Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
555 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. Low pressure may impact the area Friday into
Saturday. High pressure returns for the second half of the
weekend. A frontal system approaches and affects the area for the
beginning of next week.
Near term /until 6 am Wednesday morning/...
thunderstorms continue north of the County Warning Area where there is some upper support.
Across the County Warning Area...subsidence still limiting initiation. Laps at
19z has about 2500 j/kg SBCAPE on Li...with about 1000-2000
remainder of the area basically east of the Hudson. Cin is minimal.
Cumulus field on satellite but vertical extent limited across the County Warning Area. Any
focus in this MDT 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 for the eastern 2/3 of the County Warning Area.
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
A blend of guidance was used for temperatures...but limited the
radiational cooling signature across The Pine Barrens of Li with
the boundary in the vicinity.
High risk for rips continues this evening with many reports of
dangerous rips. A rip current statement is in effect.
Short term /6 am Wednesday morning 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.
There is a moderate risk for rip currents at the ocean beaches
Long term /Thursday through Tuesday/...
upper level low over southeastern Canada will push east on
Thursday...allowing for zonal flow to develop aloft. Surface high
pressure builds in at the surface keeping the area dry.
Complicated forecast thereafter in regards to the potential for low
pressure impacting the area mainly from late Thursday night through
at least Saturday. This storm will form from a shortwave currently
over The Rockies which will eject out into the middle-west Wednesday
night into Thursday morning. This will allow a weak surface low to
develop. The track of this low thereafter is very uncertain. 12z NAM
and the 00z European model (ecmwf) share a similar track...bringing the low over the
Ohio Valley overnight Thursday...over the middle-Atlantic on Friday and
off the East Coast Friday night into Saturday morning.
Thereafter...the European model (ecmwf) passes south and east Long Island Saturday.
The 12z GFS and the Canadian take the low over farther south...over
Virginia/North Carolina...then turning northeast and passing well
south and east of the area...hundreds of miles east of the 40/70
benchmark...and thus having no impact to the area whatsoever. The
00z European model (ecmwf) ensemble mean follows a similar track to the
operational...but there is a good deal of spread and thus
uncertainty with the low as it ejects out of The Rockies.
Therefore...expect a good deal of differences in models solutions
until this feature moves out of The Rockies. Given the
uncertainty...will not make much in the way of changes with what is
currently in the forecast.
Another concern is the new 12z European model (ecmwf) has shifted farther south than
the previous run...coming more in line with the GFS and
Canadian...making the NAM more of an outlier. If this trend
continues with the models...there would be much less in the way of
Aviation /19z 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 4-6ft range on the ocean. Have extended the Small Craft Advisory
through tonight based on these observation and the 12z wavewatch.
Elsewhere...gusts mainly in the lower 20s expected through this evening. An
occasional near shore gust to 25kt possible S shore bays and Harbor until
sunset. Winds and seas subside to blw Small Craft Advisory levels all waters Wednesday and
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 the
ocean Saturday into Saturday night with the approach of the low.
Seas subside Sunday as the low pushes away from the area.
organized significant rainfall is not expected through Thursday.
A widespread significant rainfall is possible late Thursday into
Friday. 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 does develop
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-