It appears that a release has begun from Suicide Basin into Mendenhall Lake, and the rate of rise of the Mendenhall Lake is increasing. We noted a drop of about 2.6 ft in Suicide Basin through 3pm Friday from the laser pool elevation gauge before snow obscured the laser, and made it report erroneous data. There is greater uncertainty in crest timing due to cold temperatures and this being an unusually late season event. * WHAT. Flooding caused by a glacier-dammed lake outburst is expected. * WHERE. The Mendenhall Lake and River near Areas Around The Glacier Visitor Center, The Mendenhall Campground, Skaters Cabin Road, View Drive And Possibly Below Back Loop Bridge. * WHEN. Until 1000 AM AKDT Monday. * IMPACTS. Flooding of the Mendenhall Lake and Mendenhall River. * ADDITIONAL DETAILS. - At 856 AM AKDT, river gauge reports indicate rises in water levels from a glacier-dammed lake outburst across the warned area. Flooding is ongoing or expected to begin shortly, especially near the Mendenhall Lake and River. - The outburst flood forecast is based on an estimated volume of water in the glacier dammed lake and an estimated release rate based on previous events. The extent of water drainage within the basin (partial or full) can vary widely between outburst flood events and is a major source of uncertainty in the forecast, particularly with regard to the peak flood stage. - For Mendenhall Lake : At 8:15am the stage was 4.4 feet. Flood Stage is 9.0 feet. Forecast: A crest around 11 to 11.5 feet is expected between 1AM and 7AM Monday. Water levels will go above minor flood stage, 9 feet, early Sunday afternoon. Water levels will go above moderate flood stage, 10 feet, Sunday evening. Impacts: At 6.7 feet: Nugget Falls trail begins to flood near the "causeway" at the end of the trail. At 7.7 feet: Nugget Falls trail begins to flood near the beginning of the trail. Along the Mendenhall River some sections will experience bank erosion resulting in dangerous tree fall. These conditions could make floating the river more hazardous with the higher water levels. At 9.0 feet: Water starts to cover Skaters Cabin Road between Skaters Cabin and West Glacier Trailhead, also water will flow into the Mendenhall Lake Campground. At 9.5 feet: Areas along View Dr will start to flood and cause minor flooding of yards. There will be 0.5 feet of water over the Skaters Cabin Road between Skaters Cabin and West Glacier Trailhead. Campsite 7 will be flooded with water starting to flow over the road between campsites 8 and 9 in the Mendenhall Campground. At 10.0 feet: Water levels will inundate Mendenhall Campground with up to 3 feet of water covering low areas as well as up to 1.5 feet of water covering Skaters Cabin Road. Portions of West Glacier Trail will be impassable. At 10.5 feet: Significant flooding along the Mendenhall Lake area with more than 3 feet of water in places and the Mendenhall campground will be evacuated. Some homes along View Dr will have up to 3 feet of water in yards. At 11.0 feet: View Dr will be flooded and impassable with significant flooding to some homes in the area. Locations below back loop bridge will see bank erosion along unreinforced river banks along with hazardous navigation from debris in the river. Homes along the river on Meander Way will begin to see flooding of some backyards. Portions of the Dredge Lake Trail System will be impassable. Flood waters start to reach Dredge Lake. At 11.5 feet: Houses along the south side and east end of View Dr will start to flood.
