Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service New York New York
208 PM EDT Tuesday Aug 4 2015
a cold front will slowly pass through the region tonight...pushing
offshore early Wednesday. Weak high pressure builds into the area
on Thursday. Several waves of low pressure may impact the area
Friday into Saturday. High pressure returns for the second half of
Near term /through tonight/...
thunderstorms firing north of the County Warning Area where there is some upper support. Across
the County Warning Area...subsidence limiting initiation. Laps at 17z has about
3000 j/kg SBCAPE on Li...with about 1500-2000 elsewhere. Cin is
small to none. Cumulus field continues to expand on satellite. Outside the
office...not much vertical extent yet. Any focus in this MDT-high
cape environment could allow isolated cells to Blossom. With 40-50kt
0-6km shear...severe potential with any thunderstorms. As a
result...maintained isolated thunderstorms in the forecast through early this evening.
By the time there is a little middle level lift tonight...the area is
mainly stable and capped. Exception is extreme eastern Li per the NAM
where the chance for isolated thunderstorm development lingers later into the
Temperatures through the afternoon on track...with kewr to hit 90 for the 8th
day in a row. For tonight...a blend of guidance was used...but
limited the radiational cooling signature across The Pine Barrens
of Li with the boundary in the vicinity.
High risk for rips continues today with many reports of dangerous
rips. A rip current statement is in effect.
Short term /Wednesday through Wednesday night/...
upper jet dives into the area by afternoon. Despite limited
instability...the NAM is picking up on scattered-isolated convection into
the early evening. The GFS is dry. Lapse rates are slightly steeper in
the NAM...with around 8c between h85-h7. The GFS is around 7c in
the same layer. With the approaching cold pool aloft...jet and
warm SST/S...did not discount the NAM and have therefore included
20 probability of precipitation for diurnal activity. Isolated lightning strikes today in vicinity of
lakes Huron and Ontario lend some support to thunderstorms chances. Temperatures a
blend of the guidance which was in good agreement.
Long term /Thursday through Tuesday/...
upper level trough lifts into southeast Canada on Thursday with
weak ridging at the surface and aloft. Upper level
vorticity/energy currently over The Rockies will slowly slide east
into the Ohio Valley by Thursday. The strength of this energy will
be key to the development and track of low pressure across the
middle-Atlantic and northeast Thursday night into Saturday.
The latest 00z models offer slightly more confidence that there will
be low pressure impacting the area sometime on Friday into at least
the first portion of Saturday. The details are still very much in
question...but a widespread significant rainfall is possible Friday
into Saturday morning.
The 00z GFS is the flatest and slowest as it does not really develop
the low until Friday night as a second piece of energy amplifies
behind the main one. The 00z European model (ecmwf) is the strongest with this energy
and develops the low across the middle Atlantic on Friday and moves it
just south and east of Long Island into Saturday morning. The 00z
gefs are a bit faster...with the mean low track and timing similar
to the 00z European model (ecmwf).
Have continued with likely probability of precipitation on Friday...and have increased probability of precipitation
to likely Friday night. Probability of precipitation then decrease to chance during the day
on Saturday. As timing becomes clearer...expect adjustments to the
timing of probability of precipitation.
The low lifts northeast of the area Saturday night into Sunday
morning with weak high pressure returning on Sunday with dry
Temperatures will be near to slightly below seasonable levels during
the period. Friday and Saturday will likely be the coolest as
temperatures struggle to get out of the 70s.
Aviation /18z Tuesday through Sunday/...
a cold front will move east across the area tonight followed by high
pressure on Wednesday.
VFR weather conditions will prevail through Wednesday.
Chance of isolated thunderstorms with strong wind gusts...mainly east of NYC
Sea breezes will increase SW winds to around 15 knots with gusts to 25 knots
until sunset across Atlantic coastal terminals including kjfk. Winds
become light and variable after sunset then shift from the west around 10
knots on Wednesday.
..NY 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 may be needed for isolated thunderstorms
Klga fcster comments: amendments may be needed for isolated thunderstorms
Kewr fcster comments: amendments may be needed for isolated thunderstorms
Kteb fcster comments: amendments may be needed for isolated thunderstorms
Khpn fcster comments: amendments may be needed for isolated thunderstorms
Kisp fcster comments: amendments may be needed for isolated thunderstorms
Outlook for 18z Wednesday through sun...
Wednesday aftn-Thu...VFR. Generally west flow.
Friday...chance MVFR or lower in rain. Winds becoming NE.
Sat...chance of MVFR or lower possible in rain. NE winds.
seas still in the 5-6ft range this afternoon on the ocean. Have
extended the Small Craft Advisory on the ocean through tonight based on the latest observation
and 12z wavewatch. Elsewhere...gusts into the lower 20s expected
through this evening. Winds and seas subside to blw Small Craft Advisory levels all waters
Wednesday and Wednesday night.
Several waves of low pressure may pass over the waters for the
end of the week. Occasional Small Craft Advisory conditions are possible on
Friday...especially on the ocean.
Weak high pressure will move over the waters on Thursday with low
pressure on Friday into Saturday. Sub Small Craft Advisory conditions are expected
Thursday into Friday...with seas building to around 5 feet on Saturday
on the ocean.
organized significant rainfall is not expected through Thursday.
A widespread significant rainfall is possible Friday into
Saturday. However...uncertainty exists in where and when the
heaviest of the rain will fall. Antecedent dry conditions should
limit flooding potential. However...any heavier rainfall that do
develops would have the potential for localized flooding.
tewr terminal Doppler radar remains unavailable.
New York...high rip current risk until 9 PM EDT this evening for nyz075-
Marine...Small Craft Advisory until 6 am EDT Wednesday for anz350-353-