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Area forecast discussion 
National Weather Service New York New York
1250 PM EST Friday Feb 12 2016

Synopsis...
weak high pressure builds to the south this afternoon. A low
pressure system will track southeast of the region tonight. In its
wake an Arctic cold front will approach tonight...and pass through
towards daybreak Saturday. Arctic high pressure then builds in
from the west...settling right across the region Sunday night.
High pressure over the region slides east on Monday as a
developing low pressure system well west of the region
approaching. This next low moves across the area Tuesday and
Tuesday night. Another cold front moves across Wednesday with high
pressure starting to build thereafter.

&&

Near term /until 6 PM this evening/...
minor changes were made with this update to reflect the latest
trends in observations and guidance.

SW flow aloft...so will see an increase in cirrus this afternoon
as it gets advected in per latest satellite trends. Also
monitoring an area of snow showers over north central PA...which could
reach far northwest zones by late afternoon...so have slight chance probability of precipitation
in there.

Cold this afternoon...with highs mainly in the 20s. It should be
warmest across NYC/Long Island...with some higher elevations
across far north tier of the County Warning Area possible staying in the upper teens.

&&

Short term /6 PM this evening through Saturday night/...
polar low continues to descend into the northeast through Saturday
night with a short lived but dangerous to potentially life
threatening Arctic intrusion Sat into sun.

Leading up to this...shortwave energy rounding the base of the
polar low will approach the region this evening and cross tonight
into early Saturday morning. This will coincide with the approach
of the Arctic front late tonight and crossing early Sat morning.
Meanwhile a Pacific shortwave dives to the southern middle Atlantic coast
this evening...spawning low pressure that will track well southeast of
the region tonight.

Scattered snow showers/flurries expected ahead of approaching
shortwave energy this evening...with potential for even a period
of light snow across eastern Long Island/southeast CT with initial
onshore flow and then fringe impacts from offshore low. Scattered
snow showers expected once again ahead of/along Arctic frontal
passage late tonight into Sat morning. Overall potential for a
dusting in most spots...with up to an inch or two across far
eastern Long Island and possible southeast CT.

Arctic intrusion begins early Sat morning in wake of Arctic front
with northwest of 20 to 30 miles per hour with gusts to 45 miles per hour. Potential for a few
gusts to 50 miles per hour Sat after/evening based on more favorable momentum
Transfer. There is potential for Wind Advisory conditions to be
met for both marginal sustained winds and gusts along the New Jersey/NYC
metropolitan...coast and higher elevations. Winds will be slow to
subside Sat night with strong gradient between Arctic high and
Canadian Maritimes low.

Dangerously cold air mass advects into the region Sat morning in
the wake of Arctic front. Highs will likely be reached ahead of
the front in the morning in the teens. Then temperatures should steadily
falling into the single digits and lower teens through the
afternoon...with wind chills falling to 10 to 20 degrees below
zero. Heart of cold enters Sat night into Sunday morning...with
temperatures likely to fall to around zero for NYC/New Jersey metropolitan and
coast...and 5 to 10 below zero across interior portions of the
tri-state. Combined with slow to diminish winds...dangerous to
potentially life threatening wind chills of 20 to 30 below
expected. High enough confidence for a rare windchill warning
across northern zones...and windchill advisory for city/coast.
Windchill watch remains for coastal CT...with temperatures on borderline
for advisory vs warning.

With upper low approaching in the after/evening and residual lake streamer
moisture...scattered instability cumulus and scattered flurries possible from late
morning into evening. Across Twin Forks of Long Island...maybe
enough of a fetch over Long Island Sound and instability for
scattered snow showers/flurries Sat after into Sat evening. Clearing
skies late Sat night on backside of upper low.

&&

Long term /Sunday through Thursday/...
one of the coldest days of the season will occur on Sunday as the
polar vortex remains over the region. Early morning temperatures
will be in the single digits across northeast New Jersey...NYC...and Long
Island. Across the interior...temperatures will start the morning in
the 0 to -10 degree range. With mostly sunny skies on
Sunday...expect temperatures to rise into the teens for daytime
highs. With windy conditions early Sunday morning...expect wind
chills in the -15 to -25 range. These wind chills likely do not
rise above 0 until the early to middle afternoon.

The upper level trough...and cold surface high pressure over the
region will slide east late Sunday into Sunday night...allowing
temperatures to moderate through the first part of the new week.
Expect temperatures Sunday night to remain somewhat steady with
temperatures in the teens. By Monday...temperatures slowly rise
through the 20s and into the lower 30s.

A trough moving out of the middle of the country will approach on
Monday. Expect clouds to thicken and lower through the day...with
probability of precipitation gradually increasing through the afternoon. With temperatures
still below freezing...expect precipitation to start as snow.

Southerly flow out ahead of the low pressure system will result in
warm air advection continuing Monday night and Tuesday. As
temperatures rise through this period...expect precipitation to
gradually change from snow to rain. The transition from snow to rain
will occur from the southeastern portion of the County Warning Area...to the
northwestern. By middle morning on Tuesday...it is expected that
temperatures warm enough everywhere for just plain rain across the
entire County Warning Area. Highs on Tuesday climb into the upper 40s and lower 50s.

00z forecast guidance in decent agreement with the low pressure
system...and associated cold front moving across the region Tuesday
night into Wednesday morning...with most of the precipitation ending
early Wednesday. The models do however differ on the exact placement
of the low...and the track it takes across the region. For
now...expecting rainfall amounts between 1 and 2 inches...with at
least some of that quantitative precipitation forecast...starting as a period of snow. See
additional details on quantitative precipitation forecast in the hydrology section.

