Saturday, July 21, 2018, 3:27 AM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 210505 AAC
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
105 AM EDT Sat Jul 21 2018

.SYNOPSIS...
Periodic rain chance into early next week with the encroachment
and passage of slow moving low pressure.

&&

.NEAR TERM /THROUGH TODAY/...
Only minor changes to the overnight period. PoPs were adjusted
in line with radar trends and latest model guidance. Expect to
see showers expand in coverage over the west late tonight as a
band of moisture drifts eastward ahead of the main 500mb low.
Also, a noticeable area of low-level convergence will develop
underneath this moisture band which will assist in expanding
rainfall eastward as dawn approaches. 

Upper low will sit and rotate over Ohio today. This will provide
the risk for showers and possibly a thunderstorm throughout the
entire day. The trough axis, extending southward from the center
of the low will remain over the western half of the region and
this will be the primary area where large scale ascension will
rest. Because of this, have kept higher PoPs generally over my
Ohio counties and with these likely PoPs, have included the
mention of thunder. Atmosphere does not destabilize much today,
and there will be little to no sun to stir things up, but low-
level moisture convergence will continue under the 500 low which
will cause an increase in parcel ascension and thus possibly
lead to iso-sct convection.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
The aforementioned upper low will slowly transition south into 
Monday, before phasing out in the increasing southerly flow 
aloft. This will result in continued unsettled conditions with 
periodic showers and thunderstorms. A diurnal trend to POPs and 
storms was maintained in the forecast, which seem appropriate 
with this pattern. Extensive cloud coverage will keep high 
temperatures slightly below average and lows slightly above 
through the weekend.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Minimal change made to the extended today with decent model
continuity with previous runs. Shower/storm chances will
continue daily as the upper low over Ohio continues south and  
another upper low approaches southeastern Canada. The best
chance for areawide activity will be Wednesday with a surface 
cold front. Temperatures will be near seasonable levels.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
Mainly VFR conditions are expected for most ports through the
TAF period, though low level moisture in place across OH could 
result in some MVFR cigs at ZZV this morning. Otherwise, swd 
drifting low pressure across the OH Valley should result in 
mainly diurnally driven sct showers with local restrictions. 
Enough instability is progged across OH for a VCTS mention at 
ZZV during the aftn.

OUTLOOK...
Periodic restriction potential continues through mid week with
the slow moving low and subsequent upper troughing.

&&

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

&&

$$

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