Scientific Forecaster Discussion
fxus61 kokx 131952
Area forecast discussion
National Weather Service New York New York
352 PM EDT sun Oct 13 2019
weak low pressure passes just to our southeast tonight,
followed by building high pressure Monday into Tuesday.
Low pressure and a cold front will affect the region Wednesday
and Wednesday night. The low moves to the northeast Thursday as
high pressure begins to build to the southwest. High pressure
will then dominate Friday into next weekend.
Near term /until 6 PM this evening/...
increasing cyclonic flow aloft along with a southern stream jet
streak passing just off to our southeast tonight will help develop a weak
surface low. The center of this low should remain offshore, but
will be close enough to bring chances of rainfall mainly east
of NYC, but still at least a slight chance in the vicinity of
the city. Any accumulations would be light.
Short term /6 PM this evening through Tuesday/...
there will be a chance of lingering rain during the first half
of Monday morning over Li and southeast CT. Otherwise, dry weather and
diminishing clouds on Monday with highs above normal across the
tri-state area. The flow aloft Monday night through Tuesday
becomes more zonal and surface high shifts towards US through
the period with its axis moving offshore Tuesday afternoon.
Rain-free conditions therefore continue, and temperatures will
return closer to seasonable levels.
Long term /Tuesday night through Sunday/...
a progressive northern stream will dominate the weather through the
long term period with a relatively amplified pattern.
The beginning of the long term will be tranquil as ridging moves
into the western Atlantic and a significant shortwave amplifies into
the Great Lakes region. The forecast as been consistent, and
confidence increasing, for a deep coastal low to develop Wednesday
afternoon and the upper trough closes off and becomes negative. An
impulse moving into the base of the trough emerges off the mid
Atlantic late Wednesday with a coastal low expected to develop along
the cold front, and along a thermal ridge, and quickly deepen
Wednesday night. There will be a lot of lift with the low along with
elevated instability and elevated cape. Precipitable water vales
quickly increase to 1 1/2 inches during this time. A brief period of
moderate to heavy rainfall is likely late Wednesday afternoon into
the evening with embedded convective elements in the rain. A rumble
of thunder is a possibility at that time as well. There is also a
flood threat. See the hydrology section for details. The low tracks
quickly along the New England coast Wednesday night and
precipitation then ends. With wrap around moisture Thursday, and
some energy rotating around the west side of the upper low, there is
a slight chance of a few showers across the far interior zones
Temperatures Tuesday night will not be diurnal as strong warm
advection develops. Lows will most likely occur Tuesday evening,
then temperatures will rise through the night, especially across the
Strong and gusty westerly winds develop behind the low Thursday,
mainly near the coast. Winds and gusts are expected to remain below
advisory levels at this time.
Tranquil weather returns as an amplified ridge builds into the area
Thursday night through the upcoming weekend. Next weekend
temperatures are likely to be above normal.
Aviation /20z Sunday through Friday/...
weak high pressure moves east tonight. A wave of low pressure passes
south of Long Island tonight, with a cold front moving through
VFR through evening push. MVFR or even IFR is possible in
developing stratus late tonight into Monday morning push. Rain
chances will be confined to eastern terminals and off the coast.
Light S/southeast seabreeze development evident on radar, working north
through coastal terminals through late afternoon. Winds become light
and variable winds tonight into morning push, becoming SW Mon
Outlook for 18z Monday through Friday...
Wednesday...MVFR/IFR likely developing in rain. Chc southeast gusts
Thursday...VFR. Northwest gusts around 35kt.
Friday...VFR. Northwest winds, diminishing gusts.
a weak pressure gradient will prevail over the waters through
Tuesday. Sustained winds for much of this period are expected to be
at 10 kt or less, but may briefly approach 15 kt Monday night. Seas
should remain below 5 ft.
High pressure over the forecast waters Tuesday moves offshore
through Tuesday night as a deepening low, and associated cold front,
approaches from the Great Lakes. A coastal low is expected to
develop south of Long Island Wednesday afternoon and track along the
New England coast Wednesday night.
Conditions will be sub Small Craft Advisory levels Tuesday into Wednesday morning.
Wednesday afternoon Small Craft Advisory conditions develop. Wind gusts increase
Wednesday night into Thursday as the low moves away and a strong
west to northwest flow develops. Gale force gusts are likely
Wednesday night on the ocean waters, and across all the forecast
waters Thursday, possibly into early Thursday evening.
Winds subside Thursday night into Friday, along with ocean seas.
no hydrologic impacts for any rainfall that occurs tonight into early
A significant rainfall of 1 1/2 to 2 inches is likely Wednesday and
Wednesday night, with locally higher amounts possible. The bulk of
the rainfall is currently expected Wednesday afternoon into
Wednesday evening. Urban, poor drainage, and low lying flooding is a
significant threat. There is a possibility of flash flooding with a
few of the smaller, and fast responding, rivers and streams
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) remains off the