okx-afd on 2025-05-13

555
FXUS61 KOKX 131939
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
339 PM EDT Tue May 13 2025

.SYNOPSIS...
-- Changed Discussion --Low pressure slowly drifts closer tonight into Wednesday before
weakening into Thursday. Another frontal system moves across the
area Friday through Saturday. High pressure gradually returns
Sunday into early next week as low pressure lingers just east of
the New England coast.-- End Changed Discussion --

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --A closed upper level low over the Ohio and TN valleys and Western
Appalachians will slowly draw closer throughout the course of
tonight. At the same time a high pressure ridge off the New England
coast which has been holding will edge further off shore. This
gradually paves the way for increased forcing to slowly work in from
the WSW. An onshore E flow will continue through tonight. Look for
PoPs to increase slowly from WSW to ENE, more so towards and after
06z. Increased convergence towards the frontal boundary nearby will
result in an overall increase in shower coverage. Especially for
western portions of the area where likely PoPs give way to
categorically PoPs. Further east PoPs increase to chance closer 09z.
A mild night with cloud cover and an onshore flow results in above
average temperatures with lows in the middle and upper 50s, to
around 60 in the metro.

During Wednesday look for the steadiest rain to arrive for most of
the area during the morning and a portion of the afternoon. What
drives the vertical motion leading to more enhanced shower / rain
activity will be increased warm advection at 850 mb. Further east
and northeast more widespread and consistent rain will arrive into
the afternoon and into Wednesday evening. There do remain some
timing difference among the various HREF members and high res
guidance. BUFKIT soundings are not very suggestive of thunder for
the most part early on, with only the slightest hint of elevated
instability. Showalter indices approach zero late in the day and
perhaps this is the greatest chance at seeing some quasi-embedded
convective elements in the precip shield. Thus, carried only slight
chance thunder mainly for the southern 2/3rds of the area into
Wednesday and Wednesday night.-- End Changed Discussion --

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --During Wednesday night the more widespread rain / shower activity
should decrease in coverage for the most part. But with the upper
level portion of the disturbance moving slowly and any vorticity
becoming concentric with PVA decreasing look for shower activity
coverage overall to decrease, especially later at night. The surface
low should continue to slowly weaken in response to the upper level
trough deamplifying. With cloud cover and a moist SE to E low level
flow continuing temperatures will remain elevated with lows once
again in the upper half of the 50s to around 60.

On Thursday clouds linger with the remnants of the sfc low remaining
to the immediate south. With the lack of a true forcing mechanism
look for just a chance of scattered to isolated shower activity.
Cannot rule out an isolated thunderstorm or two. The day however
does not appear to be a washout with an overall decrease in shower
activity from the previous 24 hours. Temperatures with the onshore
flow continuing will range from the upper 60s to lower 70s, near
normal for this time of year.-- End Changed Discussion --

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --Key Points:

*An unsettled weather regime likely continues through the upcoming
weekend, potentially next Monday.

*It will not be a washout Friday and Saturday despite chances for
showers (possibly a thunderstorm each afternoon and evening).

*Diurnally driven isolated to scattered showers remain possible
Sunday and Monday afternoon.

*Temperatures will mainly run above normal through early next week.

A blocky synoptic pattern will continue through early next week.
The upper trough/upper low that impacts the area midweek will
continue to weaken as it slides across the northeast Thursday night.
Another upper low and associated trough over the Northern Plains
will then gradually slide eastward towards the Great Lakes Friday
into Saturday and then move across New England late this weekend.
Surface low pressure over the Northern Plains on Friday will send a
warm front across the area. Shortwave energy associated with the
front is weak and dampened out by ridging over the eastern seaboard.
Have largely capped PoPs off at chance with potential of showers
mainly Friday afternoon and evening. Some CAPE may be available for
a slight chance of thunder. Low pressure weakens as it moves towards
the region this weekend due to the system becoming vertically
stacked. The associated cold front will likely move across the
region late Saturday into Saturday night. This will bring additional
chances for showers and possibly a few thunderstorms as
probabilities for SBCAPE to exceed 500 J/kg are higher in the NBM.
The highest probabilities for precip and thunder currently exist
north and west of the NYC metro.

The lingering upper low and surface system should push offshore
Sunday into early next week. Cyclonic flow and potential of a
lingering cold pool aloft may support diurnally driven isolated to
scattered showers Sunday and Monday afternoons. The upper low and
trough may linger offshore next Tuesday with ridging building just
to our west. Given a consensus of building heights aloft, have kept
the forecast dry for next Tuesday and went slightly lower than the
NBM PoPs.

Temperatures will be in the upper 70s to around 80 away from the
immediate coast, with low to middle 70s along the coast, Friday and
Saturday. Westerly flow on Sunday should allow the entire area to
reach the middle and upper 70s. Temperatures trend a bit cooler
early next week, but still may remain above normal, especially on
Monday.-- End Changed Discussion --

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --A weak frontal boundary remains nearly stationary into tonight near
the NYC metro terminals. Meanwhile, a weak area of low pressure
approaches from the south.

VFR or MVFR to start. Rain showers continue to overspread the area
especially across the NYC and Lower Hudson Valley terminals this
afternoon into start of this evening with MVFR chances increasing,
Conditions deteriorate to IFR tonight for these areas. To the east,
it should take a bit longer for rain to move in and see conditions
fall to MVFR. By tonight however, IFR or lower is expected around or
after midnight and continue into much if not all of Wednesday.

Winds through the TAF period are around 10 kts or less through
tonight, then 10-15kt on Wednesday. Wind direction will
generally be from the E to ESE.

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

MVFR and IFR timing could be a few hours off from TAF.

.OUTLOOK FOR 18Z WEDNESDAY THROUGH SATURDAY...

Wednesday and Wednesday night: Low stratus/fog with IFR
conditions at times. Periods of rain. Slight chance of
thunderstorms Wednesday afternoon into Wednesday night. E-SE
winds G20kt possible on Wednesday afternoon into early evening.

Thursday: MVFR possible with a chance of showers.

Friday and Saturday: Mainly VFR, chance of MVFR and showers.
Slight chance of thunderstorms afternoon into early evening.

Sunday...Mainly VFR. Chance of an MVFR shower.

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

.MARINE...
-- Changed Discussion --Sub advisory conditions continue through tonight. However, ocean
seas begin to build during Wednesday with small craft conditions
developing from west to east across the ocean waters along with
gusts for portions of the ocean gusting to 25 kt. Ocean seas
will range primarily from 5 to 6 feet with small craft seas
likely lingering through the day Thursday.

Conditions will be below SCA levels by Thursday night, and
remain so into the upcoming weekend with a relatively weak
pressure gradient over the waters.-- End Changed Discussion --

.HYDROLOGY...
-- Changed Discussion --There are no concerns at this time regarding hydrologic impacts from
rainfall tonight through Thursday with around 1 inch of rainfall
expected across western and southwestern portions of the area. Lower
rainfall totals are expected across the remainder of the area.

There are also no hydrologic concerns Thursday night through
early next week.-- End Changed Discussion --

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 11 AM Wednesday to 6 PM EDT Thursday
for ANZ350.
Small Craft Advisory from 6 AM Wednesday to 6 PM EDT Thursday
for ANZ353-355.-- End Changed Discussion --

SYNOPSIS...JE/DS
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...DS
AVIATION...BC
MARINE...JE/DS
HYDROLOGY...JE/DS