A couple of points to make about TD4:
1. TD4 is caught in fast westerly to west-northwesterly steering currents right now and will remain there over the next few days. Despite weak upper level wind and very warm ocean temperatures, TD4's fast motion will slow what otherwise might be a quick strengthening process. I do expect TD4 to become Colin sometime in the next 24 hours, though.
2. As TD4 moves northward, gaining latitude, it will approach higher wind shear near 15-20 degrees north latitude. Depending on the organization of the system when it reaches this area, the wind shear could have a weakening effect on the storm. A stronger storm will not "feel" the effects of the shear quite as much as a weaker storm.
3. Just a reminder: model tracks can have quite a range of error this far out. TD4 bears watching over the next few days, but is not something to be overly concerned with!
Brian
