689
FXUS61 KOKX 151755
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1255 PM EST Sun Dec 15 2024
.SYNOPSIS...
Strong high pressure shifts offshore this afternoon. A
weakening disturbance then moves across the area tonight through
Monday followed by a quick moving frontal system Monday night
into Tuesday morning. High pressure briefly moves in Tuesday
night into early Wednesday. The next area of low pressure moves
across the area late Wednesday. High pressure returns to end
the week followed by another low that potentially passes near
the area Friday night into Saturday.
&&
.NEAR TERM /THROUGH TONIGHT/...
The forecast is mainly on track with minor adjustments to
hourly temperatures and dewpoints.
Strong high pressure centered over New England will gradually
move off the New England coast this afternoon and evening. A
compact middle level shortwave moves across the Great Lakes this
afternoon and then quickly approaches this evening. The high
shifting offshore this afternoon will allow a return flow to set
up and the beginning of warm advection. The warm advection
increases further this evening in response to the approaching
shortwave. The dry air and surface ridging in place will hold
onto dry conditions through the day time hours, but there should
be increasing middle and upper level cloud cover through the
day. There will also likely be some stratocu advecting in off
the ocean as as the flow becomes more easterly. The increasing
cloud cover will impact high temperatures, but should still
reach the upper 30s and lower 40s near the coast and lower to
middle 30s inland.
Precip associated with the shortwave will start moving over the
interior and areas west of the NYC metro late this evening and
especially towards midnight. The precip will then work its way
eastward through the day break Monday. It may take some time for
precip to reach the surface across eastern CT and eastern LI due
to the closer proximity to the offshore high pressure. A brief
window of wet-bulbing due to erosion of lingering dry supports
an onset of light snow across the interior of the Lower Hudson
Valley, interior NE NJ, and into interior SW CT. Warmer air
aloft will quickly bring an end to the snow around day break
with precip likely becoming light freezing rain across the
interior. Surface temperatures will be slowly rising as the
precip overspreads the area, but ground temperatures may take
some time to respond given the recent stretch of cold weather.
Further south towards the NYC metro, Long Island, and coastal
CT, plain rain is expected.
Have expanded the Winter Weather Advisory to include Northern
Middlesex and also adjusted to the end time to 11 am. Temperatures
will be rising in the morning, but some areas may take some time
to rise enough above freezing to bring an end to icing
concerns. While precip may be lighter further east across the
Advisory, it only takes trace amounts of freezing rain to cause
hazardous travel. Less confidence further east into Northern New
London as precip hold off till day break and could be spotty.
Will mention ice potential in the HWO specifically during the
morning commute for now.
Snowfall amounts are light and under an inch with ice accumulations
anywhere from a light glaze to several hundredths of an inch.
By Late morning, plain rain is expected as temperatures continue
to rise. There is also potential for the precip to become
gradually become more spotty as the shortwave passes to the east
and heights rise aloft. However, there will still be warm
advection in the lower levels to support spotty light rain
especially near the coast. Patchy fog is also likely in the
afternoon and evening.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The flow pattern across the CONUS remains progressive. Fast on
the heels of the offshore shortwave will be a larger trough and
associated frontal system Monday night into Tuesday. The warm
front should lift north of the area Monday night followed by the
cold front on Tuesday. Rain should overspread the area Monday
night and quickly sweep off to the east early Tuesday morning.
Rainfall amounts are around one quarter inch since the system is
progressive and the majority of the more organized forcing
passes to the NW.
Any lingering rain Tuesday morning should quickly end with a
return to mostly sunny conditions. The actual cold front likely
passes late in the day allowing temperatures to reach
unseasonably warm levels in the middle to upper 50s. It would
not be surprising if a few of the warmer spots hit 60 degrees.
High pressure briefly builds in Tuesday night. The air mass
behind the front is of Pacific origin with no significant cold
air. Lows Tuesday night should only fall into the 30s for most
spots.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Aloft, an active pattern with multiple troughs moving across in
the mid to upper levels during the course of the long term,
none appearing significantly amplified. Larger wavelength and
relatively more amplification appears with the trough heading
into next weekend. With the undulating jet streaks passing over
the region this week, a more rapid progressive weather pattern
is expected. At the surface, a couple low pressure systems
impact the area, the first Wednesday afternoon and night, and
another Friday night into Saturday.
First low pressure system approaches Wednesday with rain
expected region wide in the late afternoon and into the
overnight, perhaps ending as some wet flakes in the interior
Thursday morning as colder air works in and the low pushes
offshore.
Dry the rest of Thursday and Friday with high pressure moving
in from the west. The next area of low pressure dives south out
of the Great Lakes Friday night into start of next weekend with
potentially more snow, particularly across the interior. Still
plenty uncertainty and model disagreement here so low confidence
but colder air mass expected to be in place. The forecast will
be dependent upon the evolution of low pressure and the track it
takes. Capped PoPs at 50% in this period to account for this
continued uncertainty.
Above normal temperatures Wednesday with highs near or just
above 50, then trending colder behind a frontal passage
Thursday, with a gradual cooldown through the weekend.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
Strong high pressure shifts off the New England Coast by this
afternoon.
VFR through the morning. Ceilings begin to lower toward 3 kft
this afternoon, and MVFR ceilings become likely towards 00z.
Ceilings continue to lower through the night with IFR likely by
12Z Monday. Brief periods of LIFR are possible from early to mid
Monday morning. Visibilities during the time frame will
generally be MVFR for the city terminals, with brief periods of
2 SM or lower at times. Outlying terminals will see low end
IFR, with brief periods of LIFR at times.
Light snow develops at KSWF 03-05Z, expanding eastward as light
rain into city terminals around 05-07Z. The light snow at KSWF
will change to light freezing rain after 12Z before changing to
plain rain around noon.
Several hundredths of an inch of ice along with snow under 1
inch expected at KSWF.
ENE-ESE flow is expected through the TAF period. Speeds will
remain under 10 kt, but may at times be around 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
MVFR timing may be off by 1-3 hours. Timing of IFR Monday
morning may be off by 1-3 hours.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Monday Afternoon: IFR with rain likely.
Monday Night-Tuesday: IFR and rain. The rain ends in the morning
afternoon with conditions returning to VFR. S-SW gusts 15-20 kt
late Monday night into Tuesday morning, becoming W Tues
afternoon.
Wednesday-Wednesday night: VFR early becoming MVFR-IFR with
rain by evening into the night. NW gusts 15-20 kt possible late
Wednesday night.
Thursday: Mainly VFR. NW gusts 15-25kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Conditions will remain below SCA levels on the waters through
Monday. SCA conditions look likely on the ocean Monday night
into Tuesday as the next frontal system moves across the
waters. A brief lull in the SCA conditions are expected Tuesday
night as high pressure returns.
SCA conditions are forecast to develop on the ocean waters
Wednesday night or early Thursday behind a frontal system. NW
wind gusts around 25 kt and seas 5 to 6 ft on the ocean may
linger thru Thursday evening before improving into Friday.
&&
.HYDROLOGY...
There are no hydrologic concerns through next weekend.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 1 AM to 11 AM EST Monday for
CTZ005>007.
NY...Winter Weather Advisory from 10 PM this evening to 11 AM EST
Monday for NYZ067>070.
NJ...Winter Weather Advisory from 10 PM this evening to 11 AM EST
Monday for NJZ002.
MARINE...None.
&&
$$
SYNOPSIS...DR/DS
NEAR TERM...JC/DS
SHORT TERM...DS
LONG TERM...DR
AVIATION...JP
MARINE...DR/DS
HYDROLOGY...DR/DS