textproduct: Cleveland

WHAT HAS CHANGED

Wildfire smoke will likely inhibit daytime heating a bit this afternoon and Friday so have decreased max/hourly temperatures with this update. A Slight Risk (Level 2 of 5) of severe weather has been introduced to the entire area for late Saturday afternoon into Saturday night.

KEY MESSAGES

1) Wildfire smoke will produce poor air quality and likely reduce visibilities through tonight and likely into Friday.

2) Periodic showers and thunderstorms are expected Friday through early next week. The greatest potential for strong to severe thunderstorms is late Saturday afternoon into Saturday night.

3) Hot temperatures will persist across most of the area through Saturday before cooler weather arrives by the end of the weekend.

DISCUSSION

KEY MESSAGE 1... North/northwest flow will continue to bring Canadian wildfire smoke into the area through tonight and likely into Friday. This will result in reduced visibilities in haze/smoke and unhealthy air quality conditions across the local area, especially today. Partnering agencies have issued Air Quality Advisories for ground level fine particles for today, as air quality will likely be hazardous for the general population. Given the hazardous air quality, it is recommended that people limit time outdoors today. Lingering north/northwest flow aloft may keep smoke around through Friday, but it's possible that surface smoke gradually decreases in coverage as surface winds shift to the south during the day Friday. Either way, it will likely take some time for smoke to completely diminish on Friday.

KEY MESSAGE 2... The upper level ridge will begin to break down on Friday, allowing shower and thunderstorm chances to return late week into the weekend. PoPs will begin to increase from the southwest Friday evening/night as a warm front lifts northeast with PoPs peaking as a cold front moves southeast across the area and low pressure deepens over southern Ontario Saturday evening.

Shower coverage/potential may be limited due to the stabilizing effects of wildfire smoke Friday afternoon and possibly into Friday evening. There's still uncertainty in timing, but at this point the best chance of organized convection and strong to severe storms will be with the cold front at some point late Saturday afternoon into Saturday night. MLCAPE values will likely increase to 2000-2500 J/kg (possibly as high as 3000+ J/kg) ahead of the front and bulk shear values will be 30-40+ knots which will support potential for a broken line of strong to severe storms. The main limiting factor would be stabilization from any early day showers/storms, so will need to keep an eye on rain chances Saturday morning into Saturday afternoon. The entire local area is in a Slight Risk (Level 2 of 5) of severe weather on Saturday. Storms may start off more discrete and could produce large hail early, however the threat will likely evolve into more of a damaging wind gust threat as a line begins to take form Saturday evening/night.

Dry weather is expected on Sunday, but periodic showers and thunderstorms are likely Monday night into Tuesday.

KEY MESSAGE 3... Upper ridging will produce continued hot temperatures through Saturday, although the wildfire smoke may help limit daytime temperatures today and possibly on Friday. Highs will generally be in the lower 80s across portions of far NE OH and NW PA this afternoon with mid 80s and lower 90s anticipated elsewhere. Dew points will be in the 60s and around 70 degrees in the warmer areas and heat index values will likely reach the mid to upper 90s south of U.S. Route 30 during peak heating today. Temperatures will generally be in the 80s and lower 90s on Friday, although the coverage of wildfire smoke will likely influence high temperatures; lower coverage than anticipated may result in warmer temps, whereas higher coverage may result in slightly cooler temps. Saturday will feature one last day of temperatures in the upper 80s and lower 90s before a cooler weather pattern arrives Sunday into next week. Temperatures will be below normal at times next week.

AVIATION /06Z Thursday THROUGH Monday/

Currently, the majority of the region is seeing VFR conditions with a few exceptions for terminals in Northern Ohio and Northwestern Pennsylvania. A few locations along the lakeshore are starting to see visibility reductions due to the wildfire smoke moving south. As the morning progresses, the smoke will continue moving south throughout the region dropping visibility down to MVFR and, at times, IFR. The smoke will linger through the entire TAF period and into Friday with some uncertainty in when it will dissipate. Expected non-VFR visibility through the remainder of the week due to this. Winds are currently light at around 5 knots out of the west- southwest, shifting to be out of the north by midday and increasing to 5-10 knots. By the end of the TAF period after 00Z, winds will shift to be out of the north-northeast at around 5 knots.

Outlook...Non-VFR visibility possible through Friday due to Canadian wildfire smoke. Non-VFR likely Friday night through Saturday night in showers and thunderstorms.

MARINE

A cold front has pushed south of Lake Erie this morning and winds have shifted to be out of the north at 5-10 knots. Behind the front today, winds will generally be around 5 knots or less and predominantly out of the north, but will have some variability in the direction. Visibility across the lake will vary as well due to the wildfire smoke moving in from the north. Some areas may see visibility drop down to less than 1 NM, so a Dense Smoke Advisory may be needed if coverage is great enough. A warm front will pass over the lake late Friday night into Saturday and winds will increase to 10-20 knots out of the south-southwest. Waves as a result will build to 1-3 feet mainly in the open waters and less than 2 feet in the near shore zones. Late Saturday, a cold front will move west to east across the region and winds will shift to be out of the northwest at 10-15 knots and waves building to 1-3 feet in the nearshore zones east of the Islands. Showers and thunderstorms chances will increase starting early Saturday with the warm front and be possible throughout the day until the cold front moves through. High pressure builds in briefly on Sunday persisting through Monday with winds and waves subsiding.

Another cold front will move through the region on Tuesday increasing winds and waves. There will be potential a Small Craft Advisory may be needed for Tuesday with the frontal passage as waves will build near 4 feet and winds will be 15-20 knots out of the northwest. Winds will diminish slightly behind the front into Wednesday, though should stay around 10-15 knots out of the north.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Air Quality Alert from 7 AM this morning to midnight EDT tonight for OHZ003-006>014-017>023-027>033-036>038-047- 089. PA...Air Quality Alert until midnight EDT tonight for PAZ001>003. MARINE...None.