881
FXUS61 KCTP 171802
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
202 PM EDT Mon Aug 17 2026

.WHAT HAS CHANGED...
* Minor adjustments upward in POPS today

&&

.KEY MESSAGES...
1) Scattered to numerous, brief showers ahead of a cold front
into the early/mid afternoon hours

2) High pressure yields a short dry window tonight through
Wednesday. More storms arrive Wednesday afternoon in the NW and
cross/affect the area into Thursday.

&&

.DISCUSSION...
KEY MESSAGE 1: Scattered to numerous, brief showers ahead of a
cold front into the early/mid afternoon hours

Update...
Bumped up the PoPs over a good part of the area by 10-30pct
leaning on current radar trends and expected coverage on HREF
progs.

Previous...
Warm and humid conditions cover the CWA with anomalously high
PWAT values of around 2 inches. SFC cold front pushing just SE
of the Interstate 90 corridor ATTM.

Latest mesoanalysis shows MU CAPE of over 1000 J/KG just ahead
of the aforementioned cfront from the lowlands of Western PA,
int far SW New York. This instability axis was supporting some
low-topped TSRA near KJHW with a channel of numerous showers
extending south along and to the west of the RT 219 corridor.

The frontal boundary will cross the CWA during the late morning
and afternoon hours, likely clearing the PA/MD border by dusk.

MU Cape values ramp up across the SE half of PA (to over 1500
J/KG) for the mid to late afternoon hours, supporting the
development of scattered to numerous showers with scattered
TSRA. Very weak diffluent flow aloft and the lack of significant
llvl convergence ahead of the front should temper the intensity
of the TSRA updrafts, but it wouldn`t surprise me to see a SPC
upgrade to MRGL DY1 risk for SVR TSRA across Southern and
eastern PA with their late Dye morning update.

SFC TDs in the upper 60s to low 70s today (and PWAT AOA 2
inches) will be the fuel for some brief heavy downpours with the
showers and isolated to scattered TSRA. QPF could be on the low
side in some spots today, where a 10 minute heavier shower or
TSRA could bring pinpoint 0.25 of an inch amounts.

Dewpoints will drop 5-8 degrees from today to tomorrow
afternoon accompanied by abundant sunshine on Tuesday.


------------------------------------------------------

KEY MESSAGE 2: High pressure yields a short dry window tonight
through Wednesday. More storms arrive Wednesday afternoon in the
NW and cross/affect the area into Thursday.

A cold front moves through late today and this evening.
By sunset, showers and any thunderstorms will be winding down
and gone by 9-10pm. Dewpoints drop into the 50s for the N and in
the m60s Tuesday, which is a little more moist than previous
prognostications. Large scale subsidence should yield a mostly
sunny day, then. Return flow Tuesday night and Wed will bring
the humidity up and a cold front will approach on Wednesday.
Storms are expected mainly in the Wed-Wed night timeframe, but
speed of the CFROPA will determine if all/part of Thursday will
be dry. If showers linger, they would be over the south.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Scattered showers are moving across PA as of 18Z this afternoon.
As these move southeast, the sites most likely to see effects
from this activity are JST, AOO, and IPT. Thunder is likely to accompany
the strongest cores, but will remain spotty, said cores have
IFR visibility potential. The scattered nature of these storms
means exact impacts to sites such as UNV, MDT, and LNS are more
uncertain this afternoon with confidence < 30% of impacts to any
one site. Regardless, these sites may need to be watched for a
quick amendment if they cross paths with a stronger core of
precipitation. VFR otherwise into the night.

As a cold front sweeps through the state, drying air will shunt
precipitation off to the south overnight and into Tuesday.
Lingering moisture and clearing skies are likely to lead to
visibility restrictions and low cloud ceilings across most sites
overnight and into early Tuesday morning. MDT and LNS look to
be the least impacted from these restrictions, although some
visibility drops are possible and may depend on how much rain
falls this afternoon. Once this activity burns away with the sun
rising, a dry, less cloudy postfrontal environment follows with
VFR categories.

Outlook...

Wed... VFR conditions with restrictions from afternoon SHRA/TSRA
possible in the northwest

Thu... Afternoon SHRA/TSRA with brief restrictions possible.
Otherwise, VFR conditions.

Fri...Chance of SHRA across the south, restrictions possible,
otherwise dry.

Sat...Chance of SHRA statewide, restrictions possible

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

WHAT HAS CHANGED...Dangelo
KEY MESSAGES...Lambert/Dangelo
DISCUSSION...Lambert/Dangelo
AVIATION...Lambrech