textproduct: Cleveland

WHAT HAS CHANGED

No major changes to the forecast.

KEY MESSAGES

1.) Showers and storms expected today ahead of a cold front that will track through the region tonight with potentially severe level storms.

2.) Heat will build through the week as another upper level ridge builds into the Great Lakes.

DISCUSSION

UPDATE... Increased POPS to likely and categorical across the western and southern counties through early afternoon as an MCS propagates southeastward across the area. This complex is not being modeled well at all by the CAMS, but it appears to be an old MCV that regenerated a new line of convection due to downstream heating. Strong warm air advection is rapidly raising dew points into the mid 60s this morning, and with plenty of sunshine ahead of the line and the increasing low-level moisture, expect it to continue southeastward across the area. Surface based CAPE is marginal (around 1000 J/Kg), but with around 30 knots of effective bulk shear oriented normal to the line, there will be a marginal threat for severe winds at times from about Findlay to Mt. Vernon.

This morning complex results in a high amount of uncertainty regarding the redevelopment of convection ahead of the cold front this afternoon and evening. It is possible that a trailing outflow boundary causes all new convection to develop south of our CWA for the late afternoon and evening, so this will be reevaluated with this afternoon's forecast package.

KEY MESSAGE 1... Showers moving through Michigan and southern Ontario due to a prefrontal surface trough and the emergence of a low level jet will likely begin to dip southward into our CWA over the next several hours. These will be largely low QPF producers and scattered in nature, and not every location will receive rain this morning. As we get into the daytime hours, flow aloft becomes cyclonic, and with daytime heating, expecting not only a significant increase in the instability, but a lowering of the CAPE as well. Column RH could lag a bit, but do not expect that to be an inhibiting factor to convection today. Models now showing an increase in the 0-6km bulk shear compared to last night with 50kts, and could now see this development becoming a line or cluster of storms moving mainly northwest to southeast through the CWA. Expecting mainly damaging winds as a the threat, and this potentially severe convection should initiate after 18Z when insolation has had time to destabilize after morning cloud cover exits.

KEY MESSAGE 2... High pressure in the wake of the cold front Sunday and Monday in slightly cooler weather and convective chances returning Tuesday thanks to a relatively high amplitude upper level trough axis moving through. Another more persistent upper level ridge will move in for the rest of the forecast period, through the end of the week, and will mark a period where very warm temperatures should build in along with higher dewpoints that eclipse 70F for much of the CWA Thursday and Friday. Will need to watch the apparent temperatures for the end of next week with those higher dewpoints and temperatures in place.

AVIATION /12Z Saturday THROUGH Wednesday/

Initial push of showers and thunderstorms will continue to move east across the region this morning. Have maintained TEMPO groups for TSRA across most TAF sites through ~15Z/Sat. There will be a brief break in precipitation late this morning into early this afternoon. Thunderstorms will redevelop this afternoon along a line south of Lake Erie as a cold front pushes south across the region. Maintained PROB30 for lakeshore TAF sites as convection may develop just south of them. Elsewhere, have TEMPO groups to time out non-VFR impacts in thunderstorms this afternoon and evening.

Any showers and/or thunderstorms that develop and move over a terminal will be capable of producing MVFR ceilings and/or visibilities. Any afternoon/evening thunderstorm may reach severe limits and cause strong wind gusts and large hail.

Southwest winds have decreased slightly early this morning to 8-12 knots but they are expected to increase later this morning to 10-15 knots with gusts 20-25 knots. Locally higher wind gusts possible in strong to severe thunderstorms. Winds will turn westerly while decreasing to 8 knots or less tonight.

Outlook...Non-VFR possible in patchy fog early Sunday morning. Periods of non-VFR likely in occasional showers and thunderstorms Monday night through Wednesday.

MARINE

Southwest winds increase to 15-20 knots ahead of the passage of a cold front this evening. Wave heights are expected to build to 3-6 feet across the open waters and in the nearshore zones of the eastern basin. Have issued a Small Craft Advisory and Beach Hazards Statement though this evening. As the cold front moves south across the region showers and thunderstorms will be possible this afternoon and evening. High pressure builds overhead behind the cold front allowing for northerly winds to decrease to 10 knots or less on Sunday. Easterly flow increases to 10-15 knots on Monday before southerly flow returns on Tuesday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Beach Hazards Statement until 8 PM EDT this evening for OHZ012- 089. PA...Beach Hazards Statement until 8 PM EDT this evening for PAZ001. MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ147>149.