The Mount St. Helens Volcanic Eruption of 18 May 1980: Large Short-Term Surface Temperature Effects

The surface temperature effects of the 18 May 1980 eruption of Mount St. Helens Volcano were examinedfor 1 day immediately after the eruption; 24-hour temperature differences and Model Output Statistics errors as well as the detailed temporal evolution of surface temperature at selected stations were used. During the daytime hours immediately after the eruption, the temperature was suppressed by the volcanic plume by as much as 8 degrees C. That night, low-level volcanic dust produced temperature enhancements of up to 8 degrees C. These effects quickly diminished the next day as the volcanic dust cloud dissipated and moved toward the east. The net local effect of the eruption appears to be warming, in contrast to cooling which might be expected over climatic time scales.