Scientific Forecaster Discussion
fxus61 kokx 152009
Area forecast discussion
National Weather Service New York New York
409 PM EDT Sat Jun 15 2019
a weakening cold front will approach from the Great Lakes tonight
and then passes through the area late Sunday afternoon into the
evening. The front remains close to the region through much of
the upcoming week. Several waves of low pressure may move long
the front, bringing periods of unsettled weather.
Near term /until 6 am Sunday morning/...
a weakening cold front will approach front the eastern Great
Lakes tonight. At the same time, a convectively induced vort
over the mid Mississippi Valley will track NE into the Ohio
Valley tonight, sending a frontal wave northeast into western
sections of PA/New York by daybreak. Warm advection showers ahead of
the system could develop as early as this evening north and west
of NYC, but are more likely after midnight, gradually dropping
south and east. It is quite likely coastal sections stay dry
through the night.
Gusty S-SW winds up to 30 mph will begin to gradually diminish
after dark, strongest along the coast.
Overnight lows will be in the 60s with increasing humidity.
Readings will be about 5 degrees above normal.
There is high risk of rip current development through this
Short term /6 am Sunday morning through Sunday night/...
frontal wave passes near or just north of the lower Hudson
Valley during the late morning and early afternoon hours. The
steadiest rain will be near or just north of the low track, with
the potential for up to a half inch, lesser amounts to the
south and east. Showers may more or less be scattered near the
coast if not remaining dry during the morning/early afternoon
hour. The best chance for coastal sections will be in the
late afternoon/early evening as the trailing cold front works
south and east across the area. There is good model agreement
with the front passing south of Long Island during the evening
The instability and shear are limited, so for the most part only
expecting showers with perhaps an isolated thunderstorm. Should
more heating be realized, a few strong storms are not out of
the question, especially west of the NYC Metro late in the day.
Gusty south winds on Sunday will be mainly confined to the coast
with gusts up to 25 mph.
Highs will be nearly seasonable tomorrow in the 70s with above
normal lows in the 60s. It will be more humid with dew points
in the 60s.
There is a high risk of rip current development on Sunday.
Long term /Monday through Saturday/...
the main story of the long term continues to surround a nearly
stationary frontal boundary that will bring periods of unsettled
weather. Confidence in the timing, duration, and any impacts from
showers and possible storms still remains low, especially from
Monday night through the end of the week.
The flow around the base of an upper low/trough across southeast
Canada will send several shortwaves/disturbance across the tri-
state, but the timing of these is still not well resolved by the 12z
model guidance. These shortwaves in the flow are likely convectively
induced and are difficult for models to resolve past 48 hours.
Another factor of uncertainty is how much if any of these waves
force the frontal boundary further south causing lower precipitation
The model guidance over the last 24 hours has trended towards dry
conditions on Monday as a wave that passes on Sunday forces the
frontal boundary south. Have trended pops down significantly from
the previous forecast for Monday with a chance the daytime remains
The next potential shortwave and frontal wave may occur Monday night
into Tuesday. The European model (ecmwf) and NAM are further north and a bit stronger
with this feature compared to the GFS which is further south and
weaker. Due to these model differences and uncertainty in the
strength, placement, and timing of this feature, have capped pops at
50 percent through Tuesday. Instability looks weak, but have
included mention of a slight chance of thunder.
Another possible shortwave and frontal wave may occur on Wednesday.
However, the European model (ecmwf) is much flatter and weaker compared to the GFS.
Interestingly, the deterministic models are progging a more well
defined shortwave trough and frontal wave for late Thursday into
potentially Friday. This shortwave could leave behind ridging into
early next weekend. Will continue to show chance pops for mainly
showers during much of this time period due to recent model
performance in this pattern.
Temperatures through the long term will average near to slightly
Aviation /20z Saturday through Thursday/...
high pressure centered off the southeastern coast will move into the
western Atlantic through Sunday morning. A cold front will slowly
approach from the northwest, moving into the lower Hudson Valley
VFR. Showers will become likely across the lower Hudson Valley
Sunday morning, with the potential for MVFR conditions toward
Southerly winds of 15 to 20 kt for most terminals will continue into
early this evening, with the other terminals near 15 kt. Winds will
be gusty, mainly at 20 to 25 kt, with higher gusts, up to 30 kt, at
the New York City area terminals and along coastal Long Island.
Gusts subside early this evening, with the winds also diminishing,
10 to 12 kt in the NYC Metro area and under 10 kt at the outlying
terminals. Winds become SW 10 to 15 kt Sunday.
Outlook for 18z Sunday through Thursday...
Sun afternoon-Sun night...mainly VFR. Showers likely north and
west of the NYC terminals, with a chance of showers and
isolated thunderstorms across the remainder of the region. Local
MVFR conditions possible in the showers.
Mon-Thu...there will be chances for showers and isolated
thunderstorms each day, with the better chances Tue and Wed.
VFR, becoming MVFR Monday night. IFR possible Tue and Wed.
a strong southerly flow across the waters will begin to
gradually relax this evening with sub-Small Craft Advisory conditions developing
for all by the ocean waters by midnight. Marginal wind gusts
and elevated seas will continue on the ocean through Sunday
evening until a cold frontal passage.
A frontal boundary will remain stalled near the waters through
Thursday with a relatively weak pressure gradient. Waves of low
pressure will move along this front, but their timing and
placement is uncertain. One of these waves could increase winds
on the waters, but overall conditions will stay below Small Craft Advisory levels
a frontal boundary approaches on Sunday and then stalls over
the region through much of next week. The best chance of rain
will be across the lower Hudson Valley and interior southern CT
with up to a half an inch.
Waves of low pressure moving along a nearly stationary frontal
boundary this week could produce periods of moderate to heavy
downpours. The timing, amounts, and any hydrologic impacts remain
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) remains off
New York...high rip current risk until 9 PM EDT this evening for nyz075-
Marine...Small Craft Advisory until midnight EDT tonight for anz330-335-
Small Craft Advisory until midnight EDT Sunday night for