesday night...VFR. Slight chance of a shower or
tstm.
.Thursday and Thursday night...Chance of MVFR, local IFR, with a
chance of showers and thunderstorms.
.Friday-Saturday...VFR.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

&&

.MARINE...
A weak pressure gradient will be in place across the waters.
Ocean seas have subsided to below 5 ft. SCA was cancelled.
Conditions on all waters are expected to remain below SCA
thresholds through Tuesday night with a weak pressure gradient
remaining in place.

Winds and waves are expected to remain below SCA criteria
Wednesday through Wednesday night.

A strengthening southerly flow ahead of an approaching cold
front will likely bring SCA conditions to the ocean waters late
Thursday into Thursday night. Waves will slowly subside on
Friday in a post-frontal NW flow, which may bring marginal SCA gusts
during the afternoon. Elsewhere, conditions are forecast to remain
below SCA criteria. Conditions drop below SCA conditions by Friday
night.

&&

.HYDROLOGY...
Layer PWATS reach almost 1.7 inches Tuesday night. Aside from
the possibility of minor flooding with thunderstorms in low
lying and poor drainage areas with locally higher amounts of
rainfall Tuesday night, no hydrologic issues are expected
through Tuesday night.

Looking ahead, no hydrologic impacts are expected Wednesday through
early next week.

&&

.TIDES/COASTAL FLOODING...
A high risk of rip currents is expected into this evening for
the ocean beaches.

A moderate risk of rip current development is forecast for the
ocean beaches for Tuesday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075-
     080-081-178-179.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...JM/MW
NEAR TERM...JM/MW
SHORT TERM...JM
LONG TERM...MW
AVIATION...MET
MARINE...JM/MW
HYDROLOGY...JM/MW
TIDES/COASTAL FLOODING...JC/JM

NWS OKX Office Area Forecast Discussion