000
FXUS61 KOKX 160138
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
838 PM EST Mon Jan 15 2024
.SYNOPSIS...
Low pressure approaches from the southwest tonight, and passes
nearby to the south and east on Tuesday. High pressure builds in
from the south and west midweek, sliding offshore Thursday. Low
pressure then develops off the Carolina coast Thursday night,
passing east of the region Friday. High pressure returns this
weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
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Light snow has begun to fall across southern Long Island into
southern portions of the NYC metro. Reflectivities are starting
to increase as thermal forcing expands northward. Snow should
spread northward during the next several hours as the low levels
saturate and forcing continues to expand northward. It will
take the interior longest to see snow, but should be snowing
around or just after midnight. The snow will be a drier,
powdery snow (higher ratio) for much of the night and this type
of snow tends to have a lower reflectivity then wetter snow. We
may begin to see some higher returns late tonight, early
Tuesday as some warmer air attempts to move towards the coast,
which could make the snow a bit wetter (lower ratio). Have made
some adjustments to PoPs to bring just above the entire area to
categorical (around 90 percent) after midnight.
No other changes were made to the forecast with this update.
Snowfall rates could start getting close to a half inch per
hour at times around or just after midnight. Soundings look more
saturated towards early morning and think a more traditional
10:1 snow to liquid ratio is likely at that point.
Towards daybreak the snow / wintry mix / rain line will approach
quickly from the SE as the surface low reflection is closer to the
coast in the latest guidance. The flow/advections are not that
strong, but there should be enough warming of the lower level
profile at least east of the NYC metro if not into a portion of
the metro for the snow to transition to a wintry mix. There may
be a brief period of some freezing rain/drizzle as the
transition occurs, especially if temperatures are slow to rise
above freezing in the morning. A Winter Weather Advisory remains
in effect for the entire area. Overall this is a 2 to 4 in snow
event, with locally higher amounts of around 5 inches a
possibility across interior NE NJ and the Lower Hudson Valley
having the highest chance of seeing 5 inch amounts locally. A
glaze of ice is also possible.
Tuesday morning the warm air changes the precip to a light rain
along the coast and potentially into eastern portions of the
city, but by this time much of the precipitation from this event
will have already fallen. Expect mainly all snow well inland,
with some mixing likely a touch further SE which could result up
to a tenth of an inch of ice in a few spots. Again, the
question remains is the thermal forcing / warming a touch
overdone as it certainly looks that way on the NAM guidance. As
far as upper jet dynamics implications, the overall feeling is
that with out noticeable cyclonic or anticyclonic curvature in
the upper jet structure not sure if the upper jet will enhance
upper level divergence
By the afternoon expect any precipitation to end, with the precip
tapering earlier across eastern and southeastern sections of the
area. Any precip should be light with the thermal forcing gone for
the afternoon. Not too concerned about impacts on the back side of
the low as it pulls away with any precip at that point being more
showery in nature and with temps overall warmer than they were
earlier in the morning.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY NIGHT/...
Clearing takes place toward mid evening from west to east. The
coldest air of the season then moves in. Towards late at night and
early Wednesday morning temperatures should get into teens inland,
and upper teens to around 20 for the city and the immediate coast.
Wind chills will get down to some of the coldest readings of the
season thus far with single digits wind chills widespread across the
area a few hours after midnight.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Anomalously low heights south of Hudson Bay and the Great Lakes
region into Wednesday will lead to some of the coldest air of the
season with highs in the 20s Wednesday afternoon and lows in the
teens Wednesday night (20s in the NYC metro). Some slight
temperature moderation then likely takes place Thursday and Thursday
night in advance of the next system as heights rise aloft with west
to east zonal flow.
A coastal low is expected to develop off of the Carolina coast
Thursday night with the southern branch of the jet stream. This will
then track north-northeast up the east coast in the Atlantic on
Friday then eastward out to sea on Saturday as it passes to our
southeast. With cold air in place, snow is likely Friday into
Saturday with this system. The general pattern remains the same with
most 12Z guidance, but solutions vary in terms of exact track and
magnitude to the coastal low. This will change the outcome of total
snowfall we see. For now, most solutions would give us is system.
For now, NBM probabilities hold a 50% chance of 1", 30-40% chance of
2" and a 20% chance for 3" or more. For now, expecting a prolonged
light snowfall event.
