Friday, July 20, 2018, 12:39 PM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 201439
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1039 AM EDT Fri Jul 20 2018

.SYNOPSIS...
Periodic rain chance returns today and through the weekend with
the encroachment of slow moving low pressure.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor updates to slightly increase timing of precipitation
across eastern OH zones but otherwise no changes needed this
morning.

PREVIOUS..
A cutoff low will move over the western Great Lakes 
today and swing an upper trough across a portion of the area 
this afternoon. Still seeing a great deal of model disagreement 
on how much of an impact this trough will have today. Models are
depicting a line of showers and some thunderstorms moving into 
our western counties early this afternoon and then fizzling out 
as it continues to drift eastward. The loss of upper level 
support appears to be the culprit, as the strong large scale 
ascension remains anchored near the upper low.

Additionally, deep layered moisture will be sparse, as 
atmospheric saturation will remain closer to the 500mb low. 

Temperatures will be a couple degrees above average.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
The upper level low will slowly meander south during the period,
sliding from southern Lake Michigan to southern Ohio by Sunday
afternoon. This will keep periodic showers and thunderstorms in
the forecast. Continued the inherited diurnal trend to POPs and
storms which seem appropriate with this pattern. Highs will be 
a couple degrees below average with extensive cloud cover.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
While the upper low over Ohio will continue to drift south,
another upper low will develop over central Canada and move
southeast. Between the two systems, there will be little change
in the pattern of scattered showers and thunderstorms. Likely
pops are in the forecast on Wednesday as a result of a surface
cold front. Temperatures will be near seasonable levels.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
High pressure should maintain VFR conditions as it exits this
morning. A shortwave ahead of low pressure is expected to 
approach later today. This wave should result in aftn 
shower/tstm chances W of I 79, with the highest potential for 
tstms across OH. Maintained a VCTS mention for the affected
ports, with a tempo tstm/MVFR for ZZV. Some MVFR cigs are
possible across OH toward morning with low level moisture in
place. 

OUTLOOK...
Periodic restriction potential continues through the weekend 
with slow moving low pressure.

&&

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

&&

$$

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