Essentially, the forecast models have centered upon two solutions with Ernesto:
- a developing East Coast trough will turn the storm northwest towards the central Gulf of Mexico
- developing East Coast trough is too shallow, and southern plains ridge returns to steer Ernesto towards Texas
Right now, the tropical models (GFDL and HWRF) depict this approaching trough on the stronger side, while the global models (ECMWF and GFS) show a shallower and faster trough forming. The two forecasts are shown below for comparison:
As of today, I am leaning towards the global solution, based solely on persistence. Ernesto is steamrolling westward, and the mean layer wind analysis shows no sign of that pattern fading.
As always, with any tropical cyclone, we will watch the storm and the models on a daily basis and do our best to not draw any immediate conclusions. Ernesto will be more worth watching come Sunday evening.