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Area forecast discussion 
National Weather Service New York New York
130 PM EST Friday Jan 30 2015

Synopsis...
an Arctic cold front will move through this afternoon as low
pressure rapidly deepens off the New England coast. High pressure
will build in tonight into Saturday...then pass to the south
Saturday night. Another cold front will move through on
Sunday...and low pressure will pass to the south on Monday. High
pressure will return through middle week.

&&

Near term /until 6 PM this evening/...
Arctic cold front to move across area from northwest to southeast this
afternoon...moving offshore by late after. Flurries or a brief snow
shower may accompany the boundary. Northwest winds will also increase
after frontal passage and start to usher in much colder air. Temperatures
will fall steadily toward evening into the 20s.

&&

Short term /6 PM this evening through 6 PM Saturday/...
multiple wind/cold hazards will exist during this time frame.
First...the higher elevations and the NYC metropolitan urban heat island
should be the first areas to see northwest winds gusting as high as 45-50
miles per hour tonight via the combo of strong cold air advection and a rapidly tightening
pressure gradient as the low to the east bombs out S of Nova
Scotia into the 980s. These strong winds should spread to the rest
of the area late tonight.

The combo of sustained winds 15-25 miles per hour...a little higher than MOS
guidance...and temperatures falling through the teens and into the
single digits inland...colder than the coldest of GFS/NAM MOS
guidance lows by a couple of degree...will result in hazardous wind
chills of 15 to 20 below from late tonight into Sat morning for
most inland sections...and around 10 below for NYC and urban
sections to the west...Long Island and far southeast CT.

Sat should be a very cold day despite sunshine...with highs
struggling to reach 20 in NYC and Long Island...and remaining in
the teens elsewhere.

&&

Long term /Saturday night through Thursday/...
gusty northwest winds abate Saturday night as deep low pressure moves to
the Canadian Maritimes. High pressure builds to the south as a cold
front approaches from the northwest early Sunday.

Attention then turns toward low pressure that is expected to develop
around the middle Mississippi Valley ahead of northern stream trough.
At this time...models have shifted slightly north as they track the
low from around West Virginia Sunday night to off the middle Atlantic
coast Monday morning. It appears that the low tracks south of the
area...then just southeast of the 40n/70w benchmark Monday afternoon.

Still plenty of uncertainty as main energy just moving into western
Canada...and run to run shifts in track have been observed.
However...will boost probability of precipitation into the likely category for much of the
County Warning Area...with highest probability of precipitation southern portion...lower to the north. European model (ecmwf)
and GFS output at least a half inch of measurable. Based on this
model run...agree with previous forecast of a general 4 to 8 inches
of snow in this progressive storm...although may up that by an inch
or two on the low and high end...perhaps 5 to 10. However...any
shift to the south...which is certainly possible...will result in
lower snow amounts/chances for precipitation.

Thereafter...Arctic air moves in behind the low as high pressure
that originates from the Canadian prairies builds across middle west
and toward the eastern Seaboard by Tuesday.

Dry weather returns with much uncertainty for middle to late week. The
question is whether or not southern stream phases with northern
stream trough sometime Wednesday night or Thursday. This would result in
clipper type front approaching from the west with possible low pressure
development well to the south tracking off the East Coast.
Again...European model (ecmwf) and GFS differ with timing and strength...so will cap
probability of precipitation at chance for now late Wednesday through Thursday.

Temperatures were a gridded MOS/mav and met blend Sat night and
Sunday...with gridded MOS and wpc next week. Overall...cold weather
will prevail with below or much below normal temperatures on average.

&&

Aviation /18z Friday through Wednesday/...
high pressure builds in behind a departing cold front.

VFR. Sustained winds and gusts increase through the rest of the
day...favoring north of 310 mag.

..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: occ gusts 31-35kt possible before 21z.

Klga fcster comments: occ gusts 30-34kt possible before 21z.

Kewr fcster comments: occ gusts 30-34kt possible before 21z.

Kteb fcster comments: occ gusts 26-30kt possible before 21z.

Khpn fcster comments: occ gusts 26-30kt possible before 21z.

Kisp fcster comments: chance brief MVFR visibility/ceilings with -shsn before
19z. Occ gusts 25-30kt possible before 22z.

Outlook for 18z Saturday through Wednesday...
Sat afternoon...VFR. Northwest g 25-35 knots...diminishing late.
Sat night...VFR. Northwest g 25kt evening.
Sunday...VFR.
Sunday night-Monday...potential high impact day. IFR and snow
likely. Chance mixed precipitation. NE-north g 25-35kt possible.
Monday night...becoming VFR from west to east as snow comes to an end.
North-northwest wind g20-25kt possible.
Tuesday...VFR.
Wednesday...VFR likely.

&&

Marine...
northwest gales develop on all waters by late afternoon following an
Arctic cold frontal passage. Gusts on the ocean could approach storm force
late tonight into Sat morning. The combo of strong winds and cold
water temperatures from the middle 30s to lower 40s will also result in at
least moderate freezing spray during this time frame. There is a
chance for heavy freezing spray on Li sound...New York Harbor and the
near shore ocean waters where SST is only in the middle/upper
30s...and a heavy freezing spray warning may eventually be
required for those waters.

Gusty winds will diminish Saturday night into Sunday. Seas will
respond by subsiding through this time frame. Some 5-footers may
clip the easternmost ocean waters S of Montauk into Sunday...but
sub Small Craft Advisory conditions are likely across the waters Sunday.

However...this will be brief as winds increase again ahead of low
pressure Sunday night and Monday. The low is expected to pass to the
south Monday...moving well to the east Monday night. High pressure
builds in Tuesday.

Strong Small Craft Advisory conditions Monday will improve by Tuesday as the high
builds.

&&

Hydrology...
low pressure Sunday night and Monday will bring the potential for
quantitative precipitation forecast of 1/2 to 1 inch liquid equivalent...all in the form of snow.

&&

Okx watches/warnings/advisories...
CT...Wind Advisory from 4 PM this afternoon to 4 PM EST Saturday
for ctz005>012.
Wind Chill Advisory from midnight tonight to noon EST Saturday
for ctz005>007-009-010.
New York...Wind Advisory from 4 PM this afternoon to 4 PM EST Saturday
for nyz067>075-078>081-176>179.
Wind Chill Advisory from midnight tonight to noon EST Saturday
for nyz067>071.
New Jersey...Wind Advisory from 4 PM this afternoon to 4 PM EST Saturday
for njz002-004-006-103>108.
Wind Chill Advisory from midnight tonight to noon EST Saturday
for njz002-004-103-104.
Marine...freezing spray advisory from 6 PM this evening to 6 PM EST
Saturday for anz330-335-338-340-345-350-353-355.
Gale Warning until 6 PM EST Saturday for anz330-335-338-340-
345-350-353-355.

&&

$$

Synopsis...Goodman/dw/pw
near term...Goodman/dw/pw
short term...Goodman
long term...precipitable water
aviation...jc
marine...Goodman/pw
hydrology...Goodman/pw

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