809
FXUS61 KOKX 221356
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
956 AM EDT Wed May 22 2024
.SYNOPSIS...
High pressure will be in control through tonight, then give way
to an approaching cold front on Thursday which moves through
Thursday night into Friday. Weak high pressure builds in for
Friday night. A weak trough moves through the area Saturday. A
deep low pressure system tracks through the Great Lakes and into
Canada Sunday night through Tuesday with the system`s warm
front passing north Sunday, with the cold front moving through
Monday night into Tuesday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
The forecast is on track this morning. Current temperature obs
and trends support the previous forecast high temperature
thinking for most areas. The north shore of Long Island was
running a bit warmer than forecast, but should level off or even
lower as the flow becomes more southerly and picks up a bit.
High pressure offshore today will continue a light southerly
flow, continuing to advect a warm and humid air mass into the
region, with 850 hPa temperatures in the 15 to 17 C range. This
should translate to highs in the middle to upper 80s away from
the coast, while highs along the coast will be in the upper 60s
to upper 70s thanks to the relatively cooler ocean temperatures.
A pre-frontal trough and cold front slowly approach from the
west, with much of the day and area remaining dry. However,
there may be isolated showers and possibly a thunderstorm
across northeast New Jersey and the Lower Hudson Valley before
the day ends. While CAPE values should rise to the 1000-2000
J/kg rang for this area, and lift increases as the pre-frontal
trough moves in, not expecting anything strong or severe as
shear values are rather low.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
The pre-frontal trough and cold front continue their approach
Wednesday night, with chances for showers and an isolated
thunderstorm slowly spreading east thanks to stability
increasing after sunset.
A warm night is expected as continued southerly flow and more
in the way of clouds help to keep temperatures up. Lows should
range from the upper 50s along the coast, to lower to middle 60s
elsewhere, except upper 60s in the NYC metro area.
Better chances for stronger storms on Thursday as the cold front
begins to move through. Instability away from the coast will
once again range in the 1000-2000 J/kg range, with steep low
level lapse rates. Shear seems to be a bit of a limiting factor
for the severe threat, with 0-6 km shear of 30-40 kt. So, strong
storms with isolated severe is possible. The Storm Prediction
Center has placed the entire forecast area in a marginal threat
for severe storms, with the main threat being damaging winds,
and possibly severe hail. A number of CAMs are showing a complex
of showers and thunderstorms moving across northeast New
Jersey, NYC, and Long Island in the afternoon. However, the
instability is lower here thanks to onshore flow, but there is a
fair amount of elevated instability, so cannot rule out a
severe storm here as well.
The cold front pushes through late Thursday night into Friday
morning. The chance for showers and thunderstorms continue, but
instability should weaken with the loss of daytime heating. A
slight chance of plain showers by Friday morning transitions to
dry conditions by the afternoon with the front finally clearing
eastern areas.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Key Points:
Temperatures remain above seasonal normals Friday night through
Monday night.
Potential for a few rounds of showers and possibly thunderstorms
Saturday through Memorial Day.
Near zonal flow continues across the country Friday night into
Sunday with a more amplified trough moving into the northern plains
and Great Lakes region Sunday night into the beginning of next week,
sending a cold front through the region Monday night into Tuesday.
Weaker shortwaves will be moving through the region Saturday into
Sunday Timing uncertainties remain with the shortwaves, with the
potential for showers late Friday night into Saturday night. And
with some daytime heating a few thunderstorms will also be possible
inland Saturday. A warm front passes to the north Sunday into Sunday
night in association with the low tracking into the Great Lakes
region.
Then with the area in the warm sector for Monday, and the approach
of a cold front, showers and thunderstorms will be possible. The mid
and upper level low will remain across southeastern Canada and into
the northeast Tuesday and Tuesday night with the chance of showers
remaining. With the uncertainties followed the NBM probabilities,
and for temperatures used a blend of the deterministic and 50th
percentile.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
Weak surface high pressure remains in control and just offshore
through this afternoon. The high drifts offshore this evening as a
surface trough approaches into late tonight.
VFR, becoming IFR with stratus developing first at KGON around
04Z, and at KISP and KBDR to 07Z to 09Z. VFR showers are
possible late tonight at the NYC metro terminals, a rumble of
thunder cannot be ruled out, however chances are low and not
included. A better chance for thunder is at KSWF and included in
a PROB30.
Light S to SW winds increase this morning into the afternoon
with sea breezes likely mid to late afternoon.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected. Southerly winds will be enhanced
by a developing sea breeze mid to late afternoon. The sea breeze is
expected to reach KEWR and KTEB by late afternoon. Occasional
gusts this afternoon are possible except at KJFK.
OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
Thursday: MVFR with a chance of showers and thunderstorms in the
morning, becoming likely during the afternoon.
Friday: VFR.
Saturday and Sunday: Generally VFR. A chance of showers with brief
MVFR possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Sub SCA cond expected through the weekend.
&&
.HYDROLOGY...
No hydrologic impacts expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JP/MET
NEAR TERM...JP/JT
SHORT TERM...JP
LONG TERM...MET
AVIATION...MET
MARINE...JP/MET
HYDROLOGY...JP/MET