223
FXUS61 KOKX 180814
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
414 AM EDT Fri Apr 18 2025
.SYNOPSIS...
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High pressure slides well offshore today. A cold front approaches
late Saturday and moves through Saturday night into early Sunday
morning. High pressure then follows Sunday Night into early Monday
before the next frontal system late Monday through Tuesday. High
pressure then follows into Wednesday with potential of another front
for Thursday.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TONIGHT/...
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Key Messages:
* Temps moderating to several degrees above seasonable for areas
west of the Hudson River today, with highs in the lower 70s.
Gradually rising heights today as southern ridging builds north
and sharp troughing extends from the SW US to the central
Canadian plains. In between, deep SW flow extends from sub-
tropics to New England with a strong waa regime developing. At
the surface, high pressure slides offshore today with a
strengthening low pressure system tracking from the Great Lakes
into southern Quebec tonight in response to a strong northern
stream shortwave. An associated warm front develops/lifts NW of
the region late today into tonight in response to a developing
45-50kt SW llj overhead.
This setup will bring dry conditions today, but increasing high
clouds rounding SE US ridging. A slight chance of a shower late
today/tonight across interior with warm frontal passage to the
north and weak shortwave energy moving through to the north.
Strong waa and breezy southerly flow develops this afternoon (15-
20g25-35mph), which should have areas west of the Hudson River
climbing well into the 60s to around 70. East of the Hudson
River, the strengthening southerly flow will likely have highs
progressively capped in the upper 50s to 60 towards south
coastal areas, with flow off of mid 40s degree waters. Used a
blend of NBM deterministic and HRRR to highlight the strong
mesoscale temp gradient.
The early Spring synoptic and mesoscale environment are also
supportive of a strong coastal (Ambrose) jet formation with S
winds of 25-30G35 mph likely in the late aft/early eve for
Brooklyn/Queens/W LI.
Flow veers more to the SW tonight into Sat as area is squeezed
between Canadian low pressure to the north and Atlantic high
pressure off the SE US coast to the south. Mild temps in the upper
40s for LI/CT in maritime airmass to lower to mid 50s for NYC/NJ
metro and points west with continued waa flow.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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Key Messages:
* Unseasonably warm temperatures (10 to 20 degrees above
normal) areawide Saturday, particularly away from the coast,
with highs in the 70s to lower 80s.
* Cold water submersion dangers for recreational boaters,
canoers or kayakers this weekend with warm air temperatures,
but water temps remain in the 40s.
East coast upper ridging holds strong through Saturday, giving
way to an amplifying northern stream shortwave/closed low
tracking east from Ontario on Saturday and through Quebec and
Canadian Maritimes Sat Night into Sunday Night. At the surface,
a strengthening low pressure system takes a similar track
Saturday, stacking under the upper low Sat Night into Sunday
over SE Canada.
Models continue in good agreement with flow veering more to a
gusty SW on Sat (15-20g25-35mph) as area is squeezed between SE
Canadian low pressure and elongated Atlantic high pressure to
the south. Latest guidance appears to hold off any shower
activity until early evening, and moreso with the cold front,
then the developing/approaching pre-frontal trough due to low-
mid level capping during the day. This may present potential for
a bit more warming of airmass, but could be limited with quite
a bit of high and mid cloud cover streaming in along periphery
of ridge. These competing factors bear out in the model
guidance, with quite a bit of spread in 850mb temps across
deterministic guidances (14-17C).
NBM deterministic is generally running in the lower 25th
quartile of guidance for max temps on Sat, which appears to be
low based on the anomalously warm airmass. With likely mixing to
850mb away from southern and eastern coasts, and unseasonably
warm temps aloft (+1-2 STD 850mb temps), have stayed close to
previous forecast, near the 50th NBM percentile, projecting
widespread 70s to lower 80s away from southern and eastern
coastal areas (greater maritime influence). If warmer end of
guidance verifies (NAM, HRRR, upper quartile NBM, etc.) more
widespread temps in the lower to mid 80s would result, with
record max temperatures being approached for some of the climate
stations.
Cold front approaches Sat eve, with pre-frontal trough likely
already in place across the interior. Convectively induced
vorts streaming through the upper flow likely trigger iso-sct
shower activity (particularly NW of NYC) in a moistening profile
(+2 std PWAT) Sat eve. Limited forcing and low-level
convergence, and short window of weak instability, should
preclude deep convection.
Model spread exists in the deepening rate of the SE Canadian low
pressure Sat Night into Sun, which is causing some model timing
issues with cold frontal passage Sat Night, and more so the strength
of pressure gradient and caa Sat Night into Sun. Overall gusty, dry
and much cooler temps expected Sunday (still a few degrees
above normal), but exact details will need to be refined. Have
stayed close to NBM 50th for temps based on the above, which has
a better representation of warmer temps along the coast in NW
flow than the NBM deterministic.
