Scientific Forecaster Discussion
fxus61 kokx 220526
Area forecast discussion
National Weather Service New York New York
1226 am EST Fri Nov 22 2019
high pressure shifts offshore overnight 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 this morning/...
updated current obs to reflect ongoing warming trends.
Do not foresee any rain reaching the ground as the evening
soundings looks quite dry. At most, a passing sprinkle is
possible as weak mid level shortwave, positive vorticity advection passes.
Short term /6 am this morning through 6 PM Saturday/...
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 night 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 /06z Friday through Tuesday/...
a cold front approaches this morning, and passes across the area
VFR conditions are expected this morning. Brief MVFR conditions are
possible in showers, generally during the 16-20z timeframe, west to
Thereafter, VFR again as skies clear.
Southwest winds increase this morning, and gusts become more
frequent late this morning, 14-16z. Winds veer to the west briefly,
then west/northwest after 18-20z. Gusts of 20-30 kt are expected
late this afternoon, and gusts diminish some during the evening
Outlook for 06z Saturday through Tuesday...
late tonight...VFR with diminishing northwest winds.
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.
initially light winds and sub-Small Craft Advisory conditions 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.
no hydrological concerns are expected through Saturday. 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.
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) is operating
at reduced power until further notice.
Marine...Small Craft Advisory from 5 am early this morning to 5 am EST
Saturday for anz335-338-345-355.
Gale Warning from 5 am early this morning to midnight EST
tonight for anz330-340-350-353.