High pressure builds into the region behind the cold front Wednesday
night through Friday...with mostly dry conditions. Highs on Thursday
will be in the lower 40s...with 30s expected on Friday.

&&

Aviation /17z Friday through Tuesday/...
weak high pressure in place today. Cold front moves through late
tonight.

VFR today. SW winds around 10kt.

Outlook for this overnight...scattered shsn could potentially leave a
coating of snow on the runways.

..NY 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: no unscheduled amendments expected.

Klga fcster comments: no unscheduled amendments expected.

Kewr fcster comments: occasional gusts around 15kt possible.

Kteb fcster comments: no unscheduled amendments expected.

Khpn fcster comments: no unscheduled amendments expected.

Kisp fcster comments: no unscheduled amendments expected.

Outlook for 18z Sat through Wednesday...
Sat...VFR. Northwest gusts around 35kt.
Sun...VFR. Northwest gusts 20-25kt in the morning.
Monday...VFR am. Chance late day snow with sub-VFR.
Monday night...IFR conds likely. Snow changing to rain by late
evening NYC metros/kisp...and around/shortly after midnight
khpn/kbdr/kgon...and cold ground could make for a brief period of
freezing rain on runways despite air temperatures rising above freezing.
Snow mixing with or changing to freezing rain after midnight at
kswf. Southeast gusts around 25kt late.
Tuesday...rain likely with IFR conds. Southeast-S winds g30-35kt and low level wind shear.
Wednesday...mostly VFR. Chance rain/snow shower and brief sub-VFR.

&&

Marine...
minor changes were made with this update to reflect the latest
trends in observations and guidance. The forecast appears on
track.

Sub Small Craft Advisory conditions expected this afternoon as SW winds develop
ahead of an approaching Arctic cold front. A few gusts to around
20 knots likely on the ocean this afternoon/evening.

The relatively tranquil conditions will be short lived...with
Arctic frontal passage forecast around daybreak Sat with northwest gales
developing soon thereafter. Gales expected on the ocean...and
likely for rest of the waters Saturday and Saturday night. Gales
prevail into early Sunday before decreasing to 20-30 knots during the
day. These winds should build ocean seas to 7 to 11 feet...and 3 to
6 feet on central and eastern Long Island Sound. With Arctic air
mass overspreading the waters...moderate to heavy freezing spray
expected Saturday into Saturday night for most of the waters.

Some left over gales may prevail into early Sunday before decreasing
to 20-30 knots during the day. Freezing spray is also possible on
Sunday at least the ocean waters. Weak pressure gradient Sunday
night through Monday night will lead to below Small Craft Advisory conditions.
Conditions build back to Small Craft Advisory levels ahead of the next low pressure
system Tuesday and Wednesday.

&&

Hydrology...
liquid equivalent of less than a tenth of an inch is forecast
tonight into Saturday morning in the form of snow showers.

Low pressure moving up the coast has potential to produce liquid
equivalent quantitative precipitation forecast at least 1 to 2 inches. Part of this will fall as
snow initially...but then runoff via melting snow and heavy rain
Tuesday into Tuesday night could cause at least Urban and Small
Stream flooding problems. It is too early to say if main Stem rivers
would be affected.

&&

Climate...
with the extremely cold air mass forecast Saturday into
Sunday...record minimums and record low maximums may be reached.
Here are the records and forecasts...

Station......record/forecast minimum
for 2/14

Central Park.....2 (1916) / 1
LaGuardia........1 (1979) / 2
jf Kennedy.......4 (1979) / 1
Islip............7 (2015) / 1
Newark...........0 (1979) / 0
Bridgeport.......3 (2015*) / -1

Station......record low maximum/forecast high
for 2/14

Central Park....17 (1979) / 17
LaGuardia.......15 (1979) / 17
jf Kennedy......17 (1979) / 18
Islip...........26 (1987) / 15
Newark..........15 (1979) / 17
Bridgeport......18 (1979) / 16

*in 1979 as well

&&

Okx watches/warnings/advisories...
CT...wind chill warning from 4 PM Saturday to noon EST Sunday for
ctz005>008.
Wind chill watch from Saturday afternoon through Sunday
morning for ctz009>012.
New York...Wind Chill Advisory from 4 PM Saturday to noon EST Sunday for
nyz072>075-078>081-176>179.
Wind chill warning from 4 PM Saturday to noon EST Sunday for
nyz067>070.
Wind chill watch from Saturday afternoon through Sunday
morning for nyz071.
New Jersey...Wind Chill Advisory from 4 PM Saturday to noon EST Sunday for
njz004-006-104>108.
Wind chill warning from 4 PM Saturday to noon EST Sunday for
njz002.
Wind chill watch from Saturday afternoon through Sunday
morning for njz103.
Marine...gale watch from late tonight through Sunday morning for anz330-
335-338-340-345.
Heavy freezing spray watch from Saturday evening through
Sunday morning for anz330-335-338-340-350-353-355.
Freezing spray advisory from 4 am to 6 PM EST Saturday for
anz330-335-338-340-350-353-355.
Gale Warning from 4 am Saturday to 7 am EST Sunday for anz350-
353-355.

&&

$$
Synopsis...BC/maloit/NV
near term...maloit
short term...Nevada
long term...British Columbia
aviation...jc
marine...BC/maloit/NV
hydrology...BC/NV
climate...

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