Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
959 am EST sun Feb 14 2016
high pressure builds over the area today and offshore tonight.
The high continues to move east away into the Atlantic Monday as a
low pressure system develops to the west. This low travels near or
to the west of 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 /through tonight/...
made minor changes this update to reflect the latest trends on in
observations and guidance. The forecast appears on track.
Wind chill warnings/advisories will be allowed to expire at noon
with decreasing winds moderating apparent temperatures above -15 degrees.
Today will be sunny...frigid...and dry with northwest flow aloft. After
diminishing winds and a moderating airmass should allow temperatures to
moderate into the teens...with wind chills finally rising above
zero by late day/early evening. However...temperatures have been very
slow to rise so far this morning. Have some concern that highs for
today could be around a category to high. Will continue to monitor
and change with next update if current trends hold.
High pressure moves across tonight...with strong radiational cooling
conditions likely for the first half of the night...before high
clouds begin to move in. This should allow for temperatures to fall to 5
to possibly 10 below zero across rural eastern locales like The
Pine Barrens of Long Island and interior valleys of CT where a
solid snowpack exists. 0 to 5 below zero across interior valleys
of lower Hudson Valley. Elsewhere temperatures will likely bottom out in
the single digits along the coastal plain...while holding steady
in the middle teens for NYC metropolitan. Temperatures then could rise late tonight
and towards daybreak with increasing high clouds.
Short term /Monday through Tuesday/...
models in general agreement with several pieces of Pacific energy
helping to amplify a central US trough today into Monday...which
slides into the Ohio/Tennessee valleys Monday night...and then
swings up the coast on Tuesday. Deterministic models and ensembles
still exhibiting some model spread and jumpiness on timing and
amplitude of this shortwave energy as it comes up the coast. Sbu
sensitivity tracking this model spread to the Pacific energy coming
onshore this morning.
This model spread in shortwave evolution is still manifesting
differences in timing and track of low pressure. 00z GFS/UKMET/can
and 00z gefs/03z sref are clustered on a track of low pressure from
the deep south Monday morning...to Tennessee River valley Monday
night and then an inland track up into central PA/New York on Tuesday.
NAM/European model (ecmwf) tracks low pressure right along the coast and slightly
slower. This is a significant eastward shift for the European model (ecmwf) from 12-
24 hours ago and westward shift for the GFS. Again...not instilling
12z gefs/21zsref/12z CMC ensemble means were pretty well clustered
with a mean low track along the east side of the Appalachians on
Tuesday. Much of the spread was on the west/SW side of the low...which
may signal a further west track similar to the deterministic
clustering and perhaps a bit slower. This has borne out with the 00z
sref and gefs ensemble means further west. Based on this...will lean
towards the better clustered low track near the Appalachians.
In terms of sensible weather...a likely scenario at this point
continues to be light snow development Monday morning/after from SW to
NE for the entire area with warm advection in deep SW flow aloft over
the moderating Arctic airmass. As warm air advection increases...expectation
for precipitation to change to wintry mix and then liquid Monday
evening from S to north. Along the city/coast...transition from snow
to rain should be fairly quick in the evening with strengthening
onshore flow. Generally an inch or two of snow along the
coast...but potential for Road icing exists a couple of hours
after transition to rain as air temperatures may warm above freezing
quicker than grounds temperatures. Increasing potential for icing away
from south coasts. Across interior portions of NE New Jersey...lower
Hudson Valley...and SW CT...a general 2 to 4 inches of snow
possible through Monday evening and then several hours of freezing
rain possible Monday night before low level warm air advection
finally scour low- level cold air mass by early Tuesday morning.
With preceding Arctic airmass...ground temperature warm up will likely
lag air temperature warmup...which could result in serious Road icing
issues. Will address threat in severe weather potential statement.
On Tuesday...rain...possibly heavy at times...with temperatures well
into the 40s to 50s as warm conveyor belt overrides the region if
inland track verifies. A general range of 1 to 2 1/2 inches of total
quantitative precipitation forecast is forecast in the consensus of the models. See Hydro section
for more information.
