Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service New York New York
757 PM EST Sat Feb 13 2016
high pressure builds over the area on Sunday and offshore Sunday
night. The high continues to move east away into the Atlantic
Monday as a low pressure system develops to the west. This low
travels to near or over the region Tuesday and into the Canadian
Maritimes Tuesday night. A clipper low moves in for Wednesday into
Wednesday night. Then...Canadian high pressure returns for
Thursday and Friday. For Friday night into Saturday next
week...another low approaches from the north and west.
Near term /until 6 am Sunday morning/...
forecast mainly on track. Adjusted hourly temperatures and dewpoints
a few degrees lower to better match observed trends. Adjusted
clouds higher southeast of Long Island where there is more
instability from the relatively warmer ocean temperatures.
Arctic airmass will continue to spill into the area tonight. Precipitable water/S drop
to blw 5 hundredths of an inch with strong subsidence...so will keep
the forecast dry. The strong winds will keep going right through the night.
Peak gust potential through about 3z...then winds aloft gradually
decline into Sun morning. No changes to the wind chill products
tonight...although the warning appears to be marginal along the coast.
Short term /6 am Sunday morning through Sunday night/...
the Arctic high builds right over the area by Sun night. This will
result in decreasing winds through the day...then light and vrb flow
overnight. Clear skies during the day...then high clouds begin to
overspread the area. This should...if they do indeed develop...help
to limit low temperatures. Still went blw guidance because of the extreme
nature of the airmass combating the pull towards climatology. Depending
on the exact position of the high...some weak return flow late could
allow temperatures at the coast...particularly the Li coast...to rise
Long term /Monday through Saturday/...
current low pressure disturbance over Montana and the Dakotas will
be the focus of the long term forecast. This low will eventually
make its way into the local region by Tuesday but warm air
advection ahead of it as well as an approaching shortwave and its
positive vorticity advection will lead to precipitation starting as early as Monday.
Precipitation Monday will be primarily in the form of snow and
could result in a general 1 to 3 inches total. There is a lot of
uncertainty with this though and parameters such as wet bulb
cooling...southeast flow...and the vorticity advection as well as timing
will play a role in how much snow falls.
Initially Monday...very cold with average temperatures in the
single digits to lower teens. It will take some time for these
temperatures to warm to above freezing and models are indicating
this would occur during Monday evening. So...this bears monitoring
for subsequent model trends in the initial round of precipitation
associated with the warm air advection aloft.
Models have a general agreement on substantial warm air advection
getting down to the surface Monday night with the increasing
southeast flow especially for coastal regions. The low develops
southwest of the region getting east of the Appalachians. The low
then moves near or over the region during the day Tuesday. European model (ecmwf)
is well west with the low compared to GFS...NAM...and Canadian
and would therefore be the most warm of the solutions.
Hence...more rain with the European model (ecmwf) solution as well. Took a blend of
this guidance and essentially the coastal zones will have mainly
rain by late Monday evening through Tuesday. Farther interior...southeast
flow will be lighter and will be blocked by higher terrain.
Therefore...these locations will be a few degrees colder and will
take longer to reach above freezing. Monday night...these
locations could pick up an additional inch or two of snow along
with some light ice accumulation as warmer air aloft transitions
the precipitation to freezing rain with surface temperatures still
The overall confidence is below 50 percent for reaching any sort
of warning/watch criteria. See Hydro section regarding flood
potential and rain amounts.
For the rest of the forecast Tuesday night and Wednesday...lingering
rain and snow showers as main low moves into the Canadian
Maritimes and another shortwave moves through aloft with its positive vorticity advection.
Drier conditions will become more prevalent Wednesday night
although there could be a few snow showers remaining Wednesday
night. Another round of cold air advection occurs Wednesday night
behind the shortwave. Strong Canadian high pressure moves in
Thursday through early Friday with dry weather. Another low and
another chance of precipitation arrives Friday into Saturday of
Aviation /00z Sunday through Thursday/...
Arctic high pressure building towards the region into Sunday
VFR through the taf period.
