Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 222052 CCA
AFDOKX

Area Forecast Discussion...CORRECTED
National Weather Service New York NY
452 PM EDT Thu Apr 22 2021

.SYNOPSIS...
Strong low pressure hovers in the Canadian Maritimes through
tonight and then will gradually weaken as it moves farther
northward Friday through Friday night. Meanwhile, high pressure
will move eastward out into the Atlantic Friday night into
Saturday. Low pressure approaches from the southwest late Saturday
and passes to the south and east on Sunday. High pressure then
builds in from the west Sunday night into Monday before settling
over the area on Tuesday. The high shifts offshore Wednesday and
Thursday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Going into this evening, cyclonic flow aloft will keep abundant
cloud coverage and with strong low pressure within the Canadian
Maritimes, a steep pressure gradient will remain. This will
allow for gusty NW flow to continue. Gusts up to around 35 mph
are expected into early this evening and then dropping more into
a 30 to 35 mph range. Winds will be decreasing more across the
interior, with gusts even dropping off for some locations.

After a shortwave passage this evening, heights will start to
rise overnight and some subsidence will start to decrease the
cloud coverage within the region. Closer to the coast and within
NYC, gusts are expected to continue but will be decreasing.

Radiational cooling will be more optimal across the interior.
Confidence for freezing or lower temperatures remains high
enough for the interior so there is a freeze warning for
Passaic and Western Bergen NJ, the Lower Hudson Valley except
for Southern Westchester NY and interior Southern CT. These
locations have a pretty high likelihood or dropping to 30 to 33
degrees for low temperatures, considering most of the guidance
is below freezing including new runs of the LAMP guidance for
late tonight into early Friday.

Less confidence for freezing temperatures closer to the coast
including the rest of Northeast NJ, NYC, Long Island, and
coastal sections of CT where lows are generally more in the mid
to upper 30s but near 40 for NYC. Still think the gusty winds
will prevent the formation of frost so no frost advisories are
expected at this time.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
The upper level low and surface low will gradually move farther
northward within the Canadian Maritimes. The surface low will
gradually weaken. Meanwhile, high pressure based in the
Southeast US on Friday will move eastward out into the Atlantic
Friday night.

The NW gusty flow will be in place for Friday but less than the
previous day and will diminish more substantially for Friday
night. The national blend of models was used for the high
temperatures and these will be trending higher with some warmer
air advecting into the region with veering winds from low to mid
levels. Forecast highs are in the upper 50s to lower 60s for
much of the region. More sun is expected with the ridging aloft
promoting more subsidence.

The mostly clear conditions are expected to continue Friday
night and with winds diminishing more, more optimal radiational
cooling conditions are expected. The airmass will be moderating
however with slightly warmer air at 850mb getting advected into
the region. The lows forecast are a combination of MOS consensus
and national blend of models, ranging from the upper 30s to
upper 40s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
The upper trough crosses the area on Sunday, with its associated
surface low passing south of Long Island during the day. After a
wet start to the day, rain will taper off from west to east during
the afternoon as the low moves east of the area. Gusty northwest
flow then develops Sunday night into Monday as the pressure
gradient tightens between the departing low and high pressure
building to the west.

The high builds over the area on Tuesday before shifting offshore
on Wednesday. With rising heights aloft, this should lead to a
gradual warming trend. After near normal temperatures on Sunday
and Monday, temperatures return to above normal Tuesday, and by
Wednesday temperatures may be as much as 10 degrees above seasonal
normals.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
High pressure builds towards the area tonight and pushes off the
southeast coast Friday afternoon.

VFR conditions through the TAF period.

W to NW wind gusts 30-35 kt late this afternoon will diminish this
evening, with gusts falling to 25 kt or less at coastal
terminals. Gusts may come to an end entirely for a few hours
very late tonight into early Friday morning at outlying
terminals. Gusts return Friday morning, although they should not
be as strong as today, with W winds gusting to 25-30 kt.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

No unscheduled amendments expected.

.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY....
.Friday...VFR. WNW winds G25-30kt.
.Saturday...VFR.
.Saturday night-Sunday...MVFR/IFR in rain.
.Monday-Tuesday...VFR.

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

&&

.MARINE...
Winds expected to peak late this afternoon into early this
evening. Gale warnings remain for all the waters until 8PM this
evening and then for the ocean until 11PM. There may be a few
occasional gales on the non-ocean waters this evening. There may
be a few occasional gales on the ocean waters going into the
overnight. Overall though, the non-ocean waters are expected to
transition to SCA level wind gusts for this evening and
overnight with the ocean having SCA level wind gusts late this
evening and overnight. Widespread SCA conditions are expected
Friday and then just for the ocean Friday evening. Non-ocean
waters will have winds drop to below SCA Friday night. For seas,
3-5 ft seas will continue on Eastern Long Island Sound into this
evening before dropping below 5 ft overnight. The ocean is
forecast to stay in a 5 to 7 ft range on average through tonight.
4 to 6 ft seas on the ocean are expected Friday into Friday
evening. Below SCA seas on the ocean are expected overnight Friday
night.

Sub-SCA conditions are forecast across all waters Saturday and
Saturday night as high pressure moves offshore and low pressure
approaches Saturday night. As the low tracks south and east of Long
Island Sunday into Sunday night, while deepening, SCA conditions are
expected to develop Sunday as both winds and seas increase. As the
low moves off to the northeast, winds will shift to the NW with SCA
gusts continuing across all the waters Sunday night before gradually
diminishing from west to east, as high pressure builds west of the
waters, during the day on Monday, and by Monday evening both winds
and seas will likely fall below SCA levels on all waters.

&&

.FIRE WEATHER...
An SPS has been coordinated with the surrounding states for the
mention of elevated risk of wildfire spread should ignition occur
for Friday.

There is still SPS for NJ and CT for elevated risk of wildfire
spread into early this evening with wind gusts up to near 30 to 35
mph and relative humidity down to around 30 percent. The SPS
includes the entire region for Friday. Friday will feature winds
just a little less gusty than the previous day, up to near 30 mph
but with lower relative humidity, between 20 and 30 percent.

Rainfall amounts near 0.25 to 0.50 inches from Wednesday in some
areas will likely factor into how quickly fine fuels can dry out.
There will be some spots that have less moisture than others in
terms of ground moisture.

&&

.HYDROLOGY...
No hydrologic impacts are expected through the period.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Freeze Warning from 1 AM to 9 AM EDT Friday for CTZ005>008.
NY...Freeze Warning from 1 AM to 9 AM EDT Friday for NYZ067>070.
NJ...Freeze Warning from 1 AM to 9 AM EDT Friday for NJZ002-004-103.
MARINE...Gale Warning until 8 PM EDT this evening for ANZ331-332-335-
     338-340-345.
     Gale Warning until 11 PM EDT this evening for ANZ350-353-355.

&&

$$
SYNOPSIS...JM/MET
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...MET
AVIATION...JP
MARINE...JM/MET
FIRE WEATHER...JM
HYDROLOGY...JM/MET


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