Monday, April 20, 2015

A Tropical Storm in April? It's Not Unheard Of

The Atlantic hurricane season officially stretches from June through November. However, one tropical storm this century flared up in the Atlantic basin in late April. On April 20, 2003, Tropical Storm Ana became the only tropical storm on record to form in the Atlantic basin in April.
That early in the calendar, "April Ana" didn't form from a tropical wave coming off west Africa. It formed as an area of low pressure aloft spinning near an old surface frontal boundary about 250 miles west of Bermuda. Eventually, thunderstorms began clustering near the surface low, warming and moistening the low-mid levels of the atmosphere sufficiently enough for the National Hurricane Center to classify the storm as Subtropical Storm Ana during the early-morning hours of April 20.
Based on microwave satellite imagery, it was estimated Ana became the first April Atlantic tropical storm of record later on April 20, when it exhibited enough consolidated thunderstorms near the center.
Dr. Rick Knabb, current director of the National Hurricane Center, goes into much greater detail on this process in the case of Hurricane Gustav in September 2002. But Ana was deadly, at least indirectly. Two people drowned after a boat capsized in high surf generated in part by Ana near Jupiter Inlet, Florida, according to the National Hurricane Center's final report.
While Ana remains the only April Atlantic tropical storm in records dating to 1851, an April 1992 subtropical storm was found in post-analysis by the National Hurricane Center.

Since it was not classified as such at the time, a later hurricane that year, Hurricane Andrew, got the "A" name in 1992.

http://www.weather.com/storms/hurricane/news/april-tropical-storm-ana-2003


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