000
FXUS61 KOKX 182103
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
503 PM EDT Tue Apr 18 2023
.SYNOPSIS...
-- Changed Discussion --
High pressure will gradually build from the west tonight and
then gradually move southeast out into the Western Atlantic by
early Wednesday night into Thursday. Meanwhile, a low pressure
system will approach from the west with its warm front
approaching from the north and west late Wednesday night into
early Thursday morning. This warm front will move northeast of
the area on Thursday. Another warm front to the south will then
slowly approach from Thursday night into Friday night and lift
north on Saturday. A strong cold front and wave of low pressure
will approach Saturday night into Sunday, and may linger into
early next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
A large mid level low will move across SE Canada with its
associated trough axis moving across the local region tonight.
With this cyclonic flow aloft, clouds will linger around and
will be slow to decrease.
At the surface, a trough will move across this evening with high
pressure gradually building in from the west. The clouds will
decrease more overnight into early Wednesday morning.
Enough of a pressure gradient will remain between low pressure
in Eastern Canada and high pressure from the Great Lakes through
the Tennessee Valley to keep a westerly breeze ongoing through
tonight.
With continuing westerly flow, low levels will dry out more
late this afternoon into tonight. Dry weather conditions are
expected late this afternoon through tonight.
Regarding temperatures, radiational cooling will be partially
mitigated tonight. Went a little above MET MOS guidance by using
a little more weight with NBM for the low temperature forecast
tonight with a range of lows mainly from the mid 30s to lower
40s. Lows more in the lower 30s for NW Orange County.
Concerning potential for frost for those locations where the
growing season has begun, some parts of Eastern Long Island
especially near the Pine Barrens will have isolated lows in the
mid 30s. Frost will be possible in these isolated locations but
winds stay up in the forecast so did not mention any frost in
the forecast.-- End Changed Discussion --
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
-- Changed Discussion --
For Wednesday, the mid level low weakens and continues moving
east, eventually transitioning into an open wave on Wednesday.
The wave will eventually get north of Maine and begin to enter
the Canadian Maritimes by early Wednesday evening.
At the surface, high pressure moves southeast with its center
remaining to the south and west relative to the local region. The
high pressure area will eventually make its way offshore out into
the Western Atlantic by early Wednesday night.
With less clouds and low level veering of winds, warm air advection
is expected in the afternoon. With less maritime influence with an
increasing westerly component to surface wind, coastal locations
will just be slightly cooler than NYC with respect to temperatures.
The range of high temperatures forecast is from the upper 50s across
the interior to mainly lower 60s across the coastal areas with
potential for mid 60s for NYC and parts of Northeast NJ.
For Wednesday night, high pressure remains out in the Western
Atlantic. The axis of high pressure moves across with mid level
ridging aloft. The pressure gradient weakens allowing for winds to
decrease at the surface with variable direction. Lows still expected
to be on the milder side, ranging from the upper 30s to upper 40s.
Warmer air at 850mb will continue to advect into the area. Clouds
increase late Wednesday night into early Thursday morning as a
warm front approaches from the north and west.
The models convey an embedded shortwave riding along the eastern
side of the mid level ridge that will traverse from northwest to
southeast late Wednesday night into Thursday morning. Mid level
ridging increases Thursday afternoon with ridge axis moving in.
Clouds will increase and there could even be a rain shower,
mainly north and west of NYC late overnight Wednesday night into
early morning hours of Thursday. However only have slight
chance POPs as low levels will still be relatively dry and upper
level disturbance will not have much moisture to work with.
A much warmer day is in store Thursday away from the coast (well
into the 70s) with more SW flow developing and warmer air
continuing to advect in at 850mb. It will be cooler at the coast
(mainly lower 60s) as the surface flow will be more southerly
flow along the coast, thereby allowing for more maritime
influence. The abundance of clouds in the morning will decrease
in the afternoon with that ridging aloft. The warm front will be
moving farther northeast of the region.-- End Changed Discussion --
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
With one warm front off to the north and another to slowly
approach, things will start off warm, with temps Thu night
bottoming out mostly from the mid 40s to mid 50s, then with
onshore SE flow rising to the lower 80s inland well away from
the ocean, into the 70s most elsewhere, and only into the 60s
near south facing showers out east. A milder night Fri night
expected, with lows near 60 in midtown NYC and in the 50s
elsewhere as the onshore flow continues and even backs east for
a time.
