Flood in Alaska, July 11, 2014

Name: Flood in Alaska, July 11, 2014
Start: 2014-07-11T08:00
End: 2014-07-11T20:00
Location: Alaska

July 11, 2014 · NWS AJK · 1 event in 1 county or zone

Where it happened

Every event with a place to put it. Tap one for its entry below.

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Tropical storms and surge
Floods
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Heat and drought
Cold
Fire, smoke and dust
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The toll

Deaths: 0
Injuries: 0
Property damage: $311,000
Crop damage: None recorded
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS AJK wrote it up.

The lake in Suicide Basin, dammed by the Mendenhall Glacier, had been filling all spring and into the early summer. After a warm and dry spring there was ample amount of snow melt from higher elevation into Suicide Basin. There was record amount of rain for the month of June in the Juneau area and with freezing levels above six thousand feet Suicide Basin filled rapidly as seen on the real-time lake gauge in the basin. The water level in the basin filled about two in a half feet per day on average and was past the previous height of sixty-two feet from the glacier lake outburst flooding event from 2011 by end the June. Water from the dammed lake in Suicide Basin started to drain into the Mendenhall Lake/River system on Wednesday July 9 after it crested at eighty-nine feet. The water level in Mendenhall Lake began to slowly rise 9 hours later early Thursday evening with the rise showing up on Mendenhall River twelve hours later. It was calculated that there was about twelve billion gallons of water in the basin before it started to drain. The rate of rise increased through the event and by Friday afternoon it was on a steep and fast rise upward.

Both the Mendenhall Lake and River rose significantly for the next forty-two hours and broke the record for stream flow and stage levels before it crested Friday afternoon July 11. The record flows and stages produced moderate flooding and damaged homes, campgrounds and roads in places along Mendenhall Lake and River.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Juneau, AK wrote its last area forecast discussion before the first event at Jul 11, 3:56 AM AKST, 4 hours 4 minutes earlier.

Area forecast discussion, Jul 11, 3:56 AM AKST, 4 hours 4 minutes before

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
456 AM AKDT FRI JUL 11 2014

.SHORT TERM...A FRONT OVER THE EASTERN GULF WILL REMAIN NEARLY
STATIONARY DUE TO A RIDGE OF HIGH PRESSURE LOCATED OVER THE
PANHANDLE AND BLOCKING ANY SIGNIFICANT EASTWARD PROGRESS. NET
EFFECT OF THIS WILL BE A STEADY STREAM OF PRECIPITATION TRAINING
FROM SOUTH TO NORTH OVER THE COURSE OF THE SHORT TERM FORECAST
PERIOD. 24 HOUR PRECIPITATION FORECAST RANGING FROM ZERO FOR
LOCATIONS SOUTH AND EAST OF KUIU ISLAND TO 1.5 INCHES OR MORE IN
AND AROUND YAKUTAT. THESE NUMBERS ARE PREDICATED ON A GRADUAL
SHIFT TO THE EAST BY THE FRONT. IF THE RIDGE PREVENTS ANY
SIGNIFICANT MOVEMENT TO THE EAST, TOTAL RAINFALL WILL BE CONFINED
TO AREAS FURTHER WEST AND BE MORE THAN CURRENTLY FORECAST.

 WINDS ASSOCIATED WITH THE FRONT WILL BE LIMITED TO THE GULF FOR
THE MOST PART. HAVE EASTERLY 40 KT GALES IN THE FORECAST FOR
COASTAL MARINE ZONE 52 WITH LOWER VALUES TO THE SOUTH AND EAST.
MAX CONDITIONS EXPECTED TO OCCUR THIS MORNING AND GRADUALLY
DIMINISH THROUGH THE AFTERNOON AND OVERNIGHT. POSSIBILITY OF SOME
GUSTY CONDITIONS IN YAKUTAT, AND HAVE INCLUDED UP TO 19 KTS IN
THE TAF. ELSEWHERE, EASTERLY 20 KT WINDS OVER WESTERN ICY STRAIT
AND CROSS SOUND AND 15 KTS OR LESS FOR THE REMAINDER OF THE INNER
CHANNELS.

