Flood, Lower Koyukuk Middle Ykn Vlys
- When
- May 12, 11:00 AM AKST to May 14, 2:00 PM AKST
- Where
- Lower Koyukuk Middle Ykn Vlys County, 0.53 mi ENE of Nulato to 1.77 mi NE of Nulato
- Cause
- Ice Jam
- Reported by
- NWS Employee
- Coordinates
- 64.734, -158.054
Flood in Alaska, May 12 to 14, 2012
An ice jam caused minor flooding in Nulato. The ice jam was caused by large sheets of ice on the Yukon River about 2 1/2 miles above the village of Kaltag.
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
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 AFG wrote it up.
An ice jam caused minor flooding in Nulato. The ice jam was caused by large sheets of ice on the Yukon River about 2 1/2 miles above the village of Kaltag. Above the jam, the ice was packed tight for about 30 miles upriver to Nulato. On the afternoon of the 12th the Yukon River was backing up a significant amount of water into the Nulato River and Mukluk Slough. Water began to flow over several low lying roads, but was only a nuisance to village residents at this time. Water was flooding a smoke house at the mouth of the Mukluk Slough on the north end of town. By the morning of the 13th, the water levels had risen about 1 foot at Nulato. The spur road to the cemetery and tank farm, the south Frontage Road, and the road to the Nulato River were impassable at this time, but the flooding was still only considered to be a nuisance to residents of the village. The water continued to slowly rise during the day, and by the evening of the 13th the water was covering the road to the airport. The water continued to rise slowly rise into the morning of the 14th, and had come up 1 1/2 feet since the 13th. Access to the airport was limited to large trucks or boats. Water was also beginning to inundate the area around the fuel depot, prevent vehicle access to at least 2 homes, and flow under one residence. By the early afternoon of the 14th the ice jam released and the water rushed out of the village and the threat of flooding quickly ended.
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 Fairbanks, AK wrote its last area forecast discussion before the first event at May 12, 4:42 AM AKST, 6 hours 18 minutes earlier.
Area forecast discussion, May 12, 4:42 AM AKST, 6 hours 18 minutes before
NORTHERN ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FAIRBANKS AK 542 AM AKDT SAT MAY 12 2012 .DISCUSSION... THE WEATHER MAPS THIS MORNING ARE TYPICAL OF EARLY SUMMER...A PATTERN ANY EXPERIENCED ANALYST HAS SEEN HUNDREDS OF TIMES BEFORE. CIRCULATION OVER THE REALM IS WEAK AND FORECAST BY THE COMPUTER MODELS TO REMAIN SO THROUGH NEXT WEEK. THE NAM AND GFS COMPUTER WEATHER FORECAST MODELS FORECAST A COLD LOW PRESSURE SYSTEM ALOFT TO MOVE SOUTH SOUTHEASTWARD...AND TO REACH KODIAK ISLAND SUNDAY MORNING. A TROUGH OF LOW PRESSURE WILL REMAIN EXTENDING FROM THE LOW ALOFT TO THE SOUTHERN CHUKCHI SEA THROUGH EARLY MONDAY. FOLLOWING THIS...HIGH PRESSURE ALOFT WILL GRADUALLY AND STEADILY BUILD OVER THE EASTERN BERING SEA STARTING LATE MONDAY. BY WEDNESDAY NIGHT...THE HIGH PRESSURE ALOFT WILL COVER THE WEST HALF OF THE REALM AND HOLD THERE. THE FRIDAY EVENING GFS MODEL RUN DIFFERS FROM THE FRIDAY AFTERNOON FORECASTS OF THE GFS AND EUROPEAN MODELS. THE FRIDAY AFTERNOON RUNS FORECAST THE HIGH PRESSURE ALOFT TO BUILD OVER ALL BUT THE EASTERNMOST PART OF THE REALM...WITH VERY WEAK CIRCULATION. THIS IS A PATTERN TYPICAL OF EARLY SUMMER IN ALASKA. THE FRIDAY EVENING GFS MODEL RUN FORECASTS NORTH FLOW ALOFT OVER THE EASTERN HALF OF NORTHERN ALASKA STARTING WEDNESDAY...AND TO CHANGE TO NORTHEASTERLY FLOW WITH A SERIES OF SMALL DISTURBANCES MOVING ALONG WITH IT. THE INTERMEDIATE GFS MODEL RUNS VERY OFTEN TAKE EXCURSIONS OFF THE PREVIOUS MODEL RUNS COURSE...SO THE PREVIOUS