textproduct: State College

WHAT HAS CHANGED

* The risk for heavy rain and severe weather has ended for this evening.

KEY MESSAGES

1) Areas of dense fog possible tonight.

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

DISCUSSION

KEY MESSAGE 1: Areas of dense fog possible tonight.

Widespread rainfall today followed by clearing conditions, diminishing winds, and high pressure building in tonight should allow for formation of radiation fog primarily in the valleys. Some of the fog may become locally dense with vis 1/4 mi or less into early Friday morning. Any fog should dissipate by 8-10 AM Fri.

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

The cold front responsible for Thursday's storms will drift south on Friday but remain very close to the Mason-Dixon line. As such we can't rule out a spotty shower/t-storm in far southern PA Friday afternoon. However, most locations will stay dry and Friday looks like 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 /00Z FRIDAY THROUGH TUESDAY/

Clearing skies (VFR) in the wake of regionwide rainfall earlier today, along with winds trending light/variable as low pressure moves off the New Jersey coastline, will promote radiation fog across much of the area tonight. Confidence in fog is lower at KMDT/KLNS where NW winds may remain elevated enough (~5 kts) to limit fog development, though 6SM BR VCFG was added to account for spotty fog development on HREF. Timing of fog in TAFs was skewed toward 10th- 25th percentile HREF visibilities with concerns that the LAMP may be too slow with fog onset / too quick with fog dissipation given clear skies, calm winds, and recent rainfall.

Morning fog will give way to plentiful sunshine with some high clouds and E/NE winds of around 5 kts on Friday. Fair-weather VFR cumulus may also develop, primarily near the departing coastal low (mainly around and east of KMDT/KLNS).

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

None.