Scientific Forecaster Discussion
fxus61 kokx 161652
Area forecast discussion
National Weather Service New York New York
1252 PM EDT Wed Oct 16 2019
a strong frontal system will approach today as a low pressure
develops just off the mid Atlantic coast. This low will track
just across Long Island and Connecticut tonight and continue
northeast Thursday. Meanwhile, high pressure will build to the
west and move over the region Friday, remaining through the
weekend. Another frontal system affects the region Sunday night
Near term /through tonight/...
strong upper jet dynamics noted on latest water vapor imagery
with transverse banding across the eastern Great Lakes.
Leading edge of rain working across eastern PA and does remain
on track to work into western portions between 2 and 4 PM.
Conditions will gradually deteriorate form west to east this
afternoon as an amplifying northern stream trough interacts
with southern stream energy. This will cause rapid development
of low pressure along the mid-Atlantic coast. Strong upper
dynamics aided by the negatively tilted trough, upper jet exit
and entrance regions and thermal forcing will result in the
potential for several inches of rainfall as the secondary low
develops. Widespread moderate to locally heavy rain will produce
a general 1 to 3 inches, with the potential for higher amounts
in any convectively enhanced bands. Much of this rain will fall
in a 6 to 9 hour period from late afternoon/early evening to
around midnight. If higher amounts materialize, there could be
localized flooding, however the probability remains low with the
exception for NE New Jersey where a Flash Flood Watch remains in effect
based on 6 hour gridded ffg.
Ahead of the low, a period of east/southeast winds 15 to 20 mph with gusts up
to 30 mph are likely. Then as the secondary low deepens, the
pressure gradient between the two systems will result in stronger
northwest winds developing overnight especially across the coast.
After collaboration with neighboring offices, have issued a Wind
Advisory for eastern Suffolk County and southern New London
beginning tonight just ahead of the low where winds will be
Highs will be in the 60s today and in the upper 40s to 50 degrees
Short term /Thursday/...
as the low pulls away into Maine on Thursday, strong cyclonic
flow and cold pool instability could result in a few showers
lingering through the afternoon and a mostly cloudy sky.
Strong, gusty winds will prevail on Thursday and it is possible that
wind headlines may be needed with later forecasts. Strongest
winds will be across the far eastern zones where the best mixing
and low level winds will be.
High temperatures on Thursday will be in the 50s to around 60.
Long term /Thursday night through Tuesday/...
upper level low will be northeast of the region for Thursday
night. The upper level jet streak SW to NE will be located from
southeast US to Nova Scotia.
Expecting rising heights thereafter through Saturday as upper
level low moves farther away into the Canadian Maritimes and an
upper level ridge moves in from the west for the local region.
The upper level ridge axis moves east of the region Saturday night
and will then begin getting amplified Sunday into early next week
along the eastern Seaboard. The next jet streak moves in towards
the middle of next week.
At the surface, the surface low will move into the Canadian
Maritimes while weakening for Thursday night into Friday. High
pressure then builds in from the west for much of the upcoming
weekend. High pressure will be moving offshore Saturday night
into Sunday and will be slow to move eastward. High pressure
gets reinforced offshore for early next week. The next storm
system approaching from the west will start to move in by Monday
night and continue moving in through Tuesday.
No significant changes were made compared to the last long term
forecast. 12z to 00z model trends comparing the ECMWF, GFS, and
Canadian trended a little slower with the next low pressure
system and its associated rain for early next week. The timing
of the next system seems to be more focused in the Tuesday into
Tuesday night timeframe so increased pops to better reflect that
Temperatures forecast trend warmer from Friday into the weekend.
Below normal high temperatures forecast for Friday (mid 50s to
near 60), near normal highs for Saturday (mainly lower 60s) and
above normal for highs on Sunday (mid to upper 60s). Then,
slightly warmer highs for forecast for early next week compared
Aviation /18z Wednesday through Monday/...
***high impact rain and wind event from late this afternoon into
High pressure will build offshore today as intensifying low
pressure approaches the west. The low will move across tonight.
Clouds will gradually lower and thicken through the day
today. Some MVFR cigs could precede the rain during the morning
and early afternoon at the NYC metros, then rain and MVFR/IFR
conditions should quickly develop after 18z. Rain will be heavy
at times. Rain tapers off after 4-6z but MVFR cigs around 3000
ft may remain through the remainder of the taf period.
