textproduct: Cleveland

WHAT HAS CHANGED

Opted to issue a Heat Advisory for Northwest Ohio and portions of North Central Ohio for Tuesday. Additional Heat Advisories may be needed for Wednesday.

KEY MESSAGES

1) Heat and humidity will build early this week with peak heat index values in the mid 90s to low 100s.

2) Periodic showers and thunderstorms return late this week and continue into the weekend.

DISCUSSION

KEY MESSAGE 1... Closed off 99th percentile mid/upper level high centered over the Upper Midwest will gradually drift southward into the Great Lakes and Ohio Valley region. Heat and humidity are expected to build across the region Tuesday into Wednesday as 850mb temperatures, also 99th percentile, peak near 23-25C. Have issued a Heat Advisory for Northwest Ohio and portions of North Central Ohio, including Cuyahoga County, for Tuesday as heat index values rise to 100-103 F. Another day of heat headlines will likely be needed on Wednesday for a similar geographical extent, but opted to hold off on issuing for Wednesday with this forecast package. Widespread Major HeatRisk (Level 3 of 4) is expected both Tuesday and Wednesday. Ensure that you remain hydrated and consider adjusting outdoor plans to the cooler parts of the day.

The upper high will gradually flatten and dissipate over the Ohio Valley mid/late this week. A cold front passes south Wednesday night but it will remain warm with highs in the 90s. However, peak heat index values will lower to the mid 90s for Thursday and Friday.

KEY MESSAGE 2... The upper level ridge moves west as an upper level trough and surface cold front sink south from the Northeast towards the eastern Great Lakes near the end of the week. Shower and thunderstorm chances will increase Friday evening through the weekend in the wake of the cold front. Some thunderstorms this weekend may reach strong to severe limits but confidence in timing and extent remains low given lower confidence in magnitude, track, and timing of the aforementioned upper level trough.

AVIATION /18Z Monday THROUGH Saturday/

Widespread VFR conditions will persist through this period as high pressure remains dominant over the area. Diurnal, scattered cu are possible this afternoon into the evening, but should remain above 4kft. Overnight, skies clear out before another round of cu develops late Tuesday morning into the afternoon hours. KCLE and KERI are currently being impacted by a lake breeze that developed with north-northwest winds around 10 knots being observed. As the sun sets, all winds will become light and variable through the overnight hours. Winds will increase to 5-10 knots from the west-southwest mid-morning on Tuesday.

Outlook...VFR favored through Thursday. Non-VFR chances increase starting late Friday into the weekend with showers and thunderstorms possible.

MARINE

Quiet marine conditions are expected under high pressure. Light winds will become southwesterly and increase to 10-15 knots overnight tonight and persist through Wednesday morning. Winds shift westerly during the day Wednesday before turning northerly behind a cold front Wednesday evening. Northerly winds Wednesday night through Thursday afternoon should remain at 10 knots or less. Waves may build to around 2 feet with the onshore flow but are otherwise expected to remain at 2 feet or less through the week.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Heat Advisory from noon to 8 PM EDT Tuesday for OHZ003-006>011- 017>019. PA...None. MARINE...None.