000
FXUS61 KOKX 181151
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
751 AM EDT Fri Aug 18 2023
.SYNOPSIS...
A cold frontal moves through the region today. High pressure
will build in for the weekend, followed by a cold front passing
through Monday afternoon into night. High pressure then returns
for the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
A weak, pesky warm front just to the south of the region attempts
to lift north early this morning as an incoming upper trough
becomes negatively titled in its advance east. Leading the
trough is a surface cold front and pre frontal trough, and this
will drive a round of showers and thunderstorms across the
region through the remainder of the morning.
While a stray shower is possible through 9z, not anticipating
much activity until after daybreak as the pre frontal trough
and associated upper forcing reach the area. In the meantime,
patchy fog may lower vsbys in spots, though not anticipating
widespread or persistent dense fog.
Broken line of showers and thunderstorms across eastern PA and
Upstate NY will advance east over the next several hours. Timing of
this line looks to get into the lower Hudson Valley around 9 or 10z,
tracking east through the remainder of the forecast area
through mid morning or so. Latest CAMs indicate the bulk of this
line may skirt or pass north of Long Island, so maintained only
chance PoPs here, with likelies to the north.
With PWATs close to 2 inches, locally heavy downpours could
produce nuisance flooding as it moves through during the morning
commute. Main limiting factor is that storm motion is progged
to be fairly rapid due to the strong middle level flow. For this
reason, minor/nuisance flooding appears to be the main hydro
threat attm. Also can`t rule out isolated damaging wind gusts
or even a brief tornado given sufficient bulk shear and veering
low level profiles. Warm SSTs this time of year could potentially
enhance the threat.
As this complex progresses east through the morning, the front
itself will lag behind, moving through in the afternoon. A
breezy westerly flow develops behind it, helping to advect in a
drier, cooler air mass. While a spotty shower or two is possible
behind the fropa as the cold pool begins to move overhead, the
remainder of the day should be predominantly dry. Temperatures
will climb into the low to mid 80s for most this afternoon, but
dew pts will be falling into the 50s by day`s end, alleviating
much of the humidity. Tonight, mostly clear skies expected as
temperatures fall into the 50s and 60s.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
The closed off trough shifts into New England on Saturday, keeping
cyclonic flow over the region. This should allow for diurnal cu
to develop, especially across the lower Hudson Valley and southern
CT, with mostly sunny skies elsewhere.
A 1020mb surface high builds east from the Midwest during the day
and will keep a modest WNW flow in place, though a bit less breezy
than Friday afternoon.
With a well-mixed BL and 850 mb temps falling to around 10C with
the cold pool overhead, surface temperatures will struggle to
reach 80. Most top out in the mid to upper 70s in the afternoon,
and coupled with lower dew pts in the 50s, should make it feel
quite comfortable outside. Dry conditions continue through Saturday
night, as lows range from the mid 50s across the interior, to the
mid 60s in the urban metro.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
No significant changes in the long term. Deep-layered ridging
with rising heights follow for Sunday. Sunny with moderating
temperatures. Based on temps at the top of the mixed layer, went
a few degrees above deterministic NBM.
Some disagreement among the global models regarding timing of the
next cold front. GFS and Canadian are more progressive with a Monday
late day or nighttime passage, and the ECMWF stalls the front nearby
before having it sink south of us on Tuesday. ECMWF is trending
toward a more progressive solution, so will go with slight chance of
a shower/thunderstorm Monday afternoon and night, and then dry for
Tuesday. With high pressure remaining in control, dry weather for
Wednesday as well with seasonable temperatures. A weak trough then
brings a slight chance of a shower on Thursday.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
A pre-frontal moves is currently moving through, then a cold
front moves through late this morning and early afternoon. High
pressure then builds to the west into tonight.
Western terminals will be mainly VFR through the day. Brief MVFR
conditions are possible with showers, while eastern terminals
will see IFR to MVFR conditions continue until the trough moves
through (such KGON). There is a low chance for TSRA for KISP.
Most terminals will be VFR by mid morning.
The actual cold front may also develop an isolated shower late
morning/early afternoon, but the probability is too low to
include in the TAF. Otherwise, VFR prevails through Friday
night.
A brief period of N to NW winds is possible this morning with
the pre-frontal passage. A shift back to the W or WSW is then
expected until the cold front moves through with wind speeds of
10-15 kt with gusts 20-25 kt expected Friday afternoon and
evening. Gusts end Friday night, around 05Z or thereafter.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Wind direction may shift more to the NNW or N through mid
morning.
Amendments likely for changing flight categories through mid
morning.
Increasing winds and gusts this afternoon could be off by 1-3
hours.
OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
Friday Night-Saturday: VFR. WNW gusts 15-20 kt in the evening.
Sunday-Monday: VFR. Slight chance of a shower or thunderstorm well
inland Monday afternoon/evening.
Tuesday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Maintained a Marine Weather Statement for patchy dense fog on
all waters except the NY Harbor until 5 am. Vsbys should start
to improve with approaching pre frontal trough and associated
showers/storms.
Otherwise, S flow will build seas on the ocean today. Small
Craft Advisory continues on the ocean thru tonight as seas will
be slow to subside behind the cold front. Winds are expected to
remain below SCA levels on the protected waters, although tstms
this morning could pose a hazard at times.
Extended the SCA until 10z Sat for lingering 5 ft seas, but may
need to be extended a bit later into Saturday, especially for
the eastern ocean waters.
Offshore winds and seas subside by Saturday night with sub
advisory conditions through the rest of the forecast period.
&&
.HYDROLOGY...
Showers and thunderstorms this morning could produce heavy
downpours that lead to nuisance urban and poor drainage
flooding. Isolated areas of flash flooding are possible.
Thereafter, no hydrologic impacts expected through the rest of
the forecast period.
&&
.TIDES/COASTAL FLOODING...
There is a high risk of rip current development at all ocean beaches
today as seas build to near 5 ft.
This high risk likely extends into Saturday for the Suffolk
County Beaches, with Nassau and the city beaches in a moderate
risk.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk through this evening for NYZ075-080-081-
178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ350-353-
355.
&&
$$
SYNOPSIS...DR
NEAR TERM...DR
SHORT TERM...DR
LONG TERM...JC
AVIATION...JP
MARINE...JC/DR
HYDROLOGY...JC/DR
TIDES/COASTAL FLOODING...