868
FXUS61 KOKX 212005
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
405 PM EDT Mon Apr 21 2025
.SYNOPSIS...
High pressure slides east and offshore today. A warm front
approaches the area this evening followed by a cold front on
Tuesday into Tuesday night. High pressure then builds back in
for Wednesday. High pressure remains over the region through
Thursday night, followed by a frontal system Friday into
Saturday. High pressure returns for the second half of the
weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --
A weakening closed upper low lifts from the upper Great Lakes
into Ontario/Quebec tonight. At the surface, a resultant low
pressure system takes a similar track. Locally, its associated
warm front approaches this evening and lifts north of most of
the area tonight, before trailing and weakening occluded/cold
front enter the region towards morning.
CAMs continue initializing too aggressive with this activity
across the area this afternoon. An isolated shower is possible
across the coastal plain late this afternoon, with more likely
just a few sprinkles with a dry subcloud layer.
Modest theta-e advection and lift with 40-45kt llj over this
boundary will bring a 6 hr period of showers traversing w to e
across the area tonight between 02z and 12z. This lift, PWATS
approaching 1.5"(+2 STD), combined with a bit of weak elevated
instability may allow for a few brief/heavy downpours. Very
slight chance for tsra along the coast. Overall light basin
averaged QPF, with NBM indicating about a 30-40% potential for
a wetting rain across interior.-- End Changed Discussion --
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
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Key Messages:
* Dry conditions and well above seasonable temps on Tuesday and
Wednesday
Great Lakes closed low slides east through Ontario/Quebec on
Tuesday into Wednesday while weakening. At the surface, a
resultant weakening low pressure slides E through Quebec and
Northern New England Tuesday into Tuesday Night, and thru the
Canadian Maritimes on Wednesday.
Locally, warm front pushes north Tuesday AM, with weakening cold
front stalling over the area Tuesday. Secondary cold front crosses
Tuesday Night with Canadian high pressure noses in from the NW on
Wednesday.
Drying conditions Tuesday with deep WSW flow. Morning stratus
should give way to a veil of high clouds, deep mixing and still
mild 850mb temps (10C dropping to 8c in the late aft), which
will result in unseasonably warm temps (mid to upper 70s) for
all but south and eastern coastal areas on gusty westerly flow.
Temps should challenge the daily record high of 75F for KISP.
Southern and eastern coastal areas could be into the mid 70s as
well (warmer than current forecast) if westerly flow is
stronger than modeled, but with weakening cold front in the
region this could allow for more backed (maritime) flow for
these area. Leaned towards 50-75th percentile NBM based on
downslope flow regime. Once again, NBM deterministic max T are
generally running in the lowest 25th quartile, which appears low
based on above.
Weak cold front sags south of the region Tuesday Night. With mixed
low-levels and little change in airmass, continued mild conditions
likely with lows in the mid to upper 40s for much of the area, lower
50s NYC/NJ metro.
High pressure builds west and south of the region on Wednesday. NW
flow to start the day will give way to afternoon sea breeze
development as thermal troughing develops. Plenty of sunshine,
filtered by a veil of high clouds, should allow temps to warm up
quickly areawide before that with deep mixing towards 850 mb (7-9
C). High temps should be able to climb into the upper 60s to lower
70 for the coast before seabreeze development knocks temps back
down, and lower to mid 70s for NYC/NJ metro and interior to the
north of sea breeze. Leaned towards 50-75th percentile NBM based on
weak offshore flow regime.-- End Changed Discussion --
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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The long term period starts off with high pressure over the region
with dry conditions and mostly clear skies for Wednesday night and
Thursday. The high starts to slide east Thursday night and Friday,
with another shortwave/low pressure system approaching for Friday
into Saturday. The surface low is expected to pass north of the
region with its associated warm front moving through on Friday and
cold front moving across the area during the day Saturday. 12Z
global guidance still varies on timing with some models such as the
12Z GFS having the front push through 15-18Z Saturday, while other
models don`t have it until after 00Z Sunday. This means the timing
of likely POPs, chance for thunder, and Saturday`s highs could still
shift some from what is currently forecast.
Overall, clouds will gradually increase Thursday night and early
Friday, with POPs gradually increasing Friday afternoon. For now,
looking at just some chance POPs Friday evening. POPs increase
further after midnight Friday night into Saturday as a cold front
approaches and moves across the region. POPs taper on Saturday night.
Mainly rain showers expected, but some instability along with lift
from FROPA could lead to a few rumbles of thunder on Saturday. The
chances for this will become more clear as the event nears.
High pressure returns Sunday from the Great Lakes region under NW
flow leading to dry weather and sunshine to end the weekend on.
Temperatures remain at or above normal for this time of year.-- End Changed Discussion --
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
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A warm front lifts north of the terminals late tonight. A cold
front approaches Tuesday morning.
VFR early this evening, becoming MVFR/IFR tonight mainly after 03Z,
along with some showers.
SE winds this evening 10-13 kt. Any gusts are now expected to be
occasional this evening. Tonight, winds diminish, falling below 10
kt and become more southerly, then SW to W with the passage of a
warm front early Tuesday morning. Wind speeds increase to 10 to 15
kt as the cold front approaches Tuesday.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts this evening of 15 to around 20 kt.
Timing of potential showers and MVFR this evening/overnight may be
off by 1-2 hours.
.OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday afternoon: VFR. SW-W winds 10 to 15 kt. Occasional gusts to
20 kt possible.
Wednesday and Thursday: VFR.
Friday: Chance of MVFR and showers, mainly in the late afternoon
into the night.
Saturday: MVFR or lower in showers. An isolated thunderstorm is
possible.
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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Occasional gusts to 25kts are possible for a short period on the
ocean waters in advance of a frontal system tonight. Not enough
confidence for SCA.
Thereafter, otherwise conditions are expected to remain below SCA
levels through Friday in a weak pressure regime.
Next chance for SCA conditions will be Friday night into
Saturday with a frontal system moving across the area waters.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic issues through next weekend.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BR/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...BR
AVIATION...JP
MARINE...BR/NV
HYDROLOGY...BR/NV