Tonight storm watchers are looking in bewilderment at Arlene, the first Tropical Storm of the 2017 Hurricane Season.
"I have to add one more surprise to my long hurricane forecasting career", wrote the hurricane center's Lixion Avila in a forecast discussion Thursday afternoon. The first was Tropical Storm Ana in 2003.
Tropical season in the Atlantic basin officially begins June 1st and ends November 30th each year, which is what makes Arlene so rare.
Prior to weather satellites, it is quite possible - if not likely- additional tropical storms formed in April but "this type of storm was practically impossible to detect", the National Hurricane Center said.
As of a 5 p.m. advisory, Arlene was estimated to have 45-mph winds and was traveling west-northwest at 25 miles per hour. Earlier forecasts had the system not strengthening at all. That storm eventually became a hurricane.
The expected downtick in named storms is due to cooler than average water in the far north Atlantic and the possibility of a weak El Nino pattern developing which creates stronger westerly winds in the upper atmosphere that can shear apart storms in the Atlantic. The Atlantic hurricane season does not officially begin until June 1 and extends through November 30. They are predicting 11 named storms in the Atlantic this year, four of which will strengthen into hurricanes, and two of those becoming major hurricanes.
"Most of the North Atlantic has anomalously cooled over the past month, and the tropical Atlantic is now slightly cooler than normal", the CSU researchers said in their Atlantic hurricane outlook.