Just because associate state climatologist in Indiana, Ken Shceeringa, doesn't expect that the mid-April eruption of a volcano in Iceland will affect weather in the U.S., it doesn't follow that the U.S. is out of the woods from outside influences on weather this year. So far, based on the earliest eruption, Scheeringa believes the ash plume won't reach the stratosphere. So while there may be impacts on European weather over the coming months, there shouldn't be any Impact on weather here in the U.S.
However, there is a second volcano which scientists are watching closely, he notes. It is a sister volcano, also in Iceland, to the one that already erupted. It is currently quiet. However, based on history, if it erupts, it could impact weather over a much larger area. It is classified as a much larger volcano and would be capable of spewing ash into the stratosphere. When that happens, weather across the hemisphere can be affected. The Mt. Pinatubo eruption in 1992 lowered the world air temperature by 1 degree F in the ensuing months after the eruption.
This sister volcano has been known to erupt early in each century. That is fueling speculation. However, at this point, it is just that-speculation, he insists. There are no reports of actual signs that an eruption is about to occur in that volcano, he emphasizes.
Without interference from other factors, Scheeringa expects a normal May after a dry April, then normal summer weather patterns across Indiana for much of the summer. He's basing his projections on the current status of the El Nino/La Nina cycle. After a cool phase, or La Nina, last year, an El Nino, or warm phase, developed. The pattern should shift toward neutral this spring, bringing more normal weather patterns. At this point he does not expect widespread drought in the Corn Belt. Obviously, pocket droughts are a part of every summer, so long-range forecasts can not be interpreted as explaining how much rain you will see in your rain gauge on your farm, or what temperatures you might record on your thermometer. Those will vary form location to location. In fact, a 'normal' year is one that includes those kinds of variations across the state.