Winter Storm Warning 1, NWS New York, NY

Area Forecast Discussion
National Weather Service New York NY
1249 PM EST Fri Jan 18 2019

.SYNOPSIS...
A weak area of low pressure passes to the south, followed by
another to the north later today. A cold front will cross the
area tonight. A significant winter storm impacts the region late
Saturday into Sunday and will be followed by arctic high
pressure Monday into Tuesday. The next frontal system approaches
Wednesday and moves across the region on Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Any lingering light snow has tapered off. Temps warm through the
remainder of the afternoon as pesky clouds hang on through much
of the day. Temps hold nearly steady in the upper 30s to around
40.

A weak area of low pres will pass to the N resulting in the
passage of a weak warm front into early this afternoon. A cold
front then passes this evening. Lows tonight drop into the 20s
area wide with partially clearing skies.

&&

.SHORT TERM /SATURDAY/...
High pressure nosing in from the north will shift east on Sat
with an easterly wind flow developing and low pres moving from
the mid Mississippi Valley into the Ohio Valley. Overrunning
pcpn well out ahead of the center of the storm could begin to
move into western portions of the forecast area as early as mid
to late aftn, but more likely during the late aftn/early eve
hours. Thermal profiles support snow across the entire Tri State
Area into the evening.

High on Sat will generally range in the lower to mid 30s,
although the normally colder spots across the interior could
struggle to get out of the 20s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A significant winter storm will impact the Tri-State area Saturday
night into Sunday with the coldest air of the season Sunday night
into Monday.

A winter storm watch remains in effect for much of the region late
Saturday into Sunday.

Models have slowly come into better agreement over the last 24
hours, but there still remains a good deal of uncertainty regarding
the exact track, thermal profiles, and precipitation types and
amounts for the winter storm. The southern stream energy with this
system is now over the western US, so continued RAOB sampling should
help establish better agreement today. However, changes in track
forecast are still possible. High confidence remains on this storm
being a high liquid equivalent event.

Strong warm advection will be underway Saturday night with snow
increasing in intensity across the entire region. A corridor of
intense 850-700 mb frontogenesis will move across from 00z Sunday
through 12z Sunday ahead of a broad middle level low. Strong
southerly low level winds will likely bring a tight thermal gradient
and warm nose from south to north through the night. Snow will
change to a wintry mix at the coast around midnight and then across
much of the interior by Sunday morning. Much of Long Island, NYC,
and southeast Connecticut should change to plain rain early Sunday
morning, but the interior may see a mix of sleet and freezing rain.
The depth of the low level cold on the NAM and NAM 3-km is quite
impressive, which may cut down on the freezing rain somewhat and
bring more sleet once the changeover occurs. This may also mean a
greater chance for freezing rain closer to the coast. Confidence in
this scenario is still low, so will continue to show a general sleet
and freezing rain mix across the interior once the warm nose moves
in aloft.

Surface temperatures are also uncertain and dependent on how much
cold air damming occurs. There is a high amount of spread from
temperatures barely rising above freezing even at the coast to
warming well into the 40s. All of this will ultimately depend on the
track of the low. If the low tracks just south of the region, then a
colder profile with potential for more ice at the coast would be
realized. If the low track is further north and over portions of the
region, then warmer air would likely occur with less ice.

The low shifts east of the region on Sunday morning into Sunday
afternoon. Once the low passes east, winds will shift to the north
and north west with a rapid cooling occurring both at the surface
and aloft. There has been a trend in the models for less precip on
the back side of the low, so there may be limited amount of frozen
precipitation as the storm pulls away Sunday afternoon.

As temperatures fall below freezing late Sunday morning into Sunday
afternoon, any standing water on untreated surfaces could quickly
freeze, creating hazardous travel conditions even where little
wintry precipitation occurs.

Highest snow/sleet accumulations are expected mainly NW of NYC where
mostly 4 to 8 inches is currently forecast, and possibly even higher
towards Putnam and Orange Counties. Most other areas are expected to
see less than 6 inches of snow/sleet, however with the potential of
at up to around a tenth or two of ice accretion in addition to
snow/sleet, hazardous conditions are possible for these locations as
well. The only areas not under a watch are parts of Long Island
where 1-3 inches of snow/sleet is expected and maybe at least a
trace of ice could occur. Some of the watch across coastal locations
and possibly NYC may eventually be converted to an advisory
depending on the forecast trends.

