Friday, August 25, 2023

Historic August Rainfall/Severe Weather Recap

The clean up continues after the second round of heavy rain/severe storms across northern Ohio.

17 school districts closed due to damage and power outages:

Here is the COMPLETE radar loop from August 23 at noon through early August 25 before sunrise. Warnings, watches and lightning are included for northern Ohio.

I separated the 2 day rain event into 3 separate radar loops starting at 9pm August 24 through August 25 at 3am:

August 23 - 12:30PM through August 24 - 5AM

August 24 - 5AM through August 24 9AM

August - 9PM through August 25 - 5AM

Historic rainfall over 48 hours with two separate large clusters of rain/storms:

Another vantage point shows the heaviest rain from southern Michigan through Ohio and western PA.

Since August 1, most of northern Ohio has received 200-400% of normal rainfall:

Severe storm warnings were widespread. Most of northern Ohio was under a severe thunderstorm warning at some point between August 23 and early August 25.

4 tornado warnings. 12 tornadoes. COMPLETE NWS RECAP

The EF-1 that occurred on the east side of Cleveland was the first tornado that occurred within the Cleveland city limits since July 12, 1992 per NWS Cleveland. That tornado occurred near Hopkins Airport.

Here are ALL of the tornadoes from 1950 to 2022 in Cuyahoga County

Why did this heavy rain occur?  What were the factors that lead to this?

The huge ridge of heat in the central US has been a fixture for at least a week. 

Where high pressure resides, low pressure has to follow either down or up stream. Disturbances rode up and over the ridge and down through the Great Lakes.  

Great lakes radar loop from Wednesday through Friday: The excessive heat watches/warnings are shown in red.

Couple this with the high humidity (dewpoints above 75) and you have the recipe for heavy rainfall.

Interestingly, the historic Derecho in 1969 on the 4th of July produced MORE rainfall!

Here are the final rainfall numbers between August 23-25 using the same perspective as the 1969 map above (for comparison)

Oh and almost 75,000 lightning strokes over the 48 hour period across Ohio!