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Area forecast discussion 
National Weather Service New York New York
330 am EST Thursday Feb 11 2016

Synopsis...
an upper level system will pass through the region today. High pressure will
drift across the area on Friday.

&&

Near term /through tonight/...
snow showers tracking through the County Warning Area this morning putting down a coating
of snow and briefly reducing visible to a half mile. This is with a
shortwave embedded in the flow. Another shortwave is prognosticated to come
through today. This will work on an increasingly unstable airmass
with nearly dry adiabatic lapse rates in the h925-500 mb layer. NAM
even suggests SBCAPE over 100 j/kg. With this setup expect snow
showers and squalls to develop by this afternoon. Increasing middle level
winds will also allow for gusts in the 30s miles per hour. Brief periods of
very hazardous travel possible in snow and wind. Although this
falls below any warning/advisory criteria...will include the threat in
the severe weather potential statement.

Lapse rates ease tonight with subsidence in the wake of the shtrwv
and any departing convection. As a result will dry things out
quickly this evening with clearing skies overnight.

&&

Short term /Friday/...
fair weather to start with a surface hi pressure ridge over the
area...then the ridge is weakened by low pressure passing offshore and
an approaching Arctic front. The data seems to be trending faster
with approaching upper trough and cold front...so went close to the 3z
sref for timing across western zones. The GFS produces some light snow
across eastern areas on the periphery of the low. Bumped up the dry
probability of precipitation in the sref across eastern zones too slight chance for this. Any westward
trend could bring a dusting by dark eastern CT and Li. A blend of
guidance was used for temperatures with readings over 10f blw average.

&&

Long term /Friday night through Wednesday/...
an Arctic cold front approaches Friday night along with a
shortwave from the north. At the same time...shortwave energy
moves off the middle Atlantic coast. The combined energy should
initiate surface cyclogenesis along a baroclinic zone to our south
with the low passing well southeast of the 40n/70w benchmark late at
night. Looks like any chance of snow directly associated with this
low looks low...however...with the Arctic front and decreasing
stability due to cyclonic flow aloft...scattered snow showers expected.
Will cap probability of precipitation at chance for now.

An anomalously cold air mass then pours in behind the cold front for
the weekend. Another shortwave arrives alongside the core of cold
air aloft during Sat/Sat evening. The atmospheric column
dries...however there is still at least a chance of flurries during
this period.

As for temperatures Sat and Sat night...the calendar day high temperature on
Saturday will probably occur during the pre-dawn hours as strong
cold advection drops temperatures throughout the day. By noon...temperatures
are probably in the teens area-wide with wind chill values below
zero. Record to near-record cold temperatures for Sat night in spite of
gusty northwest flow. Both GFS and European model (ecmwf) show 850mb temperatures dropping to -29c
to -30c during the night before rising a few degrees toward
daybreak. Based on temperatures that occurred during a similar synoptic
setup last February with warmer temperatures aloft...went slightly below
the low temperatures that had occurred...which are close to what European model (ecmwf) MOS
has been showing for the past few runs. See the climate section
below for more details. The cold air combined with winds would
produce wind chills that would warrant an advisory during Sat night
into Sunday morning...possibly even a warning for some of the
northern suburbs.

Remaining cold but dry on Sunday as high pressure builds in with
highs only in the teens. Models then in disagreement with the timing
of the next system to potentially affect the region. High pressure
shifts offshore on Monday with the likelihood that the daytime hours
remain dry. A longwave trough then shifts through the eastern half
of the U.S. With its axis prognosticated to move through during Tuesday
night. This then helps strengthen a surface low moving up the
vicinity of the eastern Seaboard. Low confidence in the
evolution...track and timing of this system...and consequently precipitation
type. Have capped probability of precipitation at 50 percent for the rest of the long term
forecast for the time being and went with a general rain...snow or
mix of the two as precipitation type.

&&

Aviation /09z Thursday through Monday/...
mainly VFR across the terminals. A weak trough passing through the
region early this morning has set off some snow showers across the
region. Expect MVFR conditions in any snow showers.

The pressure gradient tightens with winds/gusts increasing through
12z...and strengthen further between 12z and 18z.

..NY metropolitan enhanced aviation weather support...

Detailed information...including hourly taf wind component forecasts can
be found at: http://www.Erh.NOAA.Gov/zny/n90 (lower case)

Kjfk fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be slightly
higher than forecast this afternoon.

Klga fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be
slightly higher than forecast this afternoon.

Kewr fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be slightly
higher than forecast this afternoon.

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

Kteb fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be
slightly higher than forecast this afternoon.

Khpn fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be slightly
higher than forecast this afternoon.

Kisp fcster comments: brief period of MVFR conditions possible in
snow showers through 12z. Occasional wind gusts may be
slightly higher than forecast this afternoon.

Outlook for 06z Thursday through Monday...
Thursday night...VFR. Diminishing northwest winds.
Friday...VFR.
Saturday...sub-VFR possible in brief -shsn. Northwest winds around 20 knots
with gusts up to 30 knots.
Sunday-Monday...VFR.

&&

Marine...
winds will increase out of the west today with gale conditions expected.
The warning was therefore expanded to all of the waters. The warning
remains up through tonight...then winds decrease through the day on Friday.

&&

Hydrology...
liquid equivalent of less than a tenth of an inch is expected through
Friday.

&&

Climate...
with the extremely cold air mass forecast Saturday into
Sunday...record minimums and record low maximums may be reached.
Here are the records and forecasts...

Station......record/fcst minimum...record low maximum/forecast high
for 2/14 for 2/14

NYC...........2 (1916) / 1.............17 (1979) / 19
LGA...........1 (1979) / 2.............15 (1979) / 19
JFK...........4 (1979) / 2.............17 (1979) / 19
isp...........7 (2015) / 1.............26 (1987) / 18
ewr...........0 (1979) / 0.............15 (1979) / 19
bdr...........3 (2015*) / 0.............18 (1979) / 17

*in 1979 as well

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Gale Warning until 6 am EST Friday for anz330-335-338-340-345-
350-353-355.

&&

$$
Synopsis...jmc
near term...jmc
short term...jmc
long term...jc
aviation...British Columbia
marine...jmc
hydrology...jmc
climate...

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