Tropical Storm Stan seems to be strengthening explosively over the Gulf of Mexico. A very quiet period overnight has given way to an incredible burst of deep convection. NHC was already forecasting Stan to reach hurricane strength, and he may well be on his way.
This morning Stan had a very healthy circulation, and it looks like all of that low-level convergence has helped fire a very healthy burst of convection.
A quick look at the visible satellite shows that Stan is also developing healthy outflow which will be crucial to future intensification.
The latest Dvorak satellite intensity estimates put Stan at 987 mb with sustained winds of 65.0 kts (75 mph). That is the threshold of hurricane strength! It seems as if Stan may already be a hurricane. However, I think this estimate is a little too strong. The algorithm looks to think it has a weakening system, which Stan was, but I am not sure that is valid here. However, it could be an indicator of things to come.