Discussion on 2023-04-20

000
FXUS61 KOKX 210018
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
818 PM EDT Thu Apr 20 2023

.SYNOPSIS...
High pressure shifts east of the area tonight. A frontal
boundary will remain nearly stationary just south of the area
through Friday, then lift north as a warm front Friday night
into Saturday morning. An associated cold front will move
through Saturday night into early Sunday morning, with weak low
pressure lingering over the area in its wake through Sunday
afternoon. Another cold front passes through Sunday night, with
high pressure slowly building into the area early next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Mostly clear skies and light winds continue tonight as weak
high pressure builds in. Forecast remains on track and previous
discussion follows.

Surface high pressure continues to shift east of the area
tonight while an upper level ridge builds in aloft. A frontal
boundary remains nearly stationary just to our south.

Given a weak pressure gradient over the area, winds will be
very light overnight. This coupled with clear to mostly clear
skies will allow for the usual spots to take advantage of good
radiational cooling conditions. The interior and the LI Pine
Barrens likely drop to the upper 30s to lower 40s. The NYC/NJ
metro area will bottom out in the lower 50s.-- End Changed Discussion --

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Friday starts out sunny for all, as the upper level ridge axis
passes overhead around late morning. The aforementioned front
starts to slowly lift north closer to the area. Ahead of the
front, easterly flow picks up and low level moisture increases
under an inversion. High-res guidance shows low stratus
developing off the southern NJ coast and then spreading over
the area from Friday afternoon through Friday night. High
temperatures will depend on the timing of these clouds. Have
continued the trend downward in highs for tomorrow. The Lower
Hudson Valley and interior CT will likely be the warmest as they
will have the most sunshine. Low to mid 70s are expected there.
The NYC/NJ metro area is expected to reach the low 70s and LI
and coastal CT top out int he mid to upper 60s.

As moisture continues to increase, patchy fog and drizzle are
possible overnight Friday. Lows Friday night will be about 5 to
10 degrees warmer than Thursday night.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Heights fall to start the period with the exit of an upper ridge and
the entrance of a closed low trough swinging into the Upper Great
Lakes. Despite the gradually lowering cloud deck, the bulk of
Saturday appears dry as an attendant cold front and developing
frontal wave approach late in the day. Ahead of this, temperatures
climb from the 50s into the lower 70s away from the coast, and about
10 degrees cooler for coastal areas with the maritime influence
(water temps remain in the 40s and lower 50s).

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. With the LLJ strengthening to
around 40 to 50 kt just ahead of the front, this will allow
increasing SE flow at the surface, with 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 rain moves
through and exits by Sunday morning. Total rainfall generally ranges
between half an inch and an inch, with a bit higher totals possible
across interior Connecticut.

Guidance indicates the fropa early Sunday AM, with a secondary front
following later in the day Sunday. The slower progression means
clouds hang on through the day, but the bulk of the wet weather
clears east of the region by 15z Sunday. 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.

Another potent mid level disturbance pushing across Sunday evening
should help to establish low level CAA and drying conditions going
into early/mid next week. While sfc high pressure tries to build in,
the omega block should transition into more of a rex block, with the
upper high well to the north over nrn Quebec and the Davis Strait,
and the earlier Great Lakes upper low now passing across the
Northeast and New England. Disturbances riding the periphery of the
closed low along with weak lee troughing and cyclonic flow in
general should maintain more clouds than sunshine, and result in a
slight chance of showers mainly across the interior. Given this,
temperatures next week will be a bit cooler than previous days,
highs mostly in the 60s into midweek. National blended guidance was
largely followed.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --High pressure moves east of the region tonight with a stationary
front remaining south of the region through Friday. The front
returns north as a warm front Friday night.

VFR conditions expected through Friday. There will be chances
for MVFR late Friday afternoon with MVFR becoming likely Friday
night with lowering clouds and fog development.

Southerly winds near 5-8 kts this evening will become light, at
or less than 5 kts, with variable direction by mid evening to
the start of the overnight period. Winds will increase Friday
morning to near 7-10 kts and become more SE, further increasing
to near 10-12 kts Friday afternoon. A few gusts to 15-20 kt will
be possible Friday afternoon into early Friday evening.


 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Amendments probable Friday afternoon into Friday night to refine
the timing of MVFR and IFR.

OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday night: IFR probable early Friday night, becoming more
likely late Friday evening and overnight with lowering clouds
and fog. Potential for drizzle but may not be present at all
terminals.

Saturday: Conditions may improve to VFR in the morning, then MVFR,
possibly IFR develop during the late day and at night, with showers
arriving. Slight chance of thunder at night. SE wind gusts near
20-25 kt during 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 gusts
15-20 kt at night.

Monday and Tuesday: VFR. W-NW wind gusts 15-20 kt.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --

&&

.MARINE...
With a weak pressure gradient over the area, winds and waves will
remain below SCA criteria through early Saturday.

SCA cond likely develop on all waters late Saturday 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.

Winds diminish from west to east Sunday morning, returning to sub-
SCA cond on sheltered waters. Seas lower under 5 ft on the ocean by
Monday morning.

&&

.HYDROLOGY...
A frontal system may bring up to an inch of rainfall late Saturday
evening into early Sunday morning, with brief nuisance flooding
possible in urban and poor drainage areas. Given antecedent dry
conditions, no significant hydrologic impacts expected through mid
next week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...DR/JT
NEAR TERM...DR/JT
SHORT TERM...JT
LONG TERM...DR
AVIATION...JM
MARINE...DR/JT
HYDROLOGY...DR/JT