-- Discussion containing changed information from previous version are highlighted. --
746
FXUS61 KCTP 080945
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
545 AM EDT Tue Jul 8 2025

.SYNOPSIS...
* Flash flooding and damaging thunderstorm wind risk expected
  this afternoon and evening across the southeastern portion of
  central PA
* Similar pattern setup for Wednesday with renewed damaging
  wind and flash flooding risks focused over southeast PA
* Best odds for a dry day now appear to peak on Friday;
  otherwise continued seasonably warm and humid with scattered
  afternoon and evening thunderstorms through the weekend

&&

.NEAR TERM /THROUGH TONIGHT/...
Another warm and muggy morning in CPA with areas of fog and low
clouds primarily across the western and northern Alleghenies.
Shower activity has faded out for the most part overnight with
only 1 small area of precip left in the northern tier near KN38.

Not as hot today as yesterday across the northwest 3/4 of the
forecast area with 24hr MaxT changes on the order of 5-10F to
the northwest of I-81. That said, highs will still be near/above
climo in most locations. Dewpoints in the 65-75F range will
continue to bring humid conditions with max heat index values
approaching 100F advisory threshold in the Lower Susquehanna
Valley.

Convective temperatures will be breached by 17-18z as readings
climb into the mid 80s, allowing scattered thunderstorms to
readily develop. CAMs show initial t-storm development over
southwest/south central PA before noon. As this convection
moves eastward with time and takes on a more linear mode, it
will carry an attendant risk for isolated damaging wind gusts
given an environment characterized by tall/thin, weakly
sheared/capped and water loaded sounding profiles.

Speaking of water-loading, pwats eclipsing 2" over southeast PA
will support a flash flood threat with slow moving t-storms. We
issued a flood watch starting 18Z today for a portion of the
Lower Susquehanna Valley in coordination with WFO LWX. In
addition to the robust and anomalous pwat values, very efficient
warm-rain processes could lead to rain rates >2"/hr at times
resulting in potential instances of flash flooding.

Ahead of the rain, there also remains some concern for max HX
values to reach or exceed the century mark in parts of the LSV.
A heat advy may still be needed; but for now we will continue
to highlight in the HWO.

Hires models show the majority of showers/storms will shift to
the east after midnight. Min temps trend a bit cooler night over
night with fog likely forming in the valleys through the predawn
hours Wednesday.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Similar overall synoptic setup on Wednesday & Thursday with
gradual southward shift to the severe t-storm and FF risk areas
coincident with zone of max PW. Conditions will remain humid and
with daytime highs in the 80s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The forecast for Friday and the weekend is more uncertain, with
some guidance suggesting a break in the unsettled pattern, and
others suggesting active weather continues. An active pattern
would favor continue heat/humidity while a quieter pattern could
support the intrusion of lower dewpoints and more refreshing
conditions.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
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A very sluggish, weak cold frontal boundary extended from near
KELM to KPIT at daybreak this morning, preceded by a surface
trough over the Delaware Valley.

The very shallow and just slightly cooler/marginally drier air
behind the front has trapped low stratus and stratocu with IFR
to low MVFR conditions across much of far western PA, Ohio and
Western NY. The southeast half of PA was generally VFR with only
scattered clouds and a bit of haze/light fog with just a few
spots coming in with MVFR Vsbys.

The clear skies to the east and extensive low clouds through
this morning over the west will greatly increase the temp
gradient east to west across the front as strong heating occurs
in the mainly clear air with a much slower warmup west of the
front. Any IFR CIGS for the next several hours will be across
the Laurel Highlands and NW Mtns.

MVFR could linger into, or through this afternoon at KBFD, while
KJST should hold onto MVFR conditions until around 16Z, before
seeing an improvement/lifting of the low cloud bases.

Previous Disc...

Muggy air with sfc dewpoints in the upper 60s to low 70s
covered much of the SE 2/rids of the state at 06Z and these
conditions will persist ahead of this front across much of
Central and SE PA, while slightly cooler air with an 8-10 deg F
drop in dewpoint values will occur across the NW part of PA
today.

A few additional showers could develop by midday today, but
showers and thunderstorms will become more prevalent as we head
into the afternoon. Brief restrictions are possible everywhere
except BFD, with storms starting in the vicinity of a line
extending from JST/AOO to UNV to IPT and then moving east-
southeastward and affecting MDT and LNS later in the
afternoon/early evening.


Outlook...

Tue PM...Showers fade, fog possible across much of the region
into Wednesday morning.

Wed...Best chance for storms and restrictions in southern PA.

Thu-Sat...Potential for showers and thunderstorms, mainly
aftn/eve.
-- End Changed Discussion --

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 2 PM EDT this afternoon through this evening
for PAZ057-059-065-066.

&&

$$

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