210
FXUS61 KOKX 061911
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
311 PM EDT Sun Oct 6 2024
.SYNOPSIS...
A warm front passes through this evening. A cold front passes
through the area late tonight and through Monday morning. High
pressure moves in Monday night. A series of weak cold fronts
moves through the area midweek as an upper level disturbance
slides through the northeast U.S. Meanwhile, a large Canadian
high pressure system builds in west of the area midweek and
south of the area late in the week. Another cold front may move
through the area next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
A warm front, associated with low pressure moving through south
central Canada and into the Hudson Bay region, will pass through the
region this evening. This will be followed by an approaching cold
front, moving through late tonight into the mid-morning tomorrow.
Cloud cover will increase tonight due to the warm front and
increasing moistening of the atmospheric column. Overnight lows will
be in the mid-50s to low-60s. Breezier weather also sets in thanks
an increasing pressure gradient. An Ambrose jet may set up as
well along the NJ coast into NYC and western Long Island thanks
to the passage of a warm front and increasing southerly and
south- southwesterly flow.
CAMs are in good agreement with the progression and timing of the
cold front tonight into tomorrow morning and its associated showers
and/or isolated thunderstorms. Precipitation will develop as a line
ahead of the front. They will pass west to east starting in Orange
county just after midnight, give or take a few hours, then exiting
eastern fringes of our area by noon tomorrow.
The rain will likely consist of showers with only isolated
thunderstorms. Global and regional guidance show MUCAPE values
between 100-500 J/kg which may be enough to cause an isolated
thunderstorm or two, late tonight into early tomorrow morning.
As for the rain, expecting more precipitation and shower coverage
for the northern/eastern half of the area compared to the
lower/western half of the area. Many different factors are
hinting at decent forcing. Positive vorticity advection aloft
and located somewhat in the left exit region of a weak jet
streak. Other factors to consider include increasing dewpoints
in the low-60s being advected in from a 25-35 kt LLJ ahead of
the front, better forcing with said LLJ, PWATs peaking around
1.4-1.5" (which is around the 90% percentile per SPC`s Sounding
Climatology page, and warm air advection due to the passage of
the warm front.
Overall, impact from the showers should not be too concerning given
the quick progression of the cold front. Clouds clear and dry
weather returns with the passage of the cold front, and as a large
Canadian high builds toward the region Monday night.
&&
.SHORT TERM /MONDAY NIGHT/...
Cool, crisp air is expected Monday night following the passage of
the cold front and as a large Canadian high begins to build toward
the region Monday night. With a strong northwest flow, cold air will
be advected in Monday night leading to lows in the mid-50s to mid-
40s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Good model agreement on northern stream upper low over Quebec on
Tuesday, gradually sliding east into northern New England thru mid
week, before gradually lifting NE of the region Friday into
Saturday. Trend over the last 96 hours has been for the closed low
to remain a bit farther north of the region for the mid week period,
with a alter shorter duration of heart of cold core swinging
through. Thereafter, general agreement on flatter long wave
troughing remaining across the NE US for the weekend, but spread in
shortwave timing details.
Deep WNW flow continues to bring in a fall airmass through mid-week
(coolest of the early fall season so far) as high pressure gradually
builds towards the region, and a series of weak cold fronts/troughs
move through the area Tue Night and Wed Night, bringing heart of
cool airmass Thu. A slower and briefer incursion of cool air than
earlier runs had shown. Mainly dry conditions during this period,
but as southern periphery of upper low moves close with a few
embedded shortwaves rotating through sct (locally bkn) instability
cu likely, and even isolated instability shra/sprinkle activity late
Wed into Thu period as upper trough axis move through.
Highs Tue are likely to run slightly below seasonable in caa, and
down to several degrees below seasonable by Thu (Upper 50s to 60 F
interior, lower 60s to 65F city/coast) as heart of cool airmass
descends on the region. With 850 hpa T trending a bit higher over
last 24 hrs (low single digits), NBM deterministic and cooler NBM
50th percentile blend looks reasonable based on deep low-level
mixing profile.
Mixed low-levels should keep overnight lows Tue Night, Wed Night,
and Thu Night from bottoming out in most areas, but potential for
brief windows for radiational cooling across far outlying areas
which could have T`s dropping into the mid 30s, bringing a low
potential for frost.
NBM T spread increases for Friday into the weekend based on how
quickly upper trough lifts ne and depth of mean troughing, but
overall a moderating trend to seasonable signaled for Fri and then
potentially above the weekend seasonable as upper low (cold core)
likely lifts, height rise, and return flow develops. Timing
difference on potential cold frontal passage, with light rain shower
potential.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
High pressure gradually moves offshore through this evening. A
warm front will then move across the area tonight, followed by
a cold frontal passage on Monday.
VFR through 06z Monday. MVFR conditions becoming likely in -SHRA
towards 09z-11z Monday for the city terminals. There is a chance
for brief IFR conditions, however confidence too low to include
in the TAFs. Also, can not rule out a rumble of thunder. Will
not include any thunder in the TAF as confidence of timing and
placement too low at this time.
SE become a bit more S tonight. The winds then switch to the W
/ NW Monday with a cold frontal passage. Winds will remain
around 10kt or less. Once the winds switch to the W-NW,
sustained winds increase to 10-14kt with gusts possible into the
lower and middle 20kt range.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of wind gusts may be off by an hour or two.
IFR conditions Monday morning possible, confidence too low to
include in the TAF.
Can not rule out a rumble of thunder as the front moves across
the region.
OUTLOOK FOR 18Z MONDAY THROUGH THURSDAY...
Monday: Becoming VFR Monday afternoon with showers ending.
Winds NW 10-15g20kt Monday afternoon.
Tuesday: VFR.
Wednesday and Thursday: VFR. Winds W-NW g15-20kt, mainly late
morning into the afternoon.
Friday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Sub-SCA conditions remain across the forecast waters through
early this evening. Ocean seas then build to SCA levels tonight
as long period swells from Hurricane Kirk (see NHC for forecast
details) move into the waters. These long period swells peak at
5 to 6 feet Monday, gradually subsiding below SCA late Monday
night into Tuesday morning. Also, southerly winds ahead of a
cold front may briefly gust to near 25 kt on the ocean waters
Monday morning with the winds shifting to northwest with the
cold front passage. Then, Monday night northwest gusts again may
near SCA levels.
Long period swells likely subsiding below SCA Tuesday morning.
Generally sub-SCA W/NW gusts through midweek, with potential for
marginal SCA gusts over the ocean Wed Night into Thu AM in
wake of strongest cold frontal passage.
&&
.HYDROLOGY...
No hydrologic issues are expected throughout the forecast
period.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
5 to 7 ft surf causing scattered area of beach flooding and
localized dune erosion during times of high tide Monday morning in
response to 5 long period SE swells from Hurricane Kirk (see NHC
forecasts for forecast details).-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from midnight tonight to 8 AM EDT Tuesday
for ANZ350-353-355.
&&
$$
SYNOPSIS...BR/NV
NEAR TERM...BR
SHORT TERM...BR
LONG TERM...NV
AVIATION...BC
MARINE...BR/NV
HYDROLOGY...BR/NV
TIDES/COASTAL FLOODING...