000
FXUS61 KOKX 231443
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
943 AM EST Sat Dec 23 2023
.SYNOPSIS...
High pressure over the area will move east today. A weakening
warm frontal wave will approach tonight and dissipate over the
region Sunday. High pressure will reestablish itself on
Christmas Day, then moves offshore on Tuesday. The next frontal
system and associated low pressure affect the region on
Wednesday before slowly shifting away from the area Thursday
into Friday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
A narrow band of light precip (mainly in form of sleet),
associated with a weak lead vort axis, is moving across parts of
NE NJ NYC and headed toward the south shore of western Long
Island. This precip is reaching the ground in spots in the form
of graupel, so added isolated snow/rain showers to the forecast
this morning.
Otherwise, weak shortwave ridging today ahead of a weak
shortwave approaching from the Great Lakes tonight. At the
surface, high pressure gradually slides east today, with weak
return flow. High and mid clouds will advecting in from SW to NE
ahead of approaching shortwave and weak low pressure this
morning. Highs near seasonable in the upper 30s interior and
lower 40s coast.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Weak shortwave approaches from the northwest tonight and then
slowly cuts off and sinks SE through the region Sunday and to
the southeast Monday. At the surface, high pressure slides
farther offshore with a weak warm frontal/surface wave
approaching from the west tonight, and gradually dissipating
over the region on Sunday.
Models have been in general agreement with sufficient
moisture/theta-e advection ahead of the surface wave and lift
by approaching shortwave/jet streak to overspread light precip
over western portions of the region after midnight tonight and
then likely the entire region on Sunday as the closed low sinks
southeast.
Thermal profiles look marginally cold enough for a period of
light snow/sleet or mix with rain for areas well NW of NYC
(Orange/W Passaic/Putnam/N Fairfield) late tonight into Sunday
morning. Based on forecast sounding analysis, there appears to
be enough saturation in snow growth area for snow development
aloft, but as typical the magnitude of low-level warm nose and
precip intensity (diabatic cooling processes) will determine
mixing with or changeover to sleet or ra. Reality is likely
between NAM with aggressive warm nose, and weaker warm nose GFS.
NBM POWT for wintry precip are quite low for this area tonight
into Sunday, with less than 20% prob of snow for W Orange and
less than 10% for rest of NW interior, and 0% prob for sleet or
fzra. Rain probs are 70%+, basically indicating mainly rain,
perhaps mixed with some sleet/snow, and a localized fzra threat
where air/ground temps are at freezing. SPC HREF p-type
likewise indicating rain as primary p-type, with DESI HREF sounding
analysis indicating a noticeable warm nose. Overall, low prob
for a light coating of snow across Western Orange County (west
of the Hudson Highlands) late tonight into early Sunday morning.
If rain is the predominant p-type, surface/ground temps would
be primary determinant for fzra potential. Air and ground temps
are expected to rise above freezing during the day, and with
thickening cloud cover tonight, most areas should have air and
ground temps remain just above freezing. There is a low threat
that western portions of Orange county (west of the Hudson
Highlands) could be cold enough air/ground temps for spotty
icing.
So overall low confidence and coverage in wintry precip
(particularly fzra), so no winter headlines at this time, but if
traveling late tonight into Sunday morning across NW interior
(particularly W Orange County), monitor for a potential short fuse
SPS or winter wx advisory for fzra if precip is heavier than
forecast and/or surface temps do cool more than expected.
Temps should safely warm above freezing for NW interior by mid
morning for plain rain showers areawide. For the coastal plain,
thermal profiles will only be conducive for rain, spreading SE
into NYC/NJ metro late tonight into early Sunday morning and
possibly into ern Long Island and SE CT by early afternoon.
Lingering stratus likely, with isolated light rain showers and
patchy drizzle possible Sunday Night into early Monday morning
with weak onshore flow and shortwave sliding overhead. Continued
weak waa will keep thermal profiles warm enough for just plain
rain Sunday Night/Mon AM. Gradual drying likely Monday
afternoon, but stratus will likely be stubborn.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
There has been little change to the forecast thinking for the middle
to late next week time frame. The NBM was largely used for this
update.
