![Amchitka [AHT, 381 ft]](https://www.avo.alaska.edu/ashcam-api/images/amchitka_aht/2025/109/amchitka_aht-20250420T210000Z.jpg)
![Semisopochnoi [CETU, 1041 ft]](https://www.avo.alaska.edu/ashcam-api/images/semi_cetu/2025/109/semi_cetu-20250420T211600Z.jpg)
![Semisopochnoi [CEPE, 1113 ft]](https://www.avo.alaska.edu/ashcam-api/images/semi_cepe/2025/109/semi_cepe-20250420T211100Z.jpg)
Ash Forecasting
Mathematical models developed by the USGS forecast various aspects of how a volcanic ash plume will interact with wind—where, how high, and how fast ash particles will be transported in the atmosphere, as well as where ash will fall out and accumulate on the ground. AVO runs these models when a volcano is restless by assuming a reasonable hypothetical eruption, to provide a pre-eruptive forecast of areas likely to be affected. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available.
View the current airborne ash cloud models for Semisopochnoi
Ashfall thickness forecast
The Ash3d model was developed by the USGS to forecast how a volcanic ash plume will interact with wind and where ash will fall out and accumulate on the ground. AVO runs these models twice daily when a volcano is restless by assuming a reasonable hypothetical eruption altitude and duration. The map shows the model results of ashfall thickness for areas that are likely to be affected, if one were to occur. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available, and these plots will be automatically updated. The National Weather Service Anchorage Forecast Office will issue the official ashfall warning product and post them at weather.gov/afc
THESE PRODUCTS MAY NOT BE CURRENT.During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.
Ashfall Forecast
Ashfall Start Time
This map shows the modeled estimate of the time it would take for ashfall to begin following an eruption. It corresponds to the ashfall thickness forecast map shown above. This map uses the start time of either the twice-daily hypothetical model runs (time shown in the legend) or the actual eruption start time (if one were to occur). In the case of an actual eruption, the National Weather Service Anchorage Forecast Office will issue the official ashfall warning product that includes the ashfall start time and post them at weather.gov/afc
THESE PRODUCTS MAY NOT BE CURRENT.During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.