Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 211749
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1249 PM EST Thu Feb 21 2019

.SYNOPSIS...
An approaching cold front crosses the region this afternoon.
High pressure builds in from the west tonight through Friday
night, then moves offshore Saturday. A low pressure system
impacts the region Saturday night and Sunday. High pressure
returns Monday through Tuesday. Another low moves into the
region for Tuesday night and Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Westerly drying winds remain across the forecast area and fig
have dissipated along with most of the clouds. With little
moisture at the lower levels there will be a few fair weather
cumulus ahead of a cold front. The cold advection will be late
in the day and the gust potential become limited later this
afternoon as winds aloft slowly diminish. Have limited gusts to
around 20 KT, ending around sunset, by 22Z. With the westerly to
northwesterly flow temperatures have increased to the mid and
upper 40s, even across Long Island.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
For tonight and Friday, the weather remains dry with the region
getting more influenced by approaching surface high pressure
from the west, and a building ridge from the central states.
This becomes more of an extension of the sub tropical high
which will remain anchored off the southeastern coast.

The subsidence effects from the approaching high will be seen
on Friday with minimal clouds with more remarkable mid level
ridging evident in the numerical weather prediction models
during that time. A larger mid level ridge appears to take shape
across the Eastern US for tonight into Friday.

Winds being steady and not decoupling tonight will help limit
radiational cooling. Friday`s highs are several degrees cooler
than the previous day with backing of winds from low to mid
levels, conveying cold air advection.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
A Deep layer ridge builds over the area Friday night, then its
axis slowly slides to the east on Saturday. Friday night should
be dry with minimal cloud cover as a result, due to subsidence
under the ridge. The models have trended slower with the timing
of the ridge axis sliding to the east, as a result Saturday will
likely be dry for most, if not the entire Tri-state. For now
limit any slight chance to low end chance pops to far W and SW
portions of the CWA on Saturday. Lows Friday night should be
near to slightly above normal and highs on Saturday near normal.


A cutoff low tracks from the central plains to the Great Lakes
Saturday night, with strong isentropic lift and low level warm
advection supporting stratiform precipitation over the area.
Thermal profiles suggest it should mainly be in the form of
rain. Northern interior zones could see some sleet mixed in,
with a chance of some pockets of freezing rain in over interior
portions of the Lower Hudson Valley and SW CT. Lows Saturday
night should be around 10-15 degrees above normal, and likely
will occur during the evening, with slowly rising temperatures
through most, if not all the night.

The cutoff low tracks into E Ontario/W Quebec Sunday, while at
the surface, a warm front lifts to the N probably by early
Sunday afternoon. The timing of the warm front will be
determined in part by exactly when and where a secondary coastal
low forms along it during the day on Sunday. For now, figure
should be in the warm sector Sunday afternoon so transition from
rain in the morning to showers in the afternoon. This idea is
also supported by most models showing the dry slot with this
system working its way into the area Sunday afternoon as well.
Highs on Sunday should be around 15 degrees above normal.

With the region under difluent flow aloft, and under the
influence of a 40-50KT 850 hPa jet, a coupled upper jet
structure and difluent flow aloft from Saturday night into
Sunday morning, moderate to locally heavy rainfall is possible
with this system. Refer to the hydrology section of the AFD for
details.

The axis associated with the closed low lifts to the NE Sunday
night, being replaced by quasi-zonal flow over the region
through Monday. Absent any shortwaves of note being progged over
the region, coupled with dry low levels, it should be dry over
the area Sunday night and Monday. The region will be under going
strong low level cold air advection Sunday night and Monday
with a 40-50 KT 950-850 hPa jet. As a result there is the
potential for widespread wind advisory level winds - with
sustained winds of 20-30mph and gusts of 40-50mph probable. Lows
Sunday night should be around 10 degrees above normal and highs
on Monday near normal.

Models then differ about the timing and placement of systems
Monday night-Wednesday. For now it appears that there probably
will be some degree of mid-upper level ridging transiting the
area Monday night and Tuesday, with diminishing winds, fair
weather and near normal temperatures. The next storm system is
then progged in for Tuesday night and Wednesday. However, its
exact evolution, track, timing and impact is highly uncertain at
this time.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
High pressure then slowly builds in from the west tonight.

VFR through the period.

Winds increase to 10-15 kt with gusts around 20 kt this
afternoon. Gusts will diminish this evening as winds begin to
turn to the NW late tonight and Friday.


     NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: No unscheduled amendments are expected.

KLGA TAF Comments: No unscheduled amendments are expected.

KEWR TAF Comments: No unscheduled amendments are expected.

KTEB TAF Comments: No unscheduled amendments are expected.

KHPN TAF Comments: No unscheduled amendments are expected.

KISP TAF Comments: No unscheduled amendments are expected.


.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.18z Friday...VFR. NW winds 10KT.
.Saturday-Sunday...MVFR or lower in rain developing the Sat evening,
continuing into Sunday. Mixed precipitation is briefly possible
Saturday night at KSWF.
.Sunday Night into Monday...VFR. WNW 15-25KT G30-40KT. Isolated
stronger gusts.
.Tuesday...VFR.

&&

.MARINE...
No changes to the winds and seas at this time. Gusts on the
ocean waters have increased to SCA levels, and seas remain 5 to
7 feet. So the SCA continues.

Gusts will approach 25 kt at times this afternoon on the far
eastern Long Island Sound, but overall expect conditions to
remain below SCA levels.

SCA conditions continue on the ocean waters through tonight.
While winds will diminish across the waters this morning, an
increasing pressure gradient ahead of an approaching cold front
will result in a return to gusty winds by this afternoon. In
addition, seas will remain elevated through tonight. With seas
continuing to subside, sub-SCA conditions are expected during
the day on Friday.

A relaxed pressure gradient over the region will limit winds over
all waters to around 10 kt or less from Friday night through
Saturday evening. The pressure gradient then tightens from late
Saturday night into early next week. As a result, Small Craft
Advisory (SCA) conditions are possible on the coastal ocean waters
late Saturday night-Sunday. On the non-coastal ocean waters, sub-SCA
conditions should persist late Saturday night and Sunday morning,
with SCA conditions possible Sunday afternoon.

Gale conditions are likely on all waters from Sunday night into
Monday evening, with storm force gusts possible, especially on the
coastal ocean waters.

&&

.HYDROLOGY...
The weather will be dry through Friday night and through most of
the day Saturday.

There is the potential for 1 to 1.5 inches of rain, with
locally higher amounts possible from Saturday night into Sunday
afternoon. There is some uncertainty with respect to amounts,
with a chance amounts could end up higher than currently
forecast. As a result, given the wet antecedent conditions over
the region, there is the potential for at least minor urban and
poor drainage flooding over the Tri-State from Saturday night
into Sunday afternoon. There is a smaller chance for more
extensive flooding, with localized flash flooding and the
flooding of fast responding small streams something that is
within the realm of reasonable possibilities. However, at this
time, the confidence in this is not high enough to reflect in
the HWO.

&&

.EQUIPMENT...
NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable. Parts are on order.

NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Friday for ANZ350-353-355.

&&

$$
SYNOPSIS...MET
NEAR TERM...MET
SHORT TERM...JM/MET
LONG TERM...Maloit
AVIATION...IRD
MARINE...MET
HYDROLOGY...Maloit/JM/MET
EQUIPMENT...


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