Discussion on 2023-04-20

000
FXUS61 KOKX 201739
AFDOKX

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

.SYNOPSIS...
A frontal boundary will remain nearly stationary in the vicinity
of the forecast area through Friday, then lift north as a warm
front Friday night into Saturday morning as a cold front slowly
approaches for the remainder of Saturday. The 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 will pass through Sunday night,
with high pressure slowly building in at the surface through mid
week as an upper level low passes to the north.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --The forecast is mainly on track. Skies have cleared earlier than
previously forecast and have reflected this in the latest
update. Otherwise, surface high pressure pushes offshore today
as high amplitude upper level ridging over the eastern Great
Lakes approaches. Despite a weak frontal boundary in the
vicinity, conditions should remain dry today as forcing with the
front weakens through the day. Veering profiles in the forecast
soundings and building ridge aloft will mean warmer
temperatures for most places today as compared to yesterday.
Highs should top out in the middle to upper 60s away from the
coast. Sea breezes today will keep coastal areas in the middle
50s to lower 60s.-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
The surface high pressure remain off the East Coast as the upper
level ridge slowly approaches. The upper level ridge axis will move
over the area on Friday. Conditions will remain dry through then.
Building heights and continued warm advection seen in the forecast
soundings will mean temperatures will continue to rise through
Friday. Highs will range from the middle to upper 70s away from the
coast, while once again sea breezes keep coastal areas cooler, but
still warmer than Thursday. Expect highs in the lower 60s to lower
70s for these regions.

Models have backed off a bit with light precipitation Friday night
into Saturday morning. However, with the frontal boundary still in
the vicinity and a prolonged period of onshore flow, still think
there will be some isolated showers and/or drizzle as lower level
moisture increases during the time frame. Additionally, fog may also
develop.

The warm front lifts north Friday night into Saturday morning and
the forecast area will be warm sectored. Despite this fact, mostly
cloudy skies will limit diurnal heating, and highs will be a few
degrees cooler than Friday, especially away from the coast.

Chances for showers increase late in the day as lift gradually
increases with the approach of the cold front. However, the main
area of showers associated with the front should remain west of the
region through the day Saturday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The period will start off with a frontal passage as a negatively
tilted upper trough extending SE form a closed low over the upper
Great Lakes into central Canada swings through. A band of moderate
to heavy rain will likely accompany its passage, with a few tstms
possible given combo of strongly forced ascent and marginal
instability. The front should move through most sections by daybreak
Sunday, but chances of showers should continue into daytime Sunday
as the front will be slow to clear SE CT and ern Long Island, and as
the low level flow becomes sluggish in the wake of the fropa, with a
weak area of low pressure lingering to provide continued LL
moisture convergence and lift.

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.

Temps through much of the period should be close to seasonal
averages, with only Sunday being slightly warmer than normal
(mid/upper 60s for highs) before the secondary cold fropa Sunday
evening.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --VFR with high pressure over the area, and a stationary front to
the south. The front is expected to begin moving north as a
warm front tonight, and into the region Friday.

Sea breezes, with a southerly flow, have developed and are
moving through the area. Where sea breezes have not yet arrived
winds were light and variable. KSWF is expected to keep a light
westerly flow through this afternoon. Sea breezes diminish this
evening with winds becoming light and variable by late evening
across the area. Friday morning winds will become SE 5 to 10 kt.


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

No unscheduled AMD expected.

OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday: VFR, becoming MVFR, and possible IFR early Friday
evening, mainly along the coast. Becoming MVFR to IFR across the
area late at night with a slight chance of showers, and drizzle
and fog.

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.

Sunday: MVFR or lower cond possible in showers, especially E of
the NYC metros.

Monday and Tuesday: VFR.

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

&&

.MARINE...
With high pressure pushing east of the waters today, and a warm
front in the vicinity through Friday night, winds and seas
across the forecast waters will remain below advisory levels
tonight through Saturday.

SCA cond expected for all waters ahead of the approaching front Sat
night, with SE flow gusting to 30 kt and occasionally up to 35 kt on
the ocean or the adjacent-most harbor/bay waters near the south
shore of Long Island. By Sunday winds will have died down, with
lingering hazardous ocean seas into at least Sunday night, and
likely into Monday Am on the ern ocean waters.

&&

.HYDROLOGY...
No hydrologic impacts through Saturday.

A frontal system may bring up to an inch of rainfall Saturday night
into Sunday, with brief nuisance flooding possible in urban and poor
drainage areas. Given antecedent dry conditions, no significant
hydrologic impacts expected.

&&

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

&&

$$
SYNOPSIS...BG/JP
NEAR TERM...JP/JT
SHORT TERM...JP
LONG TERM...BG
AVIATION...MET
MARINE...BG/JP
HYDROLOGY...BG/JP