000
FXUS61 KOKX 211405
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1005 AM EDT Fri Apr 21 2023
.SYNOPSIS...
A warm front to the south will approach tonight but remain to
the south through Saturday. A cold front will slowly approach on
Saturday and move through late Saturday night into Sunday
morning. Another cold front will pass Sunday night, with high
pressure to the west slow to build in thereafter as weak low
pressure lingers along the New England coast through Tuesday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
The forecast is on track with only minor changes needed.
High amplitude upper level ridge axis pushes east of the area
today. This will allow an upper low over the western Great Lakes
region to slowly approach as the surface low associated with
the fill and weakens. A surface warm front will remain south of
the area.
Ahead of the front, persistent easterly flow picks up and low
level moisture increases under an inversion. Guidance continues
to show low stratus developing off the southern NJ coast and
then spreading over the area late this afternoon into this
evening.
Temperatures away from the coast will be above normal for this
time of year, with highs in the lower to middle 70s. Along the
coast, an easterly flow will limit temperatures, and highs in
the 60s and even some 50s are expected.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
The persistent easterly flow will allow for areas of fog and
possibly drizzle Friday night. There is the potential for some dense
fog, but that is a fair amount of uncertainty at this time. Any fog
and low clouds will burn off by around or just after daybreak
Saturday.
The warm front remains to the south and actually may not make it
through the region at all, though if it doesn`t, it will be close to
the region by late in the day Saturday into Saturday night to be the
focus for some showers and possibly a thunderstorm out ahead of the
approaching cold front. Additionally, a narrow corridor of Atlantic
moisture transport ahead of the front via increasing LLJ, as well as
enhanced lift ahead of a wave of low pressure along the approaching
front, results in a band of showers, and possibly a few embedded
thunderstorms, moving through the area late Saturday evening and
night.
The cold front will begin to move through the forecast area Saturday
night. Mesoscale models show a decent line of moderate to
briefly heavy showers with likely isolated thunderstorm to move
through with the passage of the cold front. The development of
any low pressure systems along the frontal boundary will aid in
enhancing any precipitation. In addition, the LLJ strengthening
to around 40 to 50 kt at around 2 kft just ahead of the front
will aid in convection formation and heavier precipitation. The
LLJ will also mean a few gusts likely in the 30 to 40 mph range
Saturday night, especially with any convection ahead of the
front.
Given a fairly progressive flow, the steadier rain moves through
much of the forecast area and exits by Sunday morning, with eastern
areas ending by the end of the day Sunday. However, an upper level
shortwave moving around the base of an upper level low just
northwest of the Great Lakes could mean light showers continue for
central and western portions of the forecast area. Total rainfall
generally ranges between three-quarters of an inch and an inch, with
up to an inch and a half across interior Connecticut.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A potent upper level shortwave trough swinging across Sunday night
will help push a secondary cold front through Sunday night. After
this wave aloft passes, an upper trough extending SE from a closed
low near the upper Great Lakes will maintain weak low pressure along
the New England coast through Tuesday, so high pressure to the west
will be slow to build in, and there will be chances for showers
mainly across srn CT and adjacent portions of the lower Hudson
Valley. The low should weak enough to let the high to the west build
in for Wed/Thu.
Temps during the period will be typical of late April, on the cooler
side through Tue with highs in the upper 50s/lower 60s while more
under the influence of the low to the east, then a little warmer
Wed/Thu with lower/mid 60s.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
High pressure to the east will continue to drift farther east
through this afternoon. A warm front will approach tonight.
Winds today increase this morning and become E-SE either side
of 10 kt, mainly stronger closer to the coast and with some
gusts 15-18 kt mainly at the coastal terminals. Winds should
back a little more easterly and slowly diminish this evening.
VFR most of today. As the warm front approaches, cigs/vsby
should lower this evening. At the NYC metros, MVFR cigs may be
possible as early as 22Z, more importantly IFR cigs should
arrive there after about 00Z-01Z, with LIFR by 03Z-05Z. Farther
north and east, IFR possible at KISP/KHPN/KBDR by 03Z-04Z. MVFR
cigs should arrive at KSWF/KGON about that same time, and may
not go IFR at all.
Guidance indicates possible improvement before 12Z Sat but that
is uncertain.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD likely this afternoon and evening to fine-tune wind
forecast and arrival of lower cigs late today or this evening.
OUTLOOK FOR 06Z FRIDAY THROUGH TUESDAY...
Saturday: Conditions may improve to VFR in the morning, then
MVFR, possibly IFR redevelop during the late day and at night,
with showers arriving. Slight chance of thunder at night. SE
winds G20-25 kt in the afternoon and at night.
Sunday: MVFR or lower in showers, especially E of the NYC metros. SW-
W wind gusts 15-20 kt during day, W-NW wind G15-20 kt at night.
Monday and Tuesday: VFR. W-NW winds G15-20 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
Monday and Tuesday: VFR. W-NW winds G15-20 kt.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
-- Changed Discussion --
Expect sub-SCA conditions in a gradually strengthening east
flow today. As a warm front approaches from the south tonight
into Saturday. a weak pressure gradient will keep winds and seas
below SCA criteria through early Saturday. Areas of fog may
develop tonight, with the possibility of dense fog affecting the
waters. However, there is some uncertainty with how dense the
fog will become.
SCA conditions likely develop on all waters Saturday afternoon into
Saturday night ahead of an approaching cold front and wave of low
pressure. Brief SE-S gales may be possible especially on the ocean
and the adjacent lower harbor/bay waters late Sat night in
association with convection along a cold front that will move
through.
SCA cond possible on the ocean and also the western Sound/Harbor for
Sunday night/Mon AM, with gusts up to 25 kt in offshore flow after a
frontal passage, and ocean seas as high as 5 ft.
Winds could also gust as high as 25 kt on the outer ocean waters
late Mon night into Tue AM.-- End Changed Discussion --
&&
.HYDROLOGY...
-- Changed Discussion --
No hydrologic impacts are expected through the weekend. A frontal
system could bring 0.75" to 1.25" rainfall from Sat night into
Sunday morning, with locally higher amounts of around 1.50"
possible, leading to nuisance impacts being the most likely
outcome due to antecedent dry conditions.
No hydrologic impacts expected from Monday onward.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
UPDATE...DW
AVIATION...BG/JT