Map: Precipitable Water = 2.78" in New Orleans, August 11, 2016

Washington Post / WxBell

Along the central Gulf Coast on August 11, a measure of atmospheric moisture (from the surface up to the jet stream level) known as precipitable water is in the top percentile (3 to 3.5 standard deviations above normal) of historical values.

In New Orleans, the precipitable water was determined to be 2.78 inches Wednesday, which ranks among the top-five highest levels on record in August. “That is higher than some soundings [weather balloon measurements] observed here during past tropical cyclones,” the National Weather Service said.