BATON ROUGE, LA (WAFB) - Weather models continue to indicate the potential for an area of low pressure to develop near or over the Bahamas this week, and then continue to drift northward. The National Hurricane Center (NHC) is currently highlighting the area north of the Bahamas and just off the Southeast U.S. Coast with a "low" chance for tropical development over the next three to five days.
If the system were to develop, the NHC is suggesting that it would likely be a sub-tropical system, which is defined as a storm that is a hybrid displaying both tropical and non-tropical characteristics. Sub-tropical storms are named the same as fully-tropical storms. If this system develops further, it would be named Ana.
Sub-tropical storms tend to be less intense than tropical storms. However, they generally have a broader area of circulation than fully-tropical storms and hurricanes. As a result, while less intense in terms of winds and storm surge threats, sub-tropical storms can produce impacts over a greater area.
WAFB's First Alert Storm Team is watching closely and asserts that even if a sub-tropical (or tropical) system were to develop, it offers virtually no chance of becoming a threat to the Gulf.
So how unusual are pre-season tropical systems for the Atlantic?
Over the past 50 years, eleven tropical systems have attained hurricane, tropical storm or sub-tropical storm status prior to June 1st, the official start of the Atlantic Hurricane Season. Of these eleven tropical systems, only 1970's Alma reached hurricane strength, doing so in mid-to-late May while over the western Caribbean.
The ten remaining pre-season storms since 1965 are evenly split as tropical and sub-tropical storms. Of these, two developed in April, but 1978's sub-Tropical Storm No. 1 (unnamed) is the earliest developing storm over the past 50 years, tracking westward over the open Atlantic for three days in mid-to-late January! The remaining seven were all May storms.
The 2012 Hurricane Season had two pre-season storms, Alberto and Beryl, both becoming tropical storms in late May. Going all the way back in the record books, 1908 and 1887 also had two pre-season storms. Both of 1908's pre-season storms have been rated as hurricanes.
Formation of a pre-season storm is not a sure sign of an active season ahead. Of the 10 seasons since 1965 with pre-season storms, only four ended the year with above-average storms counts (more than 12 named storms during that season). And all four of those years, (2003, 2007, 2008 and 2012) occurred during the recognized run of "hyper-activity" in the basin that began in 1995.
Whether or not Ana forms this week, the early consensus from several tropical forecasting teams suggests that storm counts will be below-average this season.