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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 200728
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
328 AM EDT Tue Aug 20 2019

.SYNOPSIS...
It will remain very warm and humid through mid week and a weak 
trough of low pressure will keep the chance of mainly afternoon 
and evening showers and thunderstorms in the forecast. Cooler 
and much less humid air will arrive for Thursday through 
Saturday with dry conditions expected.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A calm wind and mostly clear skies will likely result in late 
night valley fog, mainly over northern Pa, where soil moisture 
is the highest. 02Z observations indicate dewpoint depressions
are already approaching zero over northern Pa, so expect fog to
begin forming by midnight. 

Latest model blend supports lows tonight ranging from the mid
50s in the coolest valleys of the north, to around 70F across
the Lower Susq Valley.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
Approaching mid/upper level short wave trough and increasing 
south to swrly LLVL flow along and to the south of a weak warm 
frontal boundary will help ramp up convective parameters Tuesday
afternoon, with scattered afternoon showers and storms expected
in all parts of the state. Weak 0-6km shear will not be
conducive for organized severe weather. However, it will be
unstable enough across the southern half of the state to support
vigorous updrafts and the potential of isolated damaging wind
gusts/large hail.

Mixing down ensemble mean 850mb temps of around 17C should support
high temps Tuesday ranging from the low 80s over the northern 
mountains, to around 90F in the Susq Valley.

A slightly higher probability for TSRA Wednesday afternoon and 
evening as a more vigorous upper shortwave and associated sfc 
CFROPA pushes southeast through the CWA late Wednesday and Wed 
night.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Rain risk will linger across south central PA on Friday as the
frontal boundary continues to sink southward into the southern
Mid Atlantic. 

A sprawling area of Canadian high pressure should bring a
multi-day stretch of fair weather to central PA Saturday to
Monday. Temperatures will be near average with pleasant and 
warm afternoons and comfortably cool nights. 

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Fog impacts are likely early this morning with local vis/cigs 
at or below alternate/airfield minimums. Return to VFR by 
14-15Z. Showers and thunderstorms will develop and become most 
numerous across the southern airspace this afternoon and 
evening. Brief restrictions are possible in heavy downpours with
strong wind gusts. 

.Outlook...

Wed...PM thunderstorms. 

Thu...PM thunderstorms southeast 1/2.

Fri...Chance of rain southern 1/4. 

Sat...AM fog possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...La Corte
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/La Corte
LONG TERM...Steinbugl
AVIATION...Steinbugl