Using ./radar/ec-lightning-test-en.txt as test file.
Now date='Thu, 25 Apr 2024 22:43:14'
File says='Thu, 25 Apr 2024 22:43:14'
Write and read-back successful.. contents identical -- ec-lightning.php cache should work fine with $lightningDir = './radar/'; setting.
Your legendLightning.png is correctly placed in ./radar/ and shows like this:
To run the ec-lightning.php script, you also need GD enabled in PHP.
Make sure the following displays Yes for all items (except for 'WebP Support', 'T1Lib Support' and 'JIS-mapped Japanese Font Support' which are not needed).