000
FXUS61 KOKX 211454
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1054 AM EDT Thu Mar 21 2024
.SYNOPSIS...
High pressure builds into the area today and will remain in
control tonight into Friday. A frontal system approaches Friday
night and moves across the region along with low pressure
Saturday into Saturday night. High pressure ridges down from
the north Sunday into Monday as low pressure slowly pushes
further offshore. A frontal system approaches from the west
midweek.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Forecast on track this morning. Cold, dry advection will
continue leading to unseasonably chilly temperatures across
the region. Surface high pressure will build in from the west,
but its center will remain over the Great Lakes and Ohio Valley.
Low pressure continues to depart to the northeast across the
Maritimes. The pressure gradient between the two systems will be
enough to bring gusty NW winds through the day, generally 25 to
30 mph. Wind should begin to weaken late in the day as the
gradient starts relaxing and the high draws closer. Highs will
only be in the upper 30s inland to the lower 40s closer to the
coast.
High pressure settles over the area tonight with winds diminishing.
Mainly clear skies will be in place allowing for ideal radiational
cooling conditions. Lows range from the upper teens/low 20s inland
to low-mid 20s most elsewhere. Winds may stay up just enough in the
NYC metro, so lows should be in the mid-upper 20s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
High pressure remains in control Friday with temperatures
below normal in the lower to middle 40s. A southern stream
shortwave and associated low pressure will be moving across the
southeast on Friday. At the same time, a northern stream broad
upper trough and associated frontal system will be moving across
the Great Lakes and Ohio Valley. These two features will begin
interacting Friday night leading to a significant rainfall
event late Friday night into the first half of Saturday night.
*Key Messages*
*Moderate to locally heavy rainfall is becoming increasingly
likely beginning as early as late Friday night and continuing
into the first half of Saturday night.
*Forecast rainfall amounts range from 2-3 inches for much of the
area with locally higher amounts possible. Amounts may be
slightly lower across the Lower Hudson Valley. However, the
exact placement of the heaviest rain is still a bit uncertain
leading to a risk of higher totals even across the NW.
*Preliminary analysis of hourly rates indicate potential for 0.5
to 1 inch and hour are possible. These will need to be refined
in subsequent forecasts, especially as the system gets into
the time window of the high res models (HREF).
*Minor flooding appears to be the main threat at this time given
it is a relatively long duration rainfall event (6-12 hours).
However, we cannot completely rule out a localized flash flood
occurrence.
*Increasing concerns for a few rivers/streams to exceed bankfull,
especially if the higher rainfall amounts were to verify across
NE NJ and Southern CT. This will be refined in the next 24-36
hours as we begin to get a look at higher res model data for the
placement of the heaviest rainfall.
*Winds with this system are not too strong and should generally
be 25 mph or less for much of the area except the coast. Wind
gusts actually increase (25-35 mph) after the rainfall on the
backside of the system for Saturday night.
*Coastal flooding/beach erosion risk appears low at this time.
The aforementioned northern stream frontal system should be
nearing the region early Saturday morning. Low pressure over
the southeast will interact with this boundary helping to
enhance rainfall up into the northeast. The northern stream and
southern stream will then start interacting bring the low
pressure towards Long Island by Saturday evening. Strong warm
advection, deep moisture, and strong large scale lift are all
present on Saturday. The region will also lie to south of
150-170 kt upper jet over southeast Canada and northern New
England helping to enhance the lift over the region. The
interaction with a frontal boundary also presents concerns for
enhance moisture convergence. There will be enough progression
of these systems, but there are signals present on much of the
guidance supporting a heavy rainfall threat. Have also noted NBM
probabilities increasing over the last few days for seeing
greater than 2 inches. Uncertainty is greatest with the exact
location of the heaviest rain, which should be refined in the
next 24-36 hours as the system gets into the time range of the
HREF.
The low pressure pushes east of the area Saturday night with rain
tapering off from west to east. Most of the rain should be over
around midnight based on the latest model consensus. Northerly flow
will quickly increase behind the system leading to gusty winds
Saturday night, potentially 25-35 mph and strongest near the coast.
Temperatures on Saturday should be able to rise into the lower to
potentially middle 50s for all except the Lower Hudson Valley.
