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Area forecast discussion 
National Weather Service Binghamton New York
925 PM EDT Monday may 4 2015

Synopsis...
a cold front will slowly cross the region later tonight and
Tuesday...accompanied by a few showers. Wednesday and Thursday
look dry and seasonably mild...as high pressure builds back into
the area.

&&

Near term /through Tuesday/...
930 PM EDT update...
pre-frontal trough is now over the western County Warning Area and very light rain
showers are being produced from this feature. Dew point
depressions of 30 degrees or more are over the area... so expect
very little accumulations with this feature. Decided to decrease
probability of precipitation as shower coverage over the County Warning Area is small. Made minor
adjustments to the temperatures/winds to previous forecast to match the
reality of surface observation. Otherwise still think front will move through
slower than previously thought. For more information please read
the previous forecast discussions below. Overall forecast looks
like it is in good shape.

730 PM EDT update...
a pre-frontal trough is slowly pushing east this evening and is
now located over western New York/western PA. Light rain showers have
developed along this feature and are moving east as well. These
showers will drift east tonight. The surface cold front is still
well off to the north and we expect the front to move through the
County Warning Area late tonight/early tomorrow morning. This front is not very
impressive. 2-hour pressure changes are around 2.5 mb. NAM guidance
is around 4... thus not sure how quickly this front will actually
move through since guidance seems to be over estimating. This
front may meet up with this pre-frontal trough and help create
additional showers. The main forecast challenge of the night is
where will this front end up. Due to current analysis... looks
like the front will become horizontal over the County Warning Area... but there
is a lot of uncertainty of where this front will stall or move
through.

Winds will start to weaken across the region tonight as the surface
boundary decouples from the atmos and lapse rates weaken as we
lose heating from the sun. Temperatures are ranging in the 70s to low 80s
over much of the area. Expected low temperatures tonight look good.

For more information please read the previous forecast
discussion below.

Previous forecast discussion...
3 PM update...
a surface cold front and weakening middle-level shortwave are expected to cross
the region overnight. A band of showers...stretching from ont-Lake Erie-
central Ohio late this afternoon...will push eastward and likely diminish with
time...as upper-level support lessens with eastward extent. We'll continue
to advertise likely probability of precipitation for showers later this evening in our far northern and
western zones...lowering to chance/schc values farther S and east.

Due to increasing clouds and a resident warm air mass...lows will be mild
overnight...only generally falling into the 50s.

On Tuesday...the surface boundary continues to slip southward...reaching southern Ohio-southern
PA-New Jersey by later in the day. At the same time...another WV in the
700-500 mb layer moves eastward...and temporarily increases lift near the
convergence zn/frontal boundary. As a result...we expect some showers to
re-develop during the day Tuesday...mainly over our NE PA zones...perhaps
into Sullivan County New York. Due to uncertainty with how far S the front
will be/how far north the precipitation shield will be by that time...we'll
keep probability of precipitation in the chance category. Isolated thunderstorms can't be ruled out in
our far southern zones Tuesday afternoon...with some residual low-level instability
indicated in the model data.

Highs Tuesday will be a bit cooler...with less insolation...and a
slightly cooler air mass coming down from the north (max temperatures mainly in
the 60s-lower 70s).

&&

Short term /Tuesday night through Thursday/...
to begin the period, a final wave moving east along the frontal
boundary will bring a chance for some more showers Tuesday night
from around the twin tiers southward. There continues to be some
differences in forecast models regarding this feature howeveroverall
trend has been for this to be weaker so not expecting a lot of
precipitation. Beyond this time, front pushes south with high pressure
building back in for Wednesday and Thursday bringing sunshine with
highs in the 70s.

&&

Long term /Thursday night through Monday/...
no major changes to the forecast with this update.Overall trend
will be for warm temperatures with initially dry conditions giving way to
an increasing chance of showers over the weekend into early next
week.

To begin the period, low pressure moving up well to our west over Ontario
will help build up upper level ridge over the area with SW flow at
the surface. Lows Thursday night will be in the 50s with highs
Friday climbing back into the low 80s under partly to mostly sunny
skies. SW flow continues to bring warm weather into Saturday with
dew points beginning to creep up as well. A few showers or
thunderstorms will be possible, mainly in the afternoon, but not
expecting anything widespread at this point.

An approaching upper level trough along with a cold front coming
down from Ontario will bring an increasing chance for
showers/storms for Sunday into Monday however details regarding
the evolution of these features is still uncertain at this time.

&&

Aviation /01z Tuesday through Saturday/...
mainly VFR conditions the next 24 hours.

An area of showers will move across the New York terminals through 04z.
With very dry air near the surface, no restrictions are expected.
A better chance for showers will occur Tuesday at kavp, after 15z.
Showers may reach as far north as kelm and kbgm late Tuesday, but
confidence is not high enough yet to include in the tafs. Ceilings
generally between 5kft and 10kft or VFR.

Light winds tonight shifting into the west early, then due north
by daybreak. Light north to northeast winds Tuesday around 5 kts.

Outlook...

Wed-Sat...mainly VFR.

&&

Fire weather...
a red flag warning continues area-wide until 7 PM.

Dry and windy conds will continue during the late afternoon hours...with a
well mixed blyr environment still in place. Relative humidity values of
15-25%...along with gusts to 25-30 miles per hour...will persist.

Later tonight and Tuesday...it appears that winds will diminish...and relative humidity
values will increase...as a frontal boundary crosses the region from northwest to
southeast.

&&

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

&&

$$
Synopsis...mlj
near term...kah/mlj
short term...pcf
long term...pcf
aviation...heden
fire weather...

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