Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
103 PM EST Monday Dec 9 2013
low pressure off the New Jersey coast will pass slowly southeast
of Long Island today. The low will then move into the Canadian
Maritimes tonight...with high pressure building in from the west
late. Another weak low will pass to the south on Tuesday. Gusty
winds will usher in Arctic air Tuesday into Wednesday. The wintry
pattern will remain in place through the weekend...when a storm
will be possible.
Near term /until 6 PM this evening/...
widespread rain and freezing rain has ended...so will cancel the
Winter Weather Advisory that was in effect for the northern zones.
Patchy drizzle will continue region-wide...and there may be some
lingering patchy freezing drizzle early this afternoon until
temperatures rise above freezing.
Temperatures across the coast will likely rise well into the 40s...while
far interior portions of the area stay in the middle 30s.
Short term /6 PM this evening through 6 PM Tuesday/...
models in good agreement with drying conditions this evening in
the wake of departing low pressure. Gradual cold air advection expected in its
wake with temperatures falling into the upper 20s/lower 30s.
Then attention turns to potential light snow event for
Tuesday...with the main players being a strong jet streak ahead
of approaching northern stream and southern stream shortwave
energy...inducing a weak wave of low pressure along a cold front
stalled to the south. The amount of southern stream
interaction...which always poses some predictability
issues...seems to be a key in the amplitude of the trough and
amount of Gulf moisture that gets entrained in the SW flow and
over the cold airmass in place. Models have trended more
amplified...and therefore wetter across the region.
Models are signaling some good frontogenetic banding and deep
layered lift under the right entrance region of a 175 knots jet streak.
So potential is there for a few inches of snow...but banding
placement will be key. Spread exists between a solid advisory
level snow event for much of the area of 3 to 6 inches with locally
higher amounts...to just a coating to 2 inches. Will increase probability of precipitation
to likely/categorical based on models trends...with a trend towards
a middle of the Road solution for snowfall.
Long term /Tuesday night through Sunday/...
1030s hipres ridge sets up S of the Mason-Dixon line Tuesday night and
Wednesday. This will keep a tight pressure gradient over the region and brisk west
winds. DPVA sets up courtesy of the 500 mb trough late Wednesday through Thursday. This
may be enough to produce some flurries...or even light snow in vicinity of
the Twin Forks with 260 degree flow over the sound and bays. The
hipres ridge extends northward across the region Friday...so dry and cold but
with less wind.
Attention then turns to the weekend. The models have been hinting at
a storm around the Monday time period...but now both the 00z GFS and
European model (ecmwf) have converged on a Sat-sun timing. With the GFS ensembles
supporting the operational models...will expect some weather this
weekend. The GFS is much weaker...with cyclogenesis basically just
getting started at the benchmark. The European model (ecmwf) is better organized and
therefore more potent. Both solutions keep this southern stream system
displaced from the next polar intrusion. If the two were to
phase...would expect a significant storm to spin up over the
Atlantic. Previous model runs have hinted at this potential. For now
however...will side with the latest data and forecast a weaker and
quicker system...with chances for snow/rain Sat...ending as shsn sun.
Aviation /18z Monday through Saturday/...
low pressure moving south of the area will bring varying
conditions through this afternoon. Improving conditions tonight
will be short lived with another round of precipitation expected
North-north-northeast winds generally 5-10 kts shift to a west-west-southwest flow through this
afternoon into this evening. Any wind shift may occur +/- 1 hour than
Light drizzle possible through the early afternoon...with dry conditions
then expected through tonight. Light snow moves in tomorrow
morning...possible as early as 12z...with higher confidence after 15z.
Period of moderate snow with lower ceilings/visible will be possible 15-20z...but
with low confidence at exact timing at this time...will not
mention in taf. May also see rain mixing in with snow at kjfk/kisp
after 18z...but again not enough confidence to include at this
Snowfall totals right now look to be between 1-3 inches across the
Generally IFR vis/cigs...with brief period of ceilings down to 400ft
through 20z at city terminals. Both ceilings and visible may improve +1-2
hours sooner than in tafs.
New York 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: winds varying between 340 and 030 through
20z. Low confidence ceilings drop below 500ft through 20z.
Klga fcster comments: winds will vary between 340 and 030 through
Kewr fcster comments: 400ft ceilings lay linger +1-2 hours. Improving
visible possible earlier than in taf.
Kteb fcster comments: 400ft ceilings lay linger +1-2 hours. Improving
visible possible earlier than in taf.
Khpn fcster comments: moderate confidence on IFR conditions through the
Kisp fcster comments: moderate confidence 400ft ceilings last through 20z.
Outlook for 18z Tuesday through Saturday...
Tuesday...IFR conditions with -sn/sn. Possible -rasn at the coast.
Tuesday night...improving conditions. West winds 10-20 knots.
Wednesday...VFR. West-northwest winds 10-20 knots with gusts up to 25 knots.
Saturday...MVFR or lower conditions with -sn.
Small Craft Advisory remains up for the ocean waters through tonight with wind
gusts increasing to 25 knots in wake of low pressure...and Small Craft Advisory ocean
seas continuing. Conditions appear to remain just below Small Craft Advisory across
remainder of waters. Small Craft Advisory conds on ocean may continue into Tuesday on
the ocean as weak low pressure passes to the south.
Then gales are likely on the ocean Tuesday night into Wednesday...and possible
elsewhere. Conditions thereafter through the remainder of the week
will generally be at or above Small Craft Advisory levels. Best chance for gales Thursday...then
again for the second half of the weekend as low pressure develops over
1/4 to 1/2 inch liquid quantitative precipitation forecast expected on Tuesday...but it will fall
as snow...resulting in 1-3 inches of accumulation.
due to interference issues with the U.S. Coast Guard
emergency broadcast channel...the New York City National oceanic and atmospheric administration all hazards
weather radio station kwo35 remains out of service. The National
Weather Service is working with several U.S. Government agencies
to isolate and resolve this technical problem.
During this time...the transmitter may be returned to service
intermittently for use of the National oceanic and atmospheric administration all hazards weather radio
during potentially dangerous weather situations...for routine
weekly tests of the warning system...and to determine if the
interference issue has been resolved.
Marine...Small Craft Advisory until 6 am EST Tuesday for anz350-353-355.