000
FXUS61 KOKX 100601
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
201 AM EDT Wed Apr 10 2024
.SYNOPSIS...
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High pressure over eastern Canada will build east of New England
overnight, allowing a dissipating back door cold front to work
across from the east. At the same time, a warm front approaching
form the west will become stationary just west of the area
tonight into Wednesday, then lift north on Thursday as deepening
low pressure draws closer over the Ohio Valley. A cold front
will move through early Friday. As low pressure departs, a
secondary cold front will swing through early Saturday. High
pressure will then briefly nose in from the south into Sunday.
Another frontal system could move through on Monday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Upper level ridging between a closed low north of the Great
Lakes and another east of the Canadian Maritimes will translate
east across the area overnight. A confluent flow across eastern
Canada and the Northeast will also allow surface high pressure
to build south from Canada and across the waters east of New
England. The building high will send a dissipating back door
cold front west across the areas this evening into the first
half of tonight. At the same time, warm advection on the
backside of the ridge will send a warm front toward the area
from the west. The latter of which will stall before reaching
the area.
Large scale warm advection will allow for increasing mid and
high level clouds to lower overnight. Rain chances will be low
with a slight chance rain toward daybreak for mainly NE NJ and
the Lower Hudson Valley. Plenty of dry air with low-level
ridging poking in from the east will take some time to saturate.
As for temperatures, with winds becoming easterly tonight at 10
mph or less and increasing clouds, opted to go warmer than the
MOS and NBM, leaned toward the CONSALL. This will keep lows 7-10
degrees above normal, in the lower 40s eastern sections, to
the mid/upper 40s for NYC, NE NJ and the Lower Hudson Valley.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Upper level ridge axis slips east of the area on Wednesday with
a low chance for some showers working from west to east across
the area during the day. Lift is weak and will combat a drier
airmass across eastern sections of the area. Rainfall amounts
will generally be less than a tenth of an inch. Stationary front
lifts north Wednesday night as an amplifying longwave trough
approaches works across the mid section of the country. Once
again though, rain chances will be low with any rainfall amounts
being light.
For temperatures, stayed below MOS and NBM by several degrees on
Wednesday due to the cloud cover and maritime airmass. Highs
are forecast to remain in the 50s, which is close to normal. For
Wednesday night, also went a bit warmer for the same reasons
with lows mid 40 to around 50.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A surface low over the deep south on Wednesday will strengthen
and track into the eastern Great Lakes on Thursday in tandem
with a deepening upper-level trough to our west. This low will
then move to our north Friday.
A warm front ahead of the low will arrive Thursday morning and
will push north Thursday afternoon. Showers will develop with
the warm front aided by warm air advection and waves of mid-
level energy starting to arrive ahead of the low. Showers will
become more prevalent through the day as southerly flow
increases, advecting in more moisture from the Gulf stream. Peak
moisture with a strong LLJ will occur Thursday night into early
Friday morning with the latest 12Z guidance hinting at 1.3-1.6"
PWATs. This is at and above the max moving average of 1.36" for
this time of year according to SPC`s Sounding Climatology. This
may be further aided by a jet streak nearby placing us in the
left exit region during this same time frame. Its possible to
have periods of moderate to heavy rain overnight Thursday into
early Friday morning. The 13Z NBM currently gives a 30-40%
chance for at least 0.5" in 6 hours. Given the quick progression
of the LLJ and following cold front, the period of moderate to
heavy rainfall may not last long enough to meet flash flood
guidance. Only minor urban and poor drainage flooding is
expected, along with the potential for minor flooding at flashy
small streams/rivers. The areas of higher rainfall are likely to
be in the interior portions of our CWA in NY and CT. Currently
forecasting a large gradient of rainfall for the event with
southeastern portions of the CWA racking up 0.75" while
northwestern portions of the CWA total around 1.5".
A south-to-north oriented LLJ will start to build on Thursday,
reaching its peak of near 70 kt along coastal areas Thursday
night into Friday morning as it propagates west to east. Some
models have been bullish on surface winds speeds.
Climatologically speaking, colder waters in early Spring would
lead to a stronger inversion, thus preventing some of it from
mixing down to the surface. This is supported in model soundings
showing a stronger inversion. Currently forecasting peak gusts
of 35-40 kt (40-45 mph) along Long Island and other southern
coastal areas late Thursday night into Friday morning.
