From the Park:
KATAHDIN TRAILS UPDATE
Spring conditions (snow melt, rain, saturated soil) prevail on our trails. To preserve and sustain the resource, all Katahdin trails will remain closed for at least another week.
Abol is basically a stream bed that's sending a lot of sediment to lower portions of the trail. Sections below tree line are either covered by fast moving water or have a large body of standing water.
Abol Slide is usually the first trail up to open. The Hunt Trail (The AT) is usually next.