Marine Weather and Tide Forecast for Prospect, PA

KEY MESSAGES
1) Isolated strong to severe storms are possible Thursday.
Stalled boundary keeps chance of precipitation for areas south of Pittsburgh.

2) Increasing confidence in the development of hot and humid conditions next week.

DISCUSSION
KEY MESSAGE 1...
A surface low is forecast to swing across the Great Lakes on Thursday and into the northeast CONUS by Friday morning. This will push a surface boundary into the region Thursday. Due to a prefrontal surface trough, there is the chance for some early morning showers across northwestern PA. The main push of showers and storms Thursday afternoon and evening will have the support of the crossing front and trough axis. Storms should fire in a moderately favorable environment, with HRRR means suggesting around 500-750 J/kg of surface-based CAPE and 40-45 knots of 0-6km shear. It is still not clear whether this will be a line of thunderstorms or individual storms that pop-up along the boundary. Severe weather seems a possibility, with the primary threat being damaging wind gusts and hail as a secondary threat.

There continue to be signs that the boundary may stall somewhere in the Ohio Valley by Friday and into the weekend, as it aligns with quasi-zonal mid-level flow. This will keep precipitation chances continuing into Friday and Saturday mainly for areas south of Pittsburgh. Given the possibility of repeated rounds of showers and thunderstorms, rainfall totals in these areas will need to be monitored into Saturday. Precipitable water values in this region generally peak in the 90th percentile Friday night into Saturday which is enough to fuel heavy rain totals in training situations, which could occur with a quasi-stationary boundary in the area for a time.

KEY MESSAGE 2...
The boundary is forecast to move south on Sunday as a high moves in behind it. There is broad ensemble agreement of an impressive 500mb ridge building across the lower Mississippi and Ohio River Valleys by early next week. There is a high probability of 500mb heights rising above the 590dm level by next Monday. This would likely suppress anything more than isolated afternoon convection early next week. The main impact in this pattern would be the increasingly hot and humid conditions which could develop, with temperatures in the 90s looking increasingly likely to end the month of June.

AVIATION /00Z THURSDAY THROUGH MONDAY/
VFR persists through Thursday morning with increasing mid to high level cloud overnight ahead of an approaching shortwave trough.

That trough and surface cold front will help initiate generally scattered shower and thunderstorm development Thursday afternoon/evening; HRRR modeling favors the 19z-24z window (which TAFs align with) but onset could flux forward/backward an hour or so depending on how quickly the surface heats.
Additionally, lingering convection from the western Great Lakes could near FKL/DUJ during the late morning hours and start the thunderstorm window slightly earlier than forecasted, but the current expectation is for those showers to be weak and offer little lightning probability. Remember, any thunderstorm that occurs could briefly but quickly reduce visibilities while generating a gusty and erratic wind.

Outlook...
Passage of the shortwave axis after 00z Thursday through 06z Friday could spark a secondary wave of shower/thunderstorm chances after the TAF period. Any overnight restrictions are likely dependent on degree of localized wetting and overnight clearing that could favor stratus and/or fog development.

An active pattern is favored through the weekend featuring multiple rounds of showers and thunderstorms within quasi-zonal flow.

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