*Key Points*
* Low pressure and its associated frontal system impact the region
Tuesday night through Wednesday night. The system slowly pulls
away from the area Thursday into Friday. Despite there being a
large amount of uncertainty on the evolution of the system, the
probability of a significant event is very low.
* Rain is likely at some point late Tuesday night through Wednesday
night, but timing, duration, and amounts remain uncertain.
* Temperatures start out above normal, but should trend closer to
normal by the end of the week.
Complex weather pattern is expected to evolve Tuesday through the
end of next week. Ridging will gradually shift over the western
Atlantic on Tuesday ahead of closed upper low over the central
states. The upper low slowly moves towards the Great lakes on
Wednesday. The models are struggling with a complex interaction of
several pieces of energy diving southward out of central Canada. The
closed low should overall slowly track eastward through the end of
next week. The model spread remains high with the details with the
intensity of the closed low.
At the surface, primary low pressure over the central states Tuesday
will track towards the Great Lakes on Wednesday. The associated
frontal system will approach the area Tuesday night and move across
the region Wednesday into Wednesday night. The guidance continues to
waiver on whether or not a secondary low will form along the front
over the Middle Atlantic/northeast. There are some subtle trends
over the last 24 hours for a more progressive front and weaker
secondary formation. The parent low may end up being dominant and
actually slowly deepen as it moves towards New England Thursday and
then southeast Canada on Friday.
Confidence is highest that any precipitation will be in the form of
rain due to the mild air mass ahead of the system. NBM probabilities
of 1 inch of rain in a 12 hour period have actually decreased
somewhat over the last 24 hours, generally below 10 percent. NBM
probabilities of 0.50 inches of rain in a 12 hour period generally
range from 20-30 percent. These probabilities hint that rainfall may
not be significant and this could be tied to the general consensus
of a progressive weaker surface system. These details could change
in the coming days as models begin to resolve some of the complex
upper level features. It bears watching due to the recent rainfall
events, higher streamflows and soil moisture.
NBM keeps a chance PoP through the end of the week. This is due to
differing evolutions within the ensembles with the upper low as it
moves over the northeast. It should remain mostly cloudy, but
precipitation chances hinge on any enhanced lift under the upper low
which is difficult to resolve at this time range.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure remains in control through early this evening. A
warm front approaches tonight and then weakens over the area on
Sunday.
VFR through the first half of tonight. MVFR conditions are then
possible late tonight into early Sunday morning. There is a
chance for light rain late tonight into Sunday morning. The
light rain could mix with sleet and/or freezing rain at the
onset at KSWF, but not enough confidence to include in the TAF
at this time.
Light S-SE winds develop near noon with speeds around 5 kt.
Light and variable winds return tonight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of MVFR late tonight/early Sunday morning could be off
by 1-3 hours.
OUTLOOK FOR 12Z SUNDAY THROUGH TUESDAY...
Sunday: Mainly MVFR. Chance of light rain.
Christmas Day: VFR.
Tuesday: Becoming MVFR or lower late, increasing likelihood for
rain at night.
Wednesday: MVFR or lower with rain. E gusts 15-20 mph possible
late.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA through Tuesday night with a weak pressure gradient in
place.
The next chance for SCA conditions occurs Wednesday into Wednesday
night with a frontal system. The highest chance for SCA winds exists
on the ocean.
&&
.HYDROLOGY...
-- Changed Discussion --
River flood warnings are still in effect along the CT River
(handled by WFO BOX) and parts of the Passaic River basin
(handled by WFO PHI). Otherwise, no hydrologic impacts are
expected through Tuesday.
Rain is likely Tue night and Wed. Predictability remains low on
amounts and any hydrologic impacts.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BG/DS/NV
NEAR TERM...BG/NV
SHORT TERM...NV
LONG TERM...DS
AVIATION...JMC/DS
MARINE...BG/DS/NV
HYDROLOGY...DS/NV