 FAIRLY SHARP FRONTAL BOUNDARY WILL LIKELY RESULT IN PARTLY
CLOUDY SKIES FOR SOUTHERN LOCATIONS WITH DAYTIME HIGHS RANGING
FROM THE UPPER 60S ALONG THE OUTER COAST TO THE MID 80S NEAR
HYDER. OVERCAST SKIES FARTHER NORTH WILL YIELD HIGHS IN THE UPPER
50S TO LOW 60S.

&&

.HYDROLOGY...MENDENHALL LAKE AND RIVER CONTINUE TO RISE AS A
RESULT OF SUICIDE BASIN DRAINING. AS OF 4 AM, THE STAGE OF
MENDENHALL RIVER WAS 10.8 FEET. FLOOD STAGE IS 11.5 FEET. AT THE
SAME TIME, MENDENHALL LAKE WAS AT 9.1 FEET, WHICH IS JUST ABOVE A
FLOOD STAGE OF 9.0 FEET. THE RISE IN MENDENHALL LAKE HAS BEEN VERY
RAPID AND STEADY OVERNIGHT, MATCHING THE RIVER FORECAST CENTER'S
MOST RECENT PROJECTIONS VERY CLOSELY. MAX FORECAST STAGE FOR THE
LAKE IS 11.99 FEET WHICH EXCEEDS THE PREVIOUS RECORD OF 11.2 FEET.
LIKEWISE, THE RIVER IS CURRENTLY FORECAST TO REACH 14.95 FEET,
WHICH IS MORE THAN A FOOT HIGHER THAN THE PREVIOUS RECORD. MANUAL
OBSERVATIONS OF THE RIVER OVERNIGHT ARE LAGGING BEHIND THE MOST
RECENT FORECAST. UNCLEAR AT THIS TIME WHETHER THIS SIGNALS A LOWER
MAXIMUM FLOOD OR A LATER TIME OF MAXIMUM FLOOD, OR BOTH. A DELAY
OF MAXIMUM FLOOD WOULD BE BENEFICIAL, AS IT WOULD OCCUR AFTER THE
AFTERNOON HIGH TIDE AND WOULD MITIGATE THE BACKWATER EFFECT ON THE
LOWER MENDENHALL RIVER. REGARDLESS, THIS WILL BE A HIGH IMPACT
EVENT WITH SOME LOCATIONS IN THE MENDENHALL VALLEY FLOODING FOR
THE FIRST TIME. LOCATIONS ALONG THE SWIFTLY FLOWING WATER OF THE
MENDENHALL RIVER WILL BE PARTICULARLY VULNERABLE TO EROSION.

&&

.LONG TERM...MODELS ARE IN GENERAL AGREEMENT THROUGH TUESDAY WITH
AN UPPER LEVEL LOW OVER THE WESTERN GULF SLOWLY DRIFTS
SOUTHWESTWARD WHILE AN UPPER HIGH ACROSS THE WESTERN CANADA MOVES
A LITTLE TO THE EAST. THE ASSOCIATED SURFACE LOW OVER BRISTOL BAY
ON SATURDAY MOVES SOUTHWARD ACROSS THE ALASKA PENINSULA OVER THE
WEEKEND AND FARTHUR SOUTH PASS 50N THROUGH TUESDAY...WHILE SURFACE
HIGH PRESSURE CONTINUES TO BUILD ACROSS THE ALASKA GULF. REFRESHED
THE INHERITED FORECAST PACKAGE WITH THE ECMWF AND GEM GLOBAL FOR
THEIR GOOD CONSENSUS IN SYNOPTIC SCALE THROUGH TUESDAY.

 AS THE LOW DRIFTS SOUTH...THE ASSOCIATED FRONTAL PASSAGE OVER
THE EASTERN GULF WILL WEAKEN THROUGH THE WEEKND. AS SUCH...LIKELY
TO CATEGORICAL POPS ACROSS THE NORTHERN HALF OF THE PANHANDLE WILL
GRADUALLY DIMINISH BY SUNDAY EVENING...YIELDING TO CHANCE POPS
OVERNIGHT SUNDAY NIGHT INTO MONDAY MORNING FOLLOWED BY GENERALLY
DRY WEATHER THROUGH TUESDAY. AS HIGH PRESSURE BUILDS ACROSS THE
GULF...THE GENERAL SOUTHERLY LOW LEVEL WINDS WILL BECOME NORTHERLY
ON SUNDAY AND SLIGHTLY INCREASE TO 15 TO 20 KNOTS THROUGH TUESDAY.

