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fxus61 kokx 271334 
afdokx

Area forecast discussion
National Weather Service New York New York
934 am EDT Thu Apr 27 2017

Synopsis...
weak low pressure passes to the east today, while a dissipating
cold front approaches from the Ohio Valley. The front washes
out across the area on Friday. A cold front approaches Saturday
and pushes south of the area Saturday night. This front then
moves back toward the area as a warm front Sunday night into
Monday with the associated cold front moving through Monday
night into Tuesday morning.

&&

Near term /until 6 PM this evening/...
fog has improved over most locations over the last couple of
hours, however, some outlying areas can still see visibilities
of a mile or less. Fog should continue to improve over the next
couple of hours. Otherwise, forecast is on track.

Low clouds and fog this morning will be slow to lift due to a
subsidence inversion across the area and moist low-levels.

There may be some sun this afternoon, although confidence is
low. It will be considerably warmer today, with highs in the
lower 60s along the immediate coast, to the lower 70s from NYC
north and west.

&&

Short term /6 PM this evening through 6 PM Friday/...
upper level ridge passes to the east this evening as a short
wave trough pivots NE across the Ohio Valley. The latter of
which will send a dissipating cold front into the area toward
daybreak. Frontal forcing is weak with the mid level short wave
the main source of lift as the front moves into the area. There
is also weak elevated instability with a small chance of a
thunderstorm late tonight into Friday morning. Rainfall amounts
will generally be less than a tenth of inch, but isolated
higher amounts are possible with any stronger convection.

In addition, low-level warm advection and a S/southeast flow tonight
will likely result in low clouds, drizzle, and fog ahead of the
cold front.

Conditions clear out from west to east by late Friday morning
with temperatures rising into the 70s just inland from the
coast, and a warm as the lower 80s north and west of NYC. Winds
become SW in the morning with seabreeze development possible in
the afternoon. Temperatures will be about 10 degrees above
normal.

&&

Long term /Friday night through Wednesday/...
Bermuda type high pressure will set up over the north central
Atlantic Friday night into Saturday. This will set up a favorable
flow for warm temperatures, even across coastal areas, as winds
shift to the southwest. High temperatures on Saturday will reach the
lower to middle 80s away from the coast, lower to middle 70s along
the coast, and upper 60s at the immediate coast. This will also mean
a noticeable increase in the humidity levels as dew points rise into
the upper 50s to lower 60s across the area.

Surface cold front approaches the area from the northwest on
Saturday, pushing south of the region Saturday night. This will mean
temperatures and dew points drop under cold air advection as winds
shift to the north after the cold frontal passage. Zonal flow aloft
will be replaced by upper level which moves in from the Great Lakes
region Saturday night.

There may be some showers and isolated thunderstorms with the
passage of the cold front, mainly for inland areas as the marine air
over the coastal areas keeps the atmosphere more stable here.
Inland, higher temperatures and higher dew points will mean the
possibility of a shower or thunderstorm before the cold frontal
passage, however, weak ascent will limit activity.

Much of Saturday night through much of the day Sunday will remain
dry as high pressure noses in from southern Canada. The cold front
then moves north as a warm front late in the day Sunday into Sunday
night, showers are then once again possible, until the warm front
moves north of the area Monday, then showers with slight chance of
thunderstorms will be possible, until the associated cold front
moves through Monday night into early Tuesday morning. Thereafter,
conditions should remain dry through mid-week as the associated low
pressure heads away from the area.

&&

Aviation /14z Thursday through Monday/...
a weakening cold front approaches from the west today and into
tonight. Possibly moving to just west of the terminals by 12z
Friday.

Variability from IFR/vlifr to MVFR this morning, mainly with
ceilings. Conditions improve to MVFR around midday everywhere except
at kgon, where conditions remain no better than IFR. VFR possible
this afternoon at kewr/kteb/khpn/kswf for a few hours. Return to IFR
or lower throughout this evening.

There is a low chance for a passing shower and possibly a rumble
of thunder late tonight, with the best chance at western
terminals, and even there it is less likely than not to occur.

Light and variable winds become south-southeast-southeast at under 10 knots inland and
around 10 knots at coastal terminals from mid morning into early
afternoon. Winds become light and variable again this evening.

New York Metro enhanced aviation weather support...

Detailed information...including hourly taf wind component fcsts
can be found at:
http:/www.Weather.Gov/zny/n90

Kjfk taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

Klga taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

Kewr taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

The afternoon kewr haze potential forecast is yellow...which implies
slant range visibility 4-6sm outside of cloud.

Kteb taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

Khpn taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

Kisp taf comments: amendments due to variability in ceilings and
visibility. Still more likely to be IFR than any other category this
morning.

Outlook for 12z Friday through Monday...
Friday morning...IFR or lower probable. Isolated to scattered
showers, a rumble of thunder possible.
Friday afternoon-Sunday...most likely VFR.
Sunday night-Monday...MVFR or lower possible.

&&

Marine...
dense fog advisory remains in effect for all waters through mid
morning due to a weak pressure gradient and abundant low level
moisture. The fog is expected to gradually dissipate by mid to
late morning before returning again tonight into early Friday.

Winds will stay below Small Craft Advisory through Friday but the higher ocean
seas will remain through tonight and perhaps into Friday as
well. Non-ocean waters stay below Small Craft Advisory. Ocean seas are more
marginal for Small Craft Advisory Friday, at near 5 ft, so left end time of 6am
Friday for Small Craft Advisory for hazardous seas on the ocean.

Waves diminish Friday night, with 5 ft waves lingering over the
eastern ocean zone through midnight. Thereafter, seas should
remain below 5 ft through Sunday night, though they may touch 5
ft for a few hours late in the day Saturday into Saturday
evening as a southerly to southwesterly flow develops ahead of
an approaching cold front.

Waves then build Monday through early Tuesday morning, from 5
to 8 ft over the western ocean zone, to 8 to 10 ft over the
eastern ocean zone, in response to stronger southerly flow out
ahead of another approaching cold front. Wind gusts during late
Monday into Monday night could reach 25 kt or slightly higher at
times. Waves diminish slowly, but should remain above 5 ft
through the rest of the long term.

&&

Hydrology...
rainfall amounts tonight through Friday morning are generally
expected to remain below a tenth of an inch. However, there may
be isolated brief heavy downpours in any thunderstorms that
develop.

No significant rainfall expected in the long term. However,
there may be isolated brief heavy downpours in any thunderstorms
that develop during this time period.

&&

Tides/coastal flooding...
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.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...dense fog advisory until 10 am EDT this morning for anz330-335-
338-340-345-350-353-355.
Small Craft Advisory for hazardous seas until 6 am EDT Friday
for anz350-353-355.

&&

$$
Synopsis...jp/dw
near term...jp
short term...dw

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