957
FXUS61 KOKX 011147
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
747 AM EDT Sun Sep 1 2024
.SYNOPSIS...
A pre-frontal trough will move slowly across the area today and
then gets kicked eastward by a cold frontal passage tonight. High
pressure will then build east through the middle of the week,
gradually moving offshore mid to late next week. A frontal system
may approach the area Friday into next weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
With this latest update, have stepped rain chances down this
morning, but taking a small step here. Latest SPC mesoanalysis
does show destabilization, especially across LI into CT at
around 500 J/kg. An area of light showers is approaching from
central NJ, associated with incoming mid level shortwave trough.
Expect at least some expansion as it works into the area,
albeit CAMs aren`t showing much.
A deepening upper trough moving across the Great Lakes today
and into the Northeast tonight will send a pre-frontal trough
into the area today, followed by a strong cold frontal passage
tonight. Over the last few days, guidance and forecasts have
trended toward with rainfall amounts and potential impacts.
This is partly due to the timing of the trough (washed out cold
front) moving into the area this morning and the lack of instability
and large scale forcing. CAMs continue to show little in the
way of an organization. The FV3 and NSSL WRF are more aggressive
with coverage later this morning, but still not expecting any
strong and/or severe convection. There still looks to be the
potential for a few pockets of heavier rain, but cells should be
progressive. However, confidence undoubtedly in the forecast is
waning at this time.
A mid level vort over south central PA shows up with colder
cloud tops on water vapor imagery. Regional radar does some
showers moving into eastern PA with little development. It is
this area that will be watched the next several hours for
development as it approaches toward daybreak. The combination
of high PWATs of around 2" and modest deep-layered lift should
help to expand coverage of showers this morning. Airmass has
been slowly destabilizing overnight, but still CAPE values are
generally below 250 J/Kg. Therefore, expect mainly showers this
morning with embedded thunderstorms possible. Have also backed
off on the basin average rainfall across the area to a quarter
inch or less. This does not mean there will not be higher amounts,
but this should be localized with any stronger convection. 00Z HREF
3h QPF PMM generally less than a tenth of an inch with pockets
as high as 0.75". Probability of seeing an inch in any 3 hour
window is only about 10%. For one-hour probabilities of greater
than inch an hour, they remain below 10%. So with the lack of
deep convection, the flood threat at this time mainly looks to
be of the minor nuisance variety.
For the afternoon hours, airmass destabilizes, especially north
and west where more more sun will be realized. However, the
better frontal forcing will reside west of the area and a
veering wind profile is likely to bring drier air into the
region. The latter of which is a limiting factor as it gets
mixed into the the low-levels. Thus, only looking for widely
scattered to scattered thunderstorms during the afternoon hours.
SPC has maintained a slight risk for severe thunderstorms
across the area, with localized damaging winds being the primary
threat.
Cold front will move through the area mainly dry the first half
of tonight. Northerly winds develop behind the front bringing
in drier, cooler air.
Highs today will be in the upper 70s to around 80 for LI and
CT, with the lower to mid 80s possible for areas to the west.
This is close to normal, but the high humidity will make it feel
less comfortable. Lows Monday morning will be cooler, but still
a few degrees above normal as the cold advection will still be
ongoing. Northerly winds Monday into Monday night could gust up
to 20 mph, but diminishing on Tuesday as the center of the high
approaches.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
A large dome of high pressure over the Great Lakes on Monday
will build east and into the area through midweek. By Tuesday,
temperatures will average 5 to 10 degrees below normal. It will
also be very comfortable with dew points dropping into the 40s,
possibly even the 30s on Tuesday.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
High pressure moves overhead Tuesday night into Wednesday morning,
then gradually pushes offshore Wednesday night into Thursday. Skies
are expected to be clear to mostly clear during this time frame. The
high remains offshore Friday leading to a return flow from the
south, which means increasing temperatures and dewpoints late next
week and an increase in cloud cover.
Conditions look to become unsettled next weekend as a frontal system
approaches from the west. At the same time, low pressure develops
along an old frontal boundary to the south, which also may approach
the area.
Highs during the long term will be in the 70s. Lows Tuesday night
into Wednesday morning will dip into the 40s in the interior and
into the 50s most everywhere else. Thereafter, overnight lows are
expected to warm to the 50s and 60s by the weekend due to increased
cloud cover, warm advection, and a more humid air mass in place.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A pre-frontal trough slowly moves through today. A cold front
follows tonight with high pressure building in thereafter.
Low confidence forecast regarding ceilings. MVFR conditions
continue this morning. IFR is possible, but more likely for
eastern terminals, such as KISP and possibly KGON and KBDR. A
return to VFR is expected this afternoon (17-19Z from west to
east). MVFR conditions linger for KGON into the evening hours.
Low confidence forecast regarding showers for much of tonight into
this morning. With the lack of development of showers overnight,
backed off on the showers in the forecast. It appears now that
shower activity will be widely scattered through the afternoon
and early early evening hours, thus VCSH in the TAFs. Still, an
isolated thunderstorm is not out of the question.
A S to SW wind of around 10 kt or less this morning will shift
to the W this evening, then NW overnight tonight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely for the timing of MVFR conditions. There is also a
low chance for IFR early this morning.
Isolated thunderstorm cannot be ruled out this morning and then
again this afternoon and evening, but confidence too low to include
in the TAFs.
OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
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. Northerly winds gusts may reach 20 kts both Monday
morning and Monday night into Tuesday morning.
&&
.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 on Saturday with most Long Island
beaches reporting moderate rip activity. Given guidance
continues to show moderate in spots and a similar set up
today, except stronger winds, will stay with moderate for all
beaches. 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.
&&
$$
SYNOPSIS...JP/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...JP
AVIATION...JP
MARINE...JP/DW
HYDROLOGY...JP/DW
TIDES/COASTAL FLOODING...