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Area forecast discussion 
National Weather Service New York New York
719 PM EDT Wednesday Jul 27 2016

Synopsis...
weak high pressure tonight will give way to an approaching cold
front Thursday. A wave of low pressure approaches and passes
nearby Friday. This low moves east of the region Friday night.
Weak high pressure briefly builds into the region for Saturday.
Unsettled weather returns for the end of the weekend and start of
next week with the passage of another low pressure system. Drier
weather is expected for Tuesday and Wednesday as high pressure
returns.

&&

Near term /until 6 am Thursday morning/...
mostly clear conditions early this evening with temperatures and
dewpoints within a few degrees of forecast values. Only slight
adjustments were made to better match observed trends. The
forecast is on track.

Aloft, upper trough moves across the upper Great Lakes region. A
surface cold front accompany this features moves well to the
north. Meanwhile, another weak frontal boundary remains to our
south, with a series of weak lows along it.

Weak high pressure remains offshore, and a light south flow
prevails across the region. Dew points increase slightly, and as
temperatures fall tonight under mostly clear skies, patchy fog
formation is possible as boundary layer begins to saturate. Not
quite sure of extent of any fog, but it is possible as hinted at
by the models.

Lows tonight will range from around 60 well inland, to the middle
70s in NYC Metro. Followed a MOS and model blend.

&&

Short term /6 am Thursday morning through Friday/...
through this time period, upper trough axis extending south
across the Great Lakes region/Ohio Valley and into the upper
Mississippi Valley will move east, with embedded vorts in the mid
and upper level flow tracking east. Frontal boundary to the south
remains Thursday, as a series of low pressure centers ride along
it, the strongest of which approaches Thursday night and Friday.
Better jet support Friday, and enhanced lift along with abundant
moisture advecting east/northeast will allow for rain/possibly
heavy Friday.

Prior to that, isolated thunder per high resolution models
develops along seabreeze boundary Thursday afternoon. Kept pops
in slight chance range as coverage should be isolated, and this
assumes ample moisture up the column materializes.

One more warm to hot day is expected Thursday, with highs in the
upper 80s to around 90 under partly sunny skies. With higher
humidity levels, heat indices will run a degree or two above
actual air temps.

Temps will remain seasonably warm Thursday night, and not quite as
much of a range is expected as clouds increase, and rain chances
increase.

With the passage of a wave of low pressure, possibly just to our
south, temperatures on Friday will be cooler, upper 70s to around
80 thanks to clouds and rain. This has trended lower than previous
forecast.

&&

Long term /Friday night through Wednesday/...
low pressure moving across the region moves east Friday night, with
just some left over showers and possibly a thunderstorm. Weak high
pressure briefly returns on Saturday, with most of the forecast
guidance keeping conditions dry. As a result, will keep conditions
dry on Saturday.

Unsettled weather returns Saturday night into Monday, as another
shortwave and low pressure system moves across the region. Expect
another round of showers and thunderstorms, with some storms
producing locally heavy rainfall.

High pressure builds back into the region early next week, providing
dry conditions.

Temperatures will remain seasonable Saturday through Wednesday with
temperatures climbing into the 80s each day.

&&

Aviation /00z Thursday through Monday/...
southerly flow will weaken tonight and become light and variable
at outlying terminals and light SW at city terminals. Winds will
become southerly at all terminals on Thursday increase to around
10 kt near the coast in the afternoon with seabreeze enhancement.

Mainly VFR through the taf period. There is a low probability of
MVFR/IFR ceilings or visibilities late tonight at coastal
terminals. Preference continues to be for VFR to prevail, but have
added tempo MVFR visibility at kgon towards daybreak.

A few showers and thunderstorms possible Thursday
afternoon/evening, mainly northwest of the city terminals, but
probability is too low to include in tafs at this time.

New York Metro enhanced aviation weather support...

Detailed information, including hourly taf wind component forecasts,
can be found at: http:/www.Weather.Gov/zny/n90

Kjfk taf comments: low probability for MVFR/IFR ceilings or
visibilities late tonight.

Klga taf comments: no unscheduled amendments expected.

Kewr taf comments: no unscheduled amendments expected.

Kteb taf comments: no unscheduled amendments expected.

Khpn taf comments: MVFR/IFR visibilities possible around daybreak
Thursday.

Kisp taf comments: low probability for MVFR/IFR ceilings or
visibilities late tonight.

Outlook for 00z Friday through Monday...
Thursday night into Friday night...MVFR or lower possible in
showers and thunderstorms, possibly widespread on Friday. Patchy
fog.
Saturday...VFR.
Saturday night into Monday...iso-sct showers and thunderstorms
possible.

&&

Marine...
some gusts early this evening on the western ocean waters up to
near 20 kt with otherwise lower winds for all other forecast
waters. Ocean seas are below 2 ft. The forecast is on track.
Conditions will remain below Small Craft Advisory.

As a weak front approaches, and weak wave of low pressure moves
by Thursday night and Friday, expect sub Small Craft Advisory conditions to
continue across the area waters.

A light pressure gradient over the area waters will result in sub-
sca conditions this weekend and early next week. However, any
thunderstorms that develop on the waters may produce brief Small Craft Advisory
conditions.

&&

Hydrology...
there is potential for significant rainfall from late Thursday
night into Friday night. Locally heavy rainfall is possible, which
could cause flooding. Exact evolution of this potential storm
remains unclear, so it remains too early for specifics.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.

&&

$$
Synopsis...BC/pw
near term...jm/pw
short term...precipitable water
long term...British Columbia
aviation...ds
marine...BC/jm/pw
hydrology...BC/pw

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