11:20 AM

Tropical Storm Erika continues to weaken late this morning as strong southwesterly shear has sufficiently disrupted the low level circulation.  Sustained winds have fallen off from 60 mph to 40 mph and the pressure has now risen to 1008 MB.

There is a pretty wide range in the models as far as solutions for Erika.  Looking at the 12 Z model guidance, there is just as much chance as Erika being downgraded to a tropical depressions as there is that Erika becomes a major hurricane in the next three days. The difference in the model guidance stems from the uncertainty of the development of upper level shear.  The majority of “global models” like the GFS, ECMWF, and CMC suggest that shear will remain strong and thus limit the development of Erika to much more than a weak tropical storm at worse.  The usually reliable tropical model guidance suggest that shear will weaken as the upper low over the Caribbean shifts to the west, thus allowing Erika to rapidly intensify over the very warm waters around the Bahamas.  The NHC is reasonable in siding with the global model guidance considering the upper level wind shear this morning ended up being strong than forecasted by any guidance and the trends clearly side with the GFS, EMCF, CMC family.  However, I want to stress that there is a lot of uncertainty with this forecast and that the degree in which wind shear will have to decrease to allow Erika to intensify is not overwhelming significant.  My point is that Erika has the potential to pull a big surprise for everyone from the Bahamas to Maine, and as such, this storm needs to be monitored carefully.