Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 280307

Area Forecast Discussion
National Weather Service New York NY
1107 PM EDT Thu Apr 27 2017

A series of weak fronts cross the region Friday through Sunday.
A more significant cold front will pass through from the west
Monday night, followed by weak high pressure into Wednesday.
Another weak frontal system may begin to approach on Thursday.


1030 PM Update - Dense fog over central Suffolk on Long Island,
but that`s is as of now. Will hold off on a Dense Fog Advisory
despite the very moist south southeast flow. The lack of fog at
KFOK makes me think that the fog will not become widespread
along with the modified Richardson`s number suggesting more

As for PCPN, latest HiRes NWP is not supporting much and have
thus dropped POPs to 20. Activity over VA is weakening as well.


The cold front washes out across the region Friday. The more SW
flow continues as the airmass will continue to get warmer.
Ridging aloft occurs. Fog burns off in the morning. More sun is
expected. Highs Friday in the upper 60s out east where rain
showers and low clouds could linger to lower 80s for western
locations where there will be more sun. A chance of showers and
thunderstorms early but drier conditions move in the afternoon
with more of a westerly component to wind.

Next system approaches Friday night from the NW. Ridging will
make it more difficult for thunder. Showers chances increase
late at night into early Saturday. Lows in the low 50s to low
60s Friday night.


Forecast for this time frame remains rather consistent. First, a
weakening front nearby and a passing mid level shortwave may
generate some showers and possibly an elevated tstm mainly inland
Sat morning. Then Bermuda type high pressure setting up over the
western Atlantic will set up a favorable flow for warm temperatures
on Sat, even across coastal areas, as winds shift to the southwest
and then west. Have continued to trend warmer, with some places in
NE NJ reaching the upper 80s, on the higher end of guidance. If the
slightly warmer NAM were to verify, with full mixing to 850 mb and
late day downslope flow, Newark could make a run at the first 90-
degree reading of the year. Many places away from south facing
shorelines should get into at least the lower 80s, with 70s along
the coastlines and in the hither elevations inland. Capping
inversion will keep afternoon precip at bay.

A back door cold front dropping from the north should come through
at night, with some showers and possibly an elevated tstm, as low
levels stabilize but mid and upper levels remain marginally unstable.
It will be noticeably cooler for Sunday with near average temps in
the 60s.

Not much change for the long term with a warm front approaching
Sunday night and lifting through on Monday, accompanied by showers
and possibly an elevated tstm. Temps on Mon will be above average,
with upper 60s across Long Island and most of southern CT, and 70s
from NYC north/west. Some showers could come in late day ahead of an
approaching cold front, but the main push should come at night, with
only slight chance for a tstm as instability looks rather marginal.

Any remaining showers out east on Tue should end by late morning,
with fair wx and temps once again slightly above average for both
Tue and Wed as weak high pressure slides south, with upper 60s and
lower 70s. Increasing clouds on Wed ahead of the next weak frontal
system should limit high temps on Thu to the lower and mid 60s.


A weakening cold front approaches from the west tonight and
moves into the NYC area around 12Z Friday. The front moves
slowly east of the NYC terminals and dissipates Friday morning.
High pressure over the western Atlantic builds toward the
southeast coast Friday morning.

IFR/LIFR should remain through the night. Winds shifting from
SE to SW between 07z and 10z could improve conds slightly...but
should still remain IFR until at least 12z at the metro
terminals. Conditions then gradually improve W-E although exact
timing of the cold front and dissipation remains uncertain.
SHRA/TSTMS approaching from the S and W have been weakening as
they move towards the area. Thus will keep any mention of pcpn
out of the TAFs.

E-SE winds becoming S-SW late at the metro terminals and light
and variable elsewhere. Winds shift to west with the passage of
the cold front then come back around to southwest as the front
dissipates. Sea breezes are likely Friday afternoon.

.Friday night-Sunday...VFR. There is a chance of isolated
thunderstorms north and west of the metro terminals Saturday
morning into the afternoon.
.Sunday night-Monday...MVFR to IFR with light rain and fog.
.Monday night-Tuesday...MVFR with showers and isolated
thunderstorms. Improving to VFR with a cold front passage


SCA for ocean seas goes through Friday. Otherwise, sub SCA for
other waters. The SCA will be more marginal for ocean Friday
night. Dense fog redevelops tonight on the waters and lasts
until late Friday morning.

Fairly high confidence in increasing S-SW flow pushing ocean seas
above 5 ft by Mon afternoon ahead of a cold front, with gusts up to
25 kt and seas 5-8 ft Mon night. Ocean seas over 5 ft will likely
linger into Tue.


No widespread hydrologic impacts foreseen through the next 7


High tide cycle is occurring now and will allow Advisory to
expire at 03Z.

Due to high astronomical tides and an easterly swell the next
couple of days, water levels may approach minor coastal flood
benchmarks, in particular across the south shore back bays of
western LI during the evening high tide cycle. Only 1/3 to 3/4
of a foot of surge is needed for minor flooding.


MARINE...Dense Fog Advisory until 10 AM EDT Friday for ANZ330-335-338-
     Small Craft Advisory for hazardous seas until 6 PM EDT Friday
     for ANZ350-353-355.


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