Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
633 PM EDT Tuesday Sep 30 2014
a series of upper level disturbances will move across the region
through middle week. High pressure will remain anchored over the
Canadian Maritimes Thursday and Friday. A cold front will pass on
Saturday...followed by potentially another frontal system during
the beginning of next week.
Near term /until 6 am Wednesday morning/...
have lowered probability of precipitation for the evening as precipitation is mainly
outside of the region...with one vorticity maximum east of Connecticut and
an upper low and vorticity maximum west...across central Pennsylvania.
A weak surface trough will remain in the vicinity through
tonight...also an upper level low will approach the region. As
this low approaches the area and interacts with the surface
trough...precipitation is expected to increase after
midnight...especially across Long Island and Connecticut. Probability of precipitation
will increase to likely across these areas. Further west...across
NYC...New Jersey and the lower Hudson Valley...probability of precipitation are not expected to be
as high...and will limit probability of precipitation to chance. 12z models are in good
agreement with the placement of the precipitation...however there
are some discrepancies with the amount of precipitation expected.
The NAM was an outlier with rainfall amounts coming close to or
exceeding an inch overnight across eastern sections of the County Warning Area.
Followed more of a GFS/sref/CMC blend with gave the eastern
sections around a quarter to half inch.
Otherwise...expect overcast skies and an easterly wind. Temperatures
overnight will fall into the 50s to near 60. Followed a mav/met
blend for lows.
Short term /6 am Wednesday morning through Wednesday night/...
rain continues Wednesday morning and early afternoon before
starting to slowly taper off Wednesday afternoon.
There is the potential for moderate to locally heavier rain
however there is some uncertainty as to where this occurs due to
its mesoscale nature. The 12z models hint that if this does
occur...with will be across the eastern sections of Long Island
Cloudy skies and an easterly-northeasterly flow of maritime air
will persist...with temperatures slightly below average on
Probability of precipitation continues to lower overnight...but lingering light showers
may persist over eastern areas...as upper level low closes off and
Long term /Thursday through Tuesday/...
not many significant changes made to the extended. Light rain chances
remain early Thursday with the backdoor cold front...then hi pressure is prognosticated
to keep the County Warning Area dry through Friday. The cold front passage and associated rainfall are
still lined up for Sat. The 12z GFS and European model (ecmwf) continue to support
this timing. Probability of precipitation remain likely. Trimmed back probability of precipitation Friday night as most
of the precipitation is targeted for Sat. Dry for sun with all of the
moisture shunted off into eastern Canada. High temperatures in the 60s still on
track. Models continue to suggest rain chances for the beginning of
next week with the upper trough approaching. Kept the timing in the
grids mainly Monday-Monday night closer to the more consistent GFS. The
European model (ecmwf) however is trending slower.
Aviation /00z Wednesday through Sunday/...
backdoor cold front will stay west of the region with a general east-NE
flow during taf period. Conditions varying from VFR to MVFR to
localized IFR. Not much in the way of further improvement expected
for the rest of the day. Conditions trend back down tonight with
more low stratus expected to move in across all terminals.
Rain activity...mainly east of city terminals and generally
light...becomes more steady later tonight and moderate to possibly
heavy Wednesday. There is a chance the rain could move as far as
west as city terminals...but confidence is lower with this so
excluded the mention of rain in tafs for city terminals and north
and west at the current time.
Fluctuations between MVFR and VFR and IFR and MVFR are possible
through the early evening.
New York metropolitan enhanced aviation weather support...
Detailed information...including hourly taf wind component forecasts
can be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)
Kjfk fcster comments: amendments possible. MVFR timing could be
off by 1-3 hours.
Klga fcster comments: amendments possible. Some occasional gusts
to 20 knots possible. MVFR timing could be off by 1-3 hours.
Kewr fcster comments: amendments possible. MVFR timing could be
off by 1-3 hours.
Kteb fcster comments: amendments possible. MVFR timing could be
off by 1-3 hours.
Khpn fcster comments: amendments possible. Improvement from IFR
could be off by 1-3 hours.
Kisp fcster comments: amendments possible. Improvement from IFR
could be off by 1-3 hours.
Outlook for 18z Wednesday through Sunday...
Wednesday-Wednesday night...MVFR to IFR ceilings/visibilities in rain. East-NE winds 10-15
with g 20 knots along the coast.
Thursday...chance MVFR mainly am. NE winds around 10 knots.
Friday...VFR. Southeast-S winds around 10 knots.
Sat...rain likely - MVFR or lower at times. Southeast wind 10-15g20 knots.
a strong east to northeast flow of 15 to 20 knots has allowed seas on
the ocean waters to build to around 4 feet this evening...so have
increased seas. Otherwise the forecast is on track.
The easterly flow will become north to northeasterly tonight and
continue through Wednesday night...as the area waters remain
between high pressure to the north and an offshore low. This will
result in an extended period of small craft conditions on the
ocean waters. Winds will gust to near 25 knots and seas will build to
4 to 7 feet on the ocean waters. Will extend the Small Craft
Advisory through Wednesday night.
On the ocean...Small Craft Advisory seas likely Thursday-Thursday night. They may fall blw 5ft by
Friday...but will once again ramp up through the weekend.
Elsewhere...winds will be close to Small Craft Advisory levels Thursday...but should remain
blw Friday. Small Craft Advisory winds likely Sat and sun. Small Craft Advisory conditions possible all waters
again on Monday ahead of the next system.
no significant rainfall is expected across NYC...northeastern
New Jersey...and the lower Hudson Valley. Rainfall across Long Island and
Connecticut will range from a quarter of an inch across western
portions to near 1 inch across the far eastern portions. No
hydrologic issues are anticipated.
A few hundredths of rain possible Thursday. Around an inch of rain
possible on Sat.
Marine...Small Craft Advisory from 11 PM this evening to 6 am EDT
Thursday for anz350-353-355.