Area forecast discussion
National Weather Service New York New York
219 PM EDT Monday may 20 2013
Synopsis...
a warm front north of the area will 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. MLCAPE increasing to 500-1000 j/kg this afternoon
with no cap and some moisture convergence per Storm Prediction Center mesoanalysis...
so isolated to widely scattered showers and possibly a thunderstorm still on The
Table from NYC north/west into early evening. With precipitable water near 1.5
inches...any shower/thunderstorm could produce locally heavy rain.
Isolated showers could also pop up via convergence along sea breeze
front on the North Shore of Long Island.
&&
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 /18z Monday through Saturday/...
a stationary front remain north of the region this afternoon. This
leaves the region in the warm moist air that result in another
round of overnight fog and stratus.
Condition near or below minimums are possible overnight into
Tuesday morning are possible.
New York 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: broken ceiling at 025-030 should dissipate by late
afternoon. Winds not expected to gust the remainder of the afternoon.
Lots of uncertainty on timing and severity of overnight
conditions.
Kjfk fcster comments: high confidence in wind forecast this afternoon. Will
be watching for a broken ceiling at 025-030 staying just west of the
terminal.
Lots of uncertainty on timing and severity of overnight
conditions. Low IFR may develop earlier than forecast.
Klga fcster comments: broken ceiling at 025-030 should dissipate by late
afternoon.
Lots of uncertainty on timing and severity of overnight
conditions.
Kteb fcster comments: broken ceiling at 025-030 should dissipate by late
afternoon.
Lots of uncertainty on timing and severity of overnight
conditions. Could be below minimums in the morning.
Khpn fcster comments: broken ceiling at 018-022 should dissipate by late
afternoon.
Lots of uncertainty on timing and severity of overnight
conditions. Could be below minimums in the morning.
Kisp fcster comments: lots of uncertainty on timing and severity of overnight
conditions. Could be below minimums in the morning.
Outlook for 12z Tuesday through Friday...
Tuesday afternoon...VFR. Scattered thunderstorms north.
Tuesday night...becoming IFR with fog and stratus.
Wed-Fri...scattered showers/tstms. At night...a IFR possible stratus/fog.
Sat...VFR.
&&
Marine...
seas were near 5 feet at Texas tower buoy 44066 early this
afternoon...and are unlikely to decay much as they arrive this
afternoon...so Small Craft Advisory for hazardous ocean seas will continue.
If these seas do not arrive by evening it is unlikely they will
ever materialize...and Small Craft Advisory could be dropped later this afternoon.
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...Small Craft Advisory for hazardous seas until 6 PM EDT this
evening for anz350-353-355.
&&
$$
