textproduct: State College

WHAT HAS CHANGED

* No significant changes at this time.

KEY MESSAGES

1) Scattered to numerous severe thunderstorms are expected this afternoon through the evening hours today.

DISCUSSION

KEY MESSAGE 1: Scattered to numerous severe thunderstorms are expected this afternoon through the evening hours today.

We are in standby mode for now as the copious amount of energy/lift/strong upper level diffluent flow (associated with the left exit region of a 100+ KT jet) has produced an expansive area of weak convection embedded in light to moderate rain. All of this thick/debris cloud cover will prevent deep convection through the early afternoon, but pockets of fairly quick destabilization via breaks of sun should spread into western PA and remain over our far SE zones to trigger some deeper convection by or shortly after 18Z.

We'll be closely monitoring satellite trends and meso-B stability and shear fields to better hone in on areas under the gun for potential impact of fast-moving TSRA.

Previous Disc...

Thunderstorms are expected to develop ahead of an eastward- moving cold front across the Ohio Valley and along a pre- frontal trough crossing the CWA between roughly 2-9PM. No changes were made to the level 3/5 enhanced risk area from SPC for day 1 with swaths of damaging wind gusts remaining the primary hazard. Diurnal heating within cloud breaks, combined with upper 60s to lower 70s dewpoints, will support moderate surface-based instability across the broad pre-frontal warm sector. The most favorable overlap of this instability and 40-50 kt of effective shear is expected to foster a mix of organized clusters and supercells that should evolve and spread eastward through the day. Severe hail and a few tornadoes will also be possible with any sustained supercells. The enhanced level 3/5 risk favors a higher confidence/coverage in severe storms with a few significant severe storms possible reaching intensity levels (75+ mph wind gusts and/or EF-2 tornado) we may only experience 1x or 2x/year.

WPC has expanded the level 2/4 excessive rainfall outlook to cover the majority of the CWA. However, despite plenty of juice and high PWATs supportive of locally intense rain rates, overall confidence is low/limited by the lack of a hires model signal and relatively fast/progressive storm motions. Opted to pass on a FF watch for this cycle and allow the dayshift to reassess or issue a more short-fused/targeted watch.

Rain showers linger tonight into Wednesday particularly downwind of Lake Erie and over the higher elevations, but for the most part we anticipate a multi-day drying trend with near to slightly below normal temps and comfortably low humidity from midweek into the last weekend of July.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Conditions will waffle between MVFR and VFR through the rest of this afternoon as a fairly large area of mainly stratiform light to moderate rain with a few embedded low topped TSRA moves east across Central PA and the Susq Valley.

Far Eastern parts of our County Forecast/Warning Area and points east (and our far SW counties) will see the best chance for a vigorous TSRA with brief strong wind gusts and heavy rain with low end MVFR conditions.

In the wake of the storms this afternoon expect low ceilings to stick around for MVFR to IFR across the entire area leading into Wednesday.

Outlook...

Wed...Periods of lingering showers possible Wednesday morning as the frontal boundary exits the state.

Wed afternoon-Sat...Good VFR conditions expected.

CTP WATCHES/WARNINGS/ADVISORIES

None.