Marine Weather and Tide Forecast for Leesville, OH

KEY MESSAGES
1) A moist airmass develops Wednesday and results in daily thunderstorm chances into the weekend, with varying degrees of hazard risks.

DISCUSSION
KEY MESSAGE 1...
----- Overview ----- The upper Ohio River Valley is set to be positioned between an Atlantic high and western Great Lakes trough Wednesday through the weekend, resulting in moist airmass that allows for daily thunderstorm chances and varying degrees of hazard risks. Weak flow and forcing combined with convective evolution uncertainties leave lots of unknowns in timing/coverage/hazards during this period.

For Wednesday/Thursday/Friday: Ensemble models favor the area remaining east of the upper trough axis within moist, southwest flow while having the potential for embedded weak shortwaves to cross at varying times. Moisture currently pooled in the Carolinas will be drawn northward and push PWAT values toward the 90th percentile, staying there due to little to no airmass changes (i.e. frontal boundaries), while enough heating creates sbCAPE values around 1200 J/kg each day.

Thunderstorms are likely to be diurnally driven with total coverage dependent on the presence of a mid- level shortwave (which could materialize based on upstream convection evolution)
and degree of surface heating with any lingering cloud cover.
Hazardous weather threats, in the form of isolated flash flooding and downburst winds, thus hinge on higher lift - larger buoyancy scenarios (not likely as evidence by limited outlooks from SPC/WPC) that remain difficult to discern now. Greater understanding of the environmental risks may not be fully realized until the morning of.

For Saturday/Sunday: Latest guidance favors a more concentrated eastward progression of the upper trough axis this weekend, aiding greater lift to the moist/unstable airmass still in place. The resultant shear increase combined with similar sbCAPE and slightly higher dCAPE values seen in model mean outputs suggest a slightly higher severe risk (damaging wind) when this axis crosses. This assumes an afternoon/evening passage that also sees enough surface heating to reach idealized buoyancy levels.

There is even a larger caveat to forecast outlooks during this period than the late-week section due to even larger spreads in shortwave timing and its progression after passage. This includes ranging from quick passage Saturday with dry conditions developing Sunday to slow passage Saturday and residual weak NW flow that maintains storms chances into next week. It is best for users to monitor forecast trends as the weekend approaches and know understanding of timing and risks may remain clouded until the morning of.

AVIATION /18Z TUESDAY THROUGH SUNDAY/
Dry weather and few-sct diurnal cu continue the rest of today as high pressure builds across the region. Patchy fog will be possible mainly south of I-70 during pre-dawn hours Wednesday morning as the surface high shifts east of the are and moisture begins to return from south to north. A greater coverage in diurnal cu (sct-bkn) is expected Wednesday afternoon with the increasing moisture, but cigs should remain VFR.

Outlook...
Scattered showers and storms (and associated restrictions)
return Wednesday afternoon/evening with an approaching trough.
This trough will persist across the region through the remainder of the week and possibly into the weekend, supporting daily shower and storm chances especially during afternoon/evening.

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