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Area forecast discussion 
National Weather Service New York New York
523 am EDT Monday Jul 14 2014

Synopsis...
a surface trough lingers in the area with a cold front well west
of the region. This front will eventually become part of a
secondary frontal system that will impact the area Tuesday into
Wednesday...concluding with a cold frontal passage early on
Wednesday. High pressure builds over the region Wednesday
afternoon through Friday. The high moves east Saturday as a
frontal system approaches for the weekend.

&&

Near term /until 6 PM this evening/...
the first day of a series of days with very unsettled weather.
Today we will be dealing with a lingering surface trough with the
cold front still well west of the area. Multiple boundaries will
be in play today and the dry initial conditions will lead to
sufficient daytime heating to generate cape.

The convergence with the surface trough as well as sea breezes and
other outflow boundaries will allow for thunderstorms to develop
right within the forecast area and expand as well as aggregate
this afternoon. The Mode will likely be multicell clusters of cells.

Also with these boundaries in play...surface and low level winds
will have some directional change...more easterly component
compared to winds aloft. The winds aloft are reflecting the
approaching very deep trough and its southwest flow. As a
result...enhanced veering profiles in addition to moist low levels
will add some rotation potential to developing thunderstorms. This
will favor organization with possible severe thunderstorm due to
mainly wind as bulk shear 0-6 km of 30-40 knots develops this
afternoon into this evening.

In addition...heavy rain and flash flooding will be a threat with
these thunderstorms as a moisture laden airmass of precipitable waters near 2
inches will persist. See Hydro section for more details.

Maximum temperatures were a blend of mav and met guidance...yielding a range
well within the 80s. There is a moderate risk of rip currents at
ocean facing beaches today.

&&

Short term /6 PM this evening through Tuesday night/...
dynamics come more and more into play in the short term.
Specifically the trough deepens with core of colder air aloft
moving closer along with the core of the upper level jet.
Divergence aloft will thus increase and expect convection to keep
going into the night Monday night and perhaps subsiding late at
night briefly before redeveloping again on Tuesday.

Tuesday will feature the cold front getting closer to the region
with the front moving in Tuesday night. Convection could still be
severe but instability will be more limited Tuesday with less
warmth. Still though...it is not of the question that some
thunderstorms could result in severe wind gusts.

Heavy rain main feature with thunderstorms on Tuesday and Tuesday
night as cell motion slows down as low pressure develops along
the approaching cold front. The moisture laden airmass remains
with precipitable waters near 2 inches.

Temperatures still in the 80s for highs Tuesday. At
night...temperatures stay in the 70s.

&&

Long term /Wednesday through Sunday/...
the broad upper trough with the closed upper low remains well west
of the region at the start of the period...across the Great Lakes
into the Ohio Valley. The trough will be slow to move east with the
trough axis crossing the region Thursday as the trough weakens and
flow flattens. Thus the secondary cold front is a little slower to
move through the region and is expected to be across western
Connecticut into western Long Island early Wednesday morning. So
will keep likely to categorical probability of precipitation Wednesday morning. With some
cape and instability will keep mention of scattered thunder
Wednesday morning with potential of heavy rain. Also...there is
some instability across the inland regions by Wednesday afternoon
and a weak vorticity rotates around the base of the trough. Could see
some sprinkles inland during Wednesday afternoon...however not
confident to even include slight chance probability of precipitation. Heights begin to rise
late Thursday into Friday with surface high pressure building into
the area. A west flow behind the front Wednesday and continuing into
Thursday will allow even coastal areas to warm...and raised
temperatures a couple of degrees above guidance.

High pressure moves off rather quickly Friday into Saturday. A
shortwave moving into the Pacific northwest today will move to west
of the region Friday night. A frontal system will impact the region
mainly Saturday night into Sunday.

&&

Aviation /10z Monday through Friday/...
varying conditions today with a pre frontal trough impacting the
area today...with a cold front slowly approaching from the west.

