Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
356 PM EDT Sat Oct 22 2016
deepening low pressure moves through Maine and southeastern
Canada through Sunday. Another cold front associated with the low
moves through the area late Sunday night into early Monday
morning. Canadian high pressure builds behind the front Monday
through Wednesday. Low pressure approaches and moves across the
area Thursday into Friday.
Near term /until 6 am Sunday morning/...
deepening low pressure will continue to move north through Maine
and into southeastern Canada tonight, reaching as low as 978 mb by
Sunday morning. The low was making little eastward progress as a
result of a full latitude, closed off, and negatively tilted
upper trough. Deep layered moisture was wrapped around the low
and with vort maxes rotating through the trough areas of light
rain continues. Expected rain to end around 06z as the last of the
vorts rotates through the trough. Weak cold advection also
continues and with low level winds to around 50 kts some of these
winds were mixing to the surface. With cloud cover and
precipitation mixing was limited. With the best mixing through
this evening there is still the potential for gusts and perhaps
some sustained winds to reach Wind Advisory criteria. Have ended
the advisory at 04z for Nassau County and the NYC zones at 04z,
and continue through 10z for the remainder of the zones that were
in the advisory.
Short term /6 am Sunday morning through Sunday night/...
Sunday is expected to be dry with the upper trough remaining and
the upper low beginning to cut off. Gusty winds remain however low
level winds will be diminishing and cold advection shuts off 09z
to 12z and weak warm advection starts. Winds early in the morning
will be the strongest and an occasional gust may approach 45 miles per hour
across the eastern zones before winds diminish.
A northern stream shortwave moves quickly through the northern
tier of the United States and moves into the upper trough Sunday
evening. A re enforcing cold front and the shortwave then move
through 06z to 12z Monday with a chance of showers. With minimal
lift will have only chance probabilities.
Long term /Monday through Saturday/...
upper trough remains across the northeastern portion of the country
early to mid week, as ridge to the west eventually flattens per
global models. Differences arrive with handling of shortwave that
develops across the upper mid west as it traverses east late in the
At the surface, low pressure associated with lingering upper trough
moves slowly across eastern Canada, as high pressure builds out of
central Canada and into the Great Lakes region through mid week. The
high briefly slides across the area Thursday before giving way to
low pressure Thursday and Friday. Frontal boundaries, first warm
front followed by the cold front, impact the area from late
Thursday, into Friday. For Saturday, forecast becomes less clear. A
possible weak frontal boundary may move through Saturday, but
confidence in this remains low at this time.
Generally dry conditions are anticipated Monday through Wednesday
night as initial shortwave and front clears the area, and high
pressure slowly builds. Cyclonic flow could result in more cloud
cover each day, especially into New England Tuesday and possibly
The best chance for rain looks to be late Thursday, Thursday night
into Friday. European model (ecmwf) slower with upstream system compared to usually
Temperatures will initially average right around normal Monday. Then
cooler Canadian air settles in and expect readings to remain below
normal Tuesday and Wednesday.
Temperatures slowly moderate closer to normal Thursday through
Aviation /20z Saturday through Thursday/...
low pressure moves into northern New England and southeast Canada
through Sunday with high pressure building to the southwest.
West-northwest winds winds becoming 20-25 kt with gusts around 35 kt through
early this evening. An occasional gust up to 40 kt is possible,
especially near the coast. Gusty west-northwest winds will continue tonight
into Sunday. Strongest gusts may decrease a bit after 04z to around
25 to 30 kt before increasing again during the day Sunday with peak
gusts up to 35 kt.
Flight categories continue improving to VFR, but there is a chance
for brief ceilings around 030 at city terminals through around 21z.
Kgon will be the last terminal to see improvement late this
afternoon. -Ra remains possible, especially across eastern terminals.
Outlook for 18z Sunday through Thursday...
Sunday...VFR. West-northwest winds g25-35 kt.
Sunday night-Monday morning...mainly VFR, northwest winds g20-25 kt
possible early. Chance of showers after midnight.
Monday afternoon-Tuesday...VFR, northwest winds g20-25 kt.
deepening low pressure continues to track slowly to the north from
the coast of Maine into southeastern Canada through Sunday night.
Winds and gusts have increased across the forecast waters with
gale conditions, in gusts, this afternoon. As the low continues to
deepen into Sunday morning, and with cold advection into Sunday
morning, gale conditions will continue. The winds and gusts will
begin to gradually diminish late Sunday morning into Sunday
afternoon. Gale conditions may end by Sunday afternoon across New York
Harbor and the western Long Island Sound. Will leave Gale Warning
posted across all the forecast waters through Sunday.
Gusty northwest winds 25-30 kt are likely Monday through Tuesday as the
pressure gradient remains rather tight. Winds and seas are forecast
to decrease on Wednesday and into Thursday as high pressure builds.
up to an additional tenth of an inch of rainfall is possible
across the region through this evening. Dry late tonight through
Sunday evening. Sunday night around a tenth of an inch of rainfall
Rainfall amounts of 1/2 inch or more are possible Thursday into
Friday. No hydrologic impacts are anticipated.
CT...Wind Advisory until 6 am EDT Sunday for ctz007-008-011-012.
New York...Wind Advisory until 6 am EDT Sunday for nyz078>081.
Wind Advisory until midnight EDT tonight for nyz072>075-
Marine...Gale Warning until 6 PM EDT Sunday for anz330-335-338-340-345-
long term...precipitable water