000
FXUS61 KOKX 270511
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
111 AM EDT Sat Apr 27 2024

.SYNOPSIS...
Strong high pressure slides southeast of the region tonight
into Saturday, and farther offshore Saturday Night as a warm
front approaches. The warm front moves through the region Sunday
morning, with a weakening cold front passes through Sunday
Night. Weak high pressure builds across the area Sunday night
into Monday, before a back door cold front works across the area
late in the day Monday. Another frontal system approaches from
the west on Tuesday with a frontal wave passing close to the
area Tuesday night. High pressure then briefly follows for
midweek before yet another frontal system impacts the area
Thursday night into Friday.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
The forecast is on track with only minor changes needed.

Northern stream shortwave trough slides east of northern New
England this evening, with high amplitude upper ridging building
in to the west tonight. At the surface, the center of Canadian
high pressure strengthens southeast of the region tonight.

Another night of good radiational cooling tonight, although
with a slightly moderated and moistened airmass, temps should be
a few degrees warmer than last night. Temps expected to drop
into the lower to mid 30s with frost conditions across interior
of NE NJ, LoHud, and S CT, and pine barrens of LI. Upper 30s to
lower 40s elsewhere, except mid 40s for NYC/NJ metro.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SUNDAY/...
Upper ridging axis builds just to the west of the region
through the weekend. At the same time, good agreement in a
vigorous closed upper low over the northern plains today
shearing through Ontario and Quebec this weekend. This will
briefly flatten the amplitude of the ridge this weekend. At the
surface, the center of Canadian high pressure remains just S/SE
of the area Saturday. Low pressure tracks NE through
Ontario/Quebec this weekend with associated warm front
approaching Saturday Night and lifting NE of the area Sunday AM.

Continued moderation of airmass on Saturday with strengthening
return flow around high pressure to the SE and approaching warm
front to the west. Strong sea breeze signature will likely push
maritime airmass well inland and keeping temps several degrees
below seasonable once again (upper 50s to lower 60s) for much
of the coastal plain, and lower 60s to 65 for far interior. In
addition, increasing high clouds streaming in ahead of
approaching warm front and over the top of the ridge axis will
likely filter sunshine in the afternoon. Appears any light
precip should stay west of the region during the day though.

Models in fairly good agreement signaling a period of showers
Saturday night ahead/along warm front in response to left front
quad of ULJ streak, shortwave energy rounding ridge axis and
theta-e advection of 1 1/2 to 2 std PWAT airmass. Lift and
moisture is modest with instability lacking, so shower activity
should be generally light to moderate.

Forcing lifts north Sunday morning, with warm front dissipating
or lifting north, ending shower threat. Surface troughing
appears to linger over the area, with a weak cold front
approaching late. This, along with a train of weak vorts riding
over the ridge, will likely have considerable cloud cover
lingering over the area. Temps will continue to moderate to
above seasonable levels with strong waa aloft, but still quite a
bit of spread on max temps dependent on cloud cover, seabreeze
timing, and depth of mixing. Deterministic NBM temps are
generally running close to the 25th percentile of the NBM
ensemble spread. Will lean towards a blend of deterministic and
50th percentile of NBM, with potential for temps to be several
degrees warmer than forecast across NYC/NJ metro and interior
with breaks in cloud cover.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
*Key Points*

*Unseasonably warm on Monday, followed by cooler conditions Tuesday,
but still above normal.

*Mainly dry conditions expected with a few chances of showers and
thunderstorms with multiple frontal systems to impact the  area
during the period.

At the start of the period, a highly amplified ridge along the
eastern third of the country will translate eastward, while an upper
low over the Northern Plains lifts up into central Canada.
The latter of which will send a weak frontal system across the area
Tuesday afternoon/night. Before then though, strengthening high
pressure across eastern Canada will send a back door cold front
across New England Monday and across the area by evening. However,
before that happens, Monday could very will be the warmest day this
spring, in fact more summerlike. Ingredients will include the area
being in the warm sector, a high amplitude ridge aloft, and an
offshore flow to start the day (seabreezes in the afternoon). Based
on recent NBM performance in some of these warmer air masses this
spring, along with the MOS, it has been too cool. So for a starting
point, have blended the deterministic NBM with the NBM50th (middle
of distribution). This results in highs in the lower to mid 80s
inland, and generally in the 70s elsewhere. This is about 15 to 20
degrees above normal. This does look short-lived as an easterly flow
behind the back door cold fonts cool things down closer to normal
for Tuesday. What is interesting to note though, the box and whisker
plots of the NBM show a tremendous range in highs Tuesday, in some
cases more than 20 degrees from the 10th to 90th percentiles. This
is most apparent across western sections of the forecast area on the
edge of the maritime airmass.

A dissipating frontal system impacts the area Tuesday afternoon and
evening with a chance of showers and thunderstorm. High pressure
will follow for Wednesday before yet another frontal system
potentially impacts the area late in the week. Temperatures during
this time will still be a above normal (5 to 10 degrees), especially
as one works away from coastal locations during the daytime hours.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
High pressure shifts east as a warm front approaches the region
later today.

VFR through most of the TAF period; MVFR possible early Sunday.

Southerly flow, at times light and variable overnight.
Southerly flow persists on Saturday, with speeds increasing to
10 to 15 kt and gusts of 15 to 20 kt in the afternoon. Lowering
ceilings during the day as a warm front approaches.

Showers cannot be ruled out after 00Z Sunday, though confidence
and coverage remains low. For now, have treated with Prob30s,
with cigs looking to remain high end MVFR 06-12Z Sunday.

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

No unscheduled amendments expected.

OUTLOOK FOR 06Z SUNDAY THROUGH TUESDAY...

Saturday PM: Becoming MVFR late with a chance of rain.

Sunday: Return to VFR by afternoon. Light SW flow.

Monday: VFR. Winds under 10 kt.

Tuesday: MVFR or lower possible with afternoon showers and
isolated thunderstorms.

Wednesday: VFR. Winds under 10 kt.

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

&&

.MARINE...
Winds and seas will remain below advisory levels through early
next week under weal pressure regime. Coastal jet development
Sat aft/eve could have marginal SCA wind gusts (20-25kt) for
ocean waters and nearshore around the entrance to NY Harbor.

Much of next week looks to be below sub-SCA with a weak flow
across the waters. Potential fog development will have to be
watched due to warmer air moving over the colder, but it is much
too early for any specific details on timing and extent.

&&

.HYDROLOGY...
No hydrologic concerns through the end of next week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Frost Advisory until 9 AM EDT this morning for CTZ005>008-012.
NY...Frost Advisory until 9 AM EDT this morning for NYZ067>070-079-
     081.
NJ...Frost Advisory until 9 AM EDT this morning for NJZ002.
MARINE...None.

&&

$$

SYNOPSIS...NV/DW
NEAR TERM...JP/NV/DW
SHORT TERM...NV
LONG TERM...DW
AVIATION...JP/DBR
MARINE...NV/DW
HYDROLOGY...NV/DW