Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
717 am EST Wednesday Nov 26 2014

a deepening coastal low tracks from near the southeastern U.S.
Coast this morning to near Nova Scotia by Thursday morning. A
trough of low pressure lingers over the area on Thursday. High
pressure builds in to the south and east from from Thursday night
through the end of the upcoming weekend. A warm front will lift
through on Saturday....followed by a cold front on Monday. Another
area of high pressure builds from the north into the middle of
next week.


Near term /through tonight/...
coastal low to cause significant impact to Holiday travel into

Latest pressure falls and consensus of zero model guidance now
bring a coastal low to the west of the 40n/70w benchmark this
evening on average by about 75 to 100 miles. This shift in the
track westward will slow the rate at which the boundary layer
cools...especially over eastern parts of the it will
take the low level flow longer to go northerly over most of the

Temperatures are still slow to fall this morning...but northerly winds will be
increasing later this morning and this will draw colder air into
the column. Not making wholesale changes to the weather grids to delay
the mixed p-type just yet since we have received a report from
Monroe in Orange County that it is snowing there already with
temperatures ion the upper 30s. Have made adjustments to the hourly T/dew point
grids for the next few hours...but if things don't start cooling
soon...rain could linger longer and effectively affect total snow
amounts in areas well north and west of NYC.

The result in terms of sensible weather will be for a more
prolonged period of rain to start over coastal and eastern
areas. In addition...the closer proximity of the low will allow
for a pocket of above freezing air from 800 to 650 hpa to push
into roughly the southeast 1/2 of the County Warning Area...allowing for some sleet as

Areas roughly north/west of I-287...including interior SW CT will see a
mixture of rain and snow this morning change to all snow this
afternoon. Interior SW CT could see some sleet mix in as well.
Still expecting 6-12 inches of snow across this area...except 4-8
inches still across interior west CT. Highest snow amounts will be
across far West Orange County.

Areas along the I-95 corridor through coastal SW CT...including
all of Union County and northern Queens/Manhattan/the Bronx in
NYC...and interior southeast CT should see a mixture of rain/snow/sleet
change to all snow by late this afternoon/early this evening with
1 to 5 inches of accumulation.

Across the remainder of the area including the rest of
NYC...expect mainly rain this morning...mixing with sleet and snow
this afternoon...and possibly changing to all snow before ending.
Expect generally less than 2 inches of snow in this area...with
most of Long Island receiving little if any accumulating snow.

Precipitation should taper off from SW to NE tonight as the low
pulls off to the NE. Refer to the hydrology section of the afd for
quantitative precipitation forecast amounts and potential impacts.

The closeness of the low will also result in stronger winds than
originally forecast across most of the region.

With a 45-60 knots low level jet forecast cross eastern Long Island
and coastal southeast CT...have issued a Wind Advisory for S New London
and east Suffolk counties from this afternoon into tonight...with
gusts up to 50-55 miles per hour expected. Across the remainder of coastal areas
gusts of 30-45 miles per hour are forecast this afternoon/evening.


Short term /Thursday/...
the middle-upper level trough axis crosses the area Thursday...with
a lingering trough of low pressure in the wake of the departing
low at the surface. This should be sufficient to trigger isolated

Temperatures will run around 10 degrees below normal.


Long term /Thursday night through Tuesday/...
the 500 mb flow across the Continental U.S. Will be undergoing a change during the
long term period all controlled by the vortex spinning just north of
Hudson Bay. Upper trough over the eastern US will shift offshore Thursday
night/Friday as the ridge over the western states flattens as it moves
eastward. Zonal flow develops over much of the country this
weekend with amplification beginning early next week as a deep
trough/cutoff low approaches the West Coast.

Not too much to be concerned with in terms of sensible weather
locally...although winter-like temperatures will return Thursday night
through Friday night with highs/lows between 10 and 15 degrees below
normal thanks to the aforementioned upper trough.

Could see some flurries Thursday night as energy associated with the
upper trough axis swings through.

Dry weather then prevails as surface high builds across the area Friday. A
warm front lifts through on Sat...and models are now indicating some
lift quantitative precipitation forecast with its passage so have added slight chance probability of precipitation late
Friday night into Sat morning. We'll remain warm sectored into sun
with warm air advection ensuing. Warmer but still below normal Sat...then near
normal sun into Monday as a cold front approaches. The front will
track across the area on Monday...and tonight's model runs are now a
bit wetter...especially the 00z have added low chance
probability of precipitation. Timing issues with the frontal passage also is apparent...the GFS/CMC
a bit faster than the ec. The big change from last nights runs is
early next week. The deterministic runs have trended towards the
ensembles building high pressure in from the north quicker...suppressing
the front well to the S with dry weather for the beginning of next
week with temperatures falling back below normal levels.


Aviation /12z Wednesday through Sunday/...
***high impact weather event today***

Low pressure off the southeast coast will move northeast and pass
just to the south and east of the area late today and into

VFR conditions initially this morning deteriorate. Rain moving in as
surface temperatures remain fairly warm.

