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000
FXUS61 KPBZ 230638
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
238 AM EDT Wed Aug 23 2017

.SYNOPSIS...
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Quieter weather today before showers return Thursday. Cooler
and less humid are the themes through the weekend.
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&&

.NEAR TERM /THROUGH TODAY/...
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A cold front extends from around Seven Springs toward Hundred,
WV, as of 230 AM. This should continue to hold itself together
fairly well as it transits to the southeast given the rather
abrupt density discontinuity along the front in the lower levels
as dewpoints drop from the 70s in the 50s over a fairly short
distance between northern WV and Cleveland.

With the drop in dewpoints in mind, while some fog has developed,
once northwesterly dry advection begins in earnest in the
boundary layer, it would seem additional fog development will
become unlikely fairly rapidly. While some 3-5 mile visibilities
will be possible through morning, dense fog seems unlikely
given isallobaric flow and drier air moving in.

With drier air in most of the column for today, skies should
start out mostly sunny across the board save for departing
clouds in the southeastern reaches of the area. However, even
with a rather dry atmosphere aloft, the mid-level cold pool does
transit the southern Great Lakes. This will lead to enhanced
lapse rates in the mid-level and some cumulus development. While
showers will be most likely generally near and north of Lake
Erie, it seems more unlikely that they would spread as far south
as I-80. PoPs were kept non- zero, however a mention of showers
will not be added to the forecast at this time. Fries
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&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
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Large scale troughing will be the theme through the short term
forecast. With this, one decent wave embedded in the large scale
cyclonic flow over the area looks to impact Thursday.

A decent chunk of mid-level cold air drops toward the area on
Thursday. With this, a fairly vigorous short wave trough will
also transit. Moisture content in the layer is lacking, and jet
support is modest, so deep convection seems unlikely, however a
shower or two with its passage seems plausible. PoPs were thus
adjusted to chance levels, skies increased a bit in the peak
heating/destabilization hours, and high temperatures knocked
back a few degrees due to cloud expectations.

Beyond Thursday, northwesterly flow will remain entrenched. As
such, continental dry air will maintain sway over the area. This
will limit precipitation chances and keep temperatures largely
below normal with a fairly wide diurnal spread due to a dry
boundary layer. Fries
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&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
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The departing mid level trough and associated low pressure
system owes to several nice weather days late this week through
the weekend. Surface high pressure builds south from the Great
Lakes and with northerly flow on the front end expect below
normal temperatures to continue into the middle of next week.
Toward the end of the forecast /next Tuesday/, moisture from
the Gulf resulting from Harvey may provide a canopy of high
clouds, but still plenty of time to resolve that over the coming
days.
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&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
Remaining showers SE of PIT should end overnight as a cold front
completes it`s passage. Otherwise, mainly VFR conditions are
expected through the TAF period with diurnal CU and SC under
building surface high pressure.

.Outlook...
No widespread restrictions expected under surface high
pressure.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$