textproduct: Cleveland

WHAT HAS CHANGED

There were no major changes with this forecast update. Near record heat expected again today. Extreme Heat Warning for Northern Ohio and Heat Advisory for Northwest Pennsylvania will continue through Friday evening.

KEY MESSAGES

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

2) Daily chances for widely scattered showers and thunderstorms return this evening onward with better probability this weekend.

DISCUSSION

KEY MESSAGE 1... A large summertime high pressure ridge or "heat dome" is currently over the lower Ohio Valley this morning. This ridge of high pressure will continue to bring very hot temperatures and humidity across the region through Friday. Temperatures are expected to be in the middle 90s to around 100 degrees once again this afternoon. Toledo and Cleveland have the best chance of either to break or tie their daily record high temperatures for Thursday, July 2nd. All the other daily climate sites will be closer to their record highs, within a couple degrees. See the climate section below for more info. The heat index will be between 100 and 108 degrees later today. Friday's high temperatures will be back in the middle to upper 90s and the heat index between 100 and 107. The ongoing Extreme Heat Warning and Heat Advisory through Friday evening looks good at this time and no changes are needed. This ridge will weaken somewhat and flatten out by the weekend as it shifts off the southeastern U.S. Temperatures will be slightly lower but still rather hot in the upper 80s to lower 90s this weekend. By early and middle of next week, temperatures will be closer to seasonable warm weather for early July in the middle and upper 80s areawide.

KEY MESSAGE 2... The first chance for a few widely scattered showers and storms may be possible this evening across far NEOH and NWPA. The chance for POPs will be 20 to 30 percent at best. There will be a little disturbance that will try to ride over the top of the ridge of high pressure this evening which could spark off some widely scattered convection. Later on Friday, the ridge of high pressure will start to pull away allowing for the main westerlies to shift southward and closer to the eastern Great Lakes region. The chances for scattered convection will increase by late Friday afternoon into the overnight. SPC has mentioned our entire area for a marginal risk (level 1 of 5) for the potential of isolated severe storms. The main threat will be damaging wind gusts and large hail with any of the strongest convection. We will continue to remain in that westerlies flow aloft over the weekend which will bring off and on chances for scattered showers and thunderstorms, mainly during the max heating of the afternoon and evening. A couple stronger storms could be possible over the weekend as well. A lingering mid level trough may hang over the eastern Great Lakes through the middle of next week and bring the chance for daily pop-up convection in the forecast. We will hold on to daily POPs of 20 to 30 percent into early to middle of next week.

AVIATION /06Z Thursday THROUGH Monday/

VFR. FEW-SCT cumulus formation in the daytime heating hours FL035-050. Southwest winds could gust 15-20kts FDY/TOL, but further east terminals should remain under 12kts. Convective chances possible, but after the 06Z Friday time frame.

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

MARINE

Southwest winds 10-15kts will persist through the weekend, and wave heights will generally be around a foot or less in the nearshore zones of Lake Erie. With low pressure moving into the region after Sunday, onshore flow will prevail for Monday and Tuesday around 10kts with wave heights 1-2ft. Daily thunderstorm chances return Friday through the weekend.

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 07-02 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.