054 FXUS61 KCLE 240134 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 934 PM EDT Wed Sep 23 2020 .SYNOPSIS... High pressure near the Ohio River Valley will remain in place through Thursday afternoon before drifting off to the mid- Atlantic on Thursday night. A cold front will move east across the area on Sunday and Monday followed by another stronger cold front on Tuesday. && .NEAR TERM /THROUGH THURSDAY NIGHT/... Thick swath of cirrus has overspread most of the area this evening ahead of an upper level wave moving though the Ohio Valley. Low temperatures will be 5-10 degrees warmer than last night given the cloud cover and higher dewpoints in the mid 50s that have arrived across the region. Made minor adjustments to hourly forecasts but otherwise the going forecast remains on track for tonight. Previous discussion...Weak high pressure of around 1018-1020mb will remain just south of our area through Thursday afternoon before moving off to the mid-Atlantic Thursday night. High cloud cover will move into the region tonight before drifting off to the east during the morning hours tomorrow. This will give way to mostly sunny/clear skies Thursday afternoon through the overnight period. Above normal temperatures are expected once again through the near term period as the same warm airmass as the past few days remains in place. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... Fair weather is expected through most of the period as a weak surface high pressure ridge gradually exits our region to the east. Aloft, a shortwave trough exits our CWA to the east by Friday evening and is followed by westerly flow overnight Friday night through Saturday. Our flow aloft should become west-southwesterly Saturday night as a longwave trough approaches from the northern Great Plains and Upper Midwest. Isolated rain showers are possible during the predawn hours of Sunday morning as a surface cold front approaches from the Upper Great Lakes and Mid Mississippi Valley. Temperatures trend above-normal, including highs reaching the mid 70's to lower 80's Friday afternoon. Low temperatures should reach the mid 50's to lower 60's Friday night. Saturday will be warmer with afternoon highs reaching the mid 70's to mid 80's. Saturday night's low temperatures should reach the upper 50's to mid 60's. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... The aforementioned longwave trough overspreads our CWA and the Great Lakes region from the Upper Midwest Sunday through Sunday night. At the surface, the aforementioned cold front should sweep eastward across our region late Sunday afternoon through Sunday night. Scattered showers and thunderstorms are expected ahead of and along the front. Strong to perhaps severe thunderstorms are possible since moderate instability and vertical wind shear may exist within the warm sector. Afternoon high temperatures should reach the mid 70's to 80 degrees, while low temperatures should reach the 50's Sunday night. The longwave trough should deepen Monday through Wednesday and encompass most of central and eastern Canada and the United States by midweek. Multiple shortwave disturbances embedded in the longwave trough should affect the Great Lakes region, including our CWA. At the surface, a lake-aggregate trough should reside over and near the Great Lakes. Another cold front should sweep eastward through our CWA Tuesday and/or Tuesday night. Breezy winds are expected as a fairly-tight surface pressure gradient accompanies the lake- aggregate trough. Periods of scattered showers are expected and isolated thunderstorms are possible. Some of these showers and storms will probably be enhanced by Lake Erie. Pure lake effect showers and thunderstorms may occur generally east of Lake Erie on Wednesday. A cooling trend is expected. For example, Monday afternoon's high temperatures should reach the mid 60's to lower 70's. By Wednesday, morning lows only in the 40's and afternoon highs in the mid 50's to lower 60's are forecast. && .AVIATION /00Z Thursday THROUGH Monday/... High cloud will thicken overnight with mostly VFR conditions continuing through the TAF cycle. A few sites are experiencing a little haze at TAF issuance but mostly cloudy skies overnight should prevent fog formation. Winds will be 5 knots or less overnight with southwest to westerly winds of 5-10 knots on Thursday. It is a little unclear if a lake breeze may develop at CLE/ERI on Thursday afternoon but expect at least some window of variable or possibly northwest winds at CLE after 18Z Thurs. Outlook...Non-VFR possible in showers and thunderstorms Sunday afternoon/evening. && .MARINE... Winds trend southerly to southwesterly at about 5 to 15 knots over Lake Erie the rest of today through Saturday as a high pressure ridge exits gradually to the east. Waves trend 1 to 3 feet. A cold front should move eastward across the lake Sunday and Sunday night, causing southwesterly winds of 10 to 20 knots to shift to westerly. Waves should trend 2 to 4 feet and a Small Craft Advisory may be needed eventually. Southwesterly winds of 10 to 20 knots are expected on Monday as a trough lingers behind the cold front. Waves should trend 1 to 3 feet in nearshore waters and 3 to 5 feet in open waters. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Saunders NEAR TERM...KEC/Saunders SHORT TERM...Jaszka LONG TERM...Jaszka AVIATION...KEC MARINE...Jaszka