Temperatures continue to plummet as arctic air advects into the
region behind the storm. Lows Monday morning will generally be in
the single digits. There is a possibility of a few locations in
interior falling to near 0, especially with a new snow/sleet pack.
Gusty northwest winds will result in wind chills around 10 to around
15 degrees below zero. The lowest wind chills are most likely to
occur across the interior.

The arctic air remains in place on Monday as high pressure builds
into the region. Highs will only be in the teens with wind chills
staying 0 to 10 below. Temperatures should warm into to the 20s and
low 30s on Tuesday and then potentially above normal on Wednesday
ahead of the next system approaching the area.

Timing and thermal profiles with this next system are uncertain due
to model disagreement. Precip chances are in the forecast late
Wednesday into Wednesday night. The primary low tracks up into
southeast Canada, so the majority of the precip should be liquid
with warmer air ahead of the system. Precip may also occur on
Thursday depending on if low pressure develops along the front.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Low pressure pulls away as high pressure builds tonight. The
high gives way to a warm front late Saturday.

For the remainder of the afternoon, VFR/MVFR cigs vary before
these lower clouds scour out by evening. VFR overnight and
through Saturday morning.

Light winds become S/SW, then west late this afternoon and
evening. Then winds shift further to the NW and north later
tonight.

NE winds increase to around 10 kt late Saturday morning.

   ...NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component fcsts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: Amendments for ceilings varying between MVFR
and VFR likely.

KLGA TAF Comments: Amendments for ceilings varying between
MVFR and VFR likely. NE/E winds shift to the S/SW by 20-21Z.

KEWR TAF Comments: Amendments for ceilings varying between MVFR
and VFR likely.

KTEB TAF Comments: Amendments for ceilings varying between MVFR
and VFR likely.

KHPN TAF Comments: Slow improvement is expected through the
remainder of the afternoon, but timing remains uncertain.

KISP TAF Comments: Amendments for ceilings varying between MVFR
and VFR likely.

.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...

***HIGH IMPACT WEATHER SATURDAY NIGHT INTO SUNDAY NIGHT***

.Saturday afternoon...VFR initially, then snow with IFR vsby
developing late, especially from the NYC metros north/west.

.Saturday night...IFR or lower conds throughout. Snow changing
to rain after midnight at NYC/Long Island terminals, and to a
wintry mix at northern terminals. LLWS likely NYC metro/coastal
terminals.

.Sunday and Sunday night...IFR or lower likely. Rain from metro
New Jersey, into NYC, and Long Island, and along the
Connecticut coast, with a wintry mix continuing inland, in the
morning. The precipitation transitions back to snow and a wintry
mix, before ending in the afternoon, then becoming VFR. LLWS
possible in the morning. N-NW winds G25-35kt and flash freeze
likely in the afternoon.

.Monday-Monday night...VFR. NW winds G25-35KT, G25kt in the
evening.

.Tuesday...VFR.

.Wednesday...MVFR or lower developing in rain/snow mix to rain.

&&

.MARINE...
Sub-advsy conds are expected through Saturday although an
increasing easterly flow will be developing Saturday afternoon.

SCA conditions are expected to develop beginning Saturday
night. Gale force gusts on the waters east of Fire Island inlet,
eastern LI Bays, and eastern LI sound Saturday night. A gale
watch is now in effect for this time period. Gusty winds will
continue into Sunday into Monday with the possibility of gales
on the ocean waters and potentially the near shore waters Sunday
afternoon into Monday. Winds should begin to subside below SCA
levels Monday night, but ocean seas may remain elevated. Sub-SCA
conditions return on Tuesday.

&&

.HYDROLOGY...
One and a half to around two inches of liquid equivalent
precipitation is likely Saturday night through the day on
Sunday. Frozen precipitation may be predominate across the
interior. Liquid rain is probable closer to the coast late
Saturday night into Sunday morning into early Sunday afternoon
where minor urban and poor drainage flooding is possible in any
periods of heavier rain.

