textproduct: Cleveland

WHAT HAS CHANGED

Added all Ohio counties to Extreme Heat Warning based largely on cumulative multi-day effects of heat with little relief at night.

KEY MESSAGES

1) Heat and humidity have arrived through at least Thursday and possibly into Friday as well.

2) As the upper ridge breaks down and retreats back to the southeast coast, expecting chances for convective activity to increase Friday through the weekend.

DISCUSSION

KEY MESSAGE 1... Due to longevity of the heat, high dewpoints, and little recovery in the temperatures at night, have upgraded the Ohio counties of our CWA to an Extreme Heat Warning. The main setup for the heat remains the same. A 597dkm upper level high pressure system is building over the Ohio Valley and will persist through the end of the week. This is a dry system with little to no rain chances through Thursday. Where the variability in the forecast comes into play is with the 850mb temperatures. The NAM is the most aggressive with how high these temperatures will get with 24-26C for the region, while other operational models are more in the 22C range. This will ultimately be the difference between near 100F and closer to the mid 90s, respectively. Also playing a factor is that the ground has had a few days to dry out, which will foster heat, but on the other hand, 10- 15mph of southwesterly winds in the western zones could account for keeping the temperatures down a degree or two. In the end, these are fine-tuning features for the temperatures, but the story remains the same with impactful heat and dewpoints for the rest of the week.

KEY MESSAGE 2... The upper level ridge will finally break down and retreat to the southeast, putting the CWA back into a more zonal flow aloft for Friday into the weekend. The result of this will be the return of convective chances for the region, although will need to assess instability, shear, and any lingering capping issues as this time frame nears. But the thought is this could be a more active part of the forecast and will be watching for trends towards any severe potential.

AVIATION /12Z Tuesday THROUGH Saturday/

VFR conditions are expected through the forecast period with south to southwest flow across the region. The theme for the daytime hours will be an intermittent cumulus field between 3 and 5 kft that is being supported by warm air advection across the region. Some VFR ceilings will be in and out of the region with the cu field but should become more few/sct with afternoon mixing. Southwest winds may pick up a bit this afternoon, especially in NW OH, where some 20 kt gusts are possible. Otherwise, the cumulus field should decay this evening and leave VFR with high clouds overnight.

Outlook...VFR through most of Thursday. Low risk for an isolated shower or storm Thursday afternoon. Greater potential for scattered showers and storms Friday and Saturday afternoons.

MARINE

A warm front will move across the lake early this morning and usher in southwest flow to the basin. This flow averaging 10 kts should remain through the forecast period and into the weekend. There could be a lake breeze that develops east of Cleveland to allow for minor shifts in wind direction but they would be short-lived. Shower and thunderstorm activity will return starting on Thursday night into the weekend.

CLIMATE

Hotter and more 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 06-30 97(1953) 94(1970) 95(1941) 96(1913) 94(1942) 92(1930) 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)

CLE WATCHES/WARNINGS/ADVISORIES

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