AFTERNOONS MODEL RUN IS OFTEN FAVORED OVER THE RUN 6 HOURS LATER.L THE UPSHOT IS THAT AN OUTBREAK OF MOSTLY CLOUDY...COOLER AND SHOWERY WEATHER IS NOT IN THIS MORNINGS FORECASTS FOR THE EASTERN OR CENTRAL INTERIOR. A SMALL TROUGH OF LOW SURFACE PRESSURE IS FORMING IN THE EASTERN BROOKS RANGE AND IS EXPECTED TO SHIFT TO THE SOUTHERN BEAUFORT SEA JUST NORTH OF THE ARCTIC COAST OF THE YUKON TERRITORY TONIGHT. THIS PROCESS OCCURS OFTEN IN THE SOUTHEAST BERING SEA AND CAN BE FORECAST WITH CONFIDENCE...AS IT IS TODAY. THE REASON THIS IS OF INTEREST TO THE FORECASTS IS THAT IT CAUSES THE EAST WINDS OVER THE ALASKAN ARCTIC COAST FROM PRUDHOE BAY EASTWARD TO SHIFT TO THE WEST. THIS MORNINGS FORECASTS FOR THAT AREA ARE FOR EAST WINDS TODAY AND TONIGHT...AND WEST WINDS MONDAY AND BEYOND. THIS MORNINGS WEATHER BALLOON DATA INDICATES UNSTABLE AIR OVER THE EAST HALF OF NORTHERN ALASKA. SOME SHOWERS...AND ISOLATED THUNDERSTORMS...ARE EXPECTED. THE ALASKA LIGHTNING DETECTION SYSTEM RECORDED 40 LIGHTNING STRIKES FRIDAY AFTERNOON AND EVENING, THIS WAS THE LARGEST DAILY TOTAL OF LIGHTNING STRIKES FOR THE YEAR SO FAR. MOST OF THE STRIKES WERE BETWEEN BETTLES AND GALENA...AND THE REST WERE AROUND MCGRATH. THE AMOUNT OF MOISTURE IN THE AIR MASS OVER NORTHERN ALASKA THIS MORNING IS SCANTY...FROM 0.25 TO 0.35 INCH...SO STRONG THUNDERSTORMS ARE IMPOSSIBLE. THIS IS TYPICAL OF MAY...THE MONTH OF THE YEAR IN NORTHERN ALASKA WHEN AFTERNOON RELATIVE HUMIDITY IS TYPICALLY LOWER THAN IN THE REST OF THE YEAR. THE NAM AND GFS MODELS FORECAST AN AXIS OF HIGH PRESSURE NOW OVER THE NORTH GULF COAST TO BUILD NORTHWARD TOWARD THE ALASKA RANGE. THIS IS A GOOD PATTERN FOR BRISK GAP WINDS IN THE AFTERNOON AND EVENING...SO THE FORECASTS FOR THE ALASKA RANGE AND THE DELTANA AND TANANA FLATS INCLUDE GUSTY WINDS FOR THOSE AREAS THIS AFTERNOON AND EVENING. THIS MORNINGS POLAR ORBITING SATELLITE IMAGERY SHOWS LAYERED CIRRUS AND ALTOSTRATUS CLOUDS STREAMING OFF THE WESTERN ALASKA RANGE INTO THE UPPER KUSKOKWIM AND MIDDLE YUKON VALLEYS. SKIES ARE MOSTLY CLOUDY TO THE WEST. THERE ARE CONVECTIVE DEBRIS OVER THE WESTERN INTERIOR...AND LOW STRATUS OVERCAST OVER THE WEST COASTAL REGIONS. THE EASTERN INTERIOR IS MOSTLY CLEAR. && .FIRE WEATHER... GUSTY WINDS OUT OF ALASKA RANGE PASSES WILL REACH SOME VALLEY FLOORS IN THE SOUTHERN INTERIOR THIS AFTERNOON AND EVENING. THESE...AND LATE AFTERNOON RELATIVE HUMIDITY BETWEEN 20 TO 30 PERCENT IN PLACES...ARE TO BE WATCHED WITH CARE. THE WIND THIS AFTERNOON IS NOT EXPECTED TO BE AS STRONG AS YESTERDAY. && .HYDROLOGY... ASIDE FROM THE FLOODING AT MANLEY HOT SPRINGS TWO WEEKS AGO...THE 2012 NORTHERN ALASKA BREAKUP ON RIVERS HAS BEEN THE MOST QUIET IN AT LEAST 40 YEARS. THANKS TO A GRADUAL AND MODEST WARMING STARTING IN APRIL...THE SNOWMELT WAS STRETCHED OUT OVER ENOUGH TIME TO KEEP RIVERS AT MODEST STAGES. THE LOWER YUKON VALLEY DOES HAVE SOME ICE JAMS BUT SO FAR THERE HAS BEEN NO HIGH WATER WITH THEM. BREAKUP IN THE UPPER KUSKOKWIM VALLEY IS ABOUT OVER. && .AFG WATCHES/WARNINGS/ADVISORIES... NONE. && TF MAY 12
The radar
The national radar mosaic for the moment the first event began.
Event by event
1 flood. Local standard time, as filed.
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
- Heat in California, May 12, 2012
- Flash Flooding in Texas, May 12, 2012
- Hail and Damaging Wind in Mississippi, May 12, 2012
- Drought in Kentucky, May 12 to 31, 2012
- Drought in Illinois, May 12 to 31, 2012
- Hail and Lightning Strike in Texas, May 12, 2012
- Hail in New Mexico, May 12, 2012
- Hail in New Mexico, May 12, 2012
- Tornado in Florida, May 12, 2012
More
Every storm in Alaska in 2012Every state in 2012This day in weather historyWarnings in Alaska, May 2012
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: 371068.