The key to the forecast for PTC 9 is a small 300 MB upper-level low-pressure system on the Yucatan Peninsula. This feature is not being forecasted very well by the models because the orientation of the models would suggest the winds are from the southeast when, in reality, the winds are from the southwest. This difference in orientation is why model guidance would suggest this low-pressure system should be a tropical storm rather than a disorganized mess that it is right now. The vertical wind shear from the southwest is producing a low-pressure structure skewed to the northeast with a dual surface low-pressure system in the western Caribbean Sea, with one center near the deep convection and another center found to the southwest. I don’t see this vertical wind shear changing all that much over the next 48 hours, and there is no sign of the convection wrapping around either center this morning, which would be a signal that PTC9 is about to become an organized tropical low-pressure system.
However, the atmospheric environment will gradually improve, and PTC9 will eventually become a tropical storm between the Yucatan Peninsula and Cuba. With the very warm waters in the eastern Gulf of Mexico, PTC9 will have the potential to strengthen into a hurricane. If the vertical wind shear subsides enough, PTC9 could become a major hurricane. However, first PTC9 needs to solidify into an organized tropical low-pressure system, which appears to be more difficult than models had suggested.
The synoptic model guidance is in strong agreement with the development of an upper-level low-pressure system in the Mississippi River Valley, which would force any tropical disturbance in the western Caribbean Sea to lift northward towards the eastern Gulf Coast by Thursday night.
