The forecasts from all the most knowledgeable sources was that 2013's hurricane season would be extremely active. This excerpt from the official NOAA forecast is representative: "NOAA’s Atlantic Hurricane Season Outlook says there is a 70 percent likelihood of 13 to 20 named storms (winds of 39 mph or higher), of which 7 to 11 could become hurricanes (winds of 74 mph or higher), including 3 to 6 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher).
These ranges are well above the seasonal average of 12 named storms, 6 hurricanes and 3 major hurricanes."
So here we are in the very peak of the hurricane season and so far, not one storm has made it to hurricane strength and only six have reached tropical storm status.(The two systems in the picture attached to this article are not expected to have any impact on the U.S.) If Tropcial Storm Humberto, which has spun up off the African coast reaches hurricane strength after September 11, it will be the latest in modern history. So wha' happened?
Weather Underground founder Dr. Jeff Masters took a crack at explaining the difference between the predictions and reality in a recent blog post. "Unusual dryness over the Atlantic has been the main reason for this year's lack of hurricanes, it appears. Wunderblogger Lee Grenci's latest post, "The Lack of Atlantic Hurricanes: The Saga of Low Relative Humidity Continues", looks at how dry the Tropical Atlantic has been this hurricane season. Part of the unusual dryness, he maintains, is due to dry air coming off the coast of Brazil, which is in severe to extreme drought, according to the global drought monitor."
Dr. Grenci's post makes for somewhat dry *ahem* reading, but if you want a nuts and bolts explanation for what might be behind this surprisingly quiet hurricane, it's worth the effort.