Volcanoes are a source of aerosols and gases that get spread around the atmosphere. They can cause cooler temperatures because these aerosols reflect a lot of solar radiation back to space. The ask isn't good for airplanes to fly through. Lightning is also common after volcano eruptions. Weather forecasts help predict were the ash will be transported.
MODIS satellite Image on November 15, 2014 captured a view of the ash cloud:
When we zoom in and look at the shadow this plume casts, you can get an idea of how tall this plume of smoke really is. The ash reaches about 35,000 feet!
|source: NASA Worldview|
Below is a HYSPLIT model at the location of the volcano. It is an ensemble of trajectories based on atmospheric conditions that show where the ash will be transported to in six hours. Looks like the winds will likely shift from what is shown in the image above and the ash will be transported further north.