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Area forecast discussion...updated 
National Weather Service Pittsburgh PA
127 am EDT Sat Apr 18 2015

Synopsis...
dry and warmer weather will give way to increasing rain chances on
Sunday.

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Near term /through today/...
only changes to overnight forecast will account for the cirrus
shield moving across the southern half of the area and an update
to temperatures with the latest lamp numbers.

Very nice day setting up with sunshine and warm temperatures. High
cirrus clouds will cross the area from time to time...and with
warm air advection...highs will push to well above normal levels.

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Short term /tonight through Monday/...
surface high pressure and upper level ridge will keep the area dry
and comfortable through most of Sunday morning. A warm front...
associated with low pressure over the upper Midwest...will swing
through the area Sunday afternoon...increasing clouds and
bringing the risk for showers. With the slowing progression of the
warm front...the warm sector will not reach the area until late
Sunday night. A large upper level dry slot will move in with the
warmer air Sunday night...reducing shower chances and coverage.

By Monday...warmth under a middle level dry slot and relative
moisture in the boundary layer may result in sufficient
instability and mixing to support gusty surface wind as low
pressure deepens over the Great Lakes...as well as some
thunderstorms with the approach of the systems cold front.

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Long term /Monday night through Friday/...
shower chances are forecast to quickly wane overnight Monday as
the bulk of the moisture heads to the east. However...steepened
lapse rates via cool northwest flow may support some diurnal
showers Tuesday.

Unsettled weather is expected to continue through next week with
a broad upper trough influencing much of the eastern US. Confidence
is low with differing model solutions later in the week...and probability of precipitation
were kept low. Temperatures were forecast using wpc guidance...which
were at...or slightly below the seasonal averages.

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Aviation /06z Saturday through Wednesday/...
VFR conditions and light wind will prevail for the taf period as
high pressure increases subsidence over the region. Cannot rule
out some patchy fog across the region...but think that drier air
moving in should prevent any widespread formation. One exception
to this is mgw...where enough rain may have fallen in the last
24-36 hours to allow for some MVFR fog development.

Outlook.../Saturday night through Wednesday/...
restrictions are likely later Sunday and Monday as low pressure
develops toward the Great Lakes and pulls a cold front across the
region.

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Pbz watches/warnings/advisories...
Maryland...none.
Ohio...none.
PA...none.
WV...none.

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