Showers become scattered and lighter Friday afternoon, then
taper off Friday evening and Friday night as the low exits to
the north with a second cold front on Saturday. Winds will
remain breezy until Saturday morning as the pressure gradient
weakens. A deeper trough will center itself over the region
during this time frame, becoming zonal and weakening Saturday
into Sunday. At the same time, high pressure will briefly nose
in from the south leading to dry conditions Saturday night
through most of Sunday. Model guidance disagrees on Monday, but
will likely see the trough to our north begin to drop with some
mid-level energy swinging in on Monday which may provide a
chance for scattered showers on Monday along with a cold front.
High temperatures will be in the mid 60s to the west and in the
mid 50s to the east on Thursday with temperatures more uniform
on Friday near 60. Saturday will be cooler in the 50s due to a
cold front then warm into the mid 60s to mid 70s by Monday.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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VFR with high pressure the rest of tonight.
Winds back SE-E tonight, then increase to near 10 kt daytime
Wed. MVFR cigs develop in the late morning/early afternoon and
then IFR, especially eastern terminals. There are indications
that MVFR or even IFR cigs could develop along the NJ coast late
tonight and expand northward to the NYC metros between 11Z-13Z,
so this will have to be watched closely.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
MVFR or even IFR cigs could arrive as early as 11Z-13Z. Low
confidence in this worst case scenario attm.
OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
Wednesday night: IFR cond developing with chance of showers.
Thursday: IFR with chance of showers AM, then showers likely
with IFR/MVFR PM. SE winds G20-25kt.
Thursday night: IFR with showers. SE winds G30-35kt with LLWS.
Friday: IFR cond with showers and S winds G30-35kt AM. MVFR
with chance of showers PM and SW winds G30-35kt.
Saturday: Chance of MVFR in showers mainly NW of the NYC
metros, otherwise VFR. W-NW winds G30-35kt.
Sunday: Mainly VFR. Chance of MVFR and showers in the afternoon.
SW-W winds G25kt.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
A weak easterly flow across the waters through Wednesday night
will result in sub-SCA conditions.
As low pressure gets better organized to the west on Thursday
and a warm front lifts north, expect a stronger S-SE flow to
develop, with SCA cond increasingly likely later in the day.
Winds will be ramping up Thursday night with the approach of a
strong low pressure system. Southerly winds will peak late
Thursday night into Friday morning with sustained winds 30-35 kt
and gusts 40-45 kt. Added a mention of gales to the HWO for this
period. Ocean seas peak Friday morning around 12-14 ft. Seas on
Long Island Sound will also likely reach 5-7 ft, with the higher
seas closer to CT coast given the southerly flow.
SCA cond will likely linger on all waters through Saturday as
wind gusts remain around 25 kt. Sub-SCA conditions expected
thereafter, except on the ocean waters where 5-7 ft seas
could linger.
&&
.HYDROLOGY...
It`s possible to have periods of moderate to heavy rain
overnight Thursday into early Friday morning. The 13Z NBM gave a
30-40% chance for at least 1/2 inch in 6 hours. Given the quick
progression of the LLJ and following cold front, the period of
moderate to heavy rainfall may not last long enough to meet
flash flood guidance. Only minor urban and poor drainage
flooding is expected, along with the potential for minor
flooding of flashier small streams/rivers. The areas of higher
rainfall are likely to be in the interior portions of our CWA in
NY and CT. Currently forecasting a large gradient of rainfall
for the event with southeastern portions of the CWA racking up
3/4 inch, while NW portions of the CWA total 1.5 inches.
&&
.TIDES/COASTAL FLOODING...
Astronomical high tides remain elevated with the new moon /
spring tide set up from early this week. Additional rounds of
minor flooding appear likely through mid to late week for the
same areas that experienced any coastal flooding from previous
high tide cycles, as tidal departures needed for minor drop as
low as 1/4 ft thru Wed eve high tide. Localized pockets of
moderate coastal flooding remains a possibility for the
western south shore back bays.
Coastal Flood Advisories remain in effect for tonight`s high
tide cycle for tidal NE NJ, S Queens/Nassau, and S
Fairfield/Westchester. Up to 1 to 1.5 ft of inundation above
ground level is expected in the most vulnerable locations near
the waterfront. Coastal Flood statements have also been issued
elsewhere except for the Bronx, NE Suffolk and S New London.
Strengthening SE-S flow with a storm system late Thursday into
Friday morning may force more widespread minor to moderate
coastal flooding.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory until 2 AM EDT early this morning for
CTZ009.
NY...Coastal Flood Advisory until 2 AM EDT early this morning for
NYZ071.
NJ...None.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...BR/DW
NEAR TERM...JE/BR/DW
SHORT TERM...DW
LONG TERM...BR
AVIATION...JT
MARINE...BR/DW
HYDROLOGY...BR/DW
TIDES/COASTAL FLOODING...