The cloudy, off-white haze crept into Anchorage over the weekend, obscuring the once-crisp view of the Chugach Mountains with a smog-like quality more suited to a view of the Los Angeles skyline. Murky skies have spanned the state, showing up from Fairbanks to Kodiak and Valdez to the Aleutian Islands.
People called the National Weather Service asking what was happening. Meteorologists didn't know. Alaska Volcano Observatory ash-detection alarms repeatedly rang out on the Aleutians, warning of the slowly creeping haze.
"Initially, I didn't know where it was coming from," said Sam Albanese, warning coordination meteorologist with the National Weather Service. "Pretty much (Tuesday) is when we started nailing down what was causing this."
Using high-resolution satellite images, scientists tracked the haze across the Pacific Ocean and to two neighboring regions in east Asia.
Sand storms spewing dust by the ton in Mongolia's Gobi Desert are partly to blame, Albanese said. The annual storms often assault neighboring areas with the drifting dust, dubbed Kosa, meaning "yellow sand," by the Japanese, whose island it frequently crosses.
But this year it's not alone. Massive wildfires spanning a huge swath of southern Siberia in the Russian Far East have contributed smoke to the mix, worsening an already unusually dusty spring.
The wildfires erupted starting April 16, contributing to the sandstorms that kicked off around the same time. As the air currents drifted east, the smoke and dust combined and continued their march northeast across Japan until they first hit the Aleutian Islands and the Alaska Peninsula.