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

Synopsis...
the potent upper level storm system continues to sit over the
region this morning. This system will support the chance for
additional showers and thunderstorms today and tonight over New
York and Pennsylvania. The unsettled weather pattern will slowly
improve by Saturday as high pressure returns to the region.

&&

Near term /through tonight/...
650 am EDT update...
mostly cloudy skies are present this morning across portions of
central New York and northeast PA. Patchy fog have develop along the
valleys. Expect fog to lift within the next couple of hours.
Showers have also developed across western New York and PA. Expect these
to drift to the east around 15-20 miles per hour. Made minor adjustments to
the previous forecast. For more information on today's event...
please read discussion below.

Previous forecast...
430 am EDT update...
showers this morning have pretty much tapered off and just an
isolated lightning strike here are still going. Patchy valley fog
have also developed this morning and expect this to mix out
shortly after sunrise.

The upper level low located over the central Great Lakes region
that have brought US showers yesterday will slightly weaken today
and drift slowly towards New York. As this low drifts to the south it
will eject a vorticity maxima across portions of central New York and
northeast PA. This looks like it will trigger showers and
thunderstorms across the are late this morning/afternoon.

Activity that does develops today will have more instability to
work with than yesterday. Guidance is indicating SBCAPE values around
2500 j/kg... believe this may be a little high but values around
1000 j/kg aren't too unreasonable. 0-6km bulk shear values are
expected to be around 20 knots over central New York and 30 over
northeast PA. A few strong storms may develop tomorrow... and are
expected to be mainly over NE PA where the shear is a little
stronger. With the mentioned statements above... expect to see
more convection overall today than previous days. The best middle
level support during the time frame for late morning/afternoon is
expected to be I-81 and east. Precipitable water values today are also expected to
be around 1.4 inches give or take. With that being said we could
see some localized heavy rainfall rates today with the convection.

Tonight the upper level trough will continue to shift east. Showers may
linger through the night as we may remain under cyclonic flow till
late in the night. The trough axis is expected to be located over
central New York by late Thursday night/Friday morning. Depending on how
quickly the axis moves east will depend on how long showers may
linger.

Temperatures are expected to rise into the 70s and isolated spots in the
80s this afternoon as 850mb temperatures remain near 14 decrees celsius.
Temperatures tonight are expected to remain in the 60s as dense cloud
coverage will inhibit strong cooling.

&&

Short term /Friday through Saturday night/...
430 am EDT update...
by Friday the upper level trough will be east of the area and
the large ridge currently centered over the southern Continental U.S. Will
move east and become slightly amplified over the mid-west. This
will result in our pattern aloft transitioning to a northwesterly
flow. Weak spurts of energy will slide south into our area on
Friday and due to the combinations of lingering low level
moisture... weak waves... and heating from the sun... showers and
thunderstorms may develop across the area.

Late Friday night/Saturday morning weak vorticity maximums will
travel along the outer edge of the ridge aloft and may generate
some showers over the western County Warning Area. But... by Saturday afternoon
the upper ridge will be further east and subsidence will start to
take control of the area. This will create an environment that will
eventually inhibit convective development. Thus... by Saturday
evening the chance for showers will be gone.

Temperatures during this time frame will rise into the 70s each
afternoon and fall into the low to middle 50s each morning.

&&

Long term /Sunday through Wednesday/...
3 am update...medium range models indicate a strong upper level
ridge will extend from the Gulf states north into the local area.
This combined with surface high pressure along the New England coast will
provide a pleasant stretch of dry weather with temperatures running a few
degrees above seasonal normals. By late Wednesday into Wednesday
night an upper level trough and associated surface front may bring the
area some showers.

245 PM update...
wpc guidance looks fine for the extended forecast with dry weather
expected. A large ridge of high pressure aloft, with 588 dm
heights will spread into the lower Great Lakes. Sunday through
early next week we will see the impacts of this ridge with very
quiet weather. With a northerly to northeast flow aloft and near
the surface it will be comfortable with highs near 80 and
comfortable nights. Farther down the Road as the ridge moves east,
our flow aloft will become more southwesterly. Eventually this
should translate into much, much warmer air by the middle of next
week.

&&

Aviation /12z Thursday through Monday/...
most terminals are VFR early this morning with the exception of
kelm where conditions near Airport mins will continue until 14z
and kbgm where low MVFR ceilings will persist until 14z. By middle
morning conditions will remain VFR until widespread convection
develops this afternoon in response to a middle level short wave
rotating around the upper level low over the eastern lakes.
Showers and embedded thunderstorms are likely this afternoon into
the early evening. For the New York state terminals included prevailing MVFR
showers from 18z-00z, at kavp 21z-03z. MVFR restrictions will
continue this evening again due to rainfall and weak mixing. At
kelm dense fog will be likely once again after 06z.

Light winds becoming southwest around 5 knots this morning then
light again tonight.

Outlook...

Friday to Friday night...MVFR restrictions possible in afternoon shra/tsra.
Friday night...IFR fog and stratus possible.

Sat-Mon...VFR except some IFR possible in early fog at kelm.

&&

Bgm watches/warnings/advisories...
PA...none.
New York...none.

&&

$$
Synopsis...kah
near term...kah
short term...kah
long term...heden/rrm
aviation...rrm

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