textproduct: Cleveland

WHAT HAS CHANGED

Overall, the forecast remains on track. Confidence in strong to severe storms Saturday afternoon/evening continues to increase, although there is still uncertainty in timing.

KEY MESSAGES

1) Wildfire smoke will produce poor air quality and reduce visibilities today.

2) A few showers/storms are possible as early as this evening. Strong to severe thunderstorms are possible Saturday afternoon into early Saturday evening.

3) Very warm temperatures will persist through Saturday before cooler weather arrives for Sunday and the middle next week.

DISCUSSION

KEY MESSAGE 1... Northwest flow will pull additional wildfire smoke into the area through much of today, resulting in continued reduced visibilities and unhealthy to hazardous air quality conditions. Visibilities will likely be reduced to 1 to 2 miles through at least this morning with locally worse visibilities possible. Local and state partnering agencies have issued Air Quality Alerts areawide through midnight tonight. Conditions should gradually improve from the southwest this afternoon into tonight as flow becomes more south/southwesterly in response to a warm front lifting into the region. By the predawn hours Saturday morning, it's possible that patchy smoke is only present across far NW PA. In addition, any precipitation should help improve air quality.

KEY MESSAGE 2... Shower and thunderstorm chances will return as the aforementioned warm front lifts northeast into the region this evening and tonight, although confidence in coverage/placement of storms is low at this point. Storms should be relatively elevated later this evening and it's possible that precip struggles to develop due to the stabilizing effects from the wildfire smoke. Any stronger storms should largely remain to the southwest of the area this evening. Showers/storms should exit to the east by mid-morning Saturday, although some CAMs have showers/storms lingering in the warm sector throughout the morning. By Saturday afternoon, additional showers/storms will develop with a pre-frontal trough as low pressure deepens to the north of the area. The storms will push southeast across the area as a cold front begins to move southeast into the local area early Saturday evening.

Conditions still appear to be favorable for organized convection Saturday afternoon into Saturday evening. Strong southwest flow will advect moisture into the region with PWAT values increasing to 1.5 to 2 inches and dew points rising into the upper 60s and lower 70s by Saturday afternoon. If showers and remaining clouds move out of the area in the morning, MLCAPE values will likely reach 2500-3000 J/kg during the afternoon, which would certainly support a damaging wind gust threat. A LLJ will move over the region and expect shear values of 30 to 40 knots with the highest shear values close to the lakeshore and over NE OH/NW PA. As a result, storm mode will likely be a QLCS with damaging wind gusts being the primary threat. A few brief tornadoes can't be ruled along the leading edge of the line given the shear profile. The entire area is in a Slight Risk (level 2 of 5) of severe weather, although locations generally along and east of I-71 are highlighted with greater probabilities of damaging wind gusts and a slightly more enhanced tornado risk due to the higher shear values.

Dry weather will return for Sunday, although shower and thunderstorm chances increase as the next system crosses the area late Monday into Tuesday.

KEY MESSAGE 3... Smoke will help mitigate hazardous temperatures today, but still expect highs in the upper 80s and lower 90s across much of the area. Temperatures may be a few degrees warmer on Saturday and heat index values may flirt with 100 degrees over portions of northwestern and north-central Ohio Saturday afternoon. That said, there may be clouds and showers/storms around during peak heating which would result in cooler maximum temperature/heat index values. At this point, confidence in heat index values reaching Heat Advisory criteria is low and isolated. Temperatures will cool considerably Sunday; highs will only be in the mid 70s to lower 80s. Temps will warm by several degrees Monday and Tuesday before below normal temps return for mid to late next week.

AVIATION /12Z Friday THROUGH Tuesday/

Widespread IFR continues across the TAF sites this morning, associated with wildfire smoke. Gradual improvement to MVFR and eventually VFR is expected from west to east towards the end of the TAF period as a warm front lifts northeast across the region, though anticipate IFR smoke to persist for much of the day. Recent model trends indicate a slight uptick in shower and thunderstorm coverage along the warm front tonight, and may need prob30/tempo groups at some point if trends persist.

Light and variable winds will continue through this morning, before increasing out of the south to southwest behind a warm front this evening and overnight, 5 to 7 knots. A lake breeze will develop at CLE/ERI early this afternoon, resulting in north to northwest winds of 6 to 8 knots.

Outlook...Non-VFR expected in showers and thunderstorms ahead of a cold front Saturday afternoon and evening. A few storms could be strong to severe with strong wind gusts approaching 50 knots.

MARINE

Rough marine conditions will return across Lake Erie on Saturday as southwest winds of 15 to 25 knots develop ahead of a cold front. Winds will shift towards the north behind the front Saturday evening and overnight, 15 to 20 knots, before diminishing to less than 10 knots Sunday afternoon. Small Crafts will likely be needed as early as Saturday morning with the stronger offshore winds, particularly across the central and eastern basins, transitioning to both a wind and wave concern by Saturday evening and overnight with the onshore flow. Another period for rough marine conditions will arrive on Tuesday as southwest winds of 15 to 25 knots develop ahead of a cold front. Rough marine conditions appear favored to persist into Wednesday behind the cold front with north to northwest flow of 20 to 25 knots.

Confidence is increasing for strong thunderstorm wind gusts ahead of a cold front Saturday afternoon and evening across Lake Erie.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Air Quality Alert until midnight EDT tonight for OHZ003- 006>009-017>019-027>032-036>038-047. PA...Air Quality Alert until midnight EDT tonight for PAZ001>003. MARINE...Dense Smoke Advisory until 4 PM EDT this afternoon for LEZ142>149-162>169.