Marine Weather and Tide Forecast for Highland Holiday, OH

NEAR TERM /THROUGH TODAY/
Showers have shifted southeast of the region this morning, but the progression of the cold front has slowed. This is resulting in some pooling moisture and thus surface visibility reductions for portions of southern OH/northern KY and southeast IN. Dense fog is very patchy, so will just issue an SPS to highlight some of the reduced visibilities early this morning.

Dry weather conditions will initially return for the beginning of the day across the CWA However, this stalled front near the Ohio River will act as a source of lift, which will interact with a relatively warm and humid air mass that persists for locations in southern OH into northern KY. Given this setup, some CAMs try to initiate isolated shower/storm development near the Ohio River this afternoon. Any storm that spawns could produce small hail and locally gusty winds. While severe chances remain low today, it is still a non-zero threat.

A gradient in highs and especially surface dewpoints will be expected today. Highs near the I-70 corridor will be in the upper 60s to lower 70s, with dewpoints being more pleasant in the mid-40s to near 50. Further south, highs will approach the middle to upper 70s, but dewpoints will be in the upper 50s to middle 60s, making it feel a lot muggier.

SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/
The stalled front will actually begin to lift as a warm front late this evening and continue through the overnight hours. As the front lifts northward, episodic showers and thunderstorms will be possible through a good chunk of the night. These storms will be elevated, so not anticipating a severe threat.

By daybreak Thursday, the front will be located near the I-70 corridor and continue lifting northward. The ILN fa will be firmly planted in the warm sector of a surface low developing from a robust shortwave propagating northeastward from the Ark-La-Tex region.
Shower and thunderstorm chances will greatly increase by Thursday afternoon, with the potential for multiple rounds of storms. It does appear that a complex of storms will initiate during the afternoon and quickly develop into a QLCS (which would be the primary severe threat). SBCAPE values could increase to 1000-1500 J/kg just before storms build in. Wind shear profiles show sfc-3km values near 30 kts, which would help promote some organize convection. Hodographs are more straight given the unidirectional flow out of the southwest, so currently not anticipating a tornadic threat. The primary threat would be damaging straight-line winds, with hail being a secondary threat.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
Showers and thunderstorms will be ongoing at the beginning of the period, with some strong storms still possible. The more robust activity will diminish through the evening as upper support lifts northeast and instability decreases. However, some showers and thunderstorms may linger with a weakening surface boundary in the area.

Northern stream short wave will dig southeast Friday into Friday night. This, along with diurnal heating, will be sufficient to bring an increased chance of showers and thunderstorms again during the day. This will continue into Friday night as weak low pressure and a cold front finally move through.

At this point, guidance diverges as the flow transitions into a blocky pattern. The GFS and much of its ensemble system are quite progressive with the trough, not closing it off until reaching the Maritimes, allowing high pressure to build into the region and predominate. Meanwhile, the ECMWF and CMC along with many of their respective ensemble members close off a low near or west of the Appalachians which then meanders about the region through the rest of the period. Needless to say, these two scenarios would result in a substantial difference in sensible weather. The NBM and the lag built into that is still pretty optimistic. But with the trends seen in the ECE and GEPS, have begun to trend the forecast to more clouds and low PoP chances.

AVIATION /07Z WEDNESDAY THROUGH SUNDAY/
*07:30Z UPDATE*

Cold front progressing slower than anticipated. Moisture is pooling just ahead of the boundary, resulting in notable vsby reductions for locations closer towards the Ohio River. KCVG/KLUK and KILN may observe IFR/LIFR vsbys early this morning before the pool of low level moisture gets shunted southward. Have amended TAFs to account for this.

Cold front continues to work its way through during beginning of the taf period. However, the front will be just southeast of all terminals just an hour or two into the period (if not already through), resulting in a rapid shift in surface winds to the northwest. Winds will continue to veer clockwise through the rest of today, becoming northeasterly by daybreak and eventually out of the southeast by the afternoon. Surface winds will remain around 5kts through the period.

The front stalls out south of the Ohio River, which could pose a concern for additional thunderstorm development late in the day today and continuing overnight. Models keep any convection pretty isolated, so have not yet included in the TAFs but may need to at least include a PROB30 mention in the next forecast.

OUTLOOK...Additional thunderstorms are possible tonight. MVFR/IFR conditions likely Thursday into Thursday night along with a chance of thunderstorms. MVFR conditions possible Friday into early Saturday.

ILN WATCHES/WARNINGS/ADVISORIES
OH...None.
KY...None.
IN...None.