Marine Weather and Tide Forecast for Indiana, PA

KEY MESSAGES
1) Thunderstorms overspread the region this morning, featuring limited wind and flash flood risks.

2) West to east tapering of precipitation chances tonight through Wednesday.

DISCUSSION
KEY MESSAGE 1...
Latest analysis shows the surface low centered just north of Toronto, Canada with the mid-level shortwave diving SE out of northern MI. This is resulting in warm front induced scattered thunderstorms firing in northwest PA (mostly into CTP's forecast area) while growing storm coverage approaches eastern OH ahead of the mid-level wave and surface front.

Confidence is fairly high in the shortwave and pre-frontal trough traversing SE through 12z/8am to kick off mostly elevated thunderstorms tapping 1000-1500 J/kg MUCAPE. The lack of surface based storms and stronger buoyancy should limit severe potential but risks are non-zero thanks to near 1000 J/kg DCAPE that could foster strong enough descending air associated with the most organized cells to result in localized damaging winds. Increasing effective shear with the shortwave may also allow for enough updraft organization/maintenance to foster isolated instances of large hail. The biggest caveat is the likely southward path the cluster is favored to take by hi-res models, meaning far eastern OH zones are the most at-risk for this round of storm risks; areas east are likely to see more stratiform region rain showers and/or cloud cover the initially inhibits additional convective activity.

Though the shortwave exits by 14z, additional lift offered in cooler NW flow plus the cross surface cold front should result in additional afternoon convection mainly east of I-77. Buoyancy may recover near 1000 J/kg with enough DCAPE available to maintain a damaging wind threat, assuming enough clearing in clouds occurs prior to frontal passage (not a given). Loss of diurnal heating and waning upper support results in dwindling storm activity after 21z tonight, with all risks tapering off by 00z.

KEY MESSAGE 2...
The upper pattern features a closed upper trough meandering over the New England region late tonight through Thursday. Weak shortwave movement around this low plus wrap-around moisture could foster isolated to scattered diurnal storms Wednesday (east of I-77) and Thursday (mainly along higher terrain) in what otherwise would be a drying period with slowly building high pressure.

These storms are unlikely to pose risks due to limited instability (less than 500 J/kg).

AVIATION /12Z TUESDAY THROUGH SATURDAY/
An initial area of showers and thunderstorms will continue to exit the region early this morning along a pre frontal trough.

Expect a gradual deterioration to MVFR, with local IFR, later this morning with increasing low level moisture ahead of an approaching surface boundary/cold front. Additional showers and thunderstorms are expected to develop along and ahead of this boundary from mid to late afternoon. A general return to VFR is expected after the passage of the front, with some dry advection and mixing/gusty NW surface wind. Stratus is likely to then develop overnight with low level moisture in place, and diminishing wind.

Outlook...
Scattered showers and possible thunderstorms are expected Wednesday, especially east of I-79, as the shortwave trough deepens into a closed low across the NE CONUS. A return to VFR is then expected (outside of any early morning vly fg) through Saturday as high pressure tracks east across the region.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...None.
OH...None.
WV...None.