145
FXUS61 KOKX 312322
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
722 PM EDT Sat Aug 31 2024
.SYNOPSIS...
Weakening high pressure gives way to an approaching frontal system
which will move across the area tonight into Sunday morning. A cold
front will then pass through the area Sunday night. A large dome of
high pressure over the Upper Midwest will then build east through
the middle of next week, gradually moving offshore late next week.
A frontal system may approach the area Friday into next weekend.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
-- Changed Discussion --
Overcast conditions continue to move a little farther east this
evening and are likely to overspread areas that have been partly
cloudy. Hourly temperatures were also lowered in a few spots to
account for current observations.
Weak troughing aloft will help push a surface trough towards us
tonight, preceded by a weak warm front. Associated lift and
deepening moisture bring a good chance of showers to most of the
forecast area. Instability is somewhat lacking, but enough for a
mention of a possible thunderstorm. Shear is fairly weak, so no
severe thunderstorms are expected. As for heavy rainfall concerns,
PWATs increase to around 2 inches, so showers with some downpours
will be possible. Flooding concerns are mainly of the minor nuisance
variety. WPC does have locations north and west of NYC under a
marginal risk of excessive rainfall. Any flash flooding is expected
to be isolated. Muggy conditions with low temperatures above normal.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
The surface trough is expected to drift east across the forecast
area during Sunday, reaching the eastern zones by the end of the
day. Moisture convergence will be greater along this boundary, and
as instability and upper support increase, anticipating shower and
thunderstorm chances to increase. Still somewhat uncertain where the
trough will be by the time the upper support and instability become
more of a factor, but the overall trend for the past 24+ hours has
been for a slower eastward progression. Regarding the severe weather
potential, shear will be stronger this time around - enough for a
threat of strong to severe wind gusts. Potential cloud cover
hampering destabilization and the aforementioned uncertainty
regarding the position of the surface trough limit confidence in the
convective forecast. With that said, it appears that overall higher
chances of showers and thunderstorms will be from around NYC
northeastward into SW CT and to points east. The flooding threat is
uncertain, but at least minor flooding will be possible. Can`t rule
out isolated flash flooding either, especially if the 12z hi-res 3km
NAM qpf fields are correct. HREF probability of 1-hour rain amounts
of greater than an inch are low at 10-20% for parts of the area, but
it`s at least a signal for the potential of something more than
just minor/nuisance flooding. Have nudged up the forecast rain
amounts during Sunday from WPC guidance with this in mind.
Highs on Sunday will be in the upper 70s to mid 80s with the warmer
spots generally west of the city. Still muggy, with dewpoints mostly
in the lower 70s.
A cold front is then forecast to pass through the area after Sunday
evening, ending the threat of showers and ushering in a cooler and
drier airmass.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Following an exiting cold front on Monday, northwest winds will
advect in cooler, drier air into the area. Dewpoints will drop
through the day on Monday. With strong cold air advection aloft at
850 mb and a steady northwest wind, highs on Monday will be limited
to the low/mid-70s with a few reaching the upper-70s.
High pressure will continue to build in behind the exiting front
from the Great Lakes region on Monday and Tuesday with ridging
aloft, leaving a very sunny forecast for early next week. Overnight
lows will drop into the upper-40s to near-60 north-to-south Monday
night. Dewpoints drop into the 40s Monday night and remain there
through Tuesday night, reinforced by northwest flow. This will lead
to conditions feeling cool and crisp during the nights and pleasant
in the afternoons with highs in the mid/low-70s on Tuesday.
Most model guidance brings high pressure overhead on Wednesday, then
gradually push it offshore Thursday and Friday. This will lead to a
return flow from the southerly. High pressure will firmly remain in
place on Wednesday and still mainly in control on Thursday, allowing
for more cloud-free days, before cloud cover increases as the high
exits east Thursday night into Friday. Southerly winds will lead to
increasing temperatures and dewpoints late next week. Highs will be
in the mid-70s to low-80s by Friday.
Friday into Saturday, most global guidance show a developing mid-
Atlantic coastal low with a deepening trough and low over the Great
Lakes. Each model deals with these two systems in different ways.
Some bring a frontal system into the area from the west with the
coastal low well offshore. Some keep the frontal system to the west
as a coastal low sweeps up the Atlantic coast and into our area.
Which solution ends up occurring is hard to pinpoint, at this time.
However, looking ahead, more unsettled weather for next weekend
looks possible.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A pre-frontal trough slowly approaches tonight and slides
through Sunday. A cold front follows Sunday night.
Mainly VFR conditions to start will lower to MVFR this evening
with IFR/LIFR likely at KGON. MVFR to IFR conditions are then
likely overnight into early Sunday morning. MVFR likely persists
into the early afternoon before improvements to VFR occur late
in the day. MVFR likely lingers into Sunday evening at KGON.
Low confidence forecast regarding showers for much of tonight
into Sunday morning. There may be period with a better chance
10-16z, especially from around the NYC metro on east, and this
is where tempos are included. Any thunderstorm looks isolated
and have left out of the TAF. There is also a chance of a shower
or thunderstorm Sunday afternoon/evening, but again confidence
is too low to include in the TAF at this time.
Winds shift to the S-SSW tonight into Sunday morning under 10
kt. A slight increase in wind speeds is expected late Sunday
morning into the afternoon. The wind direction should begin
shifting to the SW late.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
MVFR timing this evening into tonight may be off by 1-3 hours.
IFR possible late tonight into early Sunday morning.
Isolated thunderstorm cannot be ruled out 10-15z and then again
Sunday afternoon and evening.
OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
Sunday Night: Mainly VFR with some lingering MVFR eastern Long
Island and southeast Connecticut early. Chance of a
shower/thunderstorm evening.
Monday through Thursday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds and waves will remain below SCA criteria through the middle of
next week. Winds gusts may reach 20 kts both Monday morning and
Monday night into Tuesday morning, post-front.
&&
.HYDROLOGY...
Showers and possible thunderstorms tonight through Sunday look
disorganized. The current forecast has up to an inch of rainfall
during this time, with the higher amounts generally from around the
city to points east. Locally higher amounts are also possible. The
flood threat will be mainly of the minor nuisance/poor drainage
variety. However, WPC maintains a marginal risk of excessive
rainfall north and west of the NYC metro through at least the first
half of Sunday morning. This means there is the potential for
isolated episodes of flash flooding. It appears that the period when
impacts are more likely to be realized are late tonight into Sunday
morning. No hydrologic impacts are expected thereafter.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
Rip currents over performed today with most Long Island beaches
reporting moderate rip activity. Given some guidance suggestion
for moderate in spots and a similar set up tomorrow, except
stronger winds, will go moderate for all beaches tomorrow.
Steady offshore winds and increasing surf height should lead to
another day of moderate rip activity on Monday.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JC/BR
NEAR TERM...JC/BR
SHORT TERM...JC
LONG TERM...BR
AVIATION...DS
MARINE...JC/BR
HYDROLOGY...JC/BR
TIDES/COASTAL FLOODING...