Marine Weather and Tide Forecast for Bratenahl, OH

NEAR TERM /THROUGH THURSDAY/
Scattered showers are starting to develop across NW Ohio and our first thunderstorm was noted in Seneca County. ML CAPE values have increased to between 500-800 J/kg and expect to see a continued expansion of showers and thunderstorm into this evening as the upper trough lifts northeast through tonight.
Initially the greatest coverage of thunderstorms will be in the west but also seeing a thicker cumulus field between CAK and YNG and expect thunderstorms to also develop in this area as simulated by several of the high resolution models. Severe weather is not expected today but locally heavy rain is possible especially with any training storms.

Previous discussion...
The upper level low has evolved into an upper level trough that will linger across much of the eastern CONUS through tonight.
Scattered showers with isolated, embedded thunderstorms are possible once again this afternoon and early evening as roughly 500-1000 J/kg of MLCAPE is realized during peak heating. Storms should remain sub-severe given limited wind shear, but can't rule out sub-severe gusty winds in strongest thunderstorms that develop through this evening. The airmass remains moist with PWATs well above normal for this time of year in addition to slow cloud layer wind speeds which may lead to some isolated nuisance flooding in any training thunderstorm. High temperatures settle in the lower 70s this afternoon with overnight lows settling near 60 degrees tonight.

An upper level ridge will briefly build overhead from the west tonight into the day on Thursday which will push the upper trough east. Maintained slight chance to low-end chance PoPs, mainly out west, through Thursday as the airmass remains moist underneath the ridge. Warmer on Thursday with high temperatures rising to the upper 70s to lower 80s. Unsettled weather returns after sunset on Thursday with more in the short term discussion below.

SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/
The end of the week will be unsettled with two rounds of potentially strong to severe thunderstorms that we will need to monitor and stay weather aware for. The first round of convection that could bring severe weather to northern Ohio and northwest Pennsylvania will develop on our western doorstep with our attention towards northern Indiana early Thursday evening. Forecast model guidance indicates the thermodynamics and atmospheric conditions that may develop Thursday evening looks fairly impressive for the middle of May. A lead shortwave will eject out from the base of a negatively tilted trough that will be centered over the northern CONUS Thursday evening. This shortwave will track from the Cornbelt Region into the Great Lakes and Upper Ohio Valley Thursday night. The factors that will support possible severe convection will be plenty of shear with Bulk values 40 to 50 knots. Mixed layer CAPE values will top out around 3000 or more J/kg over NWOH. Surface moisture will be adequate with dewpoint values in the middle to upper 60s. Lapse rates will approach 8C/km or slightly higher towards NWOH. There will be a slight CAP or some CIN during the afternoon to help keep convection from developing initially. But that CAP will easily be overcome with rapid convection development during the late afternoon and early evening timeframe. The convection could also become severe rather quickly once it gets going, especially in the forecasted environment that is forecasted by guidance.

The greatest severe hazard probabilities are just west and Northwest of northern Ohio it does come up towards far NWOH with all modes of severe weather potentially. The overall trend for convection will be discrete or semi-discrete storms and a couple supercells are possible in this good thermodynamic environment. There may also be a risk for an organized cluster or MCS type convection that could also try to develop and track in the area or just northwest of our CWA
That will be something nowcast closer to this severe weather event.
here biggest severe threat will be large hail and damaging winds.
There is also a low end tornado risk for any discrete cells. The greater risk is further west into NWOH but that threat will fade into north central Ohio later in the evening and overnight. The overall trend should be a decrease in organization and severity as it much further east in the NEOH and NWPA late overnight and early Friday morning.

The first round of convection will be east of the area by sunrise Friday morning. We will still have a very warm southwest flow at the surface and in the low levels. Our low level moisture content will slowly recharge later on Friday ahead of the second round of possible strong to severe will move into late Friday evening and overnight. High temperatures will be warmer Friday afternoon in the middle to upper 80s and possibly within a few degrees of daily record highs. The upper level trough will move from the northern CONUS into the western Great Lakes late Friday evening.
Diffluence mid and upper level flow on the southeastern flank of this trough and a cold front will be the mechanism to develop widespread convection across the Ohio Valley Friday evening into the late night. We have a day 3 SPC marginal outlook for our southwestern CWA or closer to central Ohio. Looking at some of the severe weather parameters and convection development from forecast models, that severe weather risk potential may need to be expanded more into northern Ohio and NWPA if those trends continue. At this time, we will mention some limited severe weather possible and a localized heavy rainfall threat given more coverage of convection with the main push of the cold front late Friday night.

THe upper level trough will swing through over our area Saturday into Saturday evening. It will be cooler Saturday in the middle 70s with some linger rain showers closer to Lake Erie as the upper level tough axis moves through. A deepening low pressure tracking across Ontario into Quebec Saturday will increase our winds from the west and southwest 15 to 25 mph with possible gusts up to 35 mph or higher if we can mix down some of the winds off the surface layer.
Saturday night temperatures will be much cooler as we see decent cool air advection coming form southern Canada across the Upper Midwest and Great Lakes region as overnight lows will drop into the upper 40s to lower 50s.

LONG TERM /SUNDAY THROUGH TUESDAY/
Much cooler weather will finish out the weekend with Sundays high temps ranging from the lower 60s over NWPA and NEOH to around 70 degrees for NWOH. A large Canadian high pressure system will build down across the region SUnday through Tuesday. Monday and Tuesday's temperatures will be below average for middle May standards. The next potential system to impact the region with rain and maybe more storms will move in the middle of next week as well as a slow warming trend.

AVIATION /18Z Wednesday THROUGH Monday/
Conditions have improved to VFR at most terminals. Scattered showers are starting to develop across NW and North Central Ohio and our first thunderstorm was noted in Seneca County. We expect to see a continued expansion of showers and thunderstorm into this evening as the upper trough lifts northeast through tonight.
Initially the greatest coverage of thunderstorms will be in NW Ohio through 00Z but also seeing a thicker cumulus field between CAK and YNG and expect thunderstorms to also develop towards YNG as simulated by several of the high resolution models. Later today, showers and thunderstorms may approach CLE, generally after 22Z. Severe weather is not expected today but locally heavy rain, wind gusts to 30 knots and IFR visibilities are possible with thunderstorms. Have include MVFR/IFR conditions in TEMPO or PROB groups with thunderstorms. Timing may need to be refined. General VFR conditions are expected to continue overnight unless a terminal receives heavy rain causing fog to develop. Otherwise, most locations will trend towards a scattered cumulus deck on Thursday.

Winds are generally out of the southeast today between 5-10 knots although easterly winds off Lake Erie are likely at TOL/ERI this afternoon. Winds shift out of the south or southwest on Thursday morning except a lake breeze is likely again at ERI towards afternoon.

Outlook...Periodic showers and thunderstorms with non-VFR are possible through Saturday.

MARINE
Winds will become weaker on Wednesday from the south or light and variable. A light southerly flow 5 to 12 knots will return over the lake Thursday ahead of a cold front. Behind the cold front, winds will become westerly 10 to 20 late Thursday night into Friday morning. There may be a brief time window where marginal SCA may occur. Winds will become southwesterly 5 to 10 knots later on Friday. A stronger low pressure system may develop and move across Lake Erie Friday night into Saturday with stronger southerly to southwesterly winds 15 to 25 knots. Westerly winds 15 to 25 knots, , maybe up to 30 knots in the open waters of Lake ERie will continue into Saturday. SCA headlines may be needed Friday night into Saturday evening. High pressure builds down from southern Canada Sunday into early next week.

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