Low Pressure Between Southeast Florida and Bahamas has Potential to Develop

Heavy thunderstorms and strong winds are increasing over the waters between Southeast Florida and the Bahama Islands, where a non-tropical region of surface low pressure is developing. Radar out of Miami shows no organization to the shower activity, with rainfall amounts mostly less than an inch over Southeast Florida as of Tuesday morning. The first week of May is usually too early for the Atlantic to see its first named storm, but this area of low pressure could become Subtropical Depression One late this week, according to two of our top computer models for forecasting genesis of tropical cyclones, the GFS and European models. These models predict that the extratropical storm will form a well-defined center on Wednesday, then drift slowly northwards towards North Carolina during the week, gradually acquiring tropical characteristics. Ocean temperatures are near 26°C (79°F), which is about 1.7°C (3°F) above average for this time of year, and just at the limit of where a tropical storm can form. If the storm manages to find a sweet spot over the core of the warm Gulf Stream current, it has the potential to develop into a subtropical or tropical depression late in the week, as indicated by Phase space diagrams from Florida State University from Tuesday morning's 06Z run of the GFS model. Steering currents are weak over the waters off the Southeast U.S. coast, and the models are split on whether or not the disturbance will eventually make landfall on the Southeast U.S. coast late this week. I give the system a 40% chance of bringing heavy rains to the coast and high surf causing rip currents and coastal erosion late this week. In their 10 am EDT Tuesday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 20% and 40%, respectively. The Hurricane Hunters are on call to investigate the disturbance on Wednesday afternoon, if necessary.


Figure 1. Wind forecast for Friday, May 8, 2015 at 2 pm EDT made by the 00Z Tuesday run of the European model. The model is predicting a possible subtropical depression to be off the coast of the Southeast U.S.

Bob Henson will have a post late this afternoon from the NOAA Hazardous Weather Testbed.

Jeff Masters