000
FXUS61 KOKX 192209
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
609 PM EDT Tue Mar 19 2024
.SYNOPSIS...
A warm front passes through tonight. This will be followed by a cold
front Wednesday afternoon into evening. High pressure will be in control
Thursday night into Friday. Low pressure to the west and an inverted
trough emanating from low pressure to the south pivot through Saturday.
The low shifts offshore for the second half of the weekend as high
pressure builds Sunday. The high will be in control early next week,
followed by a warm front approaching late Tuesday
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
Forecast remains on track early this evening. Maintained a
slight chance for a sprinkle or flurry thru about midnight or
so, otherwise conditions remain dry. Previous discussion
follows.
Low pressure just north of the Great Lakes tracks east tonight,
pushing a warm front across the forecast area. Isentropic lift
ahead of this front along with increasing mid level shortwave
forcing and moisture will bring a chance of light precip this
evening. NVA and drying in the lower levels should keep us dry
overnight. Regarding precip type. Wet bulb zero heights are cold
enough to support snow in most spots, but the limiting factor
will be freezing level heights. Snow or mixed snow showers
possible north of the city, with rain showers possible
elsewhere.-- End Changed Discussion --
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
The low center to our north continues to head east, dragging a cold
front across the area late in the day Wednesday into early evening.
Chances of showers begin near noon for western portions with the
last threat over the eastern zones by around 9 PM. The highest
chances will be toward the northern zones as shortwave lift will be
stronger here. Breezy behind the cold front with a gusty WNW flow in
a cold air advection regime. Gusts of 20-30 mph expected.
Breezy conditions continue into Thursday as high pressure builds in
from the west with low pressure slowly moving through the Canadian
Maritimes, maintaining a relatively tight pressure gradient over
here. Deep WNW flow with low level downsloping should be able to
offset the low amount of moisture trying to advect in from the Great
Lakes. Will therefore keep with a dry forecast with mostly sunny
conditions. It`ll be colder than normal however, with highs from the
upper 30s to mid 40s along with wind chills making it feel about 10
degrees colder.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
*Pattern Overview*
The northern branch of the jet stream with its strong confluence zone
across the area deposits high pressure to begin the period Thursday
night into Friday. This will bring seasonably cold and dry
conditions. The confluence zone then lifts out paving the way for a
weak disturbance from the west and upper level energy in the
southern branch to move towards the area for the first half of the
weekend. The trough then lifts and potentially closes along the
coast into Sunday and possibly into a portion of Monday. The trough
along the west coast will then pivot through the Rockies late in the
weekend and get into the Plains for early next week. This will
result in rising 500 mb heights further downstream along the Eastern
seaboard towards Tuesday. The rise in heights across our area may
get delayed with a closed low stubborn to exit the eastern seaboard.
*Details*
High pressure delivers a dry and chilly air mass for Thursday night
into Friday. The winds will gradually diminish Thursday night as
wind chill values are expected to get down into the teens to lower
20s late at night and for early Friday morning. The high will then
settle over the area Friday with light winds. Temperatures will
remain below normal with highs mainly in the lower and middle 40s.
Towards Friday evening clouds will increase from the west as a weak
disturbance approaches from the west. Much of Friday night should
remain dry as lift should remain weak, at least through the first
half of the night. Then towards Saturday morning low pressure gets
to the southeastern coast and moisture from the primary western
system moves into western portions of the CWA. At the onset there
may be some snowflakes / wintry mix across far northern and
northwestern sections. However, a quick transition to plain rain is
expected. The mid and upper levels winds become more southerly as an
inverted trough as indicated by NWP is progged to move into the
area. This will serve as an axis of moisture. The ECMWF and GEM has
now come around more to the ICON and GFS solutions with the moisture
axis setting up right along coastal sections into the day on
Saturday. Thus it now appears likely that rain will move from south
to north across the area on Saturday, and potentially into Saturday
night and into a portion of Sunday. The global model guidance
consensus points to the rain being focused over the eastern half of
the area and this is where the highest potential of 1+ inch amounts
will be. Overall, rain on the order of 0.50 to 1.50 inches is
expected for the first half of the weekend with the higher amounts
further east where flash flood guidance would be higher. See the
hydrology section regarding further details.
