Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 271808
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
208 PM EDT Mon Mar 27 2017

.SYNOPSIS...
A warm front will slowly lift into the region today. A cold
front with a wave of low pressure passes through the region
Tuesday night. High pressure builds in for Wednesday and
Thursday, and shifts offshore Thursday night. A low pressure
system approaches from the central United States Thursday night
and impacts the region Friday and Saturday. High pressure
returns for Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Issued dense fog advisory for Long Island until 12 noon. Vsby at
all ASOS stations was 1/4 mile or less even at 14Z. Rain moving
in from the west and warm front moving onshore may improve vsby
but this remains to be seen.

Also adjusted PoP based on trends of radar and in HRRR and GFS
LAMP, with one band of rain moving across from late morning
into the early afternoon, followed by scattered showers this
afternoon.

Adjusted high temps upward slightly across Long Island and
southern CT, with a little more widespread lower 50s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Convergence aloft in the dry layer does not seem conducive to
much rainfall tonight. As a result, only low chances for rain
were included in the forecast. If rain does develop, it may turn
out to be mainly sprinkles or light drizzle. Surprisingly big
differences exist between the NAM and GFS for Tuesday. The NAM
holds off on the deep lift, and therefore the bulk of the rain,
for the entire day. The GFS brings in rain by morning. The ECMWF
supports the NAM, by keeping the bulk of the rain with the main
shortwave. The GFS appears to be kicking off convection over
Pennsylvania that brings residual energy in. The forecast sides
with the drier solutions, although there may be some showers or
pockets of light rain with weak vorticity advection and a moist
airmass. A blend of the models was used for temperatures.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
A southern stream shortwave over the Oklahoma and Kansas area
this Monday morning will weaken and track to the Mid Atlantic
coast Tuesday and offshore Tuesday night. Meanwhile, a northern
stream longwave trough moving through south central Canada moves
east and passes into northern New England Tuesday night. There
is still some differences in whether or not the two systems will
phase, with consensus for the south stream to be more
progressive and remain separate, and farther south than other
models, while dampening and exiting the Mid Atlantic. The
southern movement will keep an associated warm front to the
south. This southern and separate solution has been the trend
the last several runs. With higher confidence in precipitation
affecting the area, mainly the southern half of the CWA, will
have likely probabilities Tuesday night.

A northwest flow will persist across the region as surface
high pressure builds to the north and the upper northern stream
trough moves slowly off the northeast coast through Thursday
night. The surface high weakens Thursday night as another
southern stream shortwave approaches, however the upper ridge is
holding with the axis shifting east of the area Friday. The
southern stream system will also be weakening as the wave tracks
east. Have brought in chances late Thursday night into Friday
and this may be too quick if the ridge holds. The weakening low
will re develop off the Mid Atlantic coast Saturday with chances
of precipitation remaining into Saturday night. Cold air will
be in place across the northern tier and some of the
precipitation may fall as snow or a rain snow mix.

Weak high pressure returns for Sunday into Monday.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A warm front will remain in the vicinity of the terminals this
afternoon.

Expect low stratus with periods of fog through the forecast period.
Cigs may improve to MVFR for a period this afternoon/evening,
however overnight, they are expected to fall back to IFR or
lower. Visibilities have improved to VFR in most spots. This
too should only last through the afternoon/evening, then VSBYs
fall back below IFR or less as fog re-develops. There is a
chance that VSBYs fall to 1/4 mile or less, however will leave
out of the TAFs for now and will monitor through the evening.

Winds will remain less than 10 kt through the afternoon and
evening, before falling to light and variable overnight. Some
locations may even become calm.

     NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

KLGA TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

KEWR TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

KTEB TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

KHPN TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

KISP TAF Comments: Winds generally under 10kt but with low
confidence in timing of wind direction change today. Amendments
likely for changing flight categories.

.OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
.Tuesday afternoon-Tue night...IFR likely, LIFR possible Tuesday
night with rain/low clouds/fog .
.Wednesday...VFR. NW winds G15-20KT.
.Thursday...VFR.
.Friday-Saturday...Chance of rain with MVFR or lower
conditions. E winds G25KT at coastal terminals.

&&

.MARINE...
Marine dense fog advy in effect for this morning and may have
to be extended into this afternoon/tonight.

SCA for hazardous seas remains in effect with max sea still 5
ft. Winds and seas will be below Small Craft Advisory levels
late tonight into Tuesday.

A wave of low pressure passes to the south of the forecast
waters Tuesday night along with a cold front. Winds and seas are
expected to be below small craft levels across the forecast
waters. Northwesterly winds will develop behind the cold front
and then increase into Wednesday and Wednesday night as high
pressure builds to the north. Minimal small craft conditions
will be possible across the ocean waters Wednesday night into
Thursday in the northwest flow.

Then as high pressure builds over the waters Thursday winds and
seas will fall below advisory levels.

A southeasterly flow develops Friday and increases as low
pressure approaches the Mid Atlantic region. Marginal small
craft advisory wind gusts will be possible Friday night into
Sunday, mainly across the ocean waters. In additions ocean seas
will build to small craft levels late Friday and remain into
Sunday.

&&

.HYDROLOGY...
Around a half inch of rain is possible today. Additional rain of
a quarter inch or less is forecast for Tuesday. One to two
tenths of an inch of rainfall is likely Tuesday night. Then dry
conditions expected Wednesday and Thursday.

No hydrologic concerns are anticipated.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Dense Fog Advisory until 2 PM EDT this afternoon for ANZ335-
     338-345.
     Dense Fog Advisory until 8 PM EDT this evening for ANZ330-340-
     350-353.
     Small Craft Advisory for hazardous seas until 2 AM EDT Tuesday
     for ANZ350-353-355.
     Dense Fog Advisory until 6 PM EDT this evening for ANZ355.

&&

$$
SYNOPSIS...12/MET
NEAR TERM...Goodman
SHORT TERM...12
LONG TERM...MET
AVIATION...BC
MARINE...12/Goodman/MET
HYDROLOGY...12/MET



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