Southeast winds will increase today, with gusts at or above 30 kt
likely by late evening/tonight. Direction will vary as the low
tracks over and through the area. Winds become westerly behind
the system late tonight, and remain so through Thu.
Outlook for 12z Thursday through Sunday...
Thursday...possible MVFR with showers. West winds g30-40kt.
Friday...VFR. Northwest winds g20-25kt.
a strong system will approach the waters on Wednesday with a coastal
low developing across the waters late in the afternoon/early
evening. This will bring Small Craft Advisory conditions to the area during the day
on Wednesday with southeast gusts 25-30 kt. As the low pulls away Wednesday
night and Thursday westerly gales will bring gusts up to 40 kt.
A Gale Warning continues Thursday for all waters. Gale force gusts
may continue into Thursday evening on the non ocean waters and into
late Thursday night on ocean waters. With some uncertainty regarding
the diminishing time of the gusts, the Gale Warning has not been
extended at this time.
Sca wind gusts still forecast to continue through Friday and
into Friday night, mainly for the ocean. Ocean seas are also
expected to be below Small Craft Advisory levels by Friday night. Non-ocean
Friday night expected to remain below Small Craft Advisory.
Tranquil conditions forecast for the waters for the weekend into
the beginning of next week.
a significant rainfall of 1-3 inches is likely Wednesday afternoon
into Wednesday night, with localized swaths of 2-4 inches possible.
The bulk of the rainfall is expected in a 6-9 hr period late
Wednesday afternoon through Wednesday evening.
Urban, poor drainage, and low lying flooding is expected. There is a
low probability of flash flooding along a few of the fast responding
small rivers and streams in NE New Jersey and the lower Hudson Valley if the
higher rainfall amounts are realized.
Additionally, localized flash flooding will also be an issue for
coastal roads if heaviest rain coincides with the Wed night high
the east fetch across the waters will allow for the piling of
water today into tonight, especially across western Long Island
Sound. The winds increase today into tonight and eventually
become more westerly late tonight.
Highest astronomical tide is this morning. Some isolated minor
coastal flooding will be possible across the South Shore back bays
and western Long Island Sound along the Westchester and SW
Connecticut shorelines. Water levels this morning are about 1.5
to 2 ft above astronomical. Coastal flood statement issued as a
High tide cycles are between 9am and 12pm across the South Shore
back bays and between 12pm and 3pm across the western Long Island
For tonight, astronomical tide is lower. However, the surge will be
quite more than this morning so the water levels are expected to be
about 2.5 to 3 ft above astronomical, allowing for widespread minor
coastal flooding for much of Long Island shorelines as well as
Westchester shoreline and SW Connecticut shorelines along the
western Long Island Sound. Coastal flood advisories were issued as
a result. Other coastal areas are expected to just touch minor
coastal flood benchmarks and will be more isolated where coastal
flood statements were issued. Battery New York expected to stay below
minor coastal flood benchmark.
High tide cycles tonight run between 9pm to 12am for South Shore
bays, and around 11pm to 3am for western Li sound, Long Island
shorelines, and southeast Connecticut.
Additionally, if the heaviest rain coincides with the high tide
tonight, more widespread flooding could be experienced than would
normally be expected.
With gusty westerly and mainly offshore flow on Thursday, for the
next high tide cycle for Thursday morning, no coastal flooding is
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) remains off the
CT...coastal flood advisory from midnight tonight to 4 am EDT
Thursday for ctz009-010.
Wind Advisory from 10 PM this evening to 6 PM EDT Thursday for
New York...coastal flood advisory from midnight tonight to 4 am EDT
Thursday for nyz071.
Coastal flood advisory from 10 PM this evening to 4 am EDT
Thursday for nyz078>081.
Coastal flood advisory from 9 PM this evening to 1 am EDT
Thursday for nyz178-179.
Wind Advisory from 10 PM this evening to 6 PM EDT Thursday for
New Jersey...Flash Flood Watch from 4 PM EDT this afternoon through late
tonight for njz002-004-006-103>108.
Marine...Small Craft Advisory until 6 PM EDT this evening for anz330-
Gale Warning from 6 PM this evening to 6 PM EDT Thursday for