January 22, 2013

How Dry We Are

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Q: How much rain will Oklahoma need to climb out of an official drought that has lasted for more than two years?

A: Wet-weather spells in February are lifting hopes, but much more moisture is needed. Gary McManus, associate state climatologist, said it’s difficult to pinpoint how much rain Oklahoma would need to exit the drought. For one thing, drought means different things to  different entities, such as industries and cities. A farmer might need a couple of inches  while Lake Thunderbird near Norman needs many more. Drought also varies by area, and it’s measured by various factors, including rainfall and streamflows.

Spring is the main rainy season.  Oklahoma needs above-average rainfall for the most of the spring to make a real dent in the drought. In 2012,  rainfall totaled 3.2 inches statewide from March through June, compared with a 30-year average of nearly 4 inches. A long dry stretch makes it tougher on water consumers throughout the summer. If drought is in place or intensifying in summer, there is little moisture on the surface to absorb the sun’s energy, which exacerbates the heat.

“Without the moisture there, it’s like a giant Easy-Bake Oven and it makes the drought worse. The heat and the drought feed off each other,” McManus said.