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fxus61 kokx 212321 
afdokx

Area forecast discussion
National Weather Service New York New York
621 PM EST Thu Nov 21 2019

Synopsis...
high pressure shifts offshore tonight ahead of a cold front that
will cross the area on Friday. Brief high pressure then returns
for Saturday. Low pressure impacts the region late Saturday
night through Sunday. Weak high pressure then builds in for
Monday through the middle of next week. A cold front will move
through late Wednesday into Wednesday night.

&&

Near term /until 6 am Friday morning/...
forecast is on track with only minor changes made to reflect
current conditions.

Expect the early portion of the night to be influenced by deep
layer ridging that will begin to move offshore. Initially,
favorable radiational cooling conditions will exist in light
winds and mostly clear skies. A non-diurnal trend will then
occur as the high moves offshore and a low pressure system
approaches from the west, giving way to increasing cloud cover
and warm advection as flow becomes more south-southwesterly. Low
temperatures will occur early in the night and be close to
climatological normals in the upper 30s to mid 40s, before
rising a few degrees by daybreak.

&&

Short term /6 am Friday morning through Friday night/...
warm advection will continue into the morning ahead of an
approaching low pressure system, but the antecedent dry air mass
will initially be slow to saturate. As such, any precipitation
will likely be light at onset. Deep layer moisture then quickly
increases into the afternoon, coincident with the arrival of the
strong short wave aloft. At this time, there appears to be more
phasing between the northern and southern stream jets, which
should increase upward motion and chances for rain across the
area, especially closer to the coast. Expect highs on the mild
side, generally in the 50s.

Rain then quickly ends by evening as confluent flow aloft allows
a surface high to build into the region. The tightened pressure
gradient between the departing system and incoming high pressure
will lead to strong and gusty winds across the area, which
combined with strong cold advection will yield wind chill values
in the 20s overnight. Low temperatures will be well below
normal, in the mid 20s to mid 30s.

&&

Long term /Saturday through Thursday/...
weak high pressure will move over the region Saturday. Backing
profiles during the day will mean cold air advection into the
region, with much cooler highs as compared to Friday. Highs will be
in the 40s region-wide.

High pressure then shifts offshore Saturday night, with ridging
aloft as well as veering profiles. This will mean a nearly steady or
slightly warming trend overnight.

A trough over the mid-west will allow a surface low over the Ohio
Valley to quickly intensify as it approaches the area Saturday
night. The track of this low is still very uncertain, but should
push offshore or move over the area late Saturday night into Sunday
morning, then track into the Gulf of Maine Sunday night. Right now,
the NAM is an outlier, with a well offshore track. Also, depending
on the track, a period of moderate precipitation is possible.
Finally, depending on the track and how much cold air remains at the
surface, frozen/freezing precipitation is possible for areas well
inland, mainly across the lower Hudson Valley. Again, there exists
large uncertainty at this time.

Weak surface ridging then builds in from high pressure over the Gulf
of Mexico Monday, then pushes offshore on Tuesday.

A frontal system approaches for the middle of the week, lifting a
warm front north of the area Tuesday night into early Wednesday
morning. The associated cold front quickly moves through Wednesday
into Wednesday night as the associated low passes well north and
east of the area, tracking over the eastern Great Lakes region then
into southeastern Canada. Temperatures will be warm enough at this
point for all rain everywhere.

&&

Aviation /23z Thursday through Tuesday/...
high pressure south of the region will give way to a cold front
on Friday.

Primarily VFR through the taf period. A brief period of MVFR
ceilings in rain is possible on Friday with the frontal
passage, with timing 16-20z.

A light S-SW flow this evening increases late tonight into
early Friday morning. Sustained winds 10-15 kt with gusts
around 20 kt become likely at coastal terminals around day
break. Winds shift to the northwest during the afternoon, with
continued gusts to 20-30 kt.

Outlook for 00z Saturday through Tuesday...
Friday night...VFR. Diminishing northwest winds.
Saturday...VFR.
Saturday night...becoming MVFR to IFR in rain. Wintry mix
possible at kswf.
Sunday...rain with MVFR/IFR, ending during the afternoon.
Northwest winds gusting to around 20 kt in the afternoon.
Sunday night-Tuesday...VFR.

&&

Marine...
initially light winds and sub-Small Craft Advisory will both gradually increase
through the night with the approach of a low pressure system,
reaching advisory levels by the morning to early afternoon. As
the cold front passes east of the waters on Friday, winds will
increase significantly in its wake, allowing for the potential
for gale force winds on the eastern waters, with Small Craft Advisory levels
elsewhere. Therefore, gale warnings have been issued for the
eastern sound, Peconic and gardiner's bays, and the central and
eastern ocean waters. Winds then gradually decrease into Friday
night as high pressure builds from the west, with seas slowly
beginning to subside.

Winds will remain below Small Craft Advisory criteria from Saturday through Sunday
morning. Strengthening low pressure will impact the coastal waters
on Sunday, with 25 to 30 kt gusts in the afternoon and overnight
over the ocean waters. Winds should remain below 25 kt from Monday
through Tuesday night.

Waves will continue to diminish Saturday falling below 5 ft by late
Saturday morning into the early afternoon. Waves then remain below 5
ft through Sunday morning as high pressure will be in control.
Thereafter, waves increase to 5 to 7 ft on the ocean waters through
Monday night, diminishing thereafter, as the storm pulls away. Waves
of less than 5 ft are expected Monday afternoon, and remain below 5
ft through Tuesday night.

&&

Hydrology...
no hydrological concerns are expected through Thursday. Liquid
equivalent amounts of 0.50"-075" are forecast from late Saturday
into late Sunday as an area of low pressure impacts the region.
There is some uncertainty with the amounts depending on the track
and intensity of the low.

&&

Equipment...
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) is operating
at reduced power until further notice.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory from 5 am Friday to 5 am EST Saturday for
anz335-338-345-355.
Gale Warning from 5 am Friday to midnight EST Friday night for
anz330-340-350-353.

&&

$$
Synopsis...MD/jp
near term...MD/jp
short term...Maryland
long term...jp

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