898
WGAK47 PAJK 191727
FLWAJK
BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE JUNEAU AK
927 AM AKDT SAT OCT 19 2024
.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.
AKZ325-200130-
/O.NEW.PAJK.FA.W.0003.241019T1727Z-241021T1800Z/
/00000.0.GO.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CITY AND BOROUGH OF JUNEAU AK-
927 AM AKDT SAT OCT 19 2024
...FLOOD WARNING FOR A GLACIER-DAMMED LAKE OUTBURST IN EFFECT UNTIL
10 AM AKDT MONDAY...
* 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.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
STAY TUNED TO FURTHER DEVELOPMENTS BY LISTENING TO YOUR LOCAL RADIO,
TELEVISION, OR NOAA WEATHER RADIO FOR FURTHER INFORMATION.
LAT...LON 5841 13460 5842 13460 5845 13460 5847 13456
5846 13452 5844 13447 5843 13447 5840 13454
5836 13459 5835 13460 5836 13462
GRANT.SMITH
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