textproduct: Cleveland

WHAT HAS CHANGED

Expanded the Heat Advisory to include portions of North Central Ohio, including the Cleveland metro.

KEY MESSAGES

1) Daily chances for showers and thunderstorms continue ahead of a cold front that will push across the region on Friday. Limited to isolated risks for heavy rainfall and severe weather.

2) Hot and humid conditions ahead of the cold front with little overnight relief anticipated. Daily heat index values will peak near 100F across portions of the forecast area today and Thursday. Cooler behind a cold front Friday into the weekend.

DISCUSSION

KEY MESSAGE 1... A shortwave aloft will move east early this morning allowing for any remaining scattered showers and thunderstorms to exit the region. There may be some lingering showers/storms across Northwest Pennsylvania through late this morning. A mid/upper level ridge will build across the region today which will likely bring a period of dry weather through this afternoon. A very moist and unstable airmass remains in place with the latest HREF showing moderate instability of 2000-2700 J/kg SBCAPE. Latest hi-res guidance shows the potential for a few isolated to scattered showers and storms developing later this evening in this favorable environment. A few severe storms may be possible with primary hazards of damaging wind gusts and large hail. SPC has highlighted our CWA in a Marginal Risk (Level 1 of 5) for severe weather today.

By late tonight into early Thursday morning a number of hi-res models continue to show an MCS diving southeast from the Upper Great Lakes towards the Ohio Valley. Still a fair amount of uncertainty with the evolution of the MCS as it may be weakening as it pushes towards the forecast area. Depending on the trajectory of the weakening MCS, there may be some lingering showers/storms early Thursday morning. However, the bulk of Thursday looks fairly dry outside of any isolated showers/storms that may develop in the afternoon/evening giving the hot and humid airmass.

More organized convection will be possible late Thursday night into Friday as a strong cold front pushes east into the region. The timing of the frontal passage will heavily influence the threat for severe weather. As of right now, the entire area is under a Marginal Risk (Level 1 of 5) with a Slight Risk (Level 2 of 5) across Northwest Ohio Thursday through Thursday night. Additionally, SPC has a CIG1 hatching for damaging wind gusts of 65+ knots associated thunderstorms moving into the western portion of our forecast area along and ahead of the cold front. Damaging winds will be the primary threat in any severe weather with embedded tornadoes and large hail as secondary risks. The severe weather threat continues during the day on Friday as the cold front moves through the region. The majority of the forecast area is under a Marginal Risk (Level 1 of 5) with a Slight Risk (Level 2 of 5) for Northwest Pennsylvania. Damaging wind gusts will be the primary hazard on Friday.

The airmass remains very moist ahead of the front so locally heavy rain will remain a concern with any convection until it clears. Convection should remain disorganized or sporadic enough to continue limiting the potential for flooding, though flash flooding may be an issue in any training or repeated storms over the same area.

We'll dry out behind the cold front Friday night into the weekend. Some low end precipitation chances return on Sunday into early next week as another cold front enters the region.

KEY MESSAGE 2... Hot and humid conditions continue across the region today and Thursday before the aforementioned cold front glides east. Highs today will rise into the upper 80s to lower 90s for much of the forecast area. Some lingering showers and/or cloud cover will likely keep temperatures a few degrees cooler in the mid 80s for portions of Northeast Ohio and Northwest Pennsylvania. Opted to expand the Heat Advisory for this afternoon/early evening east to include counties along and west of I-71. Peak heat indices will largely range between 95-100F this afternoon. Some spots in the advisory may not reach the 100F criteria, but given the early season nature and lack of overnight relief heat-related impacts are a concern.

Highs will once again rise into the upper 80s to near 90 degrees on Thursday with peak heat index values in the mid 90s. Still some uncertainty for if a Heat Advisory will be needed again on Thursday given lingering cloud cover and/or showers from Wednesday night's convection. Temperatures will fall behind cold front on Friday with cooler highs in the low to mid 80s expected through the weekend.

AVIATION /12Z Wednesday THROUGH Sunday/

Currently in the wake of some overnight convection as of 11Z this morning, and the rest of the trailing stratiform precipitation is waning. VFR for the most part at this point, and expect it to stay there as the sun rises and the boundary layer begins to mix. Southwest winds today under 12kts will increase to have gusts of 15-25kts later today and into tonight. There is a potential for another complex of storms tonight, and have that covered with PROB30 for CLE-MFD and east.

Outlook...Periods of non-VFR likely in isolated to scattered showers and thunderstorms through Friday. Another period of non- VFR conditions is possible in showers and thunderstorms Sunday afternoon.

MARINE

Southwest winds 10-20kts prevail through early Friday with wave heights less than 2ft in the nearshore zones. Friday, a cold front sweeps across Lake Erie with winds becoming westerly 15-20kts and wave heights 2-3ft in the central and eastern basins, less than 2ft in the western basin nearshore zones. Winds become southwesterly again for the weekend 10-20kts and wave heights 2ft or less as high pressure builds over the Ohio Valley.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Heat Advisory from noon today to 8 PM EDT this evening for OHZ003-006>011-017>020-027>030-036-037-047. PA...None. MARINE...None.