Scientific Forecaster Discussion
fxus61 kokx 221753
Area forecast discussion
National Weather Service New York New York
153 PM EDT sun Sep 22 2019
high pressure retreats offshore today ahead of a slowly
approaching cold front over the Great Lakes. The front passes
through the area Monday night, followed by high pressure
building in for the middle of the week. Another cold frontal
passage on Thursday will be followed by yet another large area
of high pressure for Friday into next weekend.
Near term /until 6 PM this evening/...
warm advection and clear skies continues to allow for
temperatures to rise more quickly than forecast, and
temperatures across northeastern New Jersey into the lower
Hudson Valley had to be raised as temperatures were in the
Deep-layered ridging along the eastern Seaboard works offshore
today with a gradually strengthening southerly flow and
increasing humidity. Additionally, there will be few to
scattered cu development this afternoon across the inland hills
due to the increasing low-level moisture and daytime heating.
There will also be a moderate rip current risk at the ocean
beaches into this evening.
Short term /6 PM this evening through Tuesday night/...
upper flow becomes more progressive this period as a short wave
trough moves across the Great Lakes tonight into Monday and
then into the northeast Monday night into Tuesday. Preceding the
feature will be a surface cold front and pre-frontal trough
that will bring showers and possibly a few thunderstorms to the
region late Monday afternoon and night. Instability remains
marginal at best, even with falling heights and increasing deep-
layered shear. The best chances for rain remains across Long
Island and Connecticut the first half of Monday night due to
increased availability of low-level moisture, and thus
instability. There is no severe weather threat at this time.
Rainfall amounts will generally be under a quarter inch with the
highest amounts to the east.
Highs and lows will remain warm for this time of year with lows
in the 60s tonight and highs in the low to mid 80s Monday.
Increasing southerly flow will likely limit patchy fog
development like recent nights. However, low clouds could be a
factor as higher dew point air traverses the cooler waters,
mainly across eastern Long Island and southeast CT. Model soundings, in
particular, the NAM are only hinting at it. Behind the front,
temperatures will return closer to normal Tuesday and Tuesday
night, but still a few degrees above normal.
Clouds will gradually increase from the west Monday afternoon
as a pre-frontal trough approaches. Southerly gusts up to 25 mph
will be possible in the afternoon. Winds will shift to the west-northwest
behind the cold front with gusts up to 20 mph on Tuesday.
There will be a high rip current risk at the ocean beaches for
Long term /Wednesday through Saturday/...
high pressure and dry conditions returning via mid level
confluence/low-level subsidence on Wednesday. A more significant
northern stream trough will push another cold front through on
Thursday, with another large surface high building in for
Saturday as heights rise aloft across the eastern states.
Temps will be above normal through the period, especially on
Thu ahead of the cold frontal passage, with highs mostly in the
Aviation /18z Sunday through Friday/...
high pressure over the western Atlantic will continue to slide
eastward. A cold front approaches late Monday.
SW flow this afternoon to near 10 kts for all terminals this
afternoon. NYC terminals may be slightly higher, closer to the
10-15 kt range. Some wind gusts up to 20 kt are expected for
this afternoon. Winds diminish tonight, however increase once
again on Monday, with gusts to near 20 kt.
Mainly VFR conditions are expected through the taf period. There
is a chance some fog returns to outlying terminals tonight if
Outlook for 18z Monday through Friday...
Monday...mainly VFR. Gusty SW winds.
Monday night...MVFR possible in showers and possible
Tuesday-Friday...mainly VFR. A slight chance of showers
a Small Craft Advisory remains in effect for the ocean waters Monday into Monday
A tightening pressure gradient between high pressure departing
into the western Atlantic and a cold front approaching from the
Great Lakes will result in a strengthening S/SW flow. Winds and
seas will gradually increase through tonight with Small Craft Advisory conditions
likely on the ocean waters on Monday.
An extended period of Small Craft Advisory conds is then possible for the ocean
waters even as winds diminish on Tue, especially out east, as
swells from ts Jerry begin to arrive.
rainfall Monday night will generally be less 1/4 inch with
localized higher amounts possible, especially across southeast CT and
eastern Long Island. Otherwise, no significant hydrologic
impacts expected through next week.
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) remains off
Marine...Small Craft Advisory from 6 am Monday to 6 am EDT Tuesday for