Area Forecast Discussion
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FXUS61 KPBZ 161938

Area Forecast Discussion
National Weather Service Pittsburgh PA
338 PM EDT Thu Aug 16 2018

Periodic shower and thunderstorm chances are expected through
part of Saturday with a series of crossing disturbances. Dry
weather returns Sunday under high pressure.


Showers and thunderstorms will continue through the period with
a relative lull in between waves this evening. Cloud cover has
limited the amount of diurnal destabilization across western
zones so expect the brunt of storm development to be farther
east through the afternoon. Overnight storm chances even out
over the area with elevated instability getting tapped by an
increasing low level jet. Instability is marginal so don`t
expect the greatest coverage or severe threat. PWATs have
increased substantially over the last 24 hours but sufficient
storm motion should preclude anything more than an isolated
flood potential...due to training storms.


Additional shortwaves in SW flow ahead of the main trough
should support periodic shower and thunderstorm chances through
Friday. Shear is progged to increase some, though cloud cover
should limit instability. A few strong storms are possible if
enough partial clearing and greater destabilization occurs.

Shower and thunderstorm chances are expected to continue Friday
night through part of Saturday as the main upper trough, and
its associated cold front, cross the region. Tapered POPs down
from N-S Sat as the front sinks S. Expect mainly dry conditions
area wide by late Saturday night as the front exits.


Sunday and most of Monday will be more comfortable with
dewpoints around 60 and dry conditions. The next trough is
progged to advance out of the Plains and approach/cross our
region Tuesday through part of Wednesday. Maintained likely POPs
Tue as the trough and its associated sfc low/cold front tracks
across the region. Slight to low chance POPs were included for
Wednesday until the trough exits E. Near to above average
temperatures should fall to below average readings by midweek.


Little change to the 18z set of TAFs as moisture increasing from
the southwest and a supporting shortwave allow for expanding
shower coverage through the afternoon. Instability will be
rather meager west of I-79 but still thought it best to keep a
VCTS mention based on the latest radar and mesoanalysis trends.
VFR should generally prevail, though some visibility
restrictions where heavier showers and storms pass over a
terminal given the saturated atmosphere.

Models continue to suggest some degradation in ceilings
overnight, which seems reasonable given upstream conditions.
Thus, will carry MVFR cigs toward morning for most sites, with
greatest confidence north and west of PIT. Fog should be limited
as a result of continued mixing overnight.

Coverage of showers should decrease toward morning, leading to
a return to high VFR/high MVFR conditions before the next
shortwave approaches later tomorrow.

Brief restrictions are possible until a cold front passage
Saturday. VFR conditions expected later Saturday and Sunday.




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