I will scatter them as with an east wind - It is the property of this wind, almost every where, to parch up, blast, and destroy grain and trees, and even cattle and men suffer from it. Hence the old metrical proverb: -
"When the wind blows from the east, 'Tis good for neither man nor beast."
I will shew them the back - The hiding of God‘s face is the sure sign of His displeasure Isaiah 1:15; Isaiah 59:2.