“before the decree becomes reality.” The sheer number of different English translations testifies to the difficulty of understanding the clipped and figurative Hebrew text. What does seem to be clear is the general message of the verse, which is captured well in the paraphrased version, the NLT: “Gather before judgment begins, before your time to repent is blown away like chaff. Act now, before the fierce fury of the LORD falls and the terrible day of the LORD’s anger begins.”
The “decree” was the Word of God that foretold the coming disaster. The phrase “becomes reality” is more literally “is brought forth” (is “born”). The scholars disagree whether the “decree” is brought forth, or if it is the decree that brings forth, i.e., the decree then brings forth all the specifics of the Day of Yahweh that have been foretold. In both cases, there is a reality coming when all kinds of disastrous things will happen on earth.
“the day passes on like the chaff.” The “day” is the Day of Yahweh, and just as chaff is driven very quickly by the wind, the Day of Yahweh is coming quickly. Here again, we see no hint of anything that can stop the Day of Yahweh from coming.
“the Day of Yahweh’s anger.” For more information on “the day of Yahweh” see commentary on Zephaniah 1:7.