 MODEL SPREADS BECOMES LARGER BY MID WEEK WITH AN UPPER LEVEL
SHORTWAVE TROUGH DIGGING DOWN ACROSS THE WESTERN
ALASKA...SUBPRESSING THE RIDGE OVER THE GULF AND THE PANHANDLE
TOWARDS THE NEXT WEEKEND. THE ECMWF SHOWS A MORE PROGRESSIVE
PATTERN AND BRINGS THE UPPER LOW OVER THE NORTHERN GULF...WHILE
THE GFS KEEPS THE UPPER LOW FARTHUR NORTH OVER THE WESTERN ALASKA
INTERIOR. USED THE WPC ENSEMBLE SOLUTIONS INTO THE INHERITED
FORECAST PACKAGE FROM LATE TUESDAY THROUGH THE END OF THE LONG
TERM PERIOD. EXPECT GENERALLY DRY WEATHER CONTINUES WITH NO
SIGNIFICANT WINDS/SEAS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...AREAL FLOOD WARNING UNTIL 10 PM AKDT SATURDAY FOR AKZ025.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ041-042.

&&

FRITSCH/AHN

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 flood. Local standard time, as filed.

Flood, Juneau Borough

When: July 11, 8:00 AM AKST to 8:00 PM AKST
Where: Juneau Borough County, 13.29 mi NNW of Douglas to 12.44 mi NW of Douglas
Cause: Dam / Levee Break
Property damage: $311,000
Reported by: River/Stream Gage
Coordinates: 58.436, -134.566

The annual glacier lake outburst flood that takes place on the Mendenhall Lake and River was a record event this year. Once the twelve billion gallons, that accumulated throughout the spring and early summer, in the basin began to drain on Thursday July 9 the lake rose significantly for next forty-two hours. There was a lot of publicity leading up to the event so this record event did not come by a surprise. The new record crest was eleven point eight feet on July 11 which was almost two feet above the moderate flood stage of 10.0 feet and broke the old record from 1994 of eleven point eighteen. The Mendenhall River crested at thirteen point fifty-two feet just under the record crest from 1995 of thirteen point seventy-five feet. After cresting both the Mendenhall Lake and River receded fast and was back at base-flow levels in 12 hours.

The record flows and stages from Mendenhall Lake and River damaged homes, campgrounds and roads. There was at least three feet of water that flooded the West Glacier spur road which borders the west side of Mendenhall Lake. The USDA Forecast Service closed the West Glacier Road and trail, Nugget Falls trail, Photo Point trail and restricted watercraft on the lake 24 hours before the flooding took place. They also closed the Mendenhall Lake Campground and evacuated 23 of the 70 sites that were occupied. Some campers moved to another campground while other moved to a designated area for them. There was significant flooding within the campground with 3-4 feet of water in places and 150 feet of road within the campground was damaged. The power was also cut by the City of Juneau to the campground.

The View Drive subdivision was cutoff with a one home sustaining significant damage. The City of Juneau told residents of View Drive, along the Mendenhall River, to shelter in place and they also cut their power once water was across the road and the subdivision was cutoff. The home that sustained significant damage was along the Mendenhall River and it had 43 inches in their garage and about 10 inches inside the house.

The City of Juneau closed the Brotherhood Bridge Trail which follows along the river. They also restricted access to all roads leading into Meander Way, from Rivercourt Drive to Killewich Ave along Riverside Drive but the closure was voluntary. The city was worried that the roads maybe impassible due to flooding from the River or water through the storm drain system.

There was a major bridge construction going on at near the mouth of the River. The construction company was pulling logs out of the river so it would not damage any of their work but logs were getting lodged and acting like a dam diverting water to the banks. This cause significant bank erosion but the bridge structure was not damaged by the trees and debris floating down the river.

What these are

Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Alaska in 2014 Every state in 2014 This day in weather history Warnings in Alaska, July 2014

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 538164.