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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 160943

Area Forecast Discussion
National Weather Service State College PA
543 AM EDT Mon Sep 16 2019

A weak stationary front overhead will get nudged off to our
south today and early tonight. High pressure will build in from
the north and bring a very long stretch of dry weather.


Short wave trough seen on water vapor imagery is moving across
nrn OH and into PA. This wave is generating a cluster of showers
over wrn PA. These should continue for the next 3-4 hrs as the
wave drops into PA. The drier air overhead will help to
diminish these showers, but the lift will remain and string out
along the upper flow as the weak low off to our west nears. That
will likely help keep showers going across the central and
northern zones for much of the day. May nudge higher PoPs
southward a little based on latest guidance. 

A nearly stationary front has developed over the CWA with
upglide on the NE side of the front responsible for light
showers. A weak 1016mb sfc low is seen over srn LM moving this
way along the front. One area of showers over the NE will dive 
SE with time, but are just making it a little wet. The next
batch of showers is over NErn OH and dropping SE as well. No 
heavy rain is expected, but a damp morning is in store for the 
northern half of the area and the Laurels. Thunder is not 
expected, either. The axis of the most numerous showers will 
drop southward through the day, laying out across the central 
zones late in the aftn. The northern tier will be drying out 
then as the wind goes decidedly NE. Again, only light precip for
the most part, but someone may pick up a quarter of an inch 
over the north. The prevalent clouds will keep the temps cooler 
- but near normal - in the northern and central zones. But, they
will be a few degs F above normal in the southern tier where 
large breaks/times of sun are expected. Maxes there 80-85F.


The front should be south of the state around sunset, but
showers could linger for much of the night over the south. The
clearing expected across the north will lead to temps getting
down into the 40s and the requisite fog in the valleys of the 
north. The fog could linger into the middle of the morning in
the deeper valleys. Overall, though, it will be a dry, sunny
day. Dewpoints will be in the 40s and lower 50s. Maxes in the
u60s-m70s will be spot on normal.


A large upper level ridge will build over the Great Lakes which
will dominate the weather pattern through the week. This should
keep central PA dry through the week, perhaps until Sunday. 
Temperatures near normal at first should rise well above normal
as the ridge pumps up and slides eastward a little.


A weak area of low pressure approaching from the midwest will
spread mid level cloudiness across central Pa tonight with a
light rain shower possible over the northern part of the state.
Model soundings and latest SREF probability charts support
widespread VFR conditions tonight. However, if clouds thin
enough, a period of fog is possible around dawn at KIPT, as the
latest LAMP and NAMNest indicate. 

The weak low pressure and trailing cold front will slide across
the region on Monday, accompanied by scattered showers. VFR
conditions should prevail Monday for much of the region.
However, post-frontal, low level moisture combined with
orographic lift is likely to result in MVFR cigs during the PM 
hours across the northern mountains. 


Tue-Fri...AM valley fog possible central/northern PA.




NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Dangelo/Ceru/Evanego