Highest confidence resides with winds for today. SW flow becoming S
aftr 12z. Should remain from the south throughout the
day...generally between 160-200 (true)...between 8 and 12 kts.

High confidence of precipitation occurring today though with lesser confidence
on exact timing. Light rain showers possible as early as 15z western
areas...with better chance of precipitation then aftr 18z. Scattered thunderstorms late
aftn-evening. While precipitation is currently mentioned as
prevailing...could very well end up being more periodic in nature.
Should see a break in the precipitation during the overnight hours...before
the next round begins Tuesday.

Low-moderate confidence on ceilings/visible early this morning. Expecting any
sub-VFR conditions to improve to VFR for the morning and afternoon.
Ceilings/visible will drop with any precipitation. Potential for fog stratus early
this morning...but confidence remains on the lower end. Higher
confidence of diminishing conditions for Monday night.

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)

Kjfk fcster comments: low confidence visible lt 5sm. Moderate confidence on
ceilings lt 1500ft. Precipitation start time +/- 1-2 hours.

Klga fcster comments: low confidence visible lt 6sm. Precipitation start
time +/- 1-2 hours.

Kewr fcster comments: precipitation start time +/- 1-2 hours...especially with
thunderstorms and rain mention.

The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.

Kteb fcster comments: low confidence visible lt 5sm. Precipitation start time
+/- 1-2 hours..esp with thunderstorm.

Khpn fcster comments: low confidence visible lt 5sm. Precipitation start time
+/- 1-2 hours..esp with thunderstorm.

Kisp fcster comments: moderate confidence visible lt 6sm. Precipitation start time
+1-2 hours...especially with thunderstorm.

Outlook for 09z Tuesday through Friday...
tues-Wed...scattered to numerous shra/tstms. Stronger thunderstorms
during this time frame could produce periods of MVFR or lower
conditions...locally heavy rainfall...and gusty winds. Conditions
improve late Wednesday.
Thursday...VFR.
Friday...VFR.

&&

Marine...
a cold front will be exiting the eastern forecast waters Wednesday
morning. With the prolonged southerly flow across the waters 5 foot
seas on the ocean waters east of Moriches Inlet will likely linger
into Wednesday evening.

High pressure builds into the waters Wednesday afternoon through the
end of the week. Once seas subside Wednesday evening seas and wind
will remain below Small Craft Advisory levels through the end of the
week.

&&

Hydrology...
a significant rainfall is possible beginning this afternoon and
continuing into early Wednesday with multiple rounds of showers
and thunderstorms. Total rainfall through this period is expected
to range from around 2 to 3 inches with locally higher amounts
possible. These higher amounts could range from 3 to 4 inches.

The most widespread heavy rainfall is expected to occur Tuesday
morning into Wednesday morning. The flash flooding threat will be
highest on Tuesday into Tuesday night due to the rainfall that
will have fallen already...saturating grounds and resulting in
greater runoff. Excessive runoff will lead to potential flooding
of urban...low lying...and poor drainage areas mostly but could
also result in some small streams and rivers reaching bankfull.

Flash Flood Watch has been issued for entire area covering time
period of this afternoon through late Tuesday night.

Rainfall ending Wednesday morning across Connecticut and Long Island
may total up to a tenth of an inch across southwestern Connecticut
to around a third of an inch across southeastern Suffolk County.

No rainfall is expected Wednesday afternoon through the end of the
week.

&&

Okx watches/warnings/advisories...
CT...Flash Flood Watch from noon EDT today through late Tuesday
night for ctz005>012.
New York...Flash Flood Watch from noon EDT today through late Tuesday
night for nyz067>075-078>081-176>179.
New Jersey...Flash Flood Watch from noon EDT today through late Tuesday
night for njz002-004-006-103>108.
Marine...Small Craft Advisory until 6 am EDT early this morning for
anz355.
Small Craft Advisory until 6 PM EDT Tuesday for anz350-353.

&&

$$
Synopsis...jm/met
near term...jm
short term...jm
long term...met
aviation...Sears
marine...jm/met
hydrology...jm/met

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