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Area forecast discussion 
National Weather Service New York New York
727 am EST Tue Dec 6 2016

Synopsis...
high pressure builds over the area this morning, then retreats to
the northeast this afternoon. Low pressure will track off of Cape
Hatteras tonight, and southeast of Long Island and out to sea on
Wednesday. A series of cold fronts will move southeast across the
region through Friday followed by cold Canadian high pressure
Saturday low pressure will approach Sunday and move across the
area early next week.

&&

Near term /until 3 PM this afternoon/...
a 1021 high was centered over the Pennsylvania/New Jersey border
at 6 am. This high will drift over the tri-state region this
morning, and over Maine this afternoon. The result will be a sunny
start, with mid and high clouds overspreading the area from south
to north through the day. The guidance was in good agreement for
temperatures, so a blend was used.

&&

Short term /3 PM this afternoon through 6 PM Wednesday/...
low pressure will develop along a warm front late today over the
southeast, with the low deepening off of Cape Hatteras by around
00z. The low will then hook to the right after 6z and track out to
sea.

The NAM, GFS and European model (ecmwf) were tightly clustered on the track and
intensity of the low.

The thermal profiles progged are minimally supportive of snow
with the system. This quickly eliminates the coasts from snow
chances with a mild boundary layer on easterly component flow.
Across the interior, any accumulating snow will depend on wet
bulbing and elevation. As a result, only minor snow amounts are
expected for the majority of the forecast area at this time.

The main exception is across Orange County, where it appears they
are far enough inland to avoid a marine influenced boundary layer,
have enough deep lift to produce moderate precipitation rates and
maximize the wet bulb effect, and have some elevation to cool the
low levels orographically. Because of this, a Winter Weather
Advisory has been issued for the County. Much of the area could
only see a slushy inch or so, but elevations over a thousand feet
could pick up around 4 inches if everything comes together as
currently forecast.

As the lift weakens after 6z and dry air aloft spills in, the
precipitation looks to transition to light rain and drizzle early
Wednesday morning into the early afternoon. There is a low chance
that some pockets of freezing drizzle develop across the interior
before 12z. The most likely spot is where the advisory has already
been issued for snow.

&&

Long term /Wednesday night through Monday/...
little change in the long term as a closed upper low remain
across southeastern Canada Wednesday night through Friday. A
shortwave will rotate around the closed low bringing a cold front
and surface trough moving through the mid Atlantic Thursday. This
may result in isolated to scattered rain/snow showers, along with
a cold air mass. This cold front will bring temperatures around 5
to 10 degrees below normal by the end of the week.

The upper low opens and moves out late Friday and Friday night with
weak upper ridging. The upper flow become nearly zonal across the
Continental United States Friday night and through the weekend.
With high pressure moving off the northeast coast Sunday a return
flow develops and warm advection sets up into Monday.

The next shortwave to affect the area will move on shore of the
Pacific northwest Friday night and quickly move across the country.
Cyclogenesis occurs across the Central Plains Sunday into Sunday
night with the low tracking through the Great Lakes. Precipitation
Sunday night may start as snow inland and transition to rain Monday
and will be dependent on how quickly the warmer air moves into the
area. If a warmer layer moves in aloft before the low level cold air
is scoured out there will be a chance for some freezing rain Sunday
night. With the uncertainty did not include in the forecast at this
time and leaned toward a warmer solution.

&&

Aviation /12z Tuesday through Saturday/...
high pressure will pass just north of the terminals this morning
and then offshore this afternoon. Low pressure approaches from
the southwest late in the day, passing to the south tonight.

VFR with gradually increasing mid and high clouds today. MVFR
conditions spread in from the SW around 00z as rain approaches
the NYC Metro. The rain and MVFR/IFR conditions sweep across the
remainder of the area during the evening. Snow expected to at
least mix with the rain at kswf with the potential for a few
inches of snowfall.

North winds this morning veer around to the east this afternoon, and
then back to the NE tonight as low pressure moves off the mid
Atlantic coast. Gusts up to 20 kt possible at the coastal
terminals tonight.

New York 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: timing of MVFR/IFR conditions could be delayed 1-2
hours.

Klga taf comments: timing of MVFR/IFR conditions could be delayed 1-2
hours.

Kewr taf comments: timing of MVFR/IFR conditions could be delayed 1-2
hours.

The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.

Kteb taf comments: timing of MVFR/IFR conditions could be delayed 1-2
hours.

Khpn taf comments: timing of MVFR/IFR conditions could be delayed 1-2
hours.

Kisp taf comments: timing of MVFR/IFR conditions could be delayed 1-2
hours.

Outlook for 12z Wednesday through Saturday...
Wednesday...MVFR/IFR in stratus, with slow improvement during
the afternoon.
Wednesday night-Thursday night...VFR.
Friday-Friday night...VFR. Northwest winds 15-20 kt, gusts 25-30 kt.
Saturday...VFR. Northwest winds 15 kt gusts 20-25 kt.

&&

Marine...
northerly flow today will veer to the northeast and intensify
tonight. A Small Craft Advisory has been issued for the ocean
tonight into Wednesday for this, with an advisory for The Harbor
for tonight. Elsewhere, winds and seas area expected to remain
below small craft levels.

Winds and seas will remain below Small Craft Advisory levels Wednesday night
through Thursday as low pressure remains to the north across
southeastern Canada. A cold front will move through Thursday and a
strong and gusty northwest flow will develops. Thursday night Small Craft Advisory
gusts develop on the ocean waters, and then during Friday winds
increase, to near gale force on the ocean waters, and Small Craft Advisory gusts on
the remainder of the forecast waters. Small Craft Advisory gusts continue into Friday
night, then subside late as high pressure begins to build to the
west. Saturday morning winds and seas are expected to be below Small Craft Advisory
levels on all the waters as high pressure continues to build. Winds
and seas increase once again early next week as another low pressure
system moves across the area.

&&

Hydrology...
a half inch or less of liquid equivalent is expected tonight.
Otherwise, no hydrologic impacts are anticipated the next 7 days.

&&

Okx watches/warnings/advisories...
CT...none.
New York...Winter Weather Advisory from 6 PM this evening to 6 am EST
Wednesday for nyz067.
New Jersey...none.
Marine...Small Craft Advisory from 6 PM this evening to noon EST
Wednesday for anz350-353-355.
Small Craft Advisory from 6 PM this evening to 6 am EST
Wednesday for anz338.

&&

$$
Synopsis...BC/jmc
near term...jmc
short term...jmc
long term...British Columbia
aviation...dw
marine...BC/jmc
hydrology...BC/jmc

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