At 11 AM this morning, invest 96L was upgraded to Tropical Depression 4, the 4th storm of the season. Then at 5 PM, the depression was upgraded to Tropical storm Danny. This is the first named storm in over a month, with the previous storm, Tropical Storm Claudette dissipating on July 15th, which is very unusual given that we are entering the heart of the hurricane season. This gap could be because the earlier storms were homegrown systems, originating from old frontal boundaries and other non-tropical features. Normally, during the peak of hurricane season, storms develop more often from African tropical waves moving through the tropical Atlantic, known as the Main development Region (MDR) but due to hostile conditions of high shear,dry air, and low vertical instability over the MDR, these waves failed to develop. These unfavorable conditions are thought to be a product of the strengthening El-Nino as well as a very strong Bermuda High. Danny seems to have happened to find a pocket of low shear and decent moisture to capitalize on.
Danny originated as a tropical wave ( a cluster of thunderstorms) over Africa over a week ago before moving into the Atlantic ocean. From the beginning, the wave defied dry air and many computer model's forecasts that the wave would never develop into anything substantial, steadily organizing its thunderstorm activity. Danny is in an environment that is conducive for strengthening, with high sea surface temperatures around 28 degrees Celsius and low wind shear, although the storm is travel ling just south of the Saharan Air Layer (SAL), which suppresses thunderstorm activity. Despite Danny's proximity to dry air and Sahara dust, the NHC has given a bullish forecast, bringing the storm up to 100 mph sustained winds (a Category 2) in 5 days as it approaches the Caribbean. This post will be updated as the storm approaches the Caribbean and possibly the US in the next 2 weeks.
