The worst is over for the ash clouds from Iceland's volcano

The worst is now over for European air traffic disruptions from the ongoing eruption of Iceland's Eyjafjallajökull volcano. The eruptions are currently only throwing ash up to 16,000 feet (4900 meters), according to the latest advisory from the UK Met Office. Lightning images from UK Met Office show no new lightning strikes from the volcano's plume since Sunday. The lower amounts of ash are due, in part, to the fact that the volcano has melted most of the ice and snow covering the crater. This ice had caused the hot magma erupting through it to fragment into fine ash capable of reaching much higher heights of 6 - 11 km (20,000 - 36,000') in the early stages of the eruption. Ash is also reduced because the volcano has entered a phase where it is producing more magma. Although it is possible that the volcano could enter a more explosive eruption phase that would throw ash high into the air once again, the winds are expected to shift over Iceland late this week. The northwest winds that have been "stuck" in place over Iceland over the past week due to a persistent trough of low pressure over northern Europe, will gradually shift to westerly by Friday and southwesterly by Saturday. This means that new eruptive material will blow over the northern British Islands and northern Scandanavia late this week, avoiding the main portion of Europe. Ash should be confined to northern Scandanavia and Greenland through most of next week, since the southwesterly winds are expected to continue through most of next week.


Figure 1. Iceland’s Eyjafjallajökull volcano began to ease out of the ash-producing phase of its eruption and started to emit magma on April 19, 2010, said the Icelandic Met Office. The cloud of ash coming from the volcano was lower than it had been in previous days, rising just 4 to 6 kilometers (2 to 3 miles) into the atmosphere. In this photo-like image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, the ash extends south in a broad brown plume. Smaller plumes extend from the coast east of the primary plume. These are likely re-suspended ash, fine volcanic ash that had settled on the land, but is now being picked up by the wind. The plume blows south and then curves east over the ocean, blending with the outer bands of a low-pressure system. Image credit: NASA.

I'll have a new post Thursday (Earth Day!)
Jeff Masters