000
FXUS61 KOKX 151201
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
701 AM EST Mon Jan 15 2024
.SYNOPSIS...
High pressure builds to the south today, weakening late in the
day as low pressure approaches from the southwest tonight, and
passes 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 /UNTIL 6 PM THIS EVENING/...
No changes to the current forecast with this update.
Today will be quiet as high pressure builds south of the region
and moves off shore late in the day and weakens. Weak low
pressure will be approaching from the southwest late in the day.
Weak warm advection will be setting up over the ocean waters
just south of the region, ahead of the low, and strengthening
isentropic lift along with the column becoming saturated, there
will be a slight chance for snow late in the day as a cold
airmass remains in place.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
Thermal forcing will be increasing further tonight, and pushes
northward as the surface low reaches the southeastern coast by
12Z Tuesday. Again there will be enough cold air in place for
all light snow pushing into the northern portions of the area by
Tuesday morning. There could be as much as 1 to 1 1/2 inches of
snow accumulation by the morning. There are some minor tracking
differences with the low with the NAM moving the center of the
low over the 40/70 benchmark by 21z Tuesday, while the GFS and
ECMWF are slightly farther to the north and west, and weaker
with the low. Warmer air will be moving toward the coastal plain
Tuesday morning into the afternoon as the surface low moves off
the Mid Atlantic coast. Also, there will be some mid level
drying and the precipitation may become lighter as a transition
to a wintry mix and then plain rain occurs. There may be a brief
period of freezing rain during the transition as a warm nose
develops before surface temperatures also rise above freezing.
While total snow accumulations will be borderline for an
advisory, have decided to issue one for most of the area, except
Suffolk County, New London County, and coastal New Haven and
Middlesex Counties where totals may be around an inch. Also
issued for impacts with the timing of the precipitation
overnight, with accumulations likely for the Tuesday morning
commute, and this will be the most significant snowfall in a
while.
The low tracks rather quickly to the east and then northeast
late Tuesday into Tuesday night with the precipitation going
back over to snow before ending.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
*Key Points*
* Below normal temperatures through the period. The first prolonged
stretch of below normal temperatures this winter season.
* Quick moving coastal low may bring snow to the region on Friday.
No significant changes in long term thinking. With a split in
the Polar Vortex and anomalously low heights south of Hudson Bay
into Wednesday look for the coldest air of the season to
arrive. Some slight temperature moderation then likely takes
place Thursday and Thursday night in advance of the next system.
There remains a good degree of uncertainty with a system
emerging out of the Gulf and SE states as a wave along the
southern branch of the jet stream pushes northeast. 00Z guidance
continues to highlight potential for a coastal low to develop
Friday into Saturday, with varying solutions. Model consensus at
this point has the low nudging offshore, but there remain
plenty of ensemble members deepening the low close enough for
the potential for an accumulating snow to fall across the
region. NBM probabilities of at least an inch of snowfall has
crept up on the 01Z run, now over 50% for much of the region,
and near 30% of at least 3". The uncertainty relates to how much
any southern branch features interact with the polar branch of
the jet stream late in the week. Based on model sensitivity the
outlook for the late week system will oscillate back a forth a
few times in all likelihood. Given the lower confidence and that
it remains over 4 days out, have capped PoPs at 60% for now.
Regardless of the outcome of this system, in its wake the
coldest air mass of the season since last February. 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 global ensemble
means prog H500 near 519 dm, or nearly 2 STD 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 this weekend.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure builds in through the day, exiting offshore this
evening ahead of an area of low pressure the develops off the
East Coast and lifts north and east of the terminals on Tuesday.
VFR thru early this evening. Light snow overspreads the area
from south to north with MVFR or lower conditions overnight into
early Tuesday morning. Total snowfall accumulations 1 to 3 inches.
The snow may taper as light rain or drizzle late Tuesday morning,
and cannot entirely rule out patchy freezing drizzle at coastal
terminals.
W winds 10 kt or less prevail the remainder of the morning before
direction shifts to the SW this afternoon. The flow goes light
and variable this evening, then a light NE flow becomes
established early Tue AM.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely tonight for changing categories.
Timing of precipitation and any ptype changes may be off by a
couple of hours.
Brief sub IFR conds possible tonight into Tuesday AM.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
Tuesday: MVFR or lower with light rain and snow, tapering off
in the afternoon. Some rain could mix in with the snow near the
coast.
Tuesday Night. Becoming VFR. NW wind gusts 15-20 kt.
Wednesday: VFR. W wind gusts near 20-25 kt.
Thursday: Mainly VFR. W wind gusts near 20 kt.
Friday...IFR with snow possible. NE-N wind gusts near 20 kt in the
afternoon.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
No changes to the forecast with this update.
Ocean seas east of Moriches Inlet remain above 5 feet early
this morning, and a SCA was extended until 1000 AM EST.
Otherwise, with high pressure building to the south today winds
and seas across the forecast waters will remain below advisory
levels through tonight.
Low pressure approaches from the southwest this evening and
deepens and passes south and east during Tuesday. By late in the
day Tuesday gusts on the ocean waters, and possibly into New
York Harbor will be near SCA levels, then wind gusts will be
borderline at SCA levels across all the waters during most of
Tuesday night. Ocean seas on the outer ocean waters west of Fire
Island Inlet may approach 5 feet Tuesday night.
Departing low pressure and a building high on Wednesday allows
small craft advisory conditions to develop 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.
Sub 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 expected through Sunday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 10 PM this evening to 7 PM EST
Tuesday for CTZ005>007-009.
NY...Winter Weather Advisory from 10 PM this evening to 7 PM EST
Tuesday for NYZ067>071.
Winter Weather Advisory from 8 PM this evening to 1 PM EST
Tuesday for NYZ072>075-176>179.
NJ...Winter Weather Advisory from 10 PM this evening to 7 PM EST
Tuesday for NJZ002-004-103-104.
Winter Weather Advisory from 8 PM this evening to 1 PM EST
Tuesday for NJZ006-105>108.
MARINE...Small Craft Advisory until 10 AM EST this morning for ANZ350.
&&
$$
SYNOPSIS...DR/MET
NEAR TERM...MET
SHORT TERM...MET
LONG TERM...DR
AVIATION...DR
MARINE...DR/MET
HYDROLOGY...DR/MET