Temperatures Saturday night quickly drop back into the 30s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
No significant changes made to the long term, and stuck fairly
close to the NBM for the period. Ensemble means depict mean
troughing over the northeast to start the period with mean
ridging building east by midweek.
*Key Messages*
* Lingering showers Sunday gives way to a short dry stretch Monday
and Tuesday.
* Unsettled, wet weather returns Wednesday and Thursday.
* Normal to slightly below normal high temperatures Sunday and
Monday with a warm up to above normal temperatures by midweek.
Sfc low pressure continues to pull away from the region on Sunday,
with lingering clouds and showers Sun AM, mainly across eastern
sections of the CWA. Winds will remain elevated for at least the
first half of Sunday as cloud cover continues to decrease with the
departing system. Thereafter, high pressure builds in to the north
which will result in NNE flow, and dry conditions though early
Wednesday.
Thereafter, the high heads east of the Canadian Maritimes as a
surface low develops over the Northern Plains and heads east.
This system will bring a frontal system to the area Wednesday
and Thursday, with increasing precip chances starting Wednesday.
Some global guidance is hinting at a secondary low developing
along the cold front to the south, potentially prolonging
precipitation chances locally into Thursday. Given this, have
maintained chance PoPs through much of Thursday.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure this afternoon through Friday.
VFR.
NW winds and gusts 15-25kt with G30kt will be diminishing after
00Z Friday. Winds becoming W around 10 kt.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
12z Friday: VFR.
Friday night: MVFR or lower developing after midnight with rain near
the coast and rain/snow inland.
Saturday: IFR and rain. SE wind gusts 20-25kt during the day with
LLWS possible city east, becoming N all areas with gusts 30-35kt at
night.
Sunday: VFR. A slight chance of rain. N-NE wind gusts around 25kt.
Monday: VFR. NE gusts 20-25kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
The Gale Warning on the NY Harbor, LI Sound and LI Bays has been
converted over to a SCA and it goes through 10pm. Gales on the
ocean continue through midday with SCA conditions likely through
tonight. A relaxed pressure gradient will result in quieter
conditions Friday increasing onshore flow Friday night will
develop SCA conditions by Saturday morning on the ocean, and by
the afternoon for the eastern bays and LI Sound. Widespread SCA
conditions with gales on the ocean appears likely Saturday
night.
Gales look likely to continue through at least Sunday afternoon
on the ocean waters and eastern LI sound. This period of gales
may possibly last into Monday night, especially on the ocean
waters. SCA conditions are likely elsewhere into Monday.
&&
.FIRE WEATHER...
Based on collaboration with Fire WX partners and WFO BOX/ALY, have
issued an SPS for southern CT with elevated fire weather concerns
today. Gusty winds around 25 mph are expected with Min RH values
25-30 percent.
&&
.HYDROLOGY...
Moderate to locally heavy rainfall is becoming increasingly likely
late Friday night into the first half of Saturday night.
Forecast rainfall amounts range from 2-3 inches for much of the area
with locally higher amounts possible. Amounts may be slightly lower
across the Lower Hudson Valley. However, the exact placement of the
heaviest rain is still a bit uncertain leading to a risk of higher
totals even across the NW.
Minor flooding appears to be the main threat at this time given it
is a relatively long duration rainfall event (6-12 hours).
However, an isolated flash flood occurrence cannot be ruled out.
There are also increasing concerns for a few rivers/streams to
exceed bankfull, especially if higher rainfall amounts were to
verify across NE NJ and Southern CT. This is hinted at on the latest
MMEFS data, especially for the Saddle River at Lodi, where the GEFS
data is showing a 21 percent probability of reaching moderate flood
stage.
Residual river flooding may continue into Sunday should higher
rainfall amounts be realized over the faster responding basins.
Otherwise, no hydrologic impacts are expected from Sunday onward.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ331-
332-335-338-340-345.
Gale Warning until noon EDT today for ANZ350-353-355.
&&
$$
SYNOPSIS...DBR/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...DBR
AVIATION...IRD
MARINE...DBR/DS
FIRE WEATHER...
HYDROLOGY...DBR/DS