textproduct: State College

WHAT HAS CHANGED

* Increased PoPs to near 20 pct in the Laurels and near 30 pct around the Poconos and Endless Mountains this afternoon as popup showers/thundershowers remain possible, but any storms should be small and weak.

KEY MESSAGES

1) Sunday will mostly be a dry day, but we still can't rule out an isolated shower or stray thundershower in the Laurels and near the Poconos.

2) Hot and humid pattern set to return for the middle of next week

DISCUSSION

KEY MESSAGE 1: Sunday will mostly be a dry day, but we still can't rule out an isolated shower or stray thundershower in the Laurels and near the Poconos.

With drier air in place today and building high pressure providing a subsidence inversion above the boundary layer, today is still on track to be a mainly dry day. However, isolated showers can not be ruled out particularly over the Laurel Highlands or near the Poconos, where the higher terrain will partially offset the stability of the subsidence inversion. Model soundings show just enough instability in some of the higher RH members to allow lifted parcels to buoyantly rise above the -10C environmental isotherm, so a stray thundershower is possible, but the drier members have much shorter parcel traces that would yield nothing more than isolated showers. With highs in the low 80s and dewpoints in the upper 50s to low 60s, overall should be a pleasant mid July day.

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KEY MESSAGE 2: Hot and humid pattern set to return for the middle of next week

Dry conditions are expected to prevail for the first half of the week with a strong ridge expected to develop over the middle of the country. Increasing heat/humidity is forecast across central Pennsylvania although there remains some uncertainty with respect to how warm temperatures and/or humidity get across the region. Current forecast favors the hottest temps returning Tue to Thu with highs 85-95F and max heat index 90-100F, potentially rising above 100F on Wednesday. Rain chances show up Thursday and into the weekend, but PoPs remain low at this time as the occurrence of rain will depend on the timing and proximity of fronts and upstream convective systems.

AVIATION /07Z SUNDAY THROUGH THURSDAY/

Current radar imagery has shows most showers dissipating, with any small ones remaining not posing a threat to any TAF sites at this time. Later tonight and into the morning, most of our guidance is indicating lower cloud development near and just to the east of the Laurel Highlands, with probable development of associated restrictions at JST and AOO. Recent guidance has walked back some of the lower cloud ceiling solutions, but still kept MVFR lines in the TAFs at JST and AOO. Will watch for any real time development of solution below MVFR fuel alternate categories.

During the predawn hours, due to recent heavy rainfall and resultant wet ground conditions, we feel fog development is likely at KLNS. Any restrictions will likely drop into the IFR category for a time, and could conceivably reach LIFR. Elsewhere overnight, we anticipate VFR conditions.

On Sunday, once any lower clouds and fog patches lift/dissipate, we should be looking at a restriction-free day. For a change, little to no shower or thunderstorm activity is foreseen during the afternoon. Some models are resolving some afternoon convective showers, but warmer and drier mid-level conditions should limit coverage and intensity. Generally light winds overnight (5 kt or less), should become easterly/southeasterly at 5-10 kt on Sunday.

Outlook...

Mon-Thu...Mainly VFR, with areas of late night/AM fog.

CTP WATCHES/WARNINGS/ADVISORIES

None.