Then precipitation type will depend on Airport locations. In
general...mainly expect rain for JFK eastward including isp and gon
today. A mix of snow and sleet is possible during the afternoon. A
brief changeover to all snow may occur late in the day and into the
evening. IFR or LIFR conditions are anticipated late this
morning...after 15-16z...through the afternoon. Improvement occurs

Most likely runway accumulations 1-3 inches NYC metropolitan
terminals...8-11 inches kswf...2 to 5 khpn...1-2 inches kbdr...1
inch or less kisp/kgon.

Winds increase from the north this morning...and pick up this
afternoon and evening before lightening as they turn toward the northwest.

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: mainly rain transitions to a wintry mix this
afternoon and evening. Runway accumulations less than an inch
expected. Strongest winds after 18-20z.

Klga fcster comments: mainly rain transitions to a wintry mix this
afternoon and evening. Runway accumulations around or less than an
inch expected. Strongest winds after 18-20z.

Kewr fcster comments: mainly rain early this morning transitions to
a wintry mix by noon. Runway accumulations 2 to 3 inches by evening.
Strongest winds after 18-20z.

The afternoon kewr haze potential forecast is yellow...which implies
slant range visibility 4-6sm outside of cloud.

Kteb fcster comments: mainly rain early this morning transitions to
a wintry mix by noon before changing to all snow late. Runway
accumulations 2 to 4 inches by evening. Strongest winds after 18-20z.

Khpn fcster comments: mainly rain early this morning transitions to
a wintry mix by noon before changing to all snow late. Runway
accumulations 2 to 5 inches by evening. Strongest winds after

Kisp fcster comments: mainly rain transitions to a wintry mix late
this afternoon and evening. Little if any snow accumulations are
expected. Strongest winds after 18-20z.

Outlook for 12z Thursday through sun...

Thursday-Thursday night...possible rain/snow showers with MVFR
conditions...otherwise VFR.
Friday night-Sat morning...VFR with possible flurries.
Sat afternoon-Sunday...VFR.


boundary layer winds are forecast to increase to 35-50 knots over the
waters from today into tonight. With decent mixing forecast from
around 950 to the surface over the waters...would expect at least
gale gusts as a result. Based on this have extended the Gale
Warning to cover all waters through midnight tonight and on
anz-350 until 3 am. Small Craft Advisory conditions will then be present on all
waters after midnight...once the gales come to an end.

Small Craft Advisory level seas will continue on the coastal ocean waters on
Thursday...while the remainder of the waters experience sub-Small Craft Advisory
conditions with some diminishing winds.

Small Craft Advisory seas possibly linger on the eastern ocean zones Thursday night...with
gusts around 20 knots on Friday. Winds gusts are forecast to remain below
Small Craft Advisory levels through the period...although could come close sun/Sun
night on the ocean. Seas could reach marginal levels on the eastern
ocean zones Sat night into Sun night with a moderate SW flow.


from 1 1/8 to 1 2/3 inches of quantitative precipitation forecast...with locally higher amounts
possible is forecast through tonight. With the precipitation
mainly in the form of snow across areas roughly west/north of
I-287...including interior SW CT...little hydrologic impact is
expected there. From the I-95 corridor on east there will be a mix of
rain and snow. This could lead to minor flooding of urban and poor
drainage areas...especially if any locally heavy rainfall occurs.

Very light quantitative precipitation forecast amounts are possible from Thursday through the


Tides/coastal flooding...
with forecast of stronger NE winds late today into this
evening...should push a bit more water into western Long Island
Sound than previously expected. Tidal departures of around 2 feet
are needed there to reach minor coastal flood benchmarks in
western Long Island Sound at the time of high tide tonight...with
currently just under 2 feet expected. The increased NE flow over the
east end of Long Island also could result in some overwash and
erosion on the Twin Forks.

Given the uncertainty still associated with this system do not
have the confidence to issue any statements at this time. The
dayshift will do a reassessment of this later today.


Okx watches/warnings/advisories...
CT...Winter Storm Warning until 1 am EST Thursday for ctz005-006.
Winter Weather Advisory until 1 am EST Thursday for ctz007>010.
Wind Advisory from 3 PM this afternoon to 1 am EST Thursday
for ctz012.
New York...Winter Storm Warning until 1 am EST Thursday for nyz067>070.
Winter Weather Advisory until 1 am EST Thursday for nyz071>073-
Wind Advisory from 3 PM this afternoon to 1 am EST Thursday
for nyz079-081.
New Jersey...Winter Storm Warning until 1 am EST Thursday for njz002-004-
Winter Weather Advisory until 1 am EST Thursday for njz006-104-
Marine...Gale Warning until midnight EST tonight for anz330-335-338-340-
Gale Warning until 3 am EST Thursday for anz350.



National Weather Service Glossary of Abbreviations