Regardless of the outcome of this system, in its wake the coldest
air mass of the season since last February is expected. In fact,
much of the region away from the coast may have to wait until early
next week to see the temperatures climb above freezing. The coldest
day appears to be Saturday, when 12Z global ensemble means
(including GEFS, EPS, CMCE) prog 500 mb heights 25-30 dam below
normal as the trough axis swings through. At this time, highs on
Saturday top out in the 20s, and perhaps the teens across the
interior if colder guidance is realized. With a blustery NW wind,
wind chill values could fall into the single digits or below zero at
points Friday and Saturday night.
A strong ridge nudges in from the west on Sunday as the trough exits
farther to our east with surface high pressure building in from the
southwest. It effects likely won`t be fully realized until Monday,
since Sunday still has highs in the low-30s to upper-20s.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
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Developing low pressure along the southeast coast tonight will track
towards the region Tuesday morning and then south and east of the
area Tuesday afternoon.
Conditions will continue to lower to MVFR and then IFR tonight
as snow overspreads from south to north. IFR and snow will
continue through day break and there is a chance at some period
of moderate snow with LIFR conditions.
The snow will likely change to a wintry mix across central/eastern
Long Island during the morning by 13-15z and could work its way
north and west into the afternoon. There is a chance at some
freezing rain within this wintry mix. Lower Hudson Valley terminals
should remain predominately snow for the duration of the event.
Southern CT terminals could see a wintry mix late morning and early
afternoon. The precip may end as a brief period of snow before
ending 20-22z.
Total snow accumulations:
KJFK/KISP/KGON: 2-3"
KLGA/KEWR/KTEB/KHPN/KSWF: 3-4"
Winds will become light and variable briefly this evening before
shifting to the NE under 10 kt through early Tuesday morning.
Winds will gradually shift towards the N and then NE by Tuesday
afternoon and evening. Wind speeds increase to around 10 kt late
morning into the afternoon.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Snow will continue to overspread the terminals through 03z.
Sleet and freezing rain are possible 14-18z.
OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday Night: Becoming VFR. NW wind gusts 15-20 kt.
Wednesday: VFR. W wind gusts near 15-20 kt.
Thursday: Mainly VFR. W wind gusts near 15-20 kt during the day.
Friday...IFR with snow likely, mainly during the day. Chances for
snow lower at night. NE-N wind gusts near 20 kt in the afternoon and
at night.
Saturday...Mainly VFR. NW wind gusts near 25-30 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds and seas across the forecast waters will remain below advisory
levels through tonight and into the first half of Tuesday. Then as
low pressure shifts away to the east and eventually northeast later
on Tuesday small craft conditions develop, first across the ocean
and western waters, then during the evening for the near shore
eastern most waters. Ocean seas should get up to around 5 ft Tuesday
night.
Departing low pressure and a building high to the west on Wednesday
allows small craft advisory conditions to develop once again on all
waters by the evening under increasing westerly flow. Gales possible
on the ocean and eastern nearshore waters Wed night into Thu. Winds
lower Thursday with sub SCA conditions returning to non ocean waters
early in the day, and on the ocean by Thu night.
SCA conditions redevelop late Friday or Friday night, and may
persist on all waters through the weekend under NW flow. Gales on
the ocean will be possible once again Sat night into Sunday.
&&
.HYDROLOGY...
No hydrologic impacts are expected through the forecast period.
&&
.TIDES/COASTAL FLOODING...
Localized minor coastal flood impacts likely for the Tue
afternoon high tide along NJ harbor and tidally affected rivers,
southern bays of Nassau and Queens, and along Western LI Sound
with onshore flow around an area of low pressure tracking SE of
the area and only 1 1/2 ft of surge needed for minor flooding.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Winter Weather Advisory until 7 PM EST Tuesday for CTZ005>009.
Winter Weather Advisory until 10 AM EST Tuesday for CTZ010>012.
NY...Winter Weather Advisory until 7 PM EST Tuesday for NYZ067>071.
Winter Weather Advisory until 10 AM EST Tuesday for NYZ078>081.
Winter Weather Advisory until 1 PM EST Tuesday for NYZ072>075-
176>179.
NJ...Winter Weather Advisory until 7 PM EST Tuesday for NJZ002-004-
103-104.
Winter Weather Advisory until 1 PM EST Tuesday for NJZ006-
105>108.
MARINE...Small Craft Advisory from 6 PM Tuesday to 6 AM EST Wednesday
for ANZ331-332-335-338-340-345.
Small Craft Advisory from 3 PM Tuesday to 6 AM EST Wednesday
for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JE/BR
NEAR TERM...JE/DS
SHORT TERM...JE
LONG TERM...BR
AVIATION...DS
MARINE...JE/BR
HYDROLOGY...JE/BR
TIDES/COASTAL FLOODING...