When you cut your bread and the crumbs fall out (like snow), you use the verb peD. It can also be used for instance, when you throw confetti, and the confetti falls down, then use peD. So, with other words, peD still means to snow, but it does not only refer to snow, but can also be used for other small things falling down slowly or rain down, like ashes.

qep'a' 30 - During the event, a leak caused water to come from the ceiling. While describing this to Dr. Okrand, I (qurgh) said "The ceiling rained" and he replied by saying that expression would be how SIS should be used. We established that the subject of SIS, and other weather verbs, is the source of that activity. In the case of SIS this could be muD, 'eng, or pa' beb.