923
FXUS61 KCTP 301802
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
202 PM EDT Mon Jun 30 2025

.SYNOPSIS...
* Stormy pattern resumes for this afternoon and again for
  tomorrow as a warm front (today), then cold front (tomorrow) pushes
  through the region, bringing a renewed risk of strong to
  severe storms and locally heavy downpours
* Drier/less humid/more comfortable conditions are likely from
  mid to late week with high confidence of nice weather on
  Independence Day

&&

.NEAR TERM /UNTIL 11 PM THIS EVENING/...
Healthy moisture return will occur through this afternoon with
PWAT values climbing by another 3-4 tenths between 17-23Z today,
peaking from about 1.8 inches across the NE Mtn zones to around
2.25 inches across the Lower Susq Valley.

Lowest FFG values and highest concentration of 3 hour QPF Ens
Probability matched mean values over 1.5 inches gave us the
backing to collaborate/issue a Flash Flood Watch for our NW Mtns
and Laurel Highlands through 10 pm this evening.

Heavy showers and TSRA forming near and to the south of a slow
moving warm front will have the potential to train NE across the
same locations and bring the risk of Flash Flooding.

Pertinent and still valid parts of the previous discussion
follow -

The NE surge of deep-layer moisture will occur downstream of an
amplifying mid-upper trough moving into the Upper Midwest and
western Great Lakes. Numerous showers and thunderstorms are
expected beginning early this afternoon and lasting through this
evening as shortwave energy supplies large scale forcing for
ascent. Given the presence of weak/modest vertical wind shear, a
few of the storms could become strong to locally severe. Strong
boundary-layer heating is expected with 2000+ J/kg of tall/thin
SBCAPE) amid relatively weak effective shear values of 25-30
knots. This environment will support the potential for wet
downbursts and damaging wind gusts.

Max temps will range from the low-mid 80s across the high
terrain of the north and west, to the upper 80s in the central
and southern valleys.

Storms will continue into this evening with cold pools taking
over and bringing an end to the widespread shower activity after
dark.

&&

.SHORT TERM /11 PM THIS EVENING THROUGH TUESDAY NIGHT/...
Given the refuel of surface water from Monday`s rain and sultry
conditions tonight, expect fog tonight into Tuesday morning,
especially where low clouds can break.

It will be quite warm and muggy tonight with temps slowly
slipping through the 70s before reaching a low in the mid to
upper 60s across the northern and western mtns and 70-75 in the
central and southern valleys.

The aforementioned mid-level trough will shift east from the
Great Lakes to the Northeast on Tuesday. Moderate mid-level flow
will overspread much of the region, including placing central PA
in the right entrance region of an upper-level jet. At the
surface, a cool front will move east across PA and will be the
primary focus for severe thunderstorm potential Tuesday
afternoon/evening.

Stronger shear profiles will be present on Tuesday and this may
result in greater storm organization/intensity including the
potential for a few supercells capable of producing large hail
and damaging wind gusts. Storms should eventually congeal into a
more solid line as the front makes closer approach, maintaining
a damaging wind threat into the Lower Susquehanna Valley.

Drier air will begin advecting into central PA late Tuesday into
Tuesday night with dewpoints dropping well into the 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
In the wake of the cold front passing east of the area by
Wednesday morning, high pressure begins to build southwest of
the region, providing fair weather for the middle of the week
and into the weekend. Best chances for precipitation through
Saturday will remain due to a cold frontal passage across the
northern half of Pennsylvania. Cold front remains relatively
moisture-starved; however, generally think forcing will be
enough to cause a shower and afternoon/evening thunderstorm.

Low pressure approaching the Great Lakes by Sunday morning will
bring about increasing chances for precipitation for the second
half of the weekend and into the beginning of next week.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
High res ensemble guidance and individual CAM members show
convective showers and TSRA steadily expanding in coverage from
SW to NE across Central PA and the Susq Valley during the mid
afternoon through early evening hours.

The bulk of the time (95+% of the TAF period) will stay VFR, but
brief periods of MVFR are likely with heavy showers or TSRA
at most airfields between 20Z today and 00-01Z Tuesday

Predominantly VFR conds are expected to continue overnight,
although there is low confidence that some spots could see the
development of fog/low clouds during the predawn hours. High and
mid level clouds may help to limit fog development.


Outlook...

Tue...PM showers & t-storms likely; areas of fog & low clouds
as well.

Wed...AM fog, then VFR.

Thu...Primarily VFR; stray PM shower/t-storm possible.

Fri...AM fog possible; otherwise VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 PM EDT this evening for PAZ004-005-010-
017-024-033.

&&

$$

SYNOPSIS...Guseman/Lambert
NEAR TERM...Guseman/Lambert
SHORT TERM...Guseman/Steinbugl
LONG TERM...Evanego/NPB
AVIATION...Lambert/Martin