I have also experienced screaming noises on AM radios.
The cause has been due to static electric charge in the rain, or often on suitably cold days static charged hail.
When I lived in the Shetland Islands, sevreral times I had to repair my car radio because the static charged hail popped the RF amplifier transistor.
Side note.
When I refer to "static" I mean static electricity, the stuff which eventually makes lightning.
I do NOT mean any random noise on the radio, as per Hollywood, and others who know nothing about radio.
RANTMODE = OFF
JimB