000
FXUS61 KOKX 241804
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
104 PM EST Sun Dec 24 2023
.SYNOPSIS...
A weak warm front will dissipate to the northwest today, while a
weak trough develops to the southeast through tonight. This
trough will move west and weaken on Christmas day, as high
pressure becomes reestablished. The high will then slowly move
east into the Atlantic Tuesday into Tuesday night. Low
pressure and its associated frontal system will approach Tuesday
night and move across from Wednesday into Wednesday night. Low
pressure or a series of troughs may linger from Thursday into
Saturday.
&&
.NEAR TERM /THROUGH TONIGHT/...
WSW cancelled for Orange County. Spotty freezing rain no longer
a concern as temps are above freezing throughout. No other
changes with this update other than to adjust diurnal temp trace
into early this afternoon from 13Z temps.
Weak shortwave approaching from the NW this AM cuts off and
slowly sinks SE through the region late today into Christmas
Day. At the surface, a weak warm frontal/surface wave to the
northwest this morning will gradually dissipate, while a a weak
trough develops just to the SE tonight.
Low clouds and isolated light rain showers expected to continue
into Monday morning with weak onshore flow and shortwave
sliding overhead. Continued weak WAA will keep thermal profiles
warm enough for plain rain tonight.
Temps several degrees above seasonable with onshore flow and
weak WAA aloft.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Cutoff upper low over the region to start slowly sinks to the
SE Mon night. Shortwave upper ridging builds in on Tue in its
wake and ahead of a developing large and deep closed low over
the Central states. Closed low slowly slides east over the
Mississippi River valley Tue night, with heights falling as
associated trough approaches.
At the surface, weak inverted trough likely develops across far
eastern portions of the region or just east tonight. This trough
gradually weakens and possibly retrogrades west over the area
Mon afternoon/night as sfc high pressure re- establishes
itself. This will likely keep a focus for isolated
showers/patchy drizzle across eastern portions of the areas
Mon morning, possibly retrograding west during the
afternoon/night. If nothing else the onshore flow under a
subsidence inversion will likely maintain stratus into Mon
night. Temps on Christmas day will be nearly 10 degrees above
seasonable (upper 40s interior to lower 50s city/coast), and if
any breaks of sun are realized, could be even warmer in spots.
High pressure gradually slides offshore Tuesday into Tuesday
Night. Dry conditions likely on Tuesday, but once again stratus
may be stubborn, particularly western portions of the region on
edge of high pressure. Highs once again about 10 degrees above
seasonable, upper 40s interior to lower 50s city/coast, and once
again if any breaks of sun are realized, could be even warmer
in spots.
This will be short-lived drying though as high and mid clouds
increase in deep SW flow aloft ahead of large closed low and
developing frontal system to the west. Increasing potential for
showers late Tuesday Night with strengthening SE flow and
Theta-E advection to north of developing warm front across Mid
Atlantic.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The forecast thinking for the extended has not changed too much
over the last 24 hours. A period of unsettled weather is
expected Wednesday into the end of the upcoming week.
*Key Points*
* Confidence continues to increase on widespread rain Wednesday into
Wednesday night. Any impacts look limited due to the progressive
nature and overall weaker system compared to recent events.
* Unsettled weather likely persists Thursday and Friday, but
uncertainty remains with timing of any potential lingering
showers.
* Temperatures will start out above normal on Wednesday and Thursday
before gradually trending below normal by next weekend.
A closed upper low will continue spinning over the central states on
Wednesday, sending a frontal system towards the east coast. Global
deterministic models and ensembles are starting to come into better
agreement on the evolution of this system. Model differences that
continue to exist revolve around where/when secondary low pressure
development occurs over the Middle Atlantic and northeast. Despite
these differences, rain will overspread the region Wednesday morning
and continue into Wednesday evening. The system will be progressive,
which should help limit impacts. The rain could become moderate at
times, but not anticipating a heavy rainfall event like the previous
system. NBM probabilities for greater than 1 inch in any 12 hour
period Wednesday into Wednesday night have come up slightly, but
still largely 15-20 percent. NBM probabilities for greater than
0.50 inches in any 12 hour period have increased over the last 24
hours and are 40-50 percent late Wednesday. This signals an
increasing potential for a half to one inch of rain. Locally higher
amounts are possible, but uncertainty remains where these higher
amounts could occur. Given recent heavy rains, higher streamflows
and soil moisture, some minor flooding cannot be completely ruled
out. Overall, probabilities for a significant event remain low.
The axis of deepest moisture and strongest lift shift to our north
and east Wednesday night allowing the rain to taper off.
The closed upper low will track towards the Great Lakes/Ohio Valley
Wednesday night into Thursday. Deterministic and ensemble mean
differences increase for the end of the week with the handling of
the upper low. GEFS/GFS keep the upper low more consolidated with
several pieces of energy interacting with the the main low into
Friday. ECMWF/ECMWF-EPS/CMC/GEPS weaken the upper low on Thursday
and then have pieces of energy interact with the leftover trough
forming a larger upper low into the weekend. These differences give
a lower forecast confidence for Thursday into Friday with regards to
timing/locations of additional low pressure/surface troughs and
potential precip. The end of the week will remain unsettled and have
followed a low chance PoP in the NBM given the aforementioned
uncertainties. The upper trough/lingering closed low could linger
over New England into Saturday.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pres remains over the area thru Christmas Day.
Low clouds will linger over the region thru the TAF period.
MVFR to IFR CIGs can be expected at times, especially tngt and
Mon mrng. VIS may drop at times in BR tngt, but confidence is
low so the TAFs only indicate 5SM attm.
Winds lgt and vrb thru the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Periods of IFR possible thru 16Z Mon. Timing and coverage too
uncertain so not included in the TAFs attm, although the best
chances are 00Z-14Z. Variability in wind direction possible at
LGA where a general NE flow is fcst.
OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
Christmas Day: Becoming VFR. Chance of MVFR or lower again aft
00Z Tue.
Tue: MVFR or lower at times.
Wed-Thu: MVFR or lower with rain.
Fri: Mainly MVFR. NE winds 20-30kt possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA cond expected through Wednesday under weak pressure
regime.
Chances for SCA cond then increase, especially on the ocean,
from late Wed into Thu night. Wind gusts of 25 kt are forecast,
with a higher chance of seeing elevated ocean seas above 5 ft.
&&
.HYDROLOGY...
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).
Hydrologic impacts, if any, appear limited to localized minor
flooding from rain Wednesday into Wednesday night.
&&
.TIDES/COASTAL FLOODING...
Monitoring potential for minor coastal flood impacts for
vulnerable coastal communities Wed/Thu with a passing frontal
system. Tidal departures of 1.25-1.50 ft needed for minor
flooding, and 2.25-2.50 for moderate flooding during the
morning high tides. About 1 ft additional surge is needed for
the evening high tides. Low predictability on details attm.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DS/NV
NEAR TERM...BG/NV
SHORT TERM...NV
LONG TERM...DS
AVIATION...JMC
MARINE...DS/NV
HYDROLOGY...DS/NV
TIDES/COASTAL FLOODING...