Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1034 PM EDT Thursday Sep 18 2014
a weak cold front moves through the region this evening. High
pressure builds in from the north tonight and Friday...then moves
off the northeast coast Friday night into Sunday. A cold front
will pass Sunday night. High pressure will then build in until
another front passes Tuesday night.
Near term /until 6 am Friday morning/...
surface high pressure continues to build north of the region into Quebec.
Light northerly winds on tap for the overnight...but some middle-
level clouds will inhibit optimal radiational cooling.
Min temperatures will drop into the middle/upper 50s in/around NYC and into
the 40s elsewhere. Temperatures will fluctuate depending on the cloud
Short term /6 am Friday morning through Saturday/...
upper ridge axis builds toward the northeast Friday morning and off
the coast Friday afternoon. The flow then become nearly zonal until
late Saturday as a weak shortwave begins to move out of the upper
Midwest. At the surface high pressure builds to the New England
coast by Friday afternoon then continues to track off shore Friday
night through Saturday. A northeast flow off the northern Atlantic
will keep temperatures down...below normal during Friday. Leaned
toward the cooler NAM guidance for highs. Mixing Friday and Saturday
will be limited to around 900 mb as strong subsidence remains across
the region. There may be some cloudiness Friday as some moisture
does get trapped under a surface inversion. Weak warm advection
begins to set up late Friday night and continues into Saturday...and
temperatures will begin to moderate.
For Friday...there will be a moderate risk of rip currents at
Atlantic Ocean facing beaches.
Long term /Saturday night through Thursday/...
the County Warning Area will be between low pressure over the ocean and an approaching
cold front Sat night into sun. This should keep the area dry. Warm aloft
but southerly flow at the surface should limit most places to the 70s to near
80. Without this onshore component...full mixing would produce
low-middle 80s. The timing of the front will be key to precipitation chances. The
NAM indicates a slower frontal passage...which is generally a preferred play
in the extended. All models indicate the precipitation should weaken as it
tracks eastward with the front overnight. Have hedged towards a slower
onset sun...but maintained chances through the night expecting the showers to
hold together at least with scattered coverage.
Hi pressure then builds in with fair weather Monday into Tuesday. The next cold front
late Tuesday/Tuesday night. Moisture is limited so kept a dry forecast. There
could be a few sprinkles out of high bases around 5k feet.
Mainly clear for the rest of the week with hipres building in.
The 1030s high builds over the region Wednesday night...so manually dropped
temperatures as guidance may be too influenced by climatology. Temperatures otherwise
a blend of the gmos25/mex/men through the extended.
Aviation /03z Friday through Tuesday/...
high pressure builds in through Friday. Mainly VFR conditions are
expected during the taf period. There are some indications of some
possible MVFR stratus Friday but there is much uncertainty...so
kept coverage to few-sct.
Variable direction to winds which are less than 10 knots. These
should all turn north/NE and then increase while gaining more of an
eastward component overnight and into Friday. Wind speeds will
increase to 10-15 knots with gusts up to near 20 knots.
For overnight and Friday...gust start and end time could vary by
Outlook for 18z Friday through Tuesday...
Sunday night-Monday...chance of MVFR or below with scattered
high pressure builds to the north. As the high builds in the
pressure gradient winds will increase from the northeast. Some
gusts on the ocean waters will be near small craft levels late
tonight and possibly into early Friday morning. In addition seas
on the ocean east of Fire Island Inlet may build to around 5 feet by
Friday morning. As the center of the high moves off the northeast
coast during Friday afternoon wind and seas are expected to
diminish. A Small Craft Advisory remains in effect for the ocean
waters east of Fire Island Inlet late tonight through Friday
Otherwise with high pressure over the waters wind and seas will be
below small craft levels Friday night through Saturday.
Marginal Small Craft Advisory winds possible on the ocean and S shore bays Sat evening
with southerly flow. Small Craft Advisory winds and seas develop behind a cold front Sun night
into Monday. The Harbor and western sound may remain just blw criteria. Chance
of Small Craft Advisory winds again behind another front Tuesday night into Wednesday.
no rainfall is expected through Saturday night. Basin average
rainfall of less the 1/4 inch expected Sun afternoon and night.
Marine...Small Craft Advisory from 4 am to 6 PM EDT Friday for anz350-