The front should get a push north first thing Sat morning, but
with more in the way of clouds ahead of an approaching frontal
system as well as continued onshore flow temps likely to end up
cooler than those of Friday, with more widespread 60s for highs
across SE CT and eastern Long Island, and failing to reach 80
from NYC north/west.
A rainy/windy and cooler period likely from Sat night into
Sunday as a closed low to the west becomes negatively tilted and
potent leading shortwave energy approaches. A long SE-S fetch
and lack of a strong sfc-based inversion likely to result in
winds approaching or exceeding advisory criteria late Sat night
into Sunday, especially along the coast. A narrow corridor of
strong Atlantic moisture transport ahead of the front via a
strong LLJ, as well as enhanced lift ahead of a wave of low
pressure along the approaching front, also likely to result in
pds of moderate to heavy rain and some rumbles of thunder from
late Sat night into Sunday night.
The aforementioned closed low to the west will become the
westernleg of a large omega block over eastern North American
and the western Atlantic, so expectations are that the forecast
trends going into early next week will slow down. So PoP
forecast remains somewhat higher than NBM during this time, with
chance PoP for ern CT/Long Island into Monday and at least
slight chance PoP otherwise going into Tuesday.-- End Changed Discussion --
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
High pressure builds into the region through Wednesday.
VFR through the TAF period.
Gusty W-WSW winds continue through this evening. Gusts are forecast
to diminish this evening/tonight, with KJFK ending the latest (after
06Z Wednesday) there is a chance that gusts never really stop,
becoming more occasional after 06Z. Gusts pick up once again by
daybreak Wednesday morning with gusts between 20-25kt, then diminish
after 21z.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of gusts diminishing this evening/tonight may be off by a
couple of hours.
OUTLOOK FOR 20Z WEDNESDAY THROUGH SUNDAY...
Wed: VFR. Westerly flow, gusts 20-25 kt in afternoon.
Thursday: VFR with southerly flow.
Friday: VFR. Light S/SE flow.
Saturday through Sunday: 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...
-- Changed Discussion --
Pressure gradient will be relatively more steep farther west
going into tonight. BUFKIT model soundings indicate more
vertical mixing and higher gusts for the more western waters in
the forecast region. Therefore, have adjusted SCAs for the
ocean, now in effect until 06Z Wednesday and for NY Harbor,
Western Long Island Sound as well as the South Shore Bays, SCA
now is in effect until 04Z Wednesday. The non-ocean waters to
the east have their SCA remain in effect until 00Z Wednesday.
Ocean seas are forecast to build to near 5 ft going into this
evening before subsiding back below SCA thresholds overnight.
Another round of SCA level winds is probable for most waters on
Wednesday, mainly late morning into mid afternoon. Then a
period of below SCA conditions forecast for the waters
thereafter through Thursday.
SCA cond likely to develop on all waters Sat night ahead of an
approaching strong cold front and wave of low pressure. SE-S
gales may be possible especially on the ocean and the adjacent
lower harbor/bay waters from late Sat night into Sunday.-- End Changed Discussion --
&&
.FIRE WEATHER...
-- Changed Discussion --
Minimum RH values expected near 25 to 35% during the day
Wednesday. Wind gusts will be a little less than the previous
day but will still be near 20 to 25 mph. So will continue to
monitor for enhanced potential of fire spread on Wednesday.-- End Changed Discussion --
&&
.HYDROLOGY...
-- Changed Discussion --
No hydrologic impacts are expected through the weekend. A
frontal system could bring a 1-2 inch rainfall from Sat night
into Sunday night, with nuisance impacts the most likely outcome
since occurring on the weekend.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ331-
332-340.
Small Craft Advisory until midnight EDT tonight for ANZ335-338-
345.
Small Craft Advisory until 2 AM EDT Wednesday for ANZ350-353-
355.
&&
$$
SYNOPSIS...BG/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...BG
AVIATION...20
MARINE...BG/JM
FIRE WEATHER...JM
HYDROLOGY...BG/JM