High pressure noses in Sunday Night with potential for good
radiational cooling conds for outlying areas with temps
dropping into the 30s, and 40s elsewhere.-- End Changed Discussion --
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
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No significant changes to the long term forecast. Stuck fairly close
to the previous forecast/NBM.
Ridging aloft and at the surface will push offshore during the day
Monday. This will allow a warm front to lift to the north of the
region Monday night, which will be quickly followed by a cold
frontal passage on Tuesday. The retreating high pressure on Monday
will set up a SE flow which will keep temperatures cooler and
largely in the upper 50s to low 60s. Probabilities for showers are
initially low Monday night, but increase once the warm front lifts
across the area late Monday night into early Tuesday morning. The
shower chances coincide with a bit better forcing as a middle and
upper level trough moves across the region. The actual cold front
will follow Tuesday afternoon and evening. The cold front should
pass through dry as heights aloft start rising and any larger scale
support moves well NE of the area. Temperatures on Tuesday push back
above normal with highs in the mid to upper 60s for most spots
except portions of NE NJ and Lower Hudson Valley where low to mid
70s are possible.
Ridging returns aloft and at the surface for Wednesday. The pattern
remains progressive with potential of another frontal system moving
across the area at some point Thursday or Thursday night into
Friday. Modeling differs on the amplitude of the next shortwave and
associated lift and moisture return. The model consensus is
currently only depicting a 20 percent chance for showers late
Thursday into Thursday night, then slightly increasing on Friday
which seems reasonable at this time range. Temperature should remain
above normal Wednesday through Friday.-- End Changed Discussion --
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
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A ridge of high pressure moves offshore today. A warm front
approaches from the SW this evening and moves across the terminals
tonight
VFR through the TAF period.
With high pressure building over the region, winds will remain light
and variable through the early morning hours. SSW winds ramp up this
morning, increasing to 15 to 20 kt with gust to around 25 kt. Some
of the coastal terminals right along the water, KJFK, KBDR, and KGON
may see less gustiness. Most of the wind gusts end around 00z-02z
Saturday. Also, a strong low level jet moves over the region around
00z Saturday. Will include a period of SW LLWS with wind speeds 45-
50kt at 2kft.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts may be more occasional at KJFK this afternoon, but with
sustained winds around 20kt.
.OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY...
Saturday: Mainly VFR. Slight chance of showers aft 18Z. SW
winds gusting to around 30kt.
Sunday: VFR. NW wind gusts 15-20kt possible.
Monday: VFR early, then sub VFR late day and at night with a chance
of showers.
Tuesday: Becoming VFR with W winds.
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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SCA conditions expected to develop on the ocean this aft/eve in
strengthening S/SW flow and building seas, continuing through
Saturday.
Nearshore S SCA winds to 25-30kt expected for NYC/W LI this aft/eve
with coastal jet development across the entrance to NY Harbor. These
nearshore winds may diminish below SCA late tonight into Sat
AM, but then re-develop for all waters Sat morning, and continue
into early eve ahead of approaching cold front.
Cold frontal passage expected late Sat Night into Sun Am, with NW
windshift. Potential for SCA winds gusts across all waters in
wake of cold front Sat night into Sun Am, with SCA southerly
swells likely slow to fall below 5 ft through Sunday AM.
Sub-SCA conditions are then expected Sunday night through much of
next week with a weak pressure gradient over the area.
Conditions will remain below SCA levels Monday through the middle
part of next week with a relatively weak pressure gradient over the
waters.-- End Changed Discussion --
&&
.FIRE WEATHER...
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Marginally elevated risk for brush fire spread for the early to
mid afternoon today as RH levels drop into the lower to mid 30
percent range away from the south coasts and frequent winds
gusts increase to the 20 to 30 mph range. Southerly wind gusts
continue to increase to 25 to 35 mph late this afternoon into
evening, while increasing RH levels to 35 to 50% range.
Met, fuel and land conditions will be re-assessed with state
fire and land management officials later this morning.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic concerns through the middle of next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Frost Advisory until 8 AM EDT this morning for CTZ010>012.
NY...Frost Advisory until 8 AM EDT this morning for NYZ079-081.
NJ...None.
MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Saturday for ANZ331-
332-340.
Small Craft Advisory from 2 PM this afternoon to 8 PM EDT
Saturday for ANZ335-338-345.
Small Craft Advisory from 6 PM this evening to 8 AM EDT Sunday
for ANZ350-353.
Small Craft Advisory from 2 PM this afternoon to 8 AM EDT
Sunday for ANZ355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BC/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...BC
AVIATION...BC
MARINE...BC/NV
FIRE WEATHER...
HYDROLOGY...BC/NV