912
FXUS61 KOKX 010616
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
216 AM EDT Sun Sep 1 2024
.SYNOPSIS...
Weakening high pressure gives way to a pre-frontal trough 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 THIS MORNING/...
-- Changed Discussion --
A couple of real spotty showers were on radar at this hour with
weak lift and instability. Next vort over south central PA
shows up with colder cloud tops on water vapor imagery. Showers
are expanding in this area, but also working across a stable
airmass. Expect showers to begin to increase in coverage over
western areas around 09Z (5 am), then work eastward through the
morning. CAMs once again are not showing much organization. The
FV3 and NSSL WRF are more aggressive with coverage, but still
not expecting any strong and/or severe convection. Expect a few
pockets of heavier rain, but cells should be progressive.
Confidence is low, but there is general deep-layered ascent
which should get something going.
Otherwise, it will be muggy conditions with low temperatures
above normal.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
Forecast confidence is low with any convection for Sunday
morning and afternoon. The latest CAMs show very little
development of convection, especially Sunday morning. Did not
make any changes to the forecast yet as would like to see the
rest of the 00z suite. However, if the latest trends continue,
PoPs will need to be lowered and any heavier downpours/thunder
look to be isolated in the morning. Previous discussion follows.
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 NIGHT 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 /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A pre-frontal trough slowly approaches tonight and slides
through Sunday. A cold front follows Sunday night.
Low confidence forecast regarding ceilings. Mainly VFR
conditions to start will lower to MVFR tonight with potential of
some IFR 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, and looks to be
limited more for eastern terminals.
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...
Amendments likely for the timing of MVFR conditions. There is
also a chance for IFR early Sunday morning.
Isolated thunderstorm cannot be ruled out Sunday morning and
then again Sunday afternoon and evening, but confidence too low
to include in the TAFs.
OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
Sunday Night: Mainly VFR with some lingering MVFR eastern Long
Island and southeast Connecticut early. Chance of a
shower/thunderstorm evening. NW wind gusts to 15 kt possible.
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...
Any showers/storms that develop on Sunday may produce locally
heavy rainfall which could lead to minor nuisance/poor drainage
flooding. Any flash flood risk looks very low and localized.
No hydrologic impacts are expected thereafter.
&&
.TIDES/COASTAL FLOODING...
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.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
UPDATE...DW
AVIATION...JP