Marine Weather and Tide Forecast for Bratenahl, OH

NEAR TERM /THROUGH FRIDAY NIGHT/
6:30 PM Update...

The forecast remains on track this evening with no changes needed.

Original Discussion...

Low pressure will begin taking shape over the central Plains tonight, lifting east-northeast into the central Great Lakes on Friday while gradually deepening. A secondary warm front (with greater moisture behind it) will lift north across the local area tonight. A cold front will sweep east across the area Friday evening and night as the low exits northeast.

For the remainder of the late afternoon and early evening, cumulus are percolating along the lake breeze just south of the lakeshore in North Central and Northeast Ohio, and from parts of the Central Highlands points south. The low-levels are very well-mixed and dry, so it's uncertain if any isolated showers or storms will develop in these areas through early this evening...
though do still hang on to 20% POPs to highlight the low- confidence possibility. There will probably be a relative lull in any shower activity later this evening (assuming we get anything earlier...). Overnight, the approach of a very weak shortwave and some increased low to mid-level moisture advection behind the secondary warm front is expected to combine with weak lingering instability to allow isolated to scattered showers to develop/lift in from the south-southwest. Lows tonight will mainly only fall into the low-mid 60s, though with some 50s in far Northeast OH and Northwest PA.

The aforementioned shower activity should be ongoing to start the day Friday...particularly from North Central OH into Northeast OH, with activity lifting northeast into Northwest PA during the morning. This activity will gradually exit east into Friday afternoon. It will be a struggle to see a prolonged period of completely dry weather across the area on Friday, as the combination of modest heating of an unseasonably moist airmass will allow modest but uncapped instability to develop through the afternoon. A more well-defined shortwave will move west-east across the area Friday afternoon/evening, with the cold front sweeping through late Friday evening and Friday night.
Given impressively moist low-levels for April (dew points into the 60s) and uncapped instability, it will not take much for scattered to numerous showers and some storms to develop along pretty much any sources of low-level convergence as broad forcing for ascent spreads in ahead of the shortwave and cold front.
Activity may initially be fairly disorganized, but should gradually increase in coverage and congeal into clusters by late afternoon or early evening while gradually working east. Hi-res models are suggesting activity will be most widespread and intense well-ahead of the cold front during the late afternoon and early evening before exiting east, with a trailing line of scattered showers/thunder pushing in along the front itself later Friday evening, which isn't unreasonable. We will generally trend drier from the northwest through Friday night behind the front, though one more trough axis pushes in very early Saturday morning, bringing one last uptick in shower potential with it...particularly downwind of Lake Erie.

Conditions are not overly conducive to severe weather on Friday, with MLCAPE values of no more than 1000 J/KG (and likely more like 400-750 J/KG) and effective bulk shear of 25-30kt supporting a modest risk for an isolated stronger storm or two with gusty winds during the afternoon/early evening.
Unseasonably high atmospheric moisture, skinny instability, and weak mid-level lapse rates supporting low-centroid convection, suggest efficient rain rates in any convection Friday afternoon and evening. Some hi-res model runs (particularly the 12z and 18z HRRR) hint at some localized training with isolated rain amounts over 3" possible, though most models suggest a lack of organization may make those types of totals difficult to achieve. Still, will need to monitor for what would be a localized flash flood risk if isolated training coincides with a more urban or otherwise prone area.

Highs on Friday will range from the upper 60s in PA to the low to mid 70s in OH...perhaps upper 70s in Northwest OH. It will be unseasonably humid with dew points pushing into the 60s. Late lows Friday night will reach the upper 40s/lower 50s.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
Scattered lake-enhanced showers may persist across NE OH/NW PA as the cold front exits to the east Saturday morning into as late as Saturday afternoon. Rain chances will taper off by Saturday evening as Canadian high pressure builds over the region behind the front.
From there, dry weather will persist through Sunday night as a ridge builds east from the central CONUS.

