FXUS61 KCTP 231713
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
113 PM EDT Sun Aug 23 2026

.WHAT HAS CHANGED...
* Added PoPs/raised them for the next several hours based on
  radar loops/convective development.

&&

.KEY MESSAGES...
1) Unseasonably deep upper low over the Upper Great Lakes today
will move Southeast to Lake Ontario by Monday morning bringing
another few rounds of showers and thunderstorms, mainly across
Northern PA this afternoon and evening.

&&

.DISCUSSION...
KEY MESSAGE 1: Unseasonably deep upper low over the Upper Great 
Lakes today will move Southeast to Lake Ontario by Monday 
morning bringing another few rounds of showers and 
thunderstorms, mainly across Northern PA this afternoon and 
evening.

Noon update...
Plenty of shallow convection out there, now and plenty already
south of where the (previously expanded) PoPs lay. NBM PoPs
doing especially poorly today with the short convection. Despite
their short stature, some are generating some ltg. Likely those
would also be making some very small hail. Temps aloft
conducive to hail formation. So, as we add some heat to the
blyr, we will get CAPEs up and get some taller cells. Those 
could make severe hail and (less probable) high gusts. MCD from 
SPC says 20% chc of a watch for our area.

Previous...
A subtle shortwave trough rotating around the southeast side of
the upper low will spark some afternoon/evening showers and TSRA
today, followed by only a brief downtrend in convection before a  
well-defined trough moves SE with its axis near the PA/OH border
by shortly after midnight tonight. 

HREF and SREF MUCAPEs will top out between 750-1000 j/kg with
wet bulb zero levels descending about 3-4 KFT to only around 6
KFT AGL across the Northern Mtns this afternoon and tonight. 
It's almost a slam dunk to see some periods of significant small
hail from the stronger low-topped TSRA between 18Z Sun and 00Z
Monday across the NW and maybe the Central/Ncent Mtns. SPC has a
marginal risk of SVR TSRA for today across all of the CWA except
for the southern tier layer of counties. Coincidentally, NBM
POPS had to be raised by at least 20 percent (to agree with the
SPC outlook) across the Central and Scent Mtns along with much 
of the Middle and Lower Susq Valley where a relative min of zero
to 10 POPs was noted. 

Luckily, this second and more potent upper trough will be 
pivoting over the Commonwealth overnight tonight with MUCAPE of 
only a few hundred J/KG, supporting mainly showers and perhaps a
low-topped TSRA or two moving inland from the warm waters of 
Lake Erie. 

Maxes only in the 60s and a brisk W wind across the northern and
western mtns will make it feel much more like Sept/Oct than 
mid- Aug. Valley locations will see more sun preceding any
convection with high temps reaching the mid 70s to near 80F in
the Lower Susq Valley.

Similar conditions are expected for Monday with the center of 
the upper low still hanging around our longitude and only moving
slowly poleward. The SHRA/TSRA will likely be confined to only 
the nrn tier of counties in PA on Monday.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Upper level trough swinging across the area along with a west
to southwest flow over Lake Erie resulted in showers across
the far northwest this morning. Low over southwestern Ontario.
Weather pattern more typical of late September than late August.

Winds slowly shifting more from the west now, resulting in the 
activity pushing more into our area this aft. Most of the 
activity is in the form of showers, with leading left moving 
cells on the wind shift line moving over the Finger Lakes. 
Thus went mainly VCSH, but did target BFD for MVFR conditions.

By late afternoon and early evening, activity should taper off,
as heating ends. MVFR and IFR conditions across BFD and JST
expected overnight with lower CIGS. Fog potential limited 
with this weather pattern.

For Monday, still VCSH possible across the Mtns. 

Outlook... 

Tue-Wed...Patchy morning fog, otherwise mainly VFR conditions.

Thu-Fri...Chance of showers and storms again.

&&

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

&&

$$

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