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Area forecast discussion 
National Weather Service New York New York
1218 PM EST Thursday Dec 18 2014

Synopsis...
high pressure from the Great Lakes builds over the northeast
through the weekend. Weak low pressure is forecast to develop
along the Carolina coast Monday afternoon and pass well south of
Long Island Monday night. A strong low pressure system is expected
to pass across the Great Lakes Wednesday pushing its cold front
through the tri-state area late in the day.

&&

Near term /until 6 PM this evening/...
cloud cover forecast remains tricky. Moisture is trapped under a
strong inversion at 900 hpa. Have revised the cloud cover forecast
again based on the trends and NAM simulated satellite data.
Rap...hrrr and narre-tl guidance continue to struggle.

Otherwise...low pressure over Nova Scotia will meander about the
Canadian Maritimes. The local area will be caught between this
system and high pressure over the upper Midwest which will result in a
gusty west/northwest flow.

Maximum temperatures a tad warmer over Long Island and coastal CT due to
downslope.

Winds remain northwest gusting up to 30 miles per hour...diminishing by middle to late
afternoon.

&&

Short term /6 PM this evening through Friday night/...
have increased cloud cover overnight into Friday which is also
reflected in the min temperature forecast as expecting winds to remain up as
well.

Basically have high pressure building in from the west and
gradually diminishing northerly flow that veers NE Friday night.
Again a lot of uncertainty with the cloud cover forecast...though
persistent 900 hpa inversion suggests a continuation of the strato-
cumulus. Followed 12z NAM simulated satellite for the most part.

Note that the northern edge of the high clouds currently in
northern Illinois Pass across the south part of the local area this
evening into the overnight. Thinking that most of this cirrus is
thin broken.

&&

Long term /Saturday through Wednesday/...
main feature continues to be wednesday's Great Lakes low and its
cold frontal passage through the local area Christmas evening.

Sat night-Sunday...a weak negatively tilted short WV trough is forecast
to mv NE across the area aided by weak low level warm air advection.
Lowered chances of precipitation as high pressure over northern New England
remains dominant and limits lift. Can not rule out a chance of light
snow/rain for Sat night into early Sunday then a chance of light rain
Sunday afternoon. A dusting is possible.

Sun night-early Tuesday...a synoptic scale trough is forecast to develop
across the central U.S. Aiding in cyclogenesis along the Carolina coast
Monday. This will increase precipitation chances Monday aftn-night.

With a new moon on Sunday...astronomical tides are high...thus
there's a chance for minor tidal flooding late Monday-early Tuesday.

Wednesday...good agreement among the global models continue for a strong middle
week storm tracking well west of the area with the development of
a southeast wind swept rain followed by strong winds during the day on
Christmas. Low pressure is forecast to rapidly deepen across the Tennessee/Ohio
valleys Tuesday night into Wednesday...wrapping up over the Great Lakes Wednesday
night into Thursday with pressures approaching 970 mb. This track
would keep the forecast area in the warm sector of the storm with
the potential for convection and even strong winds. The caveat
here is that the storm is about a week away with a lot of time for
change in track and timing. In addition...the fast Pacific flow would
lead one to believe that there are going to be timing issues with
the southern branch short wave energy.

&&

Aviation /18z Thursday through Tuesday/...
deepening low pressure will drift through the Canadian Maritimes
through the taf period. Scattered-broken 035-050 ceilings and gusty winds prevail
this afternoon with winds decreasing tonight. VFR through taf
period

Winds...direction mainly 290-300 degrees with speeds of 15-20 knots
gusts near 25 knots. There could be some variation with gusts being
intermittent for a brief period of time. Some variability of northwest wind
direction 30-40 degrees possible.

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: moderate confidence forecast. No unscheduled
amendments are expected.

Klga fcster comments: moderate confidence forecast. No unscheduled
amendments are expected.

Kewr fcster comments: moderate confidence forecast. No unscheduled
amendments are expected.

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

Kteb fcster comments: moderate confidence forecast. No unscheduled
amendments are expected.

Khpn fcster comments: moderate confidence forecast. No unscheduled
amendments are expected.

Kisp fcster comments: moderate confidence forecast. No unscheduled
amendments are expected.

Outlook for 12z Friday through Monday...
Fri-Sat...VFR.
Sat night...MVFR or lower with a slight chance of light
rain or wet snow.
Sunday...MVFR or lower with a slight chance of rain.
Monday...VFR. MVFR or lower possible in developing onshore flow.

&&

Marine...
a tight pressure gradient across the waters resulting in Small Craft Advisory wind
gusts today. Winds diminish this evening and conds on the ocean
may fall below Small Craft Advisory levels shortly after midnight...but will keep
the end time as 11z. Sub-advsy conds will then prevail through
Friday night with the gradient relaxing as high pressure builds from the
west.

Saturday through Sunday night...winds and seas are forecast to
remain tranquil under high pressure.

Monday through Tuesday...as low pressure develops over the southeast coast and
moves NE toward the coastal waters...increasing NE winds of 15-20 knots
will cause seas to build to Small Craft Advisory levels by Monday
night.

Potential for minor tidal flooding...will increase Monday based on a
predicted new moon for Sunday as both NE winds increase and an
easterly fetch increases ahead of a developing coastal low.

&&

Hydrology...
no measurable precipitation through Sat with no Hydro impacts into early
next week.

Monday night...chance of precipitation...mixed with wet snow west and north
of NYC. No Hydro problems expected.

Wednesday...increasing chance of a wind swept heavy rain of 1-2 inches.
Minor urban flooding possible.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory until 6 PM EST this evening for anz330-
335-338-340-345.
Small Craft Advisory until 6 am EST Friday for anz350-353-355.

&&

$$
Synopsis...
near term...tongue
short term...tongue
long term...gc
aviation...ird
marine...
hydrology...

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