120 FXUS61 KCLE 291626 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1226 PM EDT Wed May 29 2019 .SYNOPSIS... A stationary boundary was located over northern Ohio into north central Pennsylvania this morning. Low pressure over Indiana early this morning will move eastward along this boundary through the day. A stronger area low pressure will move along this boundary on Thursday dislodging it and taking it eastward with it. This will allow high pressure to build across the region for Friday. && .NEAR TERM /THROUGH THURSDAY/... Update...Convection developing rapidly in a training configuration. Gound saturated so have issued a flash flood watch through 6pm. Previous Discussion... Warm advection ahead an area of low pressure over Indiana has caused a few showers/thunderstorms to move across the region with most of it over Lake Erie as of 345 am. We will now await the arrival of some upper level jet energy that will help move the surface low eastward along a stationary boundary that is located over northern Ohio into north central PA. So expect to see an area of showers and thunderstorms move west to east across the region this morning. We will then wait on another piece of jet energy this afternoon/evening that should help to generate another round of thunderstorms. The strength of the thunderstorms is uncertain at this time with the recovery of the low level instablilty. If the stationary boundary does not move much with the morning round of convection then the strongest storms would generally be located near and south of a line from Upper Sandusky to Warren. This is also the area of concern for locally heavy rainfall that could lead to flooding. Actually thought about a flash flood watch for this area but will let later shifts monitor closely and issue a shorter fused watch if needed. This will give us time to let the atmosphere reveal where the heaviest swatch of rain is generating. PWAT's will remain very high into Thursday, around 1.5 inches(150% of normal). So another soaking rain is anticipated with a couple rounds possible, one Thursday morning and maybe again along the cold front Thursday afternoon/evening. Severe threat is very uncertain for Thursday with not much recovery time between the morning wave and the arrival of the front Thursday afternoon. Flooding may actually be more of an issue than the other threats. Challenging temperature forecast today and Thursday with cloud cover and the showers/thunderstorms. Any wobble of the stationary boundary will also impact these temperatures. For today warmest across the south with highs upper 70s to around 80, cooler closer to the lake with highs only in the lower 60s near Erie, PA. Cooler on Thursday with highs in the 60s to lower 70s. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... Upper level trough will move southeast across the area by the end of the work week. This in turn will cause low pressure to move northeast out of Ohio. Precipitation associated with the low will also move east and out of the area as well as high pressure begins to build southeast into the region at the surface. Broad upper level troughiness will persist across the eastern half of the country through the end of this forecast period. Another low pressure system at the surface will move east across the central Great Lakes and force a cold front south across the region Saturday. The front will have associated mean moisture associated with it as it moves south across the area. Showers and a threat for thunderstorms can be expected on Saturday and Saturday night. Temperatures through the forecast period are expected to be on the cool side even though day time highs will warm well into the 70s by Saturday but overnight lows will be in the 50s. Strongest cold air advection will take place Saturday night as high pressure builds southeast toward the area. && .LONG TERM /SUNDAY THROUGH TUESDAY/... Amplification of an upper level ridge will take place over the Plains states during the latter half of the weekend as deepening low pressure develops along the west coast. The upper level ridge is expected to move east through this forecast period. This will start to bring a surge of warm humid air back to the forecast area especially by the middle of the week. In the mean time, surface high pressure will build southeast across the Great Lakes region into the local area for late Sunday into Monday and then off the Mid- Atlantic Coast by Tuesday night. A return southwesterly flow will develop over the area by the end of the forecast period and will bring warm air advection back to the area. As this occurs, the fair weather will transition back to another potentially wet and warming period by Tuesday into Wednesday. A gradual warming back to the middle and upper 70s is expected by Tuesday with lows generally in the 50s. && .AVIATION /12Z Wednesday THROUGH Sunday/... MVFR/IFR conditions cover much of northern OH and NW PA since we have a very moist atmosphere in place. After a few morning showers expect conditions to at least briefly improve before showers and thunderstorms develop for the afternoon/evening. Locations closer to the lake which are north of the stationary boundary could see the MVFR/IFR conditions linger well into the afternoon. After sunset in the wake of the showers/thunderstorms expect to see low clouds and fog return for the overnight hours. OUTLOOK...Non-VFR possible for periods of time through Thursday and again over the weekend. && .MARINE... Lake is expected to be relatively quiet in the wind and wave departments as winds remain light and variable. Expecting winds to pick up a bit at 10 to 20 knots Saturday from the southwest but they do diminish again Saturday night into Sunday to light and variable. So no major wind systems expected to affect the lake through this forecast period. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Flash Flood Watch until 6 PM EDT this evening for OHZ022-023- 032-033-038-047. PA...None. MARINE...None. && $$ SYNOPSIS...MM NEAR TERM...TK/MM SHORT TERM...Lombardy LONG TERM...Lombardy AVIATION...MM MARINE...Lombardy