textproduct: Cleveland

WHAT HAS CHANGED

Extended the Extreme Heat Warning for Northern Ohio and Heat Advisory for Northwest Pennsylvania through Friday evening.

KEY MESSAGES

1) Dangerous heat and humidity persist through the end of the week.

2) Daily chances for showers and thunderstorms return Thursday evening onward.

DISCUSSION

KEY MESSAGE 1... Surface high pressure and an accompanying upper level ridge persist across eastern United States. Dangerous heat and humidity continue to impact the region as 850mb temperatures rise to the 20-25C range (99th percentile). Daily maximum temperatures through Friday are expected to rise into the mid to upper 90s accompanied by dew points in the mid 70s. This will lead to maximum heat index values in the 100-110F range through the end of the week. Extended the end time of heat headlines to remain valid through 8 PM Friday. Additional heat headlines may be needed on Saturday if coverage of showers and thunderstorms is lower than expected. With the continued heat and limited overnight relief, the majority of the forecast area remains under Extreme HeatRisk (Level 4 of 4). For people without effective cooling, especially heat-sensitive groups, this level of heat can be deadly.

KEY MESSAGE 2... The pattern turns more unsettled late this week as the upper level ridge begins to breakdown. Increased chances of showers and thunderstorms are expected for the holiday weekend. Confidence in timing, coverage, and placement of showers and storms remains very low Friday into the weekend. Slight chance to chance PoPs are forecast across the region Friday with higher chance to likely PoPs forecast Saturday and Sunday as surface low pressure hangs in the vicinity of the Great Lakes/Ohio Valley region. SPC has placed the entire forecast area in a Marginal Risk (Level 1 of 5) for severe weather on Friday. Will continue to monitor severe weather potential with the next few forecast cycles.

AVIATION /18Z Wednesday THROUGH Monday/

VFR conditions are expected today and tonight. Some diurnal afternoon cumulus (4-5 kft) continue this afternoon and are expected again tomorrow afternoon. Brief MVFR ceilings are possible near KYNG and KCAK mid to late tomorrow morning. Winds around 10 knots will remain southwest through the period with occasional gusts up to 20 knots during the afternoon.

Outlook...There is a very low chance of thunderstorms Thursday evening. Greater potential for scattered storms Friday through Sunday, especially during the afternoon and evening hours each day.

MARINE

With high pressure to the south, pleasant marine conditions are expected with southwest flow averaging 10 knots through the period. There could be a lake breeze that develops east of Cleveland each afternoon, which would allow for minor shifts in wind direction and brief 2 ft waves that would be short-lived.

CLIMATE

Very hot and humid weather is expected through Friday. Record warm high temperatures may be challenged. Here are those records for each of our climate stations:

Date Toledo Mansfield Cleveland Akron Youngstown Erie 07-01 98(1931) 98(1931) 95(2002) 97(1931) 96(1931) 94(2018) 07-02 98(2011) 97(1931) 97(1954) 98(1931) 98(1931) 94(1963) 07-03 100(1911) 93(2020) 98(1949) 97(1911) 98(1898) 93(1934) 07-04 100(2012) 96(2012) 98(1990) 99(1911) 99(1897) 99(1990)

CLE WATCHES/WARNINGS/ADVISORIES

OH...Extreme Heat Warning until 8 PM EDT Friday for OHZ003-006>014- 017>023-027>033-036>038-047-089. PA...Heat Advisory until 8 PM EDT Friday for PAZ001>003. MARINE...None.