Why does it say "Yamter"?
Radak: The decrees come from Shamayim [like rain does].
Refer to 11:6:3:3 and the note there.
What are "Pachim"?
Rashi: This is an expression of Pechamim (coals). Radak - this is like "Pecham l'Gechalim" (Mishlei 26:21).
Radak: This is like "Pach Yakosh" (Hoshe'a 9:8, i.e. a trap).
Radak citing Ibn Ezra: This is like "Riku'ei Pachim" (Bamidbar 17:3). They are like burning stones that descend with rain 1 .
I do not know what these are, nor their connection to Riku'ei Pachim. Perhaps words are missing; 'burning stones
What are "Zil'afos"?
Rashi: This is an expression of burning.
Rashi citing Menachem: This is like "Zal'afos Ra'av" (Eichah 5:10) and "Zal'afah 1 Achazasni" (below, 119:53).
Radak: This is shaking, or burning. Some texts of Rashi bring also "Sa'aru Sa'ar" (Yechezkel 27:35), which Radak there says is fear. (PF)
What is "Menas Kosam"?
Radak: It is their portion, like "Menas Chelki v'Chosi" (16:5) 1 .
Malbim: It is the portion that they prepared for themselves. If Hashgachah was revealed, and Hashem punished them immediately, they would have feared to do evil, and there is no test of the Rasha. Also, Hashem would not be able to give such a harsh punishment. Therefore, He waits until their measure is full and destroys them - in this world, or Pachim Esh v'Gafris in Gehinom - "u'Meshalem l'Son'av El Panav Leha'avido" (Devarim 7:10).
Radak: There, Menas is Samuch to Chelki and to Kosi", even though they [Menas and Chelek] are one matter, like "Admas Afar" (Daniel 12:2) (is Samuch, even though they are the same) and "mi'Tit ha'Yaven" (below, 40:3). Or, Menas [is Samuch to Chelek, for it] also refers to designation.
