The National Weather Service predicts the glacial lake responsible for producing Juneau’s annual glacial outburst flood will fill a bit later than the initial forecast.
Suicide Basin is expected to fill to the top between Aug. 8 and 12. That’s around the same time as last year, and a bit later than an initial estimate between Aug. 5 and 10. The timing is still subject to change. Warm and rainy weather fills the basin more quickly than cool and dry weather.
The glacial outburst flood starts when the water pressure in Suicide Basin builds up so much that it bores through the ice and floats Mendenhall Glacier, releasing billions of gallons of water into the suburban valley below.
The flood typically begins within a week after the basin is full, but it can happen at any time.
Last year, the National Weather Service issued an alert that the basin was full and spilling over the glacier on Aug. 10. Then the record-breaking flood crested on Aug. 13.
When the flood begins, the Weather Service will forecast the size of the flood and when it will peak. After scientists have about a day’s worth of data showing how quickly the water is moving, they might adjust that forecast.
In past years, the flood crested roughly 48 hours after it began.
The City and Borough of Juneau encourages Mendenhall Valley residents in the flood zone to evacuate when Suicide Basin begins to release.
