August 29th. Here are the forecasts:

Group of simulations from American (blue) and European (red)
computer models from Thursday afternoon for Hurricane Dorian. Each color strand
represents a different model simulation with slightly altered input data. Note
that the strands are clustered together where the forecast track is most
confident but diverge where the course of the storm is less certain. The bold
red line is the average of all of the European model simulations, while the bold
blue one is the average of all the American model simulations.
(https://StormVistaWxModels.com)

Note that the European models were much more predictive of what
Dorian would later do. The US models a few days later moved east to match the
European models.