The Canadian high will usher cooler temps into the region over the weekend with the coolest temps expected Saturday and Saturday night.
Saturday's highs will be in the 50s, although a few spots in northwestern and north-central OH may touch 60 degrees. Skies should clear rather quickly Saturday night and relatively light winds will provide an opportunity for efficient radiational cooling. Patchy to areas of frost are possible across the Central Highlands of Ohio and in interior NW PA Saturday night into early Sunday morning, where overnight lows will likely fall into the mid to upper 30s. Frost Advisories are possible across portions of north-central Ohio (the growing season has not yet started for local PA zones).

Temps will recover to the upper 50s to lower 60s in most locations Sunday with overnight lows in the upper 30s to low to mid 40s.
Radiational cooling may result in locally cooler low temperatures in the higher elevations of interior NW PA.

LONG TERM /MONDAY THROUGH THURSDAY/
Upper ridge and surface high will continue to maintain influence through Monday before a deep, positively-tilted trough moves east out of the western CONUS Monday night. This will cause the upper ridge axis to cross the area with a warm front lifting into the region Monday night into the predawn hours Tuesday. Moisture may be marginal with the warm front and in the warm sector through Tuesday afternoon so have limited PoPs to slight chance to low-end chance until the front begins to approach from the west Tuesday afternoon.
Still some uncertainty in the timing/placement/coverage of precipitation, but currently thinking that shower/thunderstorm chances will peak at some point Tuesday afternoon into Tuesday evening. The wind field, moisture transport, and instability will be sufficient for at least an isolated severe weather threat and possibly a localized heavy rain threat Tuesday afternoon/evening, however it's still far too early to get specific with any potential hazards. PoPs will likely taper off as the front pushes south of the area Tuesday night, but showers may periodically sneak into southern zones as the front slows over the Ohio Valley Wednesday. Another wave of rain could lift into the region as early as Thursday as low pressure tracks northeast across the Mississippi Valley.

Warm air advection will allow highs to climb well into the 70s on Monday with widespread 80s likely on Tuesday. Temps will decrease behind Tuesday night's cold front with highs in the 50s and 60s expected Wednesday and the 60s Thursday.

AVIATION /18Z Thursday THROUGH Tuesday/
Mainly VFR continues through the TAF period, though conditions will become a bit more unsettled tonight into Friday. There is a risk for isolated (<20% coverage) showers and perhaps a storm between 20z-01z this afternoon/evening, especially near MFD and perhaps CLE. Confidence is currently too low for inclusion.
Mid-level clouds and scattered showers push in from the south- southwest overnight tonight and Friday morning, especially from MNN-LPR points east. Restrictions below VFR will likely be limited, but ceilings below 5k feet will become more common after 12z Friday with brief/patchy vsby restrictions possible in showers. There may be a relative lull in shower activity around midday Friday, before showers and some storms increase in coverage late Friday afternoon into Friday evening ahead of an approaching cold front. Only included a VCTS mention at CLE with a 30 hour TAF, otherwise mentions will need to be considered with future cycles.

Generally light/southerly winds this afternoon, outside of a lake breeze at CLE and ERI. Winds remain mainly southerly at less than 10 knots through the TAF period, with the lake breeze expected to dissipate by 1z this evening.

Outlook...Non-VFR possible in scattered to widespread showers and thunderstorms Friday afternoon through Friday night, with MVFR clouds lingering into Saturday morning.

MARINE
East/southeast winds 6 to 12 knots will continue through this evening, although a lake breeze will result in a period of onshore flow in the nearshore zones this afternoon into early evening.
Southeast winds will develop ahead of an approaching warm front Friday morning and briefly shift to the southwest in the warm sector before becoming northwesterly as a cold front moves east across the lake Friday night. Winds will increase behind the front late Friday into Saturday and expect sustained winds to 15 to 20 knots with waves as high as 3 to 5 feet anticipated over most of the lake; Small Craft Advisories will likely be needed Friday night through early Saturday evening. Onshore flow will diminish below 15 knots Saturday night with variable winds under 10 knots anticipated for Sunday. Winds/waves will remain under Small Craft Advisory criteria through much of Monday, but headlines may be needed as as early as Monday night through at least Tuesday as the next system crosses the region.

CLE WATCHES/WARNINGS/ADVISORIES
OH...None.
PA...None.
MARINE...None.