Area forecast discussion
National Weather Service New York New York
1146 am EDT Monday may 20 2013
Synopsis...
a warm front north of the area sink south closer to the area on
Tuesday...then lift back north as a warm front on Wednesday. A
warm and humid air mass will then remain until a cold front moves
through Thursday night or Friday. High pressure will return for
the weekend.
&&
Near term /until 6 PM this evening/...
clearing has begun and expect partly to mostly sunny this
afternoon.
Low pressure rides along a front well to the north today.
Weak frontal boundary to the south should weaken and dissipate
this morning.
How much clearing occurs will determine the amount of daytime
heating/instability...which will aid in thunderstorm development this
afternoon and evening...however...thinking coverage will be isolated
to widely scattered at best. With precipitable water near 1.5 inches...any shower/thunderstorm
could produce locally heavy rain. Maintained chance pop inland
north/west of NYC...but reduced pop elsewhere as maritime
inversion should inhibit most convection.
&&
Short term /6 PM this evening through 6 PM Tuesday/...
frontal boundary remains just to the north as ridge prevails across
the northeast ahead of upstream trough.
Southwest low level flow will lighten this evening...and ample
moisture could lead to the development of fog once again.
Any lingering diurnal showers/thunderstorms will diminish in
coverage...and most of the night should be dry.
With area in the warm sector...temperatures will remain quite
mild...50s to around 60.
On Tuesday...temperatures warm through the 70s...to around 80 away from
the water...with 70s elsewhere. Any morning fog will burn off to
partly sunny skies. Afternoon showers or thunderstorms are
possible once again.
&&
Long term /Tuesday night through Sunday/...
medium range models/ensembles are in decent general agreement with
the region lying on the northern periphery of East Coast ridging
during the midweek...with phasing eastern Canadian and central US
troughs...eventually translating a deep trough to the East Coast for
the end of the week/weekend.
For Tuesday through Thursday...models continue to differ in location
of a frontal boundary. The predictability issues are based on
subtle differences in interaction of the upper energies and
relationship with East Coast ridging. The location of upper
confluence will determine how strongly Canadian high pressure builds
southeast into New England...and the timing and movement of a back door
cold front. Latest guidance does not bring the backdoor cold front
through the County Warning Area Tuesday night...but its still questionable whether
it sinks into the area or remains just north. Have trended in this
direction and brought it about halfway through...but temperatures Tuesday night
will be affected by this. The boundary then lifts back north as a
warm front on Wednesday.
To the south of the front...an unseasonably warm and moist air mass
will be in place. Depending on the timing and location of the
frontal boundary...shortwaves at the southern edge of the
westerlies...favorable instability and wind fields present the
potential for convective complexes to develop and propagate along
this boundary. Any mesoscale convective system would bring the threat for flash flooding and
severe weather.
Models have come better into line with the phasing of the Midwest
upper trough and eastern Canadian upper trough at the end of the
week. Cold front looks to track through the area Thursday night. A
pre-frontal trough in the warm...moist air mass preceding the front
on Thursday...will be the trigger for scattered showers and thunderstorms during the
afternoon and evening hours. There is the potential for some storms to be
strong to severe based on latest profiles. Lingering showers are
possible on Friday with the upper trough moving through.
Model guidance is signaling a drier and slightly below seasonable
weekend...with East Coast mean troughing and Canadian high pressure
builds into the region.
&&
Aviation /15z Monday through Friday/...
warm front north of the region today with morning fog and stratus
burning off by early afternoon.
High confidence in becoming VFR this afternoon as southwest low
level flow allows the morning fog and status to burn off/mix out.
As of 1330z...improvement is seen on visible satellite imagery.
First area to improve will be the NYC metropolitan with eastern terminal
holding on an hour or two more.
A few showers and thunderstorms will be possible in the late
afternoon...mainly north of the New York metropolitan.
Pattern expected to repeat itself on Tuesday.
..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)
Kewr fcster comments: high confidence in improvement to VFR this
afternoon. May be sooner...an hour or so...than forecast.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kjfk fcster comments: high confidence in improvement to VFR this
afternoon. May be sooner than forecast. High confidence in wind forecast.
Klga fcster comments: high confidence in improvement to VFR this
afternoon. Looks like it will occur sooner than forecast.
Kteb fcster comments: high confidence in improvement to VFR this
afternoon. May be sooner...an hour or so...than forecast.
Khpn fcster comments: high confidence in improvement to VFR this
afternoon. May be sooner...an hour or so...than forecast.
Kisp fcster comments: moderate confidence in improvement to VFR
this afternoon. May be sooner...an hour or so...than forecast.
Outlook for 12z Tuesday through Friday...
Tue-Fri...during the day...a chance of MVFR of lower conditions
in showers/tstms. At night...a chance of MVFR of lower conditions
in low stratus/fog.
&&
Marine...
visibilities continue to improve especially on the western waters.
Dense fog advisory will be allowed to expire at noon...but patchy fog
still possible into the afternoon and evening.
Seas were 5.6 feet in steep S-southeast swell at Texas tower buoy 44066
late this morning...and are unlikely to decay much as they arrive
this afternoon...so Small Craft Advisory for hazardous ocean seas will continue.
Marginal Small Craft Advisory seas are possible on the ocean into tonight...but
wavewatch is still running a bit high...so have only medium
confidence in extending the advisory into tonight.
A general southerly flow will prevail today through Tuesday.
Seas should slowly subside tonight and Tuesday...with mainly sub
Small Craft Advisory conditions anticipated.
Due to the poor performance of wavewatch over the last 2 days...have
low confidence in its forecast during the long term period. Small Craft Advisory for
seas may be needed on the ocean waters Tuesday night. As the pressure
gradient increases on Wednesday...sustained winds will increase with seas
likely at Small Craft Advisory levels. A strong inversion over the waters will
inhibit winds aloft from mixing down...although winds could reach
Small Craft Advisory levels on the ocean Thursday/Thursday evening. The pressure gradient relaxes as a
cold front moves into the waters Thursday night and winds and seas will
diminish below Small Craft Advisory levels through the rest of the period.
&&
Hydrology...
isolated to widely scattered showers and thunderstorms could produce local
downpours today...mainly well north/west of NYC.
Scattered showers/thunderstorms Tuesday-Friday are also capable of producing locally
heavy rainfall...with an attendant low end flash flood threat.
&&
Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...dense fog advisory until noon EDT today for anz330-335-338-340-
345-350-353-355.
Small Craft Advisory for hazardous seas until 6 PM EDT this
evening for anz350-353-355.
&&
$$
