032
FXUS61 KCTP 210827
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
427 AM EDT Fri Aug 21 2026

.WHAT HAS CHANGED...
* Issued a dense fog advisory until 10 AM today for most of the
  CWA except for parts of the southeast.

&&

.KEY MESSAGES...
1) Widespread Dense Fog until 10 AM today throughout the
Valleys of Central and Northern PA, including the Laurel
Highlands and Middle Susquehanna Valley.

2) An unsettled weekend will be bookended by fair weather
Friday and early next week.

&&

.DISCUSSION...
KEY MESSAGE 1: Widespread Dense Fog until 10 AM today throughout
the Valleys of Central and Northern PA, including the Laurel
Highlands and Middle Susquehanna Valley.

Moist ground from the widespread moderate to heavy rainfall
amounts on Friday, combined with clear skies and light wind to
create optimal conditions for widespread, dense valley fog
(with vsbys under 1/4SM) throughout about the Central two-
thirds of the Commonwealth early today. The fog will gradually
dissipate between 930 and 10 AM followed by abundant sunshine
before noon. Some high clouds moving NE from the Central
Appalachians could mix in with the sun across southern PA during
the late morning and afternoon hours.

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

KEY MESSAGE 2: An unsettled weekend will be bookended by fair
weather Friday and early next week.

The cold front that was preceded by a large area of moderate to
heavy rain and mid afternoon through early evening
thunderstorms will drift south today, but remain very close to
the Mason-Dixon line.

We can`t rule out a spotty shower/t-storm in far southern PA
this afternoon. However, most locations will stay dry and
today will turn out to be a pleasant day with plenty of
sunshine.

An upper trough digging into the Great Lakes region will bring
unsettled weather conditions over the weekend. There is still
considerable uncertainty with timing, intensity, and coverage of
showers/storms, but it is not expected to be a washout for
anyone. This system will also deliver some relatively cooler air
both at the surface and aloft. This setup could prove favorable
for clusters of gusty t-storms with small hail both Saturday
and Sunday. The best chance for strong storms will be west of
I-99 on Saturday and then across eastern PA on Sunday as a cold
front pushes through the area.

In the wake of the cold front, the start of next week (and
perhaps even late Sunday afternoon/evening) look pleasant. A
decaying secondary cold front could bring some light showers
north of I-80 on Monday, but dry conditions prevail otherwise.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Skies have cleared across the Commonwealth in the wake of
precipitation and dense valley fog is building in. With a slight
breeze still in place from low pressure off the coast of New
Jersey, the fog has been pulsing up and down in density.
Therefore, pulses up and down between categories remain
possible the rest of tonight, but IFR/LIFR will continue to
prevail at the airfields into tomorrow morning with clear skies
and plentiful moisture. GFSLAMP, NBM, and HREF don`t have only
spotty fog developing in the southeast, supported by a light
northerly wind (~5kts) and temperature-dewpoint spread.

Once fog burns away tomorrow morning, VFR conditions and mostly
clear skies are expected tomorrow. Thicker cirrus and a few
convective cumulus clouds are expected tomorrow at MDT and LNS.
winds remain light throughout the day.

Outlook...

Sat...Scattered to numerous showers/t-storms with low cigs
likely.

Sun...Restrictions likely early with showers/t-storms, followed
by possible improvement late in the day. Breezy west wind.

Mon-Tue...Patchy morning fog, otherwise mainly VFR conditions
return early next week.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EDT this morning for PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
056.

&&

$$

WHAT HAS CHANGED...Lambert/Colbert
KEY MESSAGES...Lambert/Steinbugl/Colbert
DISCUSSION...Lambert/Steinbugl/Colbert
AVIATION...Lambert/Lambrech