In the Northern Gulf of Mexico, a stalled stationary is bringing heavy thunderstorms to northern and central Florida, where heavy rains of up to six inches have caused isolated flooding problems. A weak area of low pressure along this front will move over the coastal waters several hundred miles offshore of South Carolina on Thursday, where the ECMWF and Canadian GEM models predict that development into a tropical or subtropical depression could occur by Friday. Ocean temperatures off the South Carolina coast are just warm enough for development, 26 - 27°C, so this scenario is plausible. However, the other two reliable models for tropical cyclone genesis, the GFS and UKMET models, are not predicting development. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave no odds that anything would spin up in the next five days. Out of respect for the ECMWF model, which has the lowest incidence of false alarms for predicting genesis of tropical cyclones, I put the 5-day odds of development at 20%. The ECMWF and GEM models predict that the storm will head slowly northwards, and the ECMWF model predicts that sustained winds of 30 - 40 mph will affect much of the mid-Atlantic coast on Sunday and Monday.Figure 1.
Predicted winds for 11 am EDT Sunday, September 29, 2013, from this morning's 00Z Tuesday, September 24, 2013 run of the ECMWF (European) model. The model is predicting that winds of 30 - 40 mph (light orange colors) could affect a large portion of the mid-Atlantic coast.