000
FXUS61 KOKX 172332
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
732 PM EDT Mon Apr 17 2023
.SYNOPSIS...
High pressure slowly builds in behind a departing cold front
tonight. High pressure will then continue to build in Tuesday
through Wednesday, and moves offshore Wednesday night. A warm
front approaches Wednesday night and moves through the region
Thursday as low pressure tracks through the Great Lakes with a
trailing cold front. Another low develops on the cold front
Friday night and impacts the region through the weekend, moving
east Monday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A cold front, through south central Connecticut to eastern Long
Island and south east of the New Jersey coast at 22Z, continues
to move slowly eastward with winds shifting to the west and
much drier air moving in as dew points fall into the upper 30s.
Also, and lingering stratus and fog ahead of the front was
moving out of the region. Updated for the current conditions,
and timing of the front moving east of the area this early this
evening.
Clearing and dry for tonight outside of a low chance of showers
well NW of the city through early evening. A drier WSW flow
behind a departing cold front to the east should promote better
mixing than had been seen much of the day today. This, along
with a slightly strengthening pressure gradient likely prevents
winds from becoming light to calm through the night. The wind
forecast might be a little too low at times tonight. Lows around
50 in the city with 40s elsewhere.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Cyclonic flow aloft due to a 500mb low centered near the southern
Quebec/Ontario border will allow for only slow building of high
pressure at the surface over us during this period. Expecting
diurnal cumulus to pop up with this setup. CAMs and NBM imply
isolated showers with the cumulus buildup, however with a dry sub-
cloud layer, this may end up as sprinkles as best. Will therefore go
with a dry forecast for now. With the aforementioned dry sub-cloud
layer/inverted-V profile, winds will be gusty at times. Highs 55-60
across the area.
High pressure continues to build in during Tuesday night with winds
diminishing and becoming less gusty. Not sure if winds decouple and
go calm for inland areas, but forecast lows well NW of city are in
the mid 30s. Will need to monitory trends to possibly introduce frost
into the forecast for areas where the growing season is underway.
Lows generally in 30s inland and 40s for the coastal areas.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The forecast for Wednesday into Wednesday night remains consistent
with previous forecasts as high pressure builds over the region, and
then offshore. However, the best warm frontal forcing, and
frontolysis is a little farther to the north for Wednesday night as
the surface warm front remains to the south.
With a more amplified ridge for Thursday, and strong warm advection
with low level return flow around the offshore high, the warm front
looks to move through, or redevelop well to the north during
Thursday, and the area become warm sectored into Saturday. Another
result of the stronger ridge is an even slower progression of the
surface and upper low and associated cold front for Friday. The
front does approach Friday night and stalls of dissipates as a vort
max moves into the base of the upper trough across southern Texas,
and spins up another surface low over the mid section of the nation
Friday night into Saturday. A highly amplified ridge develops and
moves slowly into the western Atlantic through the upcoming weekend,
and keeps the surface low well to the west, with this surface cold
front moving into the region Sunday. With the slower approach of the
cold front Friday the chances of thunder have decreased with
instability weakening Friday night. Yet another wave may develop on
the front over the northeast late Sunday night into Monday keeping
chances of precipitation in the region. Mainly used the NBM
probabilities as the timing and percentages look reasonable with the
expectations of the warm front, initial cold front, and the waves of
low pressure. For temperatures, used the NBM Wednesday and Wednesday
night, and Thursday through Saturday leaned toward the 75th
percentile, especially Friday which looks to be the warmest day of
the extended period. Also, Thursday through Saturday, with the area
warm sectored, raised dew points with a blend of the NBM and 90th
percentile.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
A cold front that moved through the area today continues to
push east this evening. Another weak trough passes through late
Tuesday.
VFR expected for all terminals through the TAF period. KGON has
been struggling to clear out behind the front but any reduced
visibilities and ceilings should improve to VFR in the next
hour.
Winds WSW 10-15kt with some gusts upwards of 25kt this evening.
While an occasional gust is possible through the night, more
persistent gusts 20-25 kt are expected by Tuesday morning for
most terminals. A few gusts may approach 30kt. Gusts end Tuesday
evening.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of gusts start/end may be off by a couple of hours.
OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tue Night-Wed: VFR. Westerly flow, gusts 20-25 kt in afternoon.
Thursday: VFR with southerly flow.
Friday: VFR. Light S/SE flow.
Saturday: MVFR or lower possible with chance of showers.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90.-- End Changed Discussion --
&&
.MARINE...
No changes to the winds and seas at this time.
Cold front currently moving through the waters is helping the
visibility improve. Have canceled the dense fog advisory now
that the visibility is improving to mostly over 1 NM. Still a
chance for some areas below a mile through the next couple of
hours over the easternmost parts of LI Sound. SW-W gusts
otherwise begin to pick up over the westernmost waters late
tonight before this spreads east during Tuesday. After
collaboration with the surrounding offices, have adjusted the
SCA over the western ocean waters (as well as NY Harbor) to
begin at 06z Tues. Have also extended the SCA on the ocean
waters to go through 03z Weds as seas and possibly gusts as well
are still within advisory thresholds.
Winds and seas will be below SCA levels across the forecast waters
Wednesday through Saturday as high pressure moves over the waters
Wednesday, and offshore Wednesday night. The pressure gradient
remains weak Thursday into Saturday as a warm front moves to the
north Thursday. Southerly winds will be increasing Saturday night
into Sunday as a cold front approaches to the west. Wind gusts on
the ocean water may approach SCA levels Saturday night, however,
with warmer air moving across the cooler ocean waters mixing will be
limited. However, with a long duration, and increasing southerly
flow, ocean seas are expected to builds to around 5 feet Saturday
night.
&&
.FIRE WEATHER...
RH values are expected to drop to around 30% during the daytime for
both Tuesday and Wednesday. Wind gusts will be stronger on Tuesday,
however given mainly dry conditions over the past week, will need to
monitor for enhanced potential of fire spread both days.
&&
.HYDROLOGY...
No hydrologic impacts are expected through the weekend.
&&
.TIDES/COASTAL FLOODING...
Based on observations from the most recent high tide cycle and
anticipated levels with a slightly higher astronomical tide for
the next high tide cycle, have issued a Coastal Flood Statement
for the south shore back bays of Nassau County for this
evening`s high tide cycle. A few sites should just touch or go
slightly over flooding benchmarks. The only other areas that
could come close would be the south shore of Queens, lower NY
Harbor, and the westernmost areas of LI Sound, however levels
are expected to remain just below flooding benchmarks.
Astronomical tides then lower for subsequent cycles, so no
flooding concerns after this evening.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 AM to 8 PM EDT Tuesday for ANZ331-
332-335-340-345.
Small Craft Advisory from 2 AM to 8 PM EDT Tuesday for ANZ338.
Small Craft Advisory from 6 AM to 11 PM EDT Tuesday for ANZ350-
353.
Small Craft Advisory from 2 AM to 11 PM EDT Tuesday for ANZ355.
&&
$$
SYNOPSIS...JC
NEAR TERM...JC/MET
SHORT TERM...JC
LONG TERM...MET
AVIATION...MW
MARINE...JC/MET
FIRE WEATHER...
HYDROLOGY...JC/MET
TIDES/COASTAL FLOODING...