282
FXUS61 KOKX 070553
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
153 AM EDT Mon Oct 7 2024
.SYNOPSIS...
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A cold front passes through the area mainly during the morning
hours of today. 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.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TODAY/...
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Forecast on track, as vigorous northern stream shortwave over
western Ontario, and associated ULJ streak, will pivot into the
region towards daybreak. High-res model in good agreement with
convective line across central PA/NY tonight weakening and
scattering as it races ahead of main shortwave forcing and into
a more stable airmass east of the Appalachians. As shortwave
approaches towards daybreak, with a 25-30kt llj advecting in a
+1.5-2 STD pwat airmass, marginal instability, and good moisture
convergence ahead/along the distinct cold front, likelihood for
the convective line to better organized across LI/CT later this
morning. Locally heavy downpours and isolated thunder threat as
well with a marginally unstable sounding profile, also signaled
in the SPC HREF for thunder prob low. 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. Overnight lows will be
in the mid-50s to low-60s. Breezier weather also sets in thanks
an increasing pressure gradient.-- End Changed Discussion --
&&
.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
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 NIGHT 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 /06Z MONDAY THROUGH FRIDAY/...
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An approaching cold front will pass through the terminals during
the morning into early afternoon hours today.
VFR through the most of the night with MVFR conditions likely
in showers/isolated thunderstorms during the morning. VFR
conditions return about 2-3 hours following the cold frontal
passage.
Winds will be S/SSE around 10 kt at the coast tonight, but
lighter inland. There could even be a few gusts 15-20kt along
the coast due to a strengthening southerly low-level jet. Winds
veer to the NW behind the cold front at 10-15kt with gusts
around 20kt.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts overnight may be more occasional. Best chance at KJFK.
Timing of wind shifts and changes in ceiling category may vary
by 1-2 hours.
Isolated thunderstorm possible in the morning. Confidence too
low at this time to mention in TAF.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
Late tonight: VFR.
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-- End Changed Discussion --
&&
.MARINE...
SE swells continues build to SCA levels tonight as long period
swells from Hurricane Kirk (see NHC for forecast details) build 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
likely 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...
5 to 7 ft surf is expected to cause scattered areas of beach
flooding and localized dune erosion during times of high tide
Monday morning in response to 5ft long period SE swells from
Hurricane Kirk (see NHC forecasts for forecast details).
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ350-353-355.
&&
$$
AVIATION...JC