Consensus low track would also result in windy conditions along the
coast with 60 to 65 knots jet at 950 hpa moving over the region. Winds
of 25 to 30 miles per hour with gusts to 40 miles per hour would be likely...with
potential for Wind Advisory conditions of sustained winds in the
lower 30s and gusts to 50 miles per hour.
Low level jet/deep moisture axis moves east Tuesday evening with
Long term /Tuesday night through Saturday/...
for the rest of the forecast Tuesday night and Wednesday...lingering
rain and snow showers possible 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 next week.
Aviation /15z Sunday through Thursday/...
Arctic high pressure continues to build into the region through this
evening. Pressure gradient will relax throughout the day.
VFR through the taf period.
Gusty northwest winds will diminish to 10-15 knots with gusts up to 20 knots
by 18z. Gusts should end at all but knyc terminals by then. Winds
will diminish to less than 10 knots by late afternoon/early evening.
Wind direction will be mainly at or just right of 310 magnetic.
Light/vrb winds expected tonight into Monday morning.
Outlook for 12z Monday through Thursday...
Monday...light snow likely develops from SW to NE late
morning/into the afternoon...with MVFR or lower possible. S wind
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.
wind gusts have fallen below gale force on the coastal ocean
waters/East Sound so have replaced with an Small Craft Advisory through 18z on the
sound and 23z on the coastal ocean waters.
On New York Harbor/west Long Island Sound/Long Island bays...expecting
Small Craft Advisory conditions through afternoon with wind gusts
to 25 knots. Tranquil conditions expected by this evening.
Moderate-heavy freezing spray will also continue into this
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 1/2 inches of liquid equivalent is forecast with
locally higher amounts Monday through Tuesday night. This will be
mostly be in the form of rain.
This type of rainfall and initially frozen ground will bring
potential for urban and poor drainage flooding. Eastern Long
Island and eastern CT also have more in the way of snowpack and
snow clogged drainages to add to poor drainage flood potential.
With initially frozen ground...significant rises are likely with
low potential for minor flooding along flashy small streams
across NE New Jersey/lower Hudson Valley if high end of rainfall amounts
are realized. Mmefs and Stevens fas are not showing any areas
going into minor flood as of yet.
potential exists for minor coastal flood impacts with the late
Monday night/early Tuesday morning and possibly Tuesday after high tide
cycles ahead of a developing low pressure system moving up the
coastal plain. Still quite a bit of uncertainty exists on the
timing and track of this system. Positive tidal departures of 2 to
2 1/2 feet are needed for minor flood thresholds to be reached in
the morning...and 2 1/2 to 3 feet in the afternoon.
with the extremely cold air mass...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
LaGuardia.........8 (2016) / 8
Islip.............4 (2016) / 4
Station......record low(year)/low through 8am for 2/14
Central Park.....2 (1916) / -1
LaGuardia........1 (1979) / 1
Kennedy..........4 (1979) / 1
Islip............7 (2015) / 0
Newark...........0 (1979) / 0
Bridgeport.......3 (2015*) / -6
Station......record low maximum(year)/forecast high for 2/14
Central Park....17 (1979) / 14
LaGuardia.......15 (1979) / 16
Kennedy.........17 (1979) / 16
Islip...........26 (1987) / 14
Newark..........15 (1979) / 15
Bridgeport......18 (1979) / 13
*in 1979 as well
CT...wind chill warning until noon EST today for ctz005>012.
New York...Wind Chill Advisory until noon EST today for nyz072>075-
Wind chill warning until noon EST today for nyz067>071.
New Jersey...Wind Chill Advisory until noon EST today for njz004-006-
Wind chill warning until noon EST today for njz002.
Marine...Small Craft Advisory until 1 PM EST this afternoon for anz330-
Heavy freezing spray warning until noon EST today for anz330-
Freezing spray advisory until 6 PM EST this evening for anz350-
Gale Warning until 10 am EST this morning for anz350-353-355.