Hurricanes sometimes go through a cycle where their eye wall disappears as a new eye wall forms farther out from the center and tightens up.  This is called an eye wall replacement cycle.  You can see one in Hurricane Matthew today at https://tropic.ssec.wisc.edu/real-time/mimic-tc/2016_14L/webManager/displayGifsBy12hr_06.html.  Very cool!

matthew-eyewall-replacement-static