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Area forecast discussion 
National Weather Service New York New York
1252 am EDT Thursday Aug 21 2014

high pressure remains centered to the north and east of the area
through Thursday night. Meanwhile...waves of low pressure aloft
move across the region tonight and again Thursday into Thursday
night. An upper level disturbance will track through the area on
Friday as high pressure builds down from eastern Canada. This high
will gradually build down the eastern Seaboard through the middle
of next week.


Near term /until 6 am this morning/...
showers over eastern PA and western New Jersey should begin to impact
western sections of the County Warning Area between 5-6z. 500 mb shortwave will
continue to move slowly east across the region tonight as low
level moisture increases through the night...allowing for precipitation
to reach the ground. Best chances will be across western
zones...but will keep probability of precipitation capped at chance as the activity will
be scattered.

Lows tonight will drop into the upper 60s in/around NYC and in the
low to middle 60s most other locations. Eastern zones will drop into
the middle/upper 50s.


Short term /6 am this morning through 6 PM Friday/...
there will be some showers ongoing during the first half of the a shortwave swings across the area. Best chances will again
be across western and northern ridging noses in across
our eastern sections. Included isolated thunder across the approximate
western third of the area...where model fields indicate a little
more in the way of MUCAPE. Additionally...these areas will be less
influenced by the maritime air being advected across the area thanks
to east/southeast onshore flow.

Due to the aforementioned onshore flow and increased cloud
cover...temperatures will be cooler than the previous day...with many areas
staying in the 70s / below normal for this time of year.

As the first wave departs to the east Thursday afternoon and
evening...subsidence aloft and the continued surface ridging poking
in from the north and east will allow most places to be dry later in
the day. Chances will then increase again the upper
low to the northwest opens and approaches the area.


Long term /Friday night through Wednesday/...
models are in good agreement that the 500 mb pattern across noam at the
start of the long term period will consist of a strong broad ridge
across the southeast Continental U.S. With a deep trough out west with an upper low
cutting off over the Pacific northwest and an Omega block over eastern Canada with
a weak cutoff low moving through New England.

Some uncertainty with the specific details and timing of vorticity maxes
moving around the left side of the upper low once it slides
offshore...but the general trend appears to be decreasing chc's of
showers during Friday as deep layered ridging builds into the northeast
from the north. May need to add slight to low chance probability of precipitation at times through
Sat in subsequent forecast packages to account for these timing
differences. Additionally...the amount of cloud cover for Friday and
Sat is also questionable as a result.

Otherwise...expect dry and seasonable conds through the middle of
next week as the 500 mb flow amplifies in response to the blocking
pattern. Surface high pressure will build down the eastern Seaboard during this
time with an Ely flow expected at least into Monday. This will
contribute to below normal temperatures thought this time...but as
heights rise Tuesday and Wednesday...temperatures will rebound to near normal


Aviation /06z Thursday through Monday/...
weak high pressure remains over the area.

VFR...except tempo IFR at kgon early morning Thursday.

Light and variable winds overnight becoming mostly southeast at 10kt or less

Outlook for 00z Friday through Monday...
Thursday night...VFR. Scattered thunderstorms mainly south and west of the New York metropolitan.


with high pressure still extending across the waters Thursday...and
only starting to lift out Thursday night...winds and seas will
remain below Small Craft Advisory criteria during this time. Easterly flow will be on
the increase late Thursday though.

Wind gusts are expected to remain below Small Craft Advisory levels...although could
come close to 25 knots on the ocean waters late Friday/Friday evening. An
increasing east-NE flow will result in building seas on the ocean with
Small Craft Advisory conds expected between Friday night and Sun night. The gradient
relaxes thereafter with seas diminishing.


a few thunderstorms are possible on Thursday across the lower Hudson
Valley and interior NE New Jersey. Any storms will have the potential to
produce locally heavy rain...but basin averaged totals are forecast
to remain any thunderstorms should be isolated.

No significant rainfall is expected in the extended.


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


near term...picca/jp/mps
short term...picca
long term...24

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