(Unfortunately, I don't have the direct sources in the Talmud on hand for the answer that follows. I'd appreciate people editing them in or providing them in the comments.)
The gemara states that Hashem performed a חסד for Israel when the temple was destroyed, because the trait of דין demanded absolute justice through destruction of the people, while Hashem "satisfied" the judgement through exiling the nation and destroying the בית המקדש. Similarly, the Talmud says that Hashem saw at the onset of Creation that the world couldn't stand through pure מדת הדין.
What we see is that all harsh actions from Hashem are tempered with mercy, cultivated to ultimately produce constructive ends despite short term suffering. The נביא reminds us that despite impending doom, Hashem is still relating to us with mercy and that the opportunity for salvation still exists - we haven't been "divorced" or "cut off," as other religions would have us believe.