Mount St. Helens, October 12 2004 - Mount St. Helens and similar volcanoes typically go through changes in level of unrest over a period of days to weeks or even months. Such changes are driven by variations in the rate of magma movement. Escalation in the degree of unrest could occur suddenly or with very little warning, leaving less time to raise the alert level before a hazardous event occurs. Therefore, the situation is constantly monitored by the authorities and any known changes to the alert level are communicated immediately.

On 12 October 2004, the National Oceanic and Atmospheric Administration (NOAA) agency, forecasted winds combined with eruption models from variable wind directions. Ash clouds would drift south-westward to south-eastward, as a result of the intense unrest over a period of three and a half weeks. During observations at the time, the level of magma was very shallow and extruded onto the surface. Hot rock or gases could reflect off steam clouds which were visible from the north side of the volcano.

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