Area forecast discussion
National Weather Service New York New York
359 am EDT Monday may 20 2013
Synopsis...
a warm front lifts to the north today and will sink south closer to
the area on Tuesday. A cold front in the vicinity of the area
Tuesday night will lift back as a warm front on Wednesday. A warm
and humid airmass will then remain over the region until a cold
front moves through Thursday night or Friday. High pressure
returns for the weekend.
&&
Near term /until 6 PM this evening/...
low pressure rides along a front well to the north today. Weak
frontal boundary to the south should weaken and dissipate this
morning.
Dense fog developed along and north of a frontal boundary just south
of the local area. Any morning low clouds and fog will slowly burn
off as the morning progresses. Some breaks of sun are possible
this afternoon. How much clearing occurs will determine the amount
of daytime heating/instability...which will aid in thunderstorm
development this afternoon and evening. With precipitable water near 1...
shower/thunderstorm could produce locally heavy rain. Will maintain chance
probability of precipitation.
&&
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 airmass 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 /08z Monday through Friday/...
a nearly stationary front will remain south of the area as it
weakens early this morning. The front will redevelop to the north
of the terminals as a warm front middle to late morning.
The area will then be in the warm sector ahead of low pressure
moving into the upper Midwest. Scattered showers and isolated
thunderstorms will be possible in the afternoon. The wind will be
southerly...and become more southwesterly late in the afternoon into
the early evening. Sea breeze influence is likely.
Widespread fog and drizzle...with low clouds will persist early
this morning with IFR to LIFR conditions...and at times vlifr.
Conditions improve after 13z...timing of the improvements is not
certain.
Outlook for 06z Tuesday through Friday...
tonight...mainly VFR...MVFR or lower conditions possible in
fog...mainly east of the New York City terminals.
Tuesday-Friday...chance of MVFR of lower conditions in
showers/tstms.
&&
Marine...
morning fog will slowly improve as the day progresses. Seas are
still expected to build close to 5 feet...and will convert the Small Craft Advisory to
Small Craft Advisory for hazardous seas this morning.
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...
scattered showers and thunderstorms could produce locally heavy downpours
today. This could lead to a low end flash flood threat. Scattered
showers/thunderstorms Tuesday through Friday are 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.
&&
$$
