744 FXUS61 KCLE 071149 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 749 AM EDT Sun May 7 2023 .SYNOPSIS... A warm front will lift into northern Ohio this morning and stall south of Lake Erie as a weak low passes across the region. This front will sink back south tonight and Monday as high pressure builds in. The front will lift back into the area by Monday night in response to a stronger low pressure system before high pressure returns by Tuesday and Wednesday. && .NEAR TERM /THROUGH MONDAY/... 6:30 AM Update... Moved up the timing of categorical PoPs in NW Ohio by about an hour given current radar trends, otherwise, the forecast remains on track. Convection is weakening with eastward extent, so expect mainly just showers and occasional rumbles of thunder this morning. Original Discussion... A mass of elevated convection has steadily organized across Indiana and southern Michigan over the past few hours on the nose of a west- southwesterly 40 knot low-level jet where warm/moist theta e advection has been maximized. This area of convection is the approximate location of the warm front which will slowly progress into NW Ohio this morning. The higher instability characterized by MLCAPE of 1000-2000 J/Kg beneath an EML plume (7.5 to 8 C/Km mid- level lapse rates) is currently across Illinois and Indiana, so this convection has been showing signs of weakening as it approaches NW Ohio. Surface dew points are rising into the mid 40s to near 50 in NW Ohio, but dew points in the upper 30s to mid 40s continue elsewhere. This drier, more stable air near the surface should continue to weaken the convection as it moves east, but due to continued mid-level warm air advection and the steeper mid-level lapse rates advecting east, cannot rule out some small hail in NW Ohio as this convection moves in over the next couple of hours. A more organized line of convection with a maturing MCV seen on radar and satellite loops is also occurring in central Illinois. This complex is tied to a shortwave impulse cresting the mid/upper ridge axis, and it should continue to propagate southeastward along the warm front/instability gradient, missing our area to the southwest. With all of this in mind, have likely to categorical PoPs spreading east across much of the CWA this morning, but it will mostly be showers with occasional rumbles of thunder. Any chances for thunder quickly decrease east of I-71 since the drier, more stable air will win out there as the warm front struggles to move farther NE. The entire region will dry out nicely this afternoon behind the morning showers as the mid/upper ridge axis builds a little farther east. The warm front will lift a bit farther NE in response allowing higher dew points (low/mid 60s) to spread into NW and north central Ohio beneath steepening mid-level lapse rates as the EML advects overhead. This will allow for MLCAPE to exceed 1000 J/Kg in NW and north central Ohio, but the building ridge and core of the EML overhead combined with a lack of forcing should squash any redevelopment from occurring. Blended guidance seems too high with PoPs given the aforementioned capping and lack of a trigger, and when combined with extensive debris clouds, I decided to significantly lower PoPs this afternoon and evening. Highs will warm into the upper 70s in NW Ohio today with upper 60s to low 70s across the rest of the region. The forecast is trending drier tonight and Monday as surface high pressure nosing into the Upper Great Lakes pushes the frontal boundary/instability gradient southward into the Ohio Valley. This will allow drier and slightly cooler air to filter in as the storm track is shunted south of the area. NE flow off the chilly lake and some lingering low-level moisture will support areas of fog pushing inland at times tonight as the front shifts south, but otherwise, it will be a quiet night. Chances for showers and thunderstorms will gradually increase Monday as the front begins to slowly retreat back northward in response to a mid/upper shortwave trough approaching from the Upper Midwest and flattening the ridge a bit. This shortwave will induce a weak surface wave that will ride along the warm front/quasi-stationary front helping to generate another possible MCS upstream in the Midwest late Monday, but with the stronger surface high to the north, odds are increasing that most of the activity may miss our region again, so confined the higher PoPs Monday afternoon and evening to far southern areas. Highs Monday will be cooler with mid 60s to low 70s expected. Less humid as well. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... A shortwave trough and an upper level positive vorticity maximum is progged to move east across the area Monday night. This system is expected to force a wave of low pressure east into Ohio by Monday evening with a stationary front extending northeast along the lakeshore. The forecast area should remain in the warm sector Monday night as area of fairly good moisture and upward vertical motion moves east with the low pressure system. The surface low is expected to move into the West Virginia Panhandle by Tuesday morning allowing cold air advection to take place on the northwest side of the surface low pressure system. High pressure builds southeast toward the area Tuesday night into Wednesday and will bring a round of fair weather back to the local area. Temperatures during this period should trend cooler in the wake of the low pressure and advancing high pressure from the northwest. && .LONG TERM /THURSDAY THROUGH SATURDAY/... An upper level ridge is expected to build east into the area Thursday forcing surface high pressure to move east and off the Mid Atlantic Coast. As the surface high moves east, a return southerly flow and warm air advection is expected to take place. This should help boost temperatures back into the 70s across the area each day. Exception will be a brief tough of the 70s along the lakeshore before the lake breeze and/or onshore flow develops and pushes temperatures back down into the 60s. The upper level ridge is expected to break down slightly by the end of the week allowing a short wave trough to approach the local area. An associated low pressure to the trough is also expected to approach from the west forcing a warm front north into the local area. Moisture associated with the warm front should begin to lift north into the local area and destabilization in the warm sector should help increase threat for showers/thunderstorms Saturday. && .AVIATION /12Z Sunday THROUGH Thursday/... Showers and occasional thunder will continue to spread east this morning with cigs gradually dropping to MVFR. It still looks like most of the showers will exit by early to mid afternoon, but MVFR cigs will linger through tonight in most areas. TOL and FDY may get a break and go VFR this evening into tonight as drier air briefly builds in, but cigs will lower again by Monday morning. There is potential for IFR cigs and periods of fog tonight as well at CLE, MFD, CAK, YNG, and ERI. Confidence on this is low to medium. S to SW winds of 5-10 knots this morning will veer more W this afternoon and evening before becoming more N tonight. Outlook...Showers and thunderstorms could bring Non-VFR to the local area Monday afternoon into Tuesday morning. && .MARINE... Easterly flow on the lake is expected to give way to a southerly and and then southwesterly flow later today. Weaker flow should be present over the eastern half of the lakeshore resulting in onshore flow from a lake breeze that is expected to develop in the afternoon. Otherwise, light and variable flow expected tonight becoming northeast by Monday. May be borderline small craft advisory conditions in the western basin by Monday afternoon. The northeast flow is expected to persist into Tuesday night but gradually weaken and become variable by Wednesday and Thursday. Lake breeze will likely develop Thursday afternoon in the nearshore waters and become onshore. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Garuckas NEAR TERM...Garuckas SHORT TERM...Lombardy LONG TERM...Lombardy AVIATION...Garuckas MARINE...Lombardy