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630
FXUS61 KCTP 091921
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
321 PM EDT Wed Jul 9 2025

.SYNOPSIS...
* Scattered damaging wind gusts and flash flooding are possible
  across portions of south central and southeastern Pennsylvania
  this afternoon and evening
* Continued seasonably warm and humid into mid July with daily
  chances for afternoon and evening thunderstorms

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Latest satellite and radar trends show convection developing and
intensifying along multiple convergence boundaries ahead of a
northeastward moving shortwave trough. Thus far, storms have
remained below severe limits, but we do see the chance for
damaging winds increasing into the early evening hours across
the southern tier, where low level lapse rates are above 7C/km,
MLCAPE is near 1500 J/kg, and DCAPE is between 700 and 900
J/kg. Effective wind shear is around 40 kts from the SW. This
direction aligns with the orientation of many of the initiating
boundaries, particularly those along the higher terrain of the
central Appalachians. The alignment of the shear (and the flow)
with the initiating boundaries increases the threat for training
convection and ultimately flash flooding. Thus the Flash Flood
Watch and Severe Thunderstorm Watch continue for the
southeastern tier. Convection will likely be slow to clear out
of Lancaster County, with some of the guidance depicting
moderate to heavy rain continuing as late as midnight before the
trough kicks it east.

For the rest of the night, patchy fog is possible, particularly
in places that see some clearing after earlier rainfall.
Temperatures will be in the 60s to near 70 degrees.
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&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
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Diurnal heating of a seasonably moist and weakly capped
boundary layer will result in at least isolated to scattered afternoon
thunderstorms across central PA again on Thursday and Friday.
However, precipitable water values look to trend lower vs.
previous days. This will reduce the excessive rainfall and flash
flood risk while remaining sufficient to support the potential
for wet downbursts and isolated wind damage. SPC has maintained
a MRGL risk for both D2/Thu and D3/Fri. Typical mid July
summertime temperatures expected with daytime highs in the
80-90F range and lows 60-70F.
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&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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Daily chances for afternoon/evening thunderstorms continue over
the weekend and into early next week with max/min temps trending
near to slightly above normal for mid July. Tuesday may stand
the highest chance of being a completely dry day, but even
then, PoPs are 20-35 pct.
-- End Changed Discussion --

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Variable cloudiness is expected this afternoon with scattered
mid level clouds area wide and a deck of high level clouds
moving in across the northwest. VFR conditions will prevail
until scattered showers and thunderstorms begin to build later
this afternoon and evening.

A few light showers are possible at JST and AOO, perhaps even as
far north as UNV, but any restrictions should be brief. Farther
southeast, heavier showers and stronger storms are expected in
MDT and LNS between 22 and 02Z with reductions to MVFR or IFR
vis expected as storms move through.

The forecast for tonight gets a bit more complicated in terms of
cigs and vis. High clouds should limit the potential for
radiation fog tonight, but moisture pooling as a result of
recent rains could still lead to some fog/low ceiling potential.

At this point, the best chance for radiation fog will be BFD and
JST where clearing may build in before daybreak. Have indicated
at least a period of MVFR restrictions at all airfields tonight,
but confidence remains fairly low in the extent and duration of
such impacts.

Outlook...

Thu...Restrictions in possible in scattered PM storms.

Fri-Sat...Scattered afternoon/evening storms, mainly south.

Sun...More widespread showers/storms likely.

Mon...Still storms around.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 11 PM EDT this evening for PAZ064>066.

&&

$$

SYNOPSIS...Steinbugl/Colbert
NEAR TERM...Steinbugl/Colbert
SHORT TERM...Steinbugl/Colbert
LONG TERM...Lambert/Colbert
AVIATION...Banghoff