Area Forecast Discussion
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500
FXUS61 KPBZ 261729
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
129 PM EDT Fri May 26 2017

.SYNOPSIS...
Rain chances return tonight, continuing at times through the
holiday weekend with another area of low pressure.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A narrow band of showers continues to edge slowly southward
across the central CWA along a subtle windshift boundary. The
western end is already eroding, and expect this trend to
continue as a weak ridging pattern builds in. Other scattered
showers outside of this band should mostly dissipate by early
afternoon as well. Clouds will linger through much of the day
however as low level moisture will be slow in scouring out. Kept
previous forecast of temperatures a few degrees below seasonal
levels.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
After a dry evening, shower chances are expected to increase
tonight and Saturday as a shortwave advances out of the
Midwest and crosses the region. An associated surface boundary
is progged to set up across the Lwr OH valley through Sat night.
The most favorable shear/instability is progged S of the
boundary, keeping the best chance for strong thunderstorms S of
the forecast area, though minimal instability further N could
result in a few thunderstorms.

The surface boundary is progged to lift N across the area Sunday
in response to another crossing shortwave, and low pressure
tracking from the MS Valley to the Lwr Great Lakes. Maintained
likely POPs for showers/storms with sufficient upper support
and moisture expected. The low`s associated cold front is
progged for a late Sun/Sun night passage as the low tracks to
Ontario, continuing the shower/storm chances. After any morning
showers exit Mon, little support is depicted in the models for
precip the remainder of the day. Temperatures are expected to
average a few degrees above seasonal levels through the period.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
A broad upper trough is expected to persist across the Great
Lakes and NE CONUS region through much of the week. Shortwaves
rotating through the main trough should result in periodic low
chances for showers, as temperatures return to within a few
degrees of average.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 17Z, ZZV and MGW had VFR ceilings, and ceilings should
trend upward into VFR levels slowly from south to north through
the rest of the afternoon. Little more than drizzle is expected
through the afternoon as well. Low pressure and an area of
showers and thunderstorms currently over Iowa and Illinois will
track east this afternoon/evening and should hold together into
the forecast area. There is still some uncertainty as to the
track by the time the low pressure system arrives, but the
current forecast keeps the highest chance of thunderstorms to
ZZV/HLG/MGW between midnight and sunrise. Once low pressure
passes, some showers may continue, but the greater flight impact
will come from IFR ceilings that will develop. IFR should
persist through the morning, with ceilings eventually lifting to
VFR during the afternoon.

.Outlook...
Showers continue through much of the period with episodic
restrictions.

&&

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

&&

$$



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