Questions are abound for Sunday and Sunday night, and even into
early Monday as a lot of the guidance is now closing off the 500 mb
low. This would serve to slow the progression of the system and would
keep clouds in place for the remainder of the weekend along with
shower chances. Eventually towards Monday the low and trough axis
are expected to pivot out of the area with heights building once the
low can get out of the way. Therefore look for unsettled conditions
for the majority of the weekend. Monday at this point is filled with
uncertainty as to whether the upper level low will remain stalled,
or pivots to the east. Once this happens a milder southerly flow
with building heights should allow temperatures to return to normal
on Tuesday.
Temperatures are expected to remain close to normal overall, with
daytime temperatures expected to average slightly below normal
through the period.
&&
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
A cold front passes late Wed.
VFR through at least 16Z Wed. Sct shwrs mainly aft 18Z Wed could
produce brief periods of MVFR. There is a chance a few of the shwrs
cold mix with IP or SN, especially N of the NYC arpts.
WNW winds back to the W this eve and SW overnight. Winds veer a
little to the W behind the front late Wed.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts could be a few kt higher at times, especially this afternoon.
End time of gusts may be off by 1-2 hours this evening.
Winds may shift closer to 300 true around 22-23Z Wed. Timing
uncertain so no additional group was added to the TAFs attm.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Rest of Wednesday: Brief MVFR possible in the afternoon and early
evening. SW winds becoming NW 22-03Z.
Thursday: VFR. NW wind gusts around 30 kt.
Friday: VFR through early evening. MVFR or lower possible overnight
with chances for rain near coast and rain/snow inland.
Saturday: MVFR or lower at times. Mainly rain likely. SE wind gusts
20-25 kt during the day, becoming NW with higher gusts at night.
Sunday: VFR with gusty N winds.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
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SCA on the non-ocean waters was allowed to expire for this
evening as winds have begun to relax, however advisory
conditions return Wed evening, and have hoisted a new SCA from
22Z Wed thru 10Z Thu for these waters.
On the ocean, although there will be a period late tonight into
a portion of Wed morning where conditions will likely prevail
under advisory criteria, decided to extend the SCA all the way
through Weds night as advisory conditions become more probable
by Weds afternoon. After collaboration, have decided to hold off
on a Gale Watch (more likely on the ocean) as there is higher
confidence in SCA conditions prevailing through the period.
There could be a couple of periods Weds night (right behind the
cold front in the evening) into Thursday (in the morning before
winds slowly subside) where gales could occur. Will leave the
mention of this in the HWO for now.
Small craft conditions subside Thursday night as the pressure
gradient relaxes. Lighter winds will result in sub small craft
conditions Friday. Late Friday night and Saturday morning a SE flow
increases with small craft conditions returning to the ocean waters
and the most of the near shore waters, with the possible exception
of NY Harbor and Western LI Sound. Seas will climb quickly Saturday
afternoon on the ocean waters with ocean seas reaching 10 to 12 feet
by Saturday night as small craft conditions will prevail on the near
shore waters and gale conditions a good bet on the ocean waters.
Gale conditions are also possible on the eastern near shore waters
also at this time. A strong and prolonged N to NE flow will take
place Sunday and likely linger into the early part of next week with
strong high pressure to the north and low pressure offshore.-- End Changed Discussion --
&&
.HYDROLOGY...
No hydrologic impacts are expected through Thursday. Rain on the
order of 0.50 to 1.50 inches is expected for the first half of
the weekend. At this point in time the only anticipated
hydrologic impacts would be minor nuisance urban flooding as FFG
has recovered some over the past week from previous rain
events. There remains some elevated pockets of soil moisture,
but the coverage of elevated soil moisture has decreased some.
As of now the axis of steadier, heavier rainfall would be over
eastern areas where flash flood guidance is relatively higher.
Widespread significant flooding is therefore not expected at
this time, but forecast uncertainty regarding the placement of
the axis of heaviest rainfall remains high.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM Wednesday to 6 AM EDT Thursday
for ANZ331-332-335-338-340-345.
Small Craft Advisory until 6 AM EDT Thursday for ANZ350-353-
355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/JE
NEAR TERM...JC/DR
SHORT TERM...JC
LONG TERM...JE
AVIATION...JMC
MARINE...JC/JE/DR
HYDROLOGY...JC/JE