El Nino: Impact on Virginia?

In case you missed Zach's El Nino explainer Thursday night, here's the scoop. Impacts on North American weather patterns are mild to non-existent during our Summer and early Fall. However, there have been some indications over the years that during an El Nino event, tropical cyclone activity is suppressed in the Atlantic and Caribbean basins. This is as a result of increased wind shear as you go upward in the atmosphere in the tropics. This shear essentially tears the circulation of a developing cyclone apart, preventing it from "getting its act together."

Once the Northern Hemisphere moves into the Winter months, though, El Nino can have significant impacts on our weather patterns. At this time, it does appear that this newly developed El Nino will last through the end of the year. So what does this mean for Virginia?

Historic El Nino events have meant drier than average precipitation in the Fall in Virginia, and in early Winter, slightly warmer than average temperatures. (Click to enlarge images)


As you go deeper into Winter, there have been cooler temperatures and more snow from December through March in Central Virginia, based on 12 previous moderate El Nino events. So as you can see, El Nino's impacts do depend significantly on the Northern Hemisphere season in which the El Nino occurs.

You can read the entire discussion of the current ENSO analysis here.