893 FXUS61 KCLE 130200 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1000 PM EDT Sun Sep 12 2021 .SYNOPSIS... A frontal boundary will stall this evening near the southern shores of Lake Erie. This front will lift north as a warm front Monday into Tuesday ahead of another cold front expected to move east across the area on Wednesday. High pressure will build across the area behind the front. && .NEAR TERM /THROUGH MONDAY NIGHT/... Clouds have now moved south along the northern counties at this time and this trend is expected to continue as the surface low pressure over northern Lake Erie and trailing cold front move east and southeast. Diurnal cooling dropped temperatures into the upper 70s in the west and lower 70s in the east. Still watching batch of storms over southern Ontario, Canada. Expecting this activity to track southeast with bulk of it ending up in western New York. Current forecast has this activity on track for timing. Previous Discussion... A slow moving cold was located just north of Lake Erie and drifting southward tonight. This frontal boundary is expected to stall out near the southern lakeshore of Lake Erie by late tonight or early Monday morning. Scattered showers and thunderstorms are expected to develop near this frontal boundary but will remain north of our local area as this active weather will be moving from west to east tonight. We can't rule out an isolated pop up shower this evening but warm air aloft or the "cap" will keep most the area dry and quiet tonight. The only area that may get clipped with some showers and storms late tonight will be are extremely northeast area around Erie PA. We will remain on the warm side of the front Monday with more very warm temperatures and higher humidity. Afternoon highs will climb back into the middle and upper 80s. The stalled front over Lake Erie will lift back north as a warm front Monday into Monday night. While we can't rule out a spotty shower pop near the lakeshore, most the area will remain dry and quiet weather on Monday and Monday night. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Much of the day on Tuesday should be fairly quiet with mid-level dry air in place ahead of an eastward-advancing cold front. It will be a little gusty across the area by Tuesday afternoon, with winds in the 25 to 30 mph range in some spots. The highest wind gusts are expected across NW OH. Temperatures will be above average with highs in the mid to upper 80s. By Tuesday night into Wednesday, the cold front will reach the north and northwest portions of the area, resulting in widespread showers and thunderstorms. As the upper trough continues to eject northeast across Quebec, the trailing cold front draped across the area will begin to slow, and eventually become nearly stationary. Expecting another round of showers and thunderstorms in the afternoon and evening hours, primarily across the central and eastern half of the area. Will still have to monitor instability trends for any severe weather threat, given the moderate deep layer shear profiles in place. At this point, the best chance for any decent destabilization would be across the far southeast portion of the area. We don't have a WPC ERO at this time, given Wednesday is day 4. However, anticipate we could at least be under a marginal risk by tonight's update, given favorable heavy rain profiles and cloud layer flow that is nearly parallel to the stalling front. Forecast QPF across the area on Wednesday is around an inch, with locally higher amounts possible. Temperatures will be a little cooler on Wednesday, in the upper 70s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Uncertainty grows in the long term period with no agreement in any discernible upper air patterns and thus a lack of forcing for any shower and/or thunderstorms chances. We should maintain the warm and moist airmass through at least Friday as the aforementioned stalled cold front, lifts north as a warm front on Thursday. Will mainly keep isolated mention in the afternoon/evening on Thurs/Fri at this time. A weak cold front may move across the area on Saturday, with some model guidance hinting at cooler and more pleasant weather by the end of the weekend. && .AVIATION /00Z Monday THROUGH Friday/... Main issue this forecast period is the two clusters of thunderstorms over southern Ontario, Canada and second one back over over Michigan. Expecting first cluster to move near Erie around 03Z this evening and may slip past the terminal. Uncertain as to whether terminal will be affected but added a tempo group for the time being. Second round has a shot at hitting Erie around 08Z and will add a mention of thunder then as well. Otherwise, looking at VFR across the rest of the area overnight into tomorrow. Winds will gradually diminish through tomorrow and become light. Outlook...Non-VFR possible with showers/thunderstorms through Tuesday. Non-VFR likely Wednesday in showers and thunderstorms associated with a cold front. && .MARINE... A mostly quiet marine period is forecast through Thursday with no marine headlines anticipated. Southwest winds today, 10 to 15 knots, will shift more northerly tonight, then become northeastly by Monday as a cold front stalls just south of the lake. Winds will become southwesterly once again on Tuesday as the front lifts northeast as a warm front, 10 to 15 knots, becoming 15 to 20 knots by Tuesday night. Another cold front will stall south of the lake on Wednesday, with northerly flow of 5 to 10 knots expected. Light flow is then expected to continue into Thursday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Griffin NEAR TERM...Griffin/Lombardy SHORT TERM...Kahn LONG TERM...Kahn AVIATION...Lombardy MARINE...Kahn