872
FXUS61 KCTP 080818
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
418 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 /07Z TUESDAY THROUGH SATURDAY/...
A very sluggish, weak cold frontal boundary extended from near
KBFD to KPIT early this morning, preceded by a surface trough
from the Wyoming Valley south to the Lower Susquehanna Valley.

A few small clusters of slow moving showers (with brief heavy
rain) were noted along and just ahead of the cold front across
the North-central Mountains. 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.

Patchy fog is possible at all TAF sites early this morning.
However, cloud cover and a light breeze from the west early
today will likely negate a significant threat for widespread
fog. IFR/LIFR ceilings are favored for several hours at BFD and
JST with MVFR likely at IPT, UNV, and AOO.

A few additional showers could develop by midday today, but
showers and thunderstorms will become more widespread 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.

&&

.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