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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 162319

Area Forecast Discussion
National Weather Service State College PA
719 PM EDT Sun Jun 16 2019

An unsettled and stormy weather pattern is expected across 
central Pennsylvania this week. There will be multiple rounds 
of heavy downpours with the potential for localized flooding 
and isolated severe storms. Temperatures and humidity levels are
forecast to remain near average for mid to late June.


SFC cold front is the focus for showers and thunderstorms this
evening from the Ohio Valley across north central PA. SFC CAPES
ranging from 500-1000 J/kg are taking advantage of a high
moisture, low LCL environment and favorable shear,
particularly INVOF the aforementioned front to maintain low
topped spinners tracking along the baroclinic zone from eastern
OH through western PA, prompting several TOR warnings outside of
our CWA. Still watching some of these cells closely and others
along the boundary draped just north of the I-80 corridor.
Heavy downpours also accompanying these cells feeding on 1.5"+

Showers and a few storms will likely linger into early tonight, 
with fading coverage and intensity after midnight as the
boundary drops to the south and deep layer moisture is shunted
to the southern third of central PA. Dewpoints will drop a bit  
overnight across northern PA thanks to building high pressure, 
but it will remain rather muggy across the south. Any BINOVC
will lead to fog formation later tonight and Monday morning
across central and northern PA.


Active weather pattern continues into early next week. SPC is 
targeting south-central and southeastern PA with a SLGT risk of
severe storms, with an isolated severe storm possible farther to
the north.

WPC is highlighting southwestern and south-central PA with a
SLGT risk for excessive rainfall/flash-flooding on Monday. The
airmass will be plenty juicy, with the 12z GEFS projecting PWATs
to reaching 1.5 to 2 inches (which is +1 to +2 SD above-normal).


Fairly relentless stream of showers and scattered thunderstorms
in store for much of central PA Mon into Thu as an E-W oriented 
frontal boundary wiggles over the region. Though it won't be
raining the entire time, it will definitely be a soggy and
cloudy run of weather.

Models hint at a drier period toward the end of the week into 
first half of the weekend, which translates to just isolated 
showers focused on the NW half. But precip chances increase 
again as another storm is progged to lift into the Great Lakes 
Sunday brushing our western areas.

Though elevated dewpoints will keep muggy conditions in place
with above average low temps, highs will top out a bit below
normal each day.


A dying cold front sagging into central Pa will be the focus for
evening showers, mainly along and just south of I-80. However, 
the main concern overnight will be low clouds and fog developing
in the vicinity of this front, which will be stalling out over 
the area tonight. 22Z surface analysis shows IFR cigs across the
northern mountains, with mainly VFR conditions noted across the
rest of the region. SREF/HREF probability charts support the
continued likelihood of low cigs across the northern mountains
through 06Z, with the Laurel Highlands also likely to experience
IFR/LIFR cigs toward dawn Monday. Elsewhere, plenty of low level
moisture, a diminishing wind and breaking clouds support the 
idea of patchy fog. However, confidence is not high in
significant fog formation due to an approaching area of low 
pressure and associated return of cloud cover late tonight, 
which would diminish the threat of radiation fog.

Models indicate an area of low pressure will track across
southern Pa Monday, producing rain and low cigs across the
central part of the state. Somewhat more favorable conditions
are possible along the southern tier of the state, where
precipitation will fall as scattered showers, rather than a
steady rain, and cigs are likely to be higher. More favorable 
conditions are likely over the northeast corner of the state, 
where little rain is expected and VFR cigs appear likely.


Tue...AM low cigs/fog possible. Scattered PM tsra impacts
possible south.

Wed...Patchy AM fog possible. Isold PM tsra impacts possible
western half of Pa. 

Thu...AM rain/low cigs possible. Scattered PM tsra impacts


Astronomical summer (solstice) begins Friday, June 21st at
1154AM EDT (1554 UTC).




NEAR TERM...DeVoir/Evanego
SHORT TERM...Evanego
LONG TERM...RXR/Steinbugl