112
FXUS61 KOKX 200953
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
553 AM EDT Sat Jul 20 2024
.SYNOPSIS...
High pressure moves offshore today, with a surface trough lingering
over the area through the weekend. A weak cold front approaches from
the north on Sunday and likely dissipates before reaching the area.
A wave of low pressure passes to the south Monday night into
Tuesday. A stationary boundary will then be over the region the rest
of Tuesday into much of Wednesday. The front may lift north
temporarily late Wednesday into Thursday before sagging south and
pushing through as a cold front early on Friday. Weak high pressure
should return late Friday into next weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
The forecast is on track this morning and only minor
adjustments were made to capture current trends. High clouds
can be seen increasing over the area ahead of the approaching
shortwave. Cloud cover will continue to increase through the
morning.
High pressure moves offshore today, while a surface trough lingers
over the area. Aloft, an upper level low spins in eastern Canada,
with a trough axis extending well southwest into the Southern
Plains. Multiple embedded shortwave troughs lift and approach
from the southwest this morning and pass through this afternoon
and overnight. This will bring a gradual increase of mid and
high level clouds through the day. Skies become mostly cloudy by
the late morning.
Given the S/SW flow, the area will gradually destabilize, mainly
north and west of NYC. The CAMs continue to show isolated convective
activity north and west of NYC in the afternoon and then spreading
east through the evening and overnight. Thinking much of this
activity will just be showers with model soundings not showing any
CAPE above -15C. The Lower Hudson Valley looks to be a bit more
unstable than the rest of the area, with a deeper CAPE profile,
so have kept mention of thunder there.
Highs will be just a few degrees warmer than Friday, with
dewpoints in the 60s.-- End Changed Discussion --
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The surface trough continues to linger on Sunday, becoming a bit
more pronounced, while the flow aloft becomes more zonal. A
weakening cold front also approaches from the north, but will
likely dissipate before reaching the area. Most CAMs are hinting
at some convective activity popping up around NYC and Long
Island, likely due to increased surface convergence between sea
breeze boundaries and the surface trough. Similar to today,
left out thunder due to lack of a deep CAPE profile. Only
expecting a slight chance of some pop up showers.
A wave of low pressure will pass to the south Monday night into
Tuesday and likely bring more widespread showers and
thunderstorms. Chances start Monday afternoon and ramp up into
Monday night.
Highs Sunday and Monday will be back in the upper 80s, with
dewpoints in the 60s to low 70s.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
A frontal boundary will lock up over the region Tuesday and likely
into much of Wednesday. This should lead to a rather warm and humid
period of unsettled weather. A series of shortwaves are suggested by
global NWP leading to an extended period of chance and embedded
likely PoPs Tuesday through Thursday night. The most favored time of
day will be the afternoon and evening as per any diurnally favored
convection. PWATs are likely going to run at or above the
climatological 90th percentile. Any embedded thunderstorm activity
will likely lead to intervals of moderate to locally heavy rainfall.
See the hydrology portion of the AFD for more information.
Weak high pressure likely returns for Friday and into next weekend.
Temperatures through the period are likely to be near to slightly
above normal, with more of a tendency for above normal temperatures
for the night time due to high humidity and a tendency for clouds.
Cloud cover should preclude the need for any heat headlines during
this time frame. However, if the frontal boundary gets further north
and the region gets more clearly in the warm sector for any length
of time then heat headlines would be a possibility Wednesday into
Thursday.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
High pressure resides over the area through this morning. A surface
trough will linger nearby this afternoon into Saturday night.
VFR prevails. Slight chance of an afternoon / early evening shower N
and W of the NYC metro terminals. Thus, have included a PROB30 for -
shra for KSWF. Otherwise probabilities are too low to include in the
TAF at all other terminals.
Variable and light WSW winds overnight. SW-S winds mainly 7-10 kt
Saturday afternoon, with sea breezes 10-13 kt possible at southern
coastal terminals like KJFK and KISP. Variable to light WSW winds
return late Saturday evening.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments are expected.
OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY...
Saturday night through Sunday: Mainly VFR, brief MVFR possible in
showers.
Monday: VFR. Potential MVFR for PM/Night in SHRA.
Tuesday and Wednesday: Periods of MVFR or lower likely with
SHRA/TSRA.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
With a weak pressure gradient over the area, winds and waves will
remain below Small Craft Advisory criteria. The stretch of 2 ft
ocean seas is likely to continue through Tuesday night. A S-SW
flow may increase towards Wednesday with marginal small craft
conditions becoming possible by Wednesday night.
&&
.HYDROLOGY...
There are no hydrologic concerns through early next week.
The region will be in a humid and unsettled pattern towards mid week
with anomalously high PWATs. Therefore at this time there appears to
be at least a limited risk of localized flash flooding from any
thunderstorms that produce heavy rain. It remains too soon to lock
down any details around hydrologic related impacts for the Tuesday
through Thursday time frame. ML based progs are indicative of the
potential for a marginal to slight risk of excessive rainfall.
&&
.TIDES/COASTAL FLOODING...
Today, a moderate rip current risk is forecast for the ocean
beaches, with surf heights 2-3 ft and an onshore flow increasing to
10-15 kt in the afternoon. The moderate risk continues on Sunday
with similar conditions.
Minor coastal flood benchmarks may be approached along the western
south shore bays of Nassau and Queens for the Monday and Tuesday
night high tide cycles. There remains a good deal of uncertainty
around this, thus trends in the water level forecast will need to be
monitored for these locations.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JE/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...JE
AVIATION...JE
MARINE...JE/JT
HYDROLOGY...JE/JT
TIDES/COASTAL FLOODING...JE/JT