Flood in Alaska, August 12 to 13, 2014

Name: Flood in Alaska, August 12 to 13, 2014
Start: 2014-08-12T04:00
End: 2014-08-13T03:00
Location: Alaska

August 12 to 13, 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.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
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.

A very warm front slowly moved over Southeast Alaska from August 9-12. This warm front produced areal precipitation amounts of three to four in half inches with possible double amounts in the mountains. Also there were very high freezing levels with the warm air over the area and this produced significant amounts of snow and ice melt. The runoff of the rainfall and snow/ice melt caused large rises on Mendenhall Lake and River on the 10th and 11th. Lake levels rose four feet from the runoff by the 11th and remained steady just below minor flood stage from the snow and ice melt with the warm temperatures. There was another burst of heavy rain of a half inch in three hours in the early morning hours of the 12th. This caused the Mendenhall Lake and River to rise above minor flood stage. The lake and river levels did not drop through the morning after the heavy rain stopped as there was something else at work. The hydrograph had indications of a second release of a glacier dam release from Suicide Basin due to the steady slope of rise. It was confirmed that indeed it was a second release and the Mendenhall Lake and River continued to rise through August 12 and crested in the afternoon at a level of ten point eighty-eight feet on the lake and twelve point eight feet on the river. Both of these crests were above moderate flood stage and produced significant flooding around the Mendenhall Lake area.

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 Aug 11, 1:23 PM AKST, 14 hours 37 minutes earlier.

Area forecast discussion, Aug 11, 1:23 PM AKST, 14 hours 37 minutes before

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
223 PM AKDT MON AUG 11 2014

.SHORT TERM...A STATIONARY FRONT REMAINS OVER THE EASTERN GULF
WITH THE FRONTAL BOUNDARY EXTENDING WELL TO THE SOUTH AND A
SUBTROPICAL MOISTURE CONNECTION REMAINS WELL DEFINED IN AMSU DATA.
ANOTHER WAVE RIDING NORTH ALONG THE FRONTAL BOUNDARY WILL BRING
HEAVY RAIN TO PORTIONS OF THE PANHANDLE ONCE AGAIN TONIGHT.
HEAVIEST RAIN IS EXPECTED GENERALLY TO THE WEST OF CHATHAM STRAIT
AND EAST OF CAPE FAIRWEATHER, BUT WILL ALSO INCLUDE THE SKAGWAY
ZONE. THE TAIYA RIVER REMAINS NEAR BANKFULL AND THIS ADDITIONAL
RAINFALL MAY RESULT IN FLOODING. A FLOOD WATCH HAS BEEN INCLUDED
IN THE AFTERNOON FORECAST ISSUANCE.

THE STATIONARY FRONTAL BOUNDARY WILL FINALLY BEGIN TO WEAKEN BY
TOMORROW AFTERNOON. DRYING OUT AND PARTIAL CLEARING HAS ALREADY
BEGUN IN THE FAR SOUTHERN AND SOUTHEASTERN ZONES. VISIBLE
SATELLITE IMAGERY AND WEB CAMS ARE SHOWING THAT AREAS NEAR
KETCHIKAN AND MISTY FJORDS ENJOYED A FAIRLY NICE DAY TODAY. RAIN
ENDED EARLIER TODAY EAST OF CHATHAM STRAIT AND SOUTH OF FREDERICK
SOUND, BUT SKIES REMAIN MOSTLY CLOUDY TO OVERCAST. WITH PARTIAL
CLEARING LIKELY OVERNIGHT, PATCHY FOG IS EXPECTED TO FORM OVER
PORTIONS OF THE SOUTHERN PANHANDLE TONIGHT. FARTHER NORTH, IT
LOOKS LIKE THE JUNEAU AREA WILL BE LAST TO SEE THE RAIN
END...PROBABLY NOT UNTIL TUESDAY NIGHT.

WINDS REMAINED STEADY OUT OF THE SSE AT OR NEAR SMALL CRAFT LEVELS
FOR MOST OF THE DAY OVER CLARENCE STRAIT. EASTERLY WINDS 15 TO 20
KTS OVER CROSS SOUND. ALSO AM SEEING A NORTHERLY WIND OF 20 KTS
NEAR ROCKY ISLAND THIS AFTERNOON AND WAS OBSERVING AN EASTERLY
WIND OF 20 KTS ON THE THE SOUTH SIDE OF DOUGLAS ISLAND. THESE
WINDY SPOTS ARE EXPECTED TO RELAX THIS EVENING. ELSEWHERE, NO
SIGNIFICANT WINDS OVER THE INNER CHANNELS IN THIS SHORT TERM
FORECAST PERIOD. ON THE OUTSIDE, MAIN ISSUE IS RESIDUAL SEAS AT OR
ABOVE 8 FT FOR MUCH OF THE OUTER COAST THROUGH MUCH OF TOMORROW.
GULF WINDS 20 KTS OR LESS EXCEPT FOR 25 KT SOUTHEASTERLIES OVER
OFFSHORE ZONE 310.

USED NAM FOR UPDATES TO PRESSURE AND WIND. POP FROM A BLEND OF
GFS, GEM, AND ECMWF. QPF PER RFC AND ECMWF. FORECAST CONFIDENCE IS
AVERAGE.

