Reading the engine
Jet stream above 5 km: ≥ 252 km/h, bright ≥ 324 km/h
Suction at the left exit: where the jet pulls air apart aloft (divergence at 300 hPa), sparks rise from the ground to jet level
The ball is the storm centre, resting in the pressure hollow
Ground: sea-level pressure as a surface, low = deep, strongly exaggerated
box 42° × 20°, 0–9 km, strongly exaggerated · ERA5 hourly