000
FXUS61 KOKX 211937
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
337 PM EDT Sun Apr 21 2024
.SYNOPSIS...
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A cold front will slide through early on Monday. High pressure will
assume control through Tuesday before moving offshore late Tuesday
and Tuesday night. A cold front moves through on Wednesday,
followed by high pressure to close out the week. A frontal system
may impact the area for next weekend.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH MONDAY/...
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High clouds will be around this evening as the cirrus canopy from an
upper level jet begins to lift northeast. This will pave the way for
primarily clear skies to return during the night and into Monday. A
weak sfc trough is expected to get further east tonight as a more
west to northwest flow behind it attempts to set up. The flow will
be weak resulting in light winds and will serve more to reinforce
the seasonably cool air that is already in place. Getting closer to
midnight eastern areas should primarily clear out with perhaps only
just a few high clouds left. The question tonight has to do with
whether interior and some rural sections / locations see frost, and
to what degree. With dry air in the low levels there may be little
moisture at the sfc to help in the formation of frost which was the
case last night. The winds should be light enough for a few hours
late tonight and temperatures outside of urban areas should
primarily get into the 30s, even some lower and middle 30s well to
the north in the normally colder locations. However, with the air
relatively dry patchy frost as compared to areas or widespread frost
appears to be a better fit. Thus it appears to be best not to go
with a frost advisory at this time. Also, there may be enough of a
overall synoptic flow to preclude some places other than sheltered
valleys from completely decoupling which puts the amount of coverage
of frost in doubt. With that said, lows tonight should be primarily
in the lower half of the 40s for the urban areas, and middle and
upper 30s in most outlying areas, with the coldest sheltered areas
getting down into the lower and middle 30s. This won`t be much
different from the previous night. Went with MAV guidance for min
temp and dew points.
For Monday look for a good amount of sunshine despite the fact that
a cold front slides through as BUFKIT soundings indicate a dry
column on a W to NW flow throughout. After a chilly start look for
temperatures to recover with mainly lower and middle 60s for most
places. Went above blended guidance / NBM based on synoptic regime,
think there will be enough of a NW flow for the a large majority of
the day to preclude sea breeze advancement. Higher res guidance can
overdo this at times, but usually later in the season. However, if
the synoptic driven winds end up a bit lighter then the sea breeze
can make in-roads sooner, especially for coastal and southeastern
sections. Thinking the sea breeze happens very late towards 5 pm
closer to the coast and further east, if it even happens at all. One
could make the argument to go a few degrees warmer, but based on
some sea breeze uncertainty did not get more aggressive with
temperature forecast.-- End Changed Discussion --
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
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For Monday night look again for clear skies and light winds. Dew
point readings will likely be a shade higher with a little air mass
modification in all likelihood. With light winds more of a certainty
for the duration of the night and the lack of any cloud cover the
chances for more coverage in terms of frost, and perhaps minor
agriculture impacts increases some. Subsequent forecasts will need
to take a closer look with respect to this, but expect at least some
patchy frost across interior and rural locations. Lows will be
primarily in the lower and middle 30s once again further away from
urban locales, otherwise mainly upper 30s closer to the coast, with
40s in the more urban locations. Went with MAV guidance for min
temp and dew points.
During Tuesday high pressure begins to get further east and should
be primarily offshore later in the day. A return flow gets
established quickly during the early portions of the afternoon with
the winds primarily off the colder ocean and out of the S and SSE.
This wind direction should result in a fairly wide temperatures
spread across the region for the afternoon as areas further west and
inland won`t get the entrainment of the wind off the colder ocean
compared to places further east and closer to the coast. Look for a
fair amount of sunshine across the region, with perhaps a few mid
level clouds encroaching into western sections later in the day.
Went closer to NBM 75th percentile for temps across western third of
the area, with some manual adjustments based on climo for this time
of year further east.
For Tuesday night with the high getting further east and the
approach of the next system from the west look for the winds to veer
more to the S and perhaps the SSW towards Wed AM. The column will
undergo more of a deep layered SW flow. Thus, clouds will increase,
especially above 5 kft or thereabouts. A lot will depend on the
speed and the timing of the approach of the frontal boundary, but
the column may moisten enough that some light showers or sprinkles
could very well break out before daybreak Wed, especially across
western most locations. Went slight chance to chance PoPs during
the pre-dawn hours towards sunrise.-- End Changed Discussion --
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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Unsettled weather returns to start the period as a mid level trough
swings into the Northeast, pushing a surface front through on
Wednesday. Moisture appears limited though, PWATs under an inch and
surface dew pts mostly under 50F, so not anticipating a widespread
significant rainfall with this system. However, a hint of CAPE (a
hundred or two joules), steeper low level lapse rates, and speed
shear may allow for a few thunderstorms to develop ahead of the
advancing boundary in a low CAPE, modest shear environment. As of
now, the threat window looks to be in the later morning and
afternoon hours, depending on the progression of the front.
Ensembles keep QPF light with the fropa, mostly under a quarter inch
outside any convective elements.
The boundary likely moves through by the evening, and the trough
axis shifts east of the region Wed night. Ridging gradually builds
thereafter into the start of the weekend. Conditions dry out
Thursday as a 1030 mb surface high pressure builds in from the Great
Lakes. The high remains over the region Friday, before slipping
offshore and setting up southerly flow.
Thereafter, a shortwave over the Central US will attempt to ride up
and over the amplified ridge into the weekend, bringing a return to
rain chances. This energy isn`t progged to move onshore the West
Coast until midweek, so will likely continue to see varying
solutions/timing until better sampling is achieved. Capped PoPs at
high chance (50%) to account for this uncertainty.
As for temperatures, they look to average near, to just below,
normal for late April. Afternoon highs generally climb into the 60s,
with morning lows in the 30s and 40s. The coolest day in the period
appears to be Thursday behind the frontal passage, with highs
struggling to get out of the 50s for most. Frost/freeze headlines
may be needed a couple of mornings late in the week, at least for
portions of the local area. With only subtle adjustments, stayed
closed to national blended guidance for this update.-- End Changed Discussion --
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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High pressure builds in from the west through Monday.
VFR. W-SW wind around 10-15 kts this afternoon with occasional gust
between 15-20kt should diminish by late this afternoon/early
evening. Winds will then shift around to the W-NW and remain around
10 kts through Monday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of the ending of the gusts may be off by an hour or two.
OUTLOOK FOR 20Z MONDAY THROUGH FRIDAY...
Monday-Tuesday: VFR.
Wednesday: MVFR or lower with showers. S winds 10-15G20-25kt in the
afternoon/evening, becoming NW at night.
Thursday-Friday: VFR. Gusty NW flow.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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Primarily 2 ft ocean seas prevail through Monday night with high
pressure in control and a relatively light pressure gradient
overall. Sub small craft conditions will prevail across the coastal
waters through Tuesday, with perhaps more marginal small craft
conditions out on the ocean late Tuesday night as seas begin to inch
up along with winds out of the south.
A tightening pressure gradient will lead to increasing flow into
Wednesday. This should allow SCA conditions to develop on the ocean
with seas also climbing to around 5 ft. Non ocean waters may see a
period of 25 kt gusts Wed into Wed evening before subsiding behind a
cold frontal passage. Seas could linger near SCA criteria on the
ocean Wed night before diminishing, then sub SCA conditions expected
on all waters thru late week.-- End Changed Discussion --
&&
.HYDROLOGY...
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No hydrologic concerns exist throughout the forecast period.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JE/DR
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...DR
AVIATION...20
MARINE...JE/DR
HYDROLOGY...JE/DR