Friday, July 20, 2018, 4:45 AM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 200810
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
410 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/...
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 /08Z FRIDAY THROUGH TUESDAY/...
Eroding high pressure will maintain VFR until a shortwave ahead
of low pressure approaches later today. This wave should result
in aftn shower/tstm chances W of I 79, with the highest
potential for tstms across OH. 

OUTLOOK...
Periodic restrictions are likely through the weekend with slow 
moving low pressure.

&&

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

&&

$$

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