000
FXUS61 KOKX 112119
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
519 PM EDT Wed Oct 11 2023
.SYNOPSIS...
Weakening low pressure north of the Great Lakes will track slowly
across eastern Canada through the end of the week. Weak high
pressure will set up over the northeast through Friday. Low
pressure then passes to our south this weekend. Weak high
pressure will be left in its wake on Monday before another area
of low pressure potentially impacts the region on Tuesday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
Forecast remains on track with the exception of dewpoints that
were running a little dry in spots compared to the forecast.
They were adjusted based on the current observations and some
blending with the GLAMP which seemed to have the best handle on
current observations.
The main weather feature will continue to be the stacked low north
of the Great Lakes tonight which will slowly track east overnight as
it weakens. A weak area of low pressure passes well south and east
of Long Island. Any daytime cumulus is expected to diminish quickly
after sunset with the loss of daytime heating, leaving a mostly
clear sky overnight. With light and variable winds, this will mean a
good night for radiational cooling in the outlying ares. Lows inland
and into the Long Island Pine Barrens should drop to around 40, with
isolated upper 30s possible. Elsewhere, temperatures will be
normal for this time of year, in the upper 40s to lower 50s.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The stacked low will continue to weaken and track east and will be
situated over the Canadian Maritimes by daybreak Friday, with the
trough axis also pushing east Thursday night. A weak cold front will
move through late Thursday night, but with limited moisture to work
with, it should move through dry.
Enough instability will allow for daytime fair weather cumulus
during the day Thursday, with the clouds once again diminishing
around or just after sunset. Another good night is expected for
radiational. With a light northwesterly flow developing after
the cold frontal passage, slightly cooler readings are expected
Thursday night as compared to Wednesday night.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
High pressure will briefly build out of southern Canada ahead of the
next upper low on Friday. The confluent flow aloft will likely lead
to mostly sunny conditions for Friday. Clouds should begin to
increase from west to east Friday night staying dry through Friday
night.
Thicknesses lower on Friday which should bring temperatures closer
to normal in the lower to middle 60s. Nighttime temperatures are
expected to be in the 40s inland and lower 50s closer to the coast.
A shortwave embedded in a longwave trough at 500mb digs through the
Ohio River Valley and Mid-Atlantic on Saturday before emerging off
the eastern seaboard early Sunday, then lifting NE Sunday night.
Meanwhile, a blocking 500mb low lingers over the southern Canadian
Maritimes through the weekend before shifting NE.
At the surface, low pressure to the west transfers energy to a
developing low off the Mid-Atlantic coast that passes to our SE
Saturday night into Sunday morning. This system is starting to look
more progressive as the 500mb low over the south Canadian Maritimes
and spoke of energy dropping south through the eastern Great Lakes
Region help steer the storm center eastward to our south before it
gains strength while moving NE over the Atlantic. This shift has
continued to trend more southward in the latest 12Z guidance. Rather
than a prolonged rain event, it looks like this will be a quicker
moving system when it arrives Saturday and will depart early Sunday.
The southward trend will leave lower chances for rain for northern
portions of the CWA and higher chances for rain for southern
portions of the CWA. The 12Z GFS and 12Z GDPS seem to leave some of
the northern portions of the CWA completely dry. The 12Z ECMWF still
shifts south, but it does not go quite as far south with the system,
so I have not dropped POPs altogether for this reason. Confidence in
track of this system is still low and may change as the event nears.
Overall, trends are looking better for flooding concerns with 0.5-1"
of rain now expected across the area, rather than 1-2", with higher
totals south and lower totals north. For more, see the hydrology
section. The 12Z Grand Ensemble which combines the GEFS, CMC and EPS
gives no greater than 25% chance for 0.5" and only for southern
portions of the CWA. The system will still lower temperatures in the
mid/upper 50s on Saturday with temperatures warming to near 60 along
the coast on Sunday.
Cyclonic flow aloft remains on Monday and Tuesday. A 500mb low
develops west or over the CWA in conjunction with a surface low
developing near us or to our south, sustaining a chance of showers
with cloud cover and cooler temperatures.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
Weak high pressure remains in place into Thursday afternoon.
VFR.
Southwest to south winds less than 10 kt may occasionally gust
up to 20 kt this afternoon. Winds become light and variable at
all the terminals this evening. A light westerly flow develops
Thursday morning with the timing uncertain.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Occasional wind gusts up to 20 kt possible through the
afternoon. There is a chance of late afternoon sea breeze at
KJFK. The sea breeze is not expected to reach father inland.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday afternoon through Friday: VFR.
Saturday-Sunday: MVFR/IFR in rain. NE winds 10-20G15-25KT,
becoming N Sunday.
Monday: MVFR with a chance of rain.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
A relatively weak pressure gradient will lead to winds and seas
below SCA levels through the remainder of the week.
Low pressure then approaches the Mid-Atlantic coast Friday night
into Saturday with winds veering ENE and increasing through the day
and night as a frontal system approaches us from the west. This will
help push wave heights above 5 feet over the ocean very late
SAturday night through Sunday night with advisory-level wind gusts
on the ocean waters only.
&&
.HYDROLOGY...
No hydrologic impacts are expected through Friday night.
Current forecast has 0.5-1" of rain for Saturday through Sunday.
Based on current flash flood guidance, there little risk for flash
flooding at this time. Still can`t rule out future changes in
guidance regarding potential rain amounts depending on the changing
trajectory of this weekend`s system. We also need to consider that
soil moisture, while decreasing through Friday, will still be high
enough to not completely rule out isolated flash flood potential if
more rain than currently forecast were to fall.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JP/BR
NEAR TERM...JP/BR
SHORT TERM...JP
LONG TERM...BR
AVIATION...MET
MARINE...JP/BR
HYDROLOGY...JP/BR