Juneau to Mendenhall Valley: the next glacial flood is coming, plan now

Juneau is telling anyone who lives, works or travels near the Mendenhall River to get ready. The next glacial outburst flood from Suicide Basin is expected between about Aug. 1 and 9, and roughly 1,900 valley homes sit inside the evacuation advisory area.

"The next glacial lake outburst flood is on its way," a narrator says in a city video. "Once the river begins to rise, it's too late to prepare."

The city's asks are simple: check whether your home, work, school or daily route falls inside the mapped advisory area, and build a household plan now, one that accounts for pets, a destination and what you'll take. Sign up for CBJ emergency alerts, watch the National Weather Service's Suicide Basin page, and be ready to leave if told to.

The flood forms the same way every summer. Meltwater pools in Suicide Basin behind the Mendenhall Glacier until it releases and surges down the river. The basin is at roughly 1,248 feet now; the overflow channel sits near 1,350. In past events, officials cleared the 17-foot inundation zone until an all-clear, and the state closes roads once the Mendenhall Lake gauge hits 12 feet.

One more instruction, about the temporary barriers holding back the water: stay off and away from them, especially during a flood. The city says that protects both residents and the responders who'd have to come after them.