000
FXUS61 KOKX 230550
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
150 AM EDT Sun Apr 23 2023
.SYNOPSIS...
A warm front meanders near or over the area into this evening
before a cold front and frontal wave push across the region
tonight into Sunday. Another cold front passes through Sunday
night. Weak low pressure slowly moves farther north and east
early into mid next week while high pressure slowly approaches
but its center stays south and west of the area. One area of low
pressure passes offshore Thursday into Thursday night. High
pressure stays north of the area next Friday with potential for
another low to approach for next Saturday.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Main line of convection continues to push east of the NYC metro
and Hudson River corridor late this evening. The line has
weakened over the last several hours as it moves over a more
stable surface environment. However, there is still enough
elevated CAPE to support thunder and maintenance of elevated
convection through at least 06z.
There have also been some cellular development across eastern
Long Island and SE CT. A few of these cells produced marginally
severe hail. Have noted a downward trend in the strength of this
convection, but some gusty winds and small hail cannot be ruled
out.
The main threat for the rest of tonight is mainly from moderate
to locally heavy rainfall. The severe concern from earlier this
evening has waned.
Maintained a slower progression of the front with blocking over
the North Atlantic and hi-res guidance advancing the boundary
eastward relatively slowly through the region overnight into the
daytime on Sunday.
Total rainfall should largely range between half an inch and an
inch, with a bit higher totals possible (up to 1.5") across
interior Connecticut and the lower Hudson Valley. Fortunately,
with recent dry conditions, the rain should be more beneficial
than anything else.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
While the bulk of the rain pushes east after daybreak Sunday,
given the slower progression of the front, the wet weather
likely lingers into the day Sunday across eastern Long Island
and SE CT, where enhancement from a frontal wave may allow
additional periods of moderate rain.
Winds lighten and veer westerly behind the first front Sunday
morning, with drying conditions and a bend to the NW expected
behind the secondary frontal wave Sunday evening as the trough
continues to advance east over the region.
In much of the area that dries out, the cyclonic flow will aid
scattered cloud cover development on Sunday. Temps on Sunday
should be similar to Saturday, with highs mainly in the 60s.
Another shortwave trough pivots through the area around an upper
low centered to the west late in the day, which should help
push a cold front through, with a chance of a few additional
showers, mainly for the interior, but cannot be ruled out
anywhere.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A mid level low hovering in Southeast Canada will result in a quasi
zonal mid level flow across the region through much of the week.
More of a ridging pattern shown by forecast models for Friday next
week in the mid levels but potential for the ridge to breakdown with
trough development to the south and west for next Saturday.
At the surface, low pressure slowly moves farther north and east of
the area early into midweek. Meanwhile, high pressure will slowly
approach but its center will stay to the south and west. The
pressure gradient will be not be that tight without much change in
the center magnitude of the high and low pressure areas so both the
high and low will not be that strong.
High pressure will weaken across the local area with low pressure
that is forecast to pass well south and east of the area Thursday
into Thursday night.
High pressure stays north of the region Friday with low pressure
possibly impacting the area from the south going into the start of
next weekend.
Weather conditions are forecast to be mainly dry but there could be
an isolated rain shower from time to time, mainly daytime into
evening, in response to periodic shortwave positive vorticity
advection early into midweek. The forcing towards late week will be
with one low pressure passing offshore and with another low at the
surface approaching towards next weekend. By next weekend, the
synoptic flow becomes more southerly ahead of a larger trough.
The forecast has higher chances of rain showers Thursday into
Thursday early evening and Friday afternoon into Friday early
evening as well as next Saturday.
There is a lot of model uncertainty, including significant
differences between the 12Z ECMWF deterministic and its previous run
with regards to the MSLP field for late next week.
Temperatures in the long term forecast do not exhibit much deviation
from normal values. Airmass appears to transition from more of a
continental airmass early in the week to more of a maritime one from
mid to late week. This will be as low level winds transition from
more westerly early in the week to more easterly thereafter.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A wave of low pressure and cold front will move across the area
overnight into Sunday morning.
TSRA now limited from KJFK on east over the next couple of
hours. Showers otherwise, and mainly IFR/MVFR through mid-
morning Sunday before improvement to VFR for the afternoon.
Variable winds returning to more of a SE-S flow for the pre-dawn
hours at around 10 kt, but more SE-E and stronger at KGON.
Winds then shift westerly around 10 kt Sunday morning, with some
gusts up to 20 kt possible for the city terminals.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence in flight categories. There`s a chance that a
return to IFR doesn`t occur for KJFK and KLGA. Otherwise, timing
of flight category improvement later on this morning may be off
by 1-2 hours.
For KJFK, VCTS from 07-09z might not occur or be just far enough
east of the terminal.
OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
Sunday night: VFR.
Monday and Tuesday: VFR. W-NW winds G15-20 kt.
Wednesday: VFR.
Thursday: MVFR or lower in showers.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
SCA conds expand to all ocean waters and continue on the
eastern LI Sound tonight with approaching cold front and wave
of low pressure. Seas come up to around 5 ft on the ocean waters
during this time.
Patchy fog, possibly locally dense, may develop on the waters
tonight ahead of a period of rain along a frontal boundary.
Winds subside behind the frontal passage overnight, but ocean
seas remain elevated near 5 feet into the daytime Sunday and
possibly Sunday night.
With the pressure gradient forecast to remain weak overall Monday
through Thursday night next week, conditions on all waters are
expected to remain below small craft advisory thresholds.
&&
.HYDROLOGY...
No hydrologic impacts are expected through the weekend. A frontal
system could bring 0.75" to 1.25" rainfall tonight into Sunday
morning, with locally higher amounts of up to 1.50" possible
across parts of S CT. Nuisance flooding of urban and poor
drainage areas is the most likely outcome due to antecedent dry
conditions.
No hydrologic problems are expected in the long term period
(Monday through Saturday) at this time.
&&
.TIDES/COASTAL FLOODING...
Minor coastal flooding may be possible with tonight`s high tide
cycle tonight along the south shore bays of Nassau County. A
statement or advy will be issued to address this.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
ANZ332-355.
Small Craft Advisory until midnight EDT tonight for ANZ350-353.-- End Changed Discussion --
&&
$$
AVIATION...JC