&&

.TIDES/COASTAL FLOODING...
Minor to locally moderate coastal flood impacts are possible during
the Sunday morning high tide cycle. Departures of one to one and a
half feet, locally two feet, are needed for minor benchmarks to be
reached and two and a half to three feet are needed for moderate
benchmarks to be reached.

&&

.EQUIPMENT...
NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable. Parts are on order.

NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Watch from Saturday afternoon through Sunday
     afternoon for CTZ005>012.
NY...Winter Storm Watch from Saturday afternoon through Sunday
     afternoon for NYZ067>075-078-176>179.
NJ...Winter Storm Watch from Saturday afternoon through Sunday
     afternoon for NJZ002-004-006-103>108.
MARINE...Gale Watch from Saturday evening through late Saturday night
     for ANZ330-340-350-353.

&&

Update...PW

Hazardous Weather Outlook...CORRECTED
National Weather Service New York NY
102 PM EST Fri Jan 18 2019

CTZ005>012-NJZ002-004-103>108-NYZ067>071-078-177>179-190915-
Northern Fairfield-Northern New Haven-Northern Middlesex-
Northern New London-Southern Fairfield-Southern New Haven-
Southern Middlesex-Southern New London-Western Passaic-
Eastern Passaic-Western Bergen-Eastern Bergen-Western Essex-
Eastern Essex-Western Union-Eastern Union-Orange-Putnam-Rockland-
Northern Westchester-Southern Westchester-Northwestern Suffolk-
Northern Nassau-Southern Queens-Southern Nassau-
102 PM EST Fri Jan 18 2019

...WINTER STORM WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SUNDAY AFTERNOON...

This Hazardous Weather Outlook is for southern Connecticut,
northeast New Jersey and southeast New York.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Winter Storm Watch.

Dangerous wind chills 10 to around 15 below zero are possible Sunday
night into Monday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

NYZ079>081-190915-
Northeastern Suffolk-Southwestern Suffolk-Southeastern Suffolk-
102 PM EST Fri Jan 18 2019

This Hazardous Weather Outlook is for southeast New York.

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A powerful winter storm will impact the area Saturday night into
Sunday. There is the potential for 1 to 3 inches of snow and sleet
with up to a glaze of ice. Temperatures will rapidly fall Sunday
afternoon and evening, creating the potential for a flash freeze. If
this occurs, it will create a sheet of ice on any untreated
surfaces.

In addition minor to moderate coastal flooding will be possible,
mainly with the Sunday morning high tide cycle.

Dangerous wind chills around 10 below zero are possible Sunday night
into Monday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NJZ006-NYZ072>075-176-190915-
Hudson-New York (Manhattan)-Bronx-Richmond (Staten Island)-
Kings (Brooklyn)-Northern Queens-
102 PM EST Fri Jan 18 2019

...WINTER STORM WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SUNDAY AFTERNOON...

This Hazardous Weather Outlook is for northeast New Jersey and
southeast New York.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Winter Storm Watch.

Dangerous wind chills around 10 below zero are possible Sunday night
into Monday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

ANZ335-338-345-355-190915-
Long Island Sound West of New Haven CT/Port Jefferson NY-
New York Harbor-
South Shore Bays from Jones Inlet through Shinnecock Bay-
Sandy Hook NJ to Fire Island Inlet NY out 20 nm-
102 PM EST Fri Jan 18 2019

This Hazardous Weather Outlook is for Atlantic coastal waters.

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Gale force winds are possible Sunday night into Monday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ330-340-350-353-190915-
Long Island Sound East of New Haven CT/Port Jefferson NY-
Peconic and Gardiners Bays-
Moriches Inlet NY to Montauk Point NY out 20 nm-
Fire Island Inlet NY to Moriches Inlet NY out 20 nm-
102 PM EST Fri Jan 18 2019

...GALE WATCH IN EFFECT FROM SATURDAY EVENING THROUGH LATE SATURDAY
NIGHT...

This Hazardous Weather Outlook is for Atlantic coastal waters.

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Gale Watch.

Gale force winds are also possible Sunday night into Monday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.