Flood, Upr Tanana Vly Fortymile
- When
- August 5, 3:00 AM AKST to August 6, 9:00 AM AKST
- Where
- Upr Tanana Vly Fortymile County, Chicken
- Cause
- Heavy Rain
- Reported by
- Department of Highways
- Coordinates
- 64.070, -141.950
Flood in Alaska, August 5 to 6, 2010
An area of low pressure moved out of the Gulf of Alaska and into the eastern interior of Alaska on August 6th. The low stalled out near the Alaska-Yukon border north of Eagle and produced heavy rainfall across parts of the Fortymile River Basin as well as American Creek.
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 area of low pressure moved out of the Gulf of Alaska and into the eastern interior of Alaska on August 6th. The low stalled out near the Alaska-Yukon border north of Eagle and produced heavy rainfall across parts of the Fortymile River Basin as well as American Creek. One and one half to two and one half inches of rain fell during a 24 hour period from Chicken northward to Eagle. The National Weather Service observer at O'Brien Creek recorded a peak stage of 71.3 feet, which tied the record stage set back on July 11th, 2010. It is likely that American Creek, which is located just to the north and parallels the Taylor Highway, experienced a similar record peak stage. The heavy rain fell north of the southern portion of the Fortymile basin, and the main stem of the Fortymile River at the Taylor Highway crested about 11 feet below the record stage of July 12th. The heavy rainfall produced numerous rock slides and washouts north of Chicken.
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 Aug 5, 1:29 AM AKST, 1 hour 31 minutes earlier.
Area forecast discussion, Aug 5, 1:29 AM AKST, 1 hour 31 minutes before
NORTHERN ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FAIRBANKS AK 229 AM AKDT THU AUG 5 2010 .DISCUSSION... MODELS IN DECENT AGREEMENT THROUGH 60 HOURS. UPPER LEVEL LOW CONTINUES TO PUSH EASTWARD TO BE NEAR EAGLE BY 4PM ON FRIDAY. ASSOCIATED FRONTAL BOUNDARY CLEARLY DEFINED ON SATELLITE IMAGERY. THERMAL TROUGH FINALLY BEGINNING TO FORM OVER NORTHERN ALASKA. CONVECTION RETURNED TO NORTHERN ALASKA ON WEDNESDAY ALBEIT IT WAS SLIM PICKINGS TO FIND A LIGHTNING STRIKE. HOWEVER...THE THERMAL TROUGH WILL STRENGTHEN ON THURSDAY AND THIS SHOULD ALLOW FOR MORE ISOLATED CONVECTION FOR NORTHERN ALASKA. TEMPERATURES WILL COOL OVER NORTHERN ALASKA WITH THE UPPER LEVEL LOW KICKING THE RIDGE EASTWARD. CONDITIONS WILL STAY COOLER THROUGH THE WEEKEND OVER MUCH OF THE INTERIOR. 500H WILL CONTINUE TO FALL AND THE WARM AIR AT 500H LEVEL WILL COMPRESS INITIALLY AND BUT LOWER LEVEL DRYING WILL NOT BE AS PREVALENT THROUGH THE WEEKEND. THE MODELS ARE IN ABOVE AVERAGE AGREEMENT AT THE START OF THE MEDIUM RANGE. AN UPPER TROUGH CURRENTLY JUST NORTH OF THE SEA OF OKHOTSK DEEPENS AS IT CROSSES KAMCHATKA FRI NIGHT AND MOVES EAST ACROSS THE BERING SEA. BY 12Z MON THE GFS/ECMWF AND THE GFS ENSEMBLE MEAN ARE ALL TIGHTLY CLUSTERED THAT THE LOW WILL BE BETWEEN ST MATTHEW ISLAND AND THE SOUTHWEST COAST OF AK. THIS WILL PRODUCE SLY FLOW AHEAD OF THE LOW THAT SHOULD KEEP MUCH OF THE AREA EAST OF 150W DRY FOR A DAY OR TWO. AS THE UPPER LOW THEN MAKES INROADS INTO SOUTHWEST ALASKA MUCH OF THE INTERIOR WILL LIKELY TROUGH OUT WITH AN INCREASING CHANCE OF SHOWERS. THE ECMWF KEEPS NORTHERN AK UNDER THE INFLUENCE OF THIS TROUGH THROUGH THE WEEK WHILE THE GFS TRIES TO BUILD A NORTH PAC RIDGE BACK INTO EASTERN AK WITH WELL ABOVE NORMAL HEIGHTS. FROM A CLIMATOLOGICAL STANDPOINT WOULD TEND TO SIDE WITH THE COOLER AND WETTER ECMWF. COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE && .FIRE WEATHER...NONE. && .HYDROLOGY...NONE. && .AFG WATCHES/WARNINGS/ADVISORIES... NONE. && CF AUG 10
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
- Rip Currents in Michigan, August 5, 2010
- Damaging Winds in Kentucky, August 5, 2010
- Flooding and Damaging Winds in Massachusetts, August 5, 2010
- Damaging Winds and Lightning Strike in Kentucky, August 5, 2010
- Heat in Florida, August 5, 2010
- Flash Flooding and Damaging Winds in Virginia, August 5, 2010
- Hail and Damaging Winds in Virginia, August 5, 2010
- Hail and Damaging Winds in Virginia, August 5, 2010
- Flash Flooding and Hail in Arkansas, August 5 to 8, 2010
- Hail and Damaging Winds in Tennessee, August 5, 2010
- Flash Flood and Hail in Mississippi, August 5, 2010
- Damaging Winds and Strong Wind in Tennessee, August 5, 2010
More
Every storm in Alaska in 2010Every state in 2010This day in weather historyWarnings in Alaska, August 2010
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: 241879.