-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 251748
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
148 PM EDT Thu May 25 2017

.SYNOPSIS...
Slow moving low pressure will keep rain in the forecast through
early Friday. Rain chances return for part of the weekend with
another area of low pressure.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Made some mainly cosmetic changes to the forecast for the
afternoon. Deep moisture and lift providing showers this morning
will lift north of the region by early afternoon. Some breaks in
the cloud cover will help to steepen low-level lapse rates,
allowing scattered to numerous showers to develop during peak
heating. There will be enough instability for isolated
thunderstorms. In line with SPC outlook, any isolated severe
risk will be mainly limited to areas along the ridges, along
the edge of more favorable but fading deep level shear. Slightly
lowered max temperatures, but not as low as LAMP guidance given
breaks in the clouds could still allow values to pop into at
least the mid 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
Another area of ascent and deep layer moisture is progged to
track across the region tonight as the low begins to drift E of
the area, with increasing POPs for showers. A few showers could
continue through Fri morning until the low exits the E coast and
shortwave ridging builds in.

The next approaching shortwave and surface warm front is
progged for Fri night/Sat as surface low pressure tracks NE from
the Srn Plains, resulting in shower chances increasing. Model
progged instability is sufficient S of I 80 for thunderstorm
chances also. The low is progged to track across the lower Great
Lakes Sunday, dragging a cold front across the region.
Maintained likely POPs for showers/tstms with it`s approach and
passage. After below average readings Friday, temperatures
should return to near or above average levels by the weekend.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Upper troughing is progged across the NE CONUS through most of
the period. Individual shortwaves rotating through the trough
should maintain periodic shower chances, with the Memorial Day
holiday progged to see the least activity at this time.
Temperatures should average within a few degrees of the seasonal
levels.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
Upper low continues to sit and spin across eastern Ohio. A wave
of showers has moved through the forecast area this morning, and
will rotate through the area once again this evening into the
early morning hours. Some scattered showers will remain in
between the waves, and cannot rule out a chance of an isolated
thunderstorm, although confidence/coverage is low.

In between the waves, many locations from Pittsburgh to the
south and east should have at least a few hours of VFR
ceilings, although ZZV/BVI/FKL/DUJ are expected to remain close
enough to the bands of steadier rainfall for ceilings to remain
IFR/MVFR. All terminals will drop to IFR, if not LIFR ceilings
overnight in steadier rain, and low clouds will continue well
into Friday.

.Outlook...
Showers continue through much of the period with episodic
restrictions.
-- End Changed Discussion --

&&

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

&&

$$