259 FXUS61 KCLE 081819 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 219 PM EDT Tue Jun 8 2021 .SYNOPSIS... Surface ridge across the eastern United States will persist through Wednesday. An upper level low will drift across the area through the week, weakening across the area. A weak front will dissipate over the area on Thursday and a weak trough will linger into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... For this afternoon, showers and thunderstorms are developing with the diurnal cycle and with some focus along a lake breeze boundary across far northern Ohio and NW PA. This activity is expected to continue through the next several hours. Regarding a severe threat, a marginal risk for severe weather has been introduced to the eastern half of the area. Convection is currently at a minimum in the marginal risk area; however, instability is increasing and with dry air in the mid-levels and increasing DCAPE, downburst potential is present across the region and will need to be monitored for gusty winds over the next couple of hours. As for a hydrological threat, initial storms firing along a lake breeze boundary are quickly bursting and setting off additional boundaries that more storms are generating off of. This will present some training issues in some locations and nuisance flooding could develop in some locations. Flooding would be mostly off initial rainfall rates. Convection will diminish with the diurnal cycle tonight, becoming widely scattered overnight with lingering cloud cover. Temperatures will remain elevated with the clouds overnight and have lows similar to last night with lows in the upper 60s/lower 70s. For Wednesday, the forecast area will go through the motions again with a surface ridge to the southeast, allowing for heat and moisture to build over the region and another round of mostly diurnally driven convection. The upper low will be closer to the region on Wednesday and suspect that thunderstorm coverage will be higher than today and have maintained categorical PoPs by late Wednesday afternoon. Highs should be in the 80s, limited by convection. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... Two different systems are expected to play a role in the weather during the short term period. There is one low that is expected to linger over IL/IN which is associated with a weak upper level trough. The second system located over New England is expected to move a cold front south across Lake Erie on Wednesday night into Thursday. After the frontal boundary moves south across the area, the aforementioned low pressure west of the area will finally begin to move eastward as the upper level flow becomes a bit more progressive. Areas of vorticity will rotate around the low pressure to the west of the area during the time period, which will aid in upper level support for showers and thunderstorms. As ample moisture remains over the area with a southern flow, the cold front and then low pressure will act as two mechanisms to shower development, with the greatest chance of thunderstorms during peak heating on Thursday and Friday. Confidence continues to grow in regards to widespread precipitation occurring, however there is still a bit less confidence in timing and location of convection. High PWAT values near 2 inches will be the primary concern as the atmosphere exhibits conditions closer to tropical in nature. This means that any showers that do develop will exhibit increased precipitation efficiency. With a lack of flow across the area, any showers/convection that develops will need to be monitor for the potential of flash flooding. High temperatures during this period will be in the low to mid 80s and are expected to remain humid with RH values in persisting near 80% during the daytime hours. This will result in temperatures feeling closer to 90. Overnight lows will drop into the mid to upper 60s and also remain humid. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The trough that is expected to impact the area during the short term period will move off the East Coast by the beginning of the weekend. This will result in the area being influenced by the leading edge of a ridge, leaving the area under a northwesterly flow. A shortwave trough moving along this edge, coupled with diurnal heating may provide enough energy to support scattered showers and thunderstorms Saturday afternoon. Near the end of the long term period, models suggest a full pattern shift with a trough moving south across the area. With this, the upper level jet will also move south as it has been location north of the Great Lakes lately. Once this trough moves south, cooler temperatures can be expected along with precipitation. Exact timing of this is still not in agreement amongst models. Before the cooler temperatures reach the area though, temperatures are expected to remain in the low to mid 80s through the long term period, however there is expected to be a dip in dew points, which should make these warm temperatures a bit more enjoyable. && .AVIATION /18Z Tuesday THROUGH Sunday/... Shower and thunderstorm activity across the region will continue through the evening hours and will be intermittent across most of the terminals. Convection earlier this afternoon may allow for KERI to be done with thunder chances for today and have removed from the TAF. Elsewhere, thunder chances continue and have vicinity thunder with tempo groups to address current thunder timing and conditions quickly falling to IFR or lower in heavier rain and thunderstorms. With convection waning overnight, have dry TAFs for the middle of the TAF period and VFR conditions. Wednesday will feature a similar thunderstorm setup to today but perhaps with more coverage and have vicinity rain and thunder already mentioned at the end of the TAFs. Winds through the period will generally be light and southerly outside of thunderstorms. A lake breeze may allow for more westerly winds late in the TAF period at KERI and KCLE. Outlook...Non-VFR possible Wednesday through Thursday in showers and thunderstorms. && .MARINE... Marine conditions are expected to remain calm as light southwesterly flow across Lake Erie will result in winds of 5-10 knots and waves below 1 foot. The only forecast concern at this point is with a cold front that moves south across the lake Wednesday into Thursday. Behind this boundary, winds are expected to shift and become northeasterly at 10-15 knots by Thursday afternoon and persist into Saturday morning. Waves are expected to build to 3-5 feet. With the magnitude of winds expected, lakeshore flooding across the western basin is not anticipated at this time. This time frame at the end of the week will need to be monitored for any potential marine headlines. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Sefcovic NEAR TERM...Sefcovic SHORT TERM...Campbell LONG TERM...Campbell AVIATION...Sefcovic MARINE...