textproduct: State College

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.

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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.