Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1021 am EST Sat Nov 28 2015
a cold front will move south of the area this afternoon....and
then slowly towards the middle- Atlantic through tonight. The front
will further slow down on Sunday. By Sunday night...the next
strong area of high pressure will build in from the north and
east. This will continue to build in through Monday. A low
pressure system will impact the region Tuesday into the middle of
the week. High pressure returns for the end of the week.
Near term /until 6 PM this evening/...
a broad trough gradually sinking into the northeast is helping
push a cold front south through the region this morning.
Scattered Post frontal light rain activity across New
England...now entering northern portions of tri-state...will
continuing to sink south across the entire region through the
afternoon. Rain will be light and intermittent.
Behind the front. Despite cloud cover and spotty rain...the mild
start and weak cold air advection will allow temperatures to continue above seasonable
today. Generally running in the Lower/Middle 50s across interior to
around 60 for city/coast.
Short term /6 PM this evening through Monday night/...
behind the cold front...high pressure will be slow to move in with
the cold front slowly moving south of Long Island. Zonal jet
remains aloft with another jet streak moving in on Sunday and at
the surface there will be a weak wave of low pressure moving along
the cold front but to the south of the area. Therefore...showers
will remain in the forecast tonight into early Sunday before
drying out thereafter.
The jet weakens Sunday night into Monday and is suppressed with
its southern branch to the southwest of the region. The left front
quadrant of this jet moves in Tuesday into Wednesday. Another area of
high pressure at the surface builds in from the north and east
Sunday night through Monday before moving southeast of Nova Scotia
into Tuesday. Dry weather prevails Sunday night through Monday. There
will then be some warm air advection aloft with a warm front
approaching. Dry weather remains Monday night but there will be a
low chance of precipitation going into early Tuesday which for
interior areas blocked from the relatively warmer southeast
flow...could present some possible sleet or freezing rain with
plain rain closer to the coast.
Temperatures through the period will be on a gradual decline as
the air mass transitions to a cool maritime type of air mass with
cold air advection increasing Sunday and more onshore flow for
Long term /Tuesday through Friday/...
a warm front approaches on Tuesday...pushing north of the region
into Tuesday night as low pressure over the middle of the country
moves into the western Great Lakes region and becomes vertically
stacked. A weak low pressure area develops along the warm front
Tuesday night into Wednesday. There may be a round of some
moderate precipitation depending on the track of this low.
Associated cold front approaches and moves through Wednesday. There
are some timing differences between the 00z European model (ecmwf)...12z GFS...and
12z CMC. The GFS is more progressive while the European model (ecmwf) is about 6
hours behind. However...the new 12z European model (ecmwf) is now very similar to the
12z CMC...developing a weak low pressure along the cold front over
Maryland...then heading northeast and tracking in the vicinity of
the tri-state Wednesday night into Thursday. Although this low is
weak...it could spell out more in the way of quantitative precipitation forecast if it verifies.
High pressure builds in through the end of the week with a return to
Temperatures will warm into the 50s for a majority of the area on
Wednesday in association with warm air advection with the warm front...then will
come back down to near normal behind the cold front for the end of
Aviation /15z Saturday through Wednesday/...
cold front will be south of the NYC/Li terminals by 16z with winds
shifting around to the northwest.
VFR conds to start...then MVFR ceilings should develop by early
afternoon...but as early as 15z at kswf. Some Post-frontal light
rain is also possible throughout this afternoon...then mainly
across NYC metropolitan and Long Island this evening. MVFR ceilings likely to
persist through much of the night even as rain ends.
Northwest under 10 knots this morning after frontal passage...veer north this afternoon.
Outlook for 12z Sunday through Wednesday...
Sunday...MVFR ceilings in the morning...otherwise VFR.
Tuesday...rain/fog with IFR conds. Precipitation could begin at kswf as
Wednesday...MVFR or IFR conds possible in the morning...with
swells at the ocean buoys are at 5-6 feet...with wavewatch holding
onto 5-feet swells through about midnight tonight...and 06z nwps
into Sunday morning. Will continue to split the difference...and
continue Small Craft Advisory for hazardous seas through tonight.
Next chance of Small Craft Advisory conds will come Sunday night-Mon...as strong high
pressure building from Ontario and Quebec tightens the pressure
gradient...with gusts up to 25 knots and seas building to 5-7 feet on the
ocean waters. Sub-Small Craft Advisory conds will follow for Monday night-Tuesday as the
high builds into New England.
Small Craft Advisory conds are also possible on the ocean Tuesday night into Wednesday night
with the approach and passage of a frontal system.
rainfall amounts through tonight will be light and less than a
tenth of an inch.
Low pressure could bring about 1/2 to 3/4 inch of rain Tuesday into
Marine...Small Craft Advisory for hazardous seas until 6 am EST Sunday