Northwest winds through the taf period...primarily to the right of 300
true/310 magnetic...however cannot rule out wind direction
occasionally being at 300 true. Winds starting out around 20 knots
g30-35kt this evening. Winds slowly diminish through Sunday
morning...with g15-20kt by around midday Sunday. Gusts likely
lost middle afternoon.
Outlook for 00z Monday through Thursday...
Monday...light snow likely develops from west to east late morning/into
the afternoon...with MVFR or lower possible. S wind g15-20kt
Monday night...IFR or lower developing. A wintry mix changing to
rain at S terminals...and snow changing to a wintry mix at
northern terminals. Low level wind shear possible. Low confidence forecast.
Tuesday...any lingering wintry mix north terminals changing to all
rain in the morning. Rain tapering off late. IFR or lower
possible. Low level wind shear in the am...then northwest winds g20-25kt possible in the
Wednesday...mostly VFR. MVFR or lower possible in any spotty
rain/snow shower. West-northwest winds g20-25kt possible.
Wednesday night-Thursday...VFR. Northwest winds g15-20kt possible.
gales and freezing spray will continue into Sun morning. Winds and seas
will gradually improve through the day...with all areas actually blw Small Craft Advisory
levels Sun night.
Sub Small Craft Advisory conditions Monday will be followed by Small Craft Advisory to gale
conditions Monday night into Tuesday. Gales trend to Small Craft Advisory winds
later Tuesday and Tuesday night. The winds trend below Small Craft Advisory
thereafter but Small Craft Advisory ocean seas remain.
a general 1 to 2 inches of liquid equivalent is forecast with
locally higher amounts Monday through Tuesday night. For coastal
locations...this will be mostly in the form of rain and for
these...there is the potential for urban and poor drainage
flooding. Across the interior...while more precipitation will relatively
be in the frozen form making for less rain...the rain added with
snow melt could result in flooding of rivers and streams. Most
flooding looks to be minor at this point.
potential exists for minor coastal impacts with the late Monday
night/early Tuesday morning high tide ahead of a developing low
pressure system moving up the coastal plain. Minor coastal flood
benchmarks could be met across most tidal gauges. Still quite a
bit of uncertainty exists on the evolution of this system.
Positive tidal departures of 2 to 2 1/2 feet are needed for minor
flood thresholds to be reached...and 3 to 3 1/2 feet for moderate
with the extremely cold air mass forecast tonight into
Sunday...record minimums and record low maximums may be reached.
Here are the records and forecasts...
Station......record low(year)/forecast low by midnight for 2/13
Central Park.....-1 (1914) / 5
LaGuardia.........8 (1979) / 6
Kennedy...........0 (1967) / 7
Islip.............9 (2015) / 5
Newark............4 (1979) / 6
Bridgeport.......-2 (1967) / 3
Station......record low(year)/forecast low for 2/14
Central Park.....2 (1916) / 2
LaGuardia........1 (1979) / 3
Kennedy..........4 (1979) / 3
Islip............7 (2015) / 1
Newark...........0 (1979) / 2
Bridgeport.......3 (2015*) / -1
Station......record low maximum(year)/forecast high for 2/14
Central Park....17 (1979) / 15
LaGuardia.......15 (1979) / 16
Kennedy.........17 (1979) / 17
Islip...........26 (1987) / 15
Newark..........15 (1979) / 16
Bridgeport......18 (1979) / 15
*in 1979 as well
CT...wind chill warning until noon EST Sunday for ctz005>012.
New York...Wind Chill Advisory until noon EST Sunday for nyz072>075-
Wind chill warning until noon EST Sunday for nyz067>071.
New Jersey...Wind Chill Advisory until noon EST Sunday for njz004-006-
Wind chill warning until noon EST Sunday for njz002.
Marine...Gale Warning until 10 am EST Sunday for anz330-340-345-350-353-
Heavy freezing spray warning until noon EST Sunday for anz330-
Heavy freezing spray warning until 6 am EST Sunday for anz338.
Gale Warning until 6 am EST Sunday for anz335-338.
Freezing spray advisory until 6 PM EST Sunday for anz350-353-