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT THROUGH THURSDAY
WITH AN UPPER LOW ACROSS ALASKA PENINSULA TUESDAY NIGHT SLOWLY
MOVES INTO THE WESTERN GULF WHILE AN UPPER HIGH PERSISTS OVER THE
WESTERN CANADA. A SURFACE RIDGE OF HIGH PRESSURE WILL CONTINUE TO
BUILD ACROSS THE EASTERN GULF AND PANHANDLE WITH CONTINUED DEEP
ONSHORE LOW TO MID LEVEL FLOW OVER THE AREA. REFRESHED THE
INHERITED FORECAST PACKAGE WITH THE NAM THROUGH THURSDAY FOR ITS
GOOD INITIALIZATION AND CONSISTENCY.

AS THE LOW IN THE WESTERN GULF DRIFTS NORTH...A FRONTAL PASSAGE
WILL AFFECT THE NORTHERN GULF. EXPECT CONTINUED WET PATTERN FOR
THE NORTHEASTERN GULF COAST WITH CATEGORICAL POPS THROUGH
THURSDAY. THE FRONT WILL ALSO PRODUCE SMALL CRAFT TO GALE FORCE
WINDS FOR THE OFFSHORE AND OUTSIDE WATERS THROUGH LATE THURSDAY.
THE RIDGE OF HIGH PRESSURE WILL MAINTAIN THE SOUTHERN PANHANDLE
GENERALLY DRY WITH SLIGHT CHANCE POPS. IN BETWEEN...NORTHERN AND
CENTRAL PANHANDLE WILL REMAIN WITH CHANCE POPS. CONTINUED ONSHORE
LOW TO MID LEVEL FLOW WILL KEEP SOUTHEAST ALASKA UNDER GLOOMY
SKIES.

FROM THURSDAY NIGHT ONWARD...MODEL DIFFERENCES BECOME LARGER BUT
GENERAL SYNOPTIC CONCEPT REMAINS THE SAME FROM THE PAST SEVERAL
DAYS. WITH THE UPPER LOW IN THE WESTERN GULF SLOWLY FILLS AND
DRIFTS NORTH TO THE WESTERN ALASKA. ANOTHER UPPER LOW OVER
KAMCHATKA WEDNESDAY MORNING WILL MOVE TO THE WESTERN TIP OF ALASKA
PENINSULA AND DEEPEN THROUGH THURSDAY NIGHT...THEN GRADUALLY MOVE
INTO THE WESTERN GULF BY SATURDAY NIGHT. THIS UPPER LOW WILL TRACK
NORTHEAST TO NEAR PRINCE WILLIAM SOUND THROUGH EARLY NEXT WEEK
WHILE SLOWLY FILLS. USED THE WPC ENSEMBLE SOLUTION FROM FRIDAY
THROUGH EARLY NEXT WEEK.

&&

.AVIATION...CONTINUED LOW VMC OR IMC CONDITIONS OVER THE NORTHERN
PANHANDLE THROUGH THE SHORT TERM WITH MOSTLY CLEAR SKIES AND LIGHT
WINDS OVER SOUTHEASTERN PORTIONS. PATCHY FOG OVER THE SOUTHERN
HALF AND ALONG THE OUTER COAST LATE TONIGHT INTO TOMORROW MORNING
WILL LIKELY BE A FACTOR TO EARLY MORNING AVIATION ACTIVITIES.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ036-041.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ042-043-051-052.

&&

FRITSCH/AHN

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU

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: August 12, 4:00 AM AKST to August 13, 3:00 AM AKST
Where: Juneau Borough County, 13.3 mi NNW of Douglas to 12.28 mi NW of Douglas
Cause: Dam / Levee Break
Reported by: River/Stream Gage
Coordinates: 58.434, -134.571

This event was very difficult to identify due to the heavy rain masking the the much bigger event going on, the second release of the glacier dammed lake in Suicide Basin. It was about one month to the date when the first outburst flood from Suicide Basin took place. There were two days leading up to this event that had record rainfall values. The Juneau forecast office, near the headwaters but at lower elevation, had record rainfall on August 9th and 10th of one point thirty-nine and two point thirty-three respectively. The Juneau airport also reported record rainfall for those days but not as much as in the Mendenhall Valley. It is possible that the mountains and ice field that drains into the Mendenhall system had as much as double the rain amounts at the forecast office. All of the rainfall rose the Mendenhall Lake four feet to just below minor flood stage by July 11 and then it rose above minor flood stage after a burst of heavy rain in the amounts of one half to three quarters of an inch in the early morning of Tuesday July 12. The Mendenhall Lake continue to rise on a constant slope after the rain stopped. It can to light that there was a second release from Suicide basin on going. The Mendenhall Lake and River rose above moderate flood stage in the afternoon and crested at ten point eighty-eight and twelve point eight respectively. This is was the fifth highest record stage level on Mendenhall lake. After the crest both the Mendenhall River and Lake receded very quickly and were below minor flood stage by midnight on July 13.

This event flooded the Mendenhall Lake campground with about 2 feet of water at the entrance along with flooded out many campsites. There were fourteen occupied campsites out of sixty-nine site which were evacuated by the Tuesday afternoon. There was about 3 feet of water across west glacier spur road along Mendenhall Lake. A few hikers had to get rescued on the west glacier trail due to their van getting stuck because of the flooded road. There was significant flooding along the Mendenhall River near View Drive with one house getting twenty three inches of water in their garage. They also had water in their crawl space. This area was getting repair from damaged done from the previous outburst flooding event a month earlier.

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, August 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: 541758.