Pavlof Volcano roared back to life Sunday afternoon, March 27, 2016. There was about 30 minutes warning before the eruption started. Seismicity started increasing from background around 3:53 PM AKDT. By 4:18, ash was in the air moving generally north. AVO raised the aviation color code from green to red as ash initially topped out at over Flight Level 200 (20,000 feet above the surface). Ash eventually reached over 37,000 feet during this phase of the eruption. http://www.avo.alaska.edu/activity/report.php?id=82161&mode=hans&type=3
The eruption continued throughout the night and into the next day before decreasing in intensity around 12:30 PM AKDT. At that time, AVO changed the aviation color code to orange. http://www.avo.alaska.edu/activity/report.php?id=82221&mode=hans&type=3
The aviation color code was moved from orange to yellow midday on April 6, after almost a week of quiet. No additional ash, lava fountaining, lahars or lava flows were observed for several days prior to the return to yellow. The volcano remains at yellow as of this writing. http://www.avo.alaska.edu/activity/report.php?id=82571&mode=hans&type=3
Multiple flights in interior Alaska by Alaska Air Lines, Horizon Air, PenAir, were cancelled Sunday due to the ash cloud working its way north. Over 200 flights were cancelled mostly in interior Alaska over the course of three days the ash cloud was over the state. This included all air traffic into and out of the Prudhoe Bay oil fields. International flights in and out of Anchorage International had to divert south of the Alaska Peninsula and around Pavlof so as to avoid the ash plume.
AVO was kind enough to respond to several questions about the eruption.
They explained that the lack of warning is due to Pavlof being an open system, where the conduit between the surface and the magma reservoir not being plugged. No plug means that any disruption in the chamber will almost immediately express itself with activity out of the crater at the top of the volcano.
They have not done any field studies yet to determine how big the eruption was. It was larger than the 2014 VEI1.
Black streaks down the flanks of the volcano are a combination of lahars and lava flows, with the lahars being the longer streaks.
Finally, while Pavlof is well monitored, Pavlof Sister is not, leading to some questions elsewhere. This is all due to available resources. Pavlof Sister is relatively quiet, having not erupted for at least 350 years. AVO is resource limited and concentrates its monitoring on volcanoes with a history of recent eruptions.
For more information on Pavlof and Emmons Lake Volcanic Complex, you can look at a couple past articles on the old VC site.