911
FXUS61 KOKX 050317
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1117 PM EDT Fri Oct 4 2024
.SYNOPSIS...
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A weak cold front passes through the area overnight into the
morning hours before high pressure builds back in from the west
through Saturday night. The high will then slide east on Sunday.
A cold front passes through Sunday night into Monday morning. A
series of reinforcing cold fronts moves through the area
midweek as an upper level disturbance slides through the
northeast U.S. Meanwhile Canadian high pressure then builds in
from the northern Plains to the end the week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Latest radar shows a few weak returns (showers and/or sprinkles)
across northern NJ. CAMs continue to keep the activity real
spotty over the next 3 to 5 hours, mainly from the NYC metro
across western LI. Thus, have confined chances mainly for these
locations and no higher than 30 percent. Any rain that does
fall will remain light, with perhaps a hundredth or two.
The cloud cover and southerly flow will help keep temperatures
several degrees warmer tonight compared to last night, with
overnight lows ranging from the mid 50s across the interior to
around 60 for the New York City metro and coast.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
As the front pushes offshore Saturday morning, high pressure
will build into the region from the west resulting in a dry day
overall. In the wake of the front, clearing skies and a good
deal of sunshine will yield highs in the low to mid 70s, about 5
degrees above normal for early October.
With the high building overhead Saturday night, clear skies and
light winds will allow temperatures to fall well into the 40s
away from the coast. Closer to the coast, lows will be in the
low to mid 50s, with upper 50s to around 60 expected in NYC.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Good model agreement on shortwave upper ridging over the area
on Sunday sliding east on Sunday Night. Meanwhile a vigorous
northern stream upper low interacts with Hudson Bay polar low
this weekend, and gradually sinks se into the NE US early to mid
next week, gradually sliding east to end the week/next weekend.
At the surface, high pressure slides offshore on Sunday giving
way to a fairly strong cold frontal passage Sunday Night into
Monday in response to lead shortwave energy with the developing
northern stream closed low. Dry conditions and temps running a
few degrees above seasonable on Sunday. Stayed close to NBM
deterministic, which was running close to the 75th percentile
NBM raw ensemble (upper 60s to lower 70s). Best shortwave
forcing for Sunday Night/early Mon continues to appear north of
the region, but with indication of a bit of a jet streak running
across northern CWA periphery, a 25-30kt llj advecting in a
+1.5-2 STD pwat airmass and marginal elevated instability, and
good moisture convergence ahead/along the distinct cold front,
likelihood exists for a period of showers Sun Night into early
Mon AM. Threat for thunder appears to be very low, but isolated
heavy showers possible.
Deep NW flow brings in a fall airmass (coolest of the early
fall season so far) in wake of this cold front as high pressure
gradually builds to the west of the region through mid-week, and
a series of reinforcing cold fronts move through the area Mon
Night, Tue Night and Wed Night, bringing heart of cool airmass
Wed into Thu Night. Mainly dry conditions during this period,
but as southern periphery of upper low moves overhead and
shortwaves rotate around sct-bkn instability cu likely, and even
isolated instability shra/sprinkle activity across the interior
Wed and Thu.
Highs on Monday (upper 60s/lower 70s) may be in the morning,
slowly decreasing in the afternoon as caa ensues. Highs Tue are
likely to run slightly to a few degrees below seasonable, and
then several degrees below seasonable Wed/Thu (Upper 50s to 60 F
interior, lower 60s to 65F city/coast) as heart of cool airmass
descends on the region. Bias corrected NBM deterministic is
currently running close to NBM 75th raw ensemble during this
period, so potential that the deterministic could be running a
bit high considering this regime change. Have blended NBM
deterministic and NBM 50th for this potential, with potential
diurnal temps could trend down a few degrees from current
forecast.
Mixed low-level should keep overnight lows from bottoming out
thru much of the time period, but far outlying areas would be
several degrees cooler than forecast Mon Night thru Thu Night if
able to decouple, bringing a low potential for frost,
particularly Wed and Thu Night. MOS guidance will provide a
better picture within a 72 hr window on this threat. Moderating
trend signaled for Fri into the weekend as upper low slides east
and surface high pressure builds to the SW and south of the
region.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
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A weak cold front approaches tonight and passes through the area
during the morning hours Saturday. High pressure then builds in
from the west through Saturday night.
Expect a mainly VFR forecast. Brief MVFR conditions possible
along and ahead of cold front in spotty showers. Brief IFR
possible at KGON.
S/SE winds less than 10 kt will gradually veer to the SW
tonight, likely going light and variable for time before the
cold frontal passage. Northerly winds around 10 kt can be
expected at or just after 12Z.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Brief MVFR possible in a shower overnight.
OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
Sunday through Monday: VFR Sunday. MVFR likely in showers late
Sunday night into Monday. Becoming VFR Monday afternoon with
showers ending from west to east. Chance of NW G15-20kt Monday
afternoon.
Tuesday and Wednesday: VFR. W-NW G15-20kt, mainly late morning
into the afternoon.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA conditions are expected through Saturday night as winds
generally remain 10 kt or less. Ocean seas will gradually begin
to build Saturday night under the influence of long period ESE
swell.
Long period swells from Hurricane Kirk (see NHC for forecast
details) begin building into the local ocean waters on Sunday,
building to 5 to 6 feet Sunday night into Monday. Swells will
gradually subside below SCA Monday night into Tuesday.
At the same time potential for a periods of SCA S gusts late
Sun night into early Mon Am over the ocean waters. Otherwise,
generally sub-SCA NW gusts through midweek, but potential for
brief marginal SCA gusts in wake of reinforcing cold fronts Mon,
Tue, and Wed Eve/Nights.
&&
.HYDROLOGY...
No hydrologic issues are expected throughout the forecast
period.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...FEB/NV/DW
NEAR TERM...FEB/NV/DW
SHORT TERM...FEB
LONG TERM...NV
AVIATION...DW
MARINE...FEB/NV
HYDROLOGY...FEB/NV