Area Forecast Discussion Issued by NWS Upton, NY
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000
FXUS61 KOKX 180559
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
159 AM EDT Thu Apr 18 2024
.SYNOPSIS...
A slow moving warm front approaches from the southwest and
moves through the area into Thursday. High pressure briefly
builds in for Thursday night into Friday before a cold front
passes through Friday night into Saturday morning. High pressure
then follows from Saturday afternoon through early next week. A
weak frontal system will impact the region mid week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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One area of showers over eastern portions of the forecast area
in association with overrunning moisture from an approaching
warm front will move northeast into northeastern Connecticut and
Massachusetts as another line of showers moves in from the west.
There is a small window tonight where there may be enough
instability aloft to support an isolated thunderstorm for the
western half of the area. However, this line of showers is
weakening as it moves toward the region. Otherwise, the
forecast is on track.
An approaching warm front will lead to isentropic lift in
association with overrunning moisture with rain showers across
the region going into overnight. Instability will continue to be
the challenge with the overall thunder potential but given that
there has been some lightning upstream the forecast still
includes a slight chance of some embedded thunderstorms
overnight. Confidence is low (15%) on the likelihood of
widespread mention of thunder especially with a modest low level
inversion keeping much of the area stable. The 12z suite of
CAMs still indicated the potential for some short lived embedded
heavier showers moving through southwestern portions of the
forecast area overnight tonight within the New York City metro
area.
During the overnight expect the shower coverage to increase
although decrease in intensity. As the WAA lift decreases,
showers will transition from potentially heavy at times to more
of a steady light rain.
Temperatures are expected to be near normal for this time of year.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Shower coverage looks to lower Thursday as isentropic lift
weakens over the area and high pressure building in from the
northeast brings in a cooler and drier air mass in the lower
levels.
The high building in with the weak low to our south will mean a
strengthening easterly flow develops across the area that
starts to increase late tonight. It does not look to be overly
windy, with sustained winds of 15 to 20 mph and gusts to 25 mph
by Thursday morning. Winds start to decrease Thursday afternoon
as the high continues to nose into the region, with the weak low
well out to sea by this point.
The easterly flow will also mean cooler than normal temperatures for
Thursday, with highs only in the upper 40s to lower 50s.
Mainly dry conditions from Thursday night (except perhaps some
lingering showers for eastern areas) through Friday morning with
high pressure over the region. The chances for showers increase
Friday afternoon and Friday night as the associated cold front
approaches and begins to move through late Friday night.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Little change in the long term and stuck fairly close to the
previous forecast/NBM.
A cold front approaches and passes through Friday night into
Saturday morning. Moisture will deepen along with a chance of
showers with its passage. High pressure then builds in behind
the front with dry weather for Saturday afternoon. The high will
continue to build into the region through the rest of the
weekend and remain in control of the weather through Monday.
High temperatures near normal on Saturday, but cooling off
slightly for Sunday. Temperatures rebound a few degrees on
Monday.
A 500mb trough then shifts through the Great Lakes on Tuesday
with an associated weak surface low and cold front. It appears
that we should by dry through the day, but cannot rule out a
shower for western zones by the end of the day. Rain chances
increase Tuesday night into Wednesday. Temperatures remain in
the lower and middle 60s.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Persistent pattern during the TAF period with low pressure and
a warm front approaching but staying south and west of the
region with high pressure to the northeast of the region.
MVFR or IFR everywhere to start with more widespread IFR towards
the second half of the night and into Thursday morning. Rain
showers are intermittent but eventually will become more steady
for the second half of the overnight period. Also, the rain may
be locally moderate to heavy at times. Can not rule out an
isolated embedded thunderstorm as well, however timing and
confidence too low to include in the TAF.
Rain showers will remain in the forecast through at least 18z,
however, they may be more intermittent. Rain chances lower
further this afternoon. Mainly IFR conditions are expected,
however improvement to MVFR late can not be ruled out.
Conditions start to improve late this evening and overnight to
MVFR then VFR for most terminals. Timing however amendments are
likely to adjust the timing.
Wind direction will be E to ENE for much of the TAF period.
Wind speeds will be near 10 kt tonight and then increase
Thursday to near 12-15 kt with gusts mainly in the 20-25 kt
range. KSWF expected to have lower winds near 10 kts or less
without gusts during the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely for changing flight categories.
OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...
Thu night: Showers end with slowly improving conditions
Thursday night. Improvement to MVFR then VFR expected.
Fri: VFR early, then MVFR afternoon and at night with a chance
of showers.
Sat: MVFR with showers ending in the early morning, becoming
VFR. W-WNW wind gusts 15-20 kt.
Sun through Mon: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
No changes to the winds and seas at this time.
Winds and seas remain below SCA criteria. However, easterly
winds will increase tonight as strengthening high pressure
builds in, and by late tonight will likely reach 25 kt on the
ocean waters and the entrance to the harbor. A few hours later,
all waters will see SCA wind gusts by early Thursday. A SCA is
in effect for all waters for Thursday. LI Sound and LI Bays have
SCA just for Thursday and other marine zones (ocean and NY
Harbor) have SCA begin at 06Z Thursday and go through the day
Thursday.
Winds gusts diminish Thursday night as the high continues to
build in over the area. Non ocean waters will likely drop below
25 kt early Thursday night. The ocean waters will likely have
SCA gusts hang on for the first few hours of Thursday night
before they also come down below 25 kt.
Seas build to 4 to 7 ft on the ocean by Thursday morning into
the afternoon, diminishing thereafter. However, they remain
above or right around 5 ft Thursday night, so an extension to
the SCA over the ocean may be needed for Thursday night and
perhaps into Friday with a persistent, though slowly weakening
easterly flow. Waves finally drop below 5 ft on the ocean by
Friday night.
High pressure building over the area waters Saturday through the
first part of next week should keep conditions sub-advisory waters
through at least Tuesday night. Conditions may build back to SCA
levels for Wednesday with the next low pressure and associated cold
front to approach.
&&
.HYDROLOGY...
There is the potential for 0.25" to 0.75" of rainfall through
Thursday afternoon. Although a brief heavy shower is possible,
no hydrologic impacts are expected with this event and
thereafter through the first half of next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 AM this morning to 6 PM EDT this
evening for ANZ331-332-335-340-345.
Small Craft Advisory until 6 PM EDT this evening for ANZ338-
350-353-355.
&&
$$
SYNOPSIS...
NEAR TERM...JM/JP
SHORT TERM...
LONG TERM...
AVIATION...BC
MARINE...
HYDROLOGY...