That is an EASY question to answer. The models for Dorian were bad BEFORE the G-IV flights started making the flights and dropping dropsondes into the atmosphere around Dorian on the 29th. Adding additional data points to the models helps with models resolution and it helped the models come up with a better solution. This is from the discussion at 5PM on the 29th:
"The National Weather Service has begun 6-hourly upper-air soundings across portions of the mid-Atlantic and southeastern United States. Six-hourly balloons are also being launched in Bermuda and Nassau in the Bahamas. A NOAA G-IV synoptic surveillance mission is ongoing, and the data from this flight will be assimilated into the 0000 UTC model cycle."
That 00Z model cycle would be for the models on the 30th. And if you will go back and LOOK at the forecasts - it was this additional data from the G-IV flights that helped that model data come to a BETTER solution.
THAT'S why you can trust those later models better than the earlier ones. The earlier models were steering the storm with a ridge based on largly unknown intensity. Once the G-IV missions started, it made MANY samples of the atmosphere from the surface to 50K feet and took that data and put it into the global models - ALL around the system. The global models THEN realized the ridge to the north of Dorian wasn't as strong as they had previously thought it was and thus recurved the storm.
See - this is a little more complicated than you think it is...and there are ACTUAL answers going on behind the scenes. Perhaps people who make forecasts know what they are doing. Just because you can pull some maps doesn't mean you know what you are looking at or even how the data is being produced. If you did - you would have actually known the answer to that question. Stop before you get further behind.
Behind? I am well ahead here. I never ask a question to which I do not care to know the true and real answer, and having it puts me in plus territory.
How large is the universe of people who are aware of the certainty level change impact of the dropsondes? I was aware of these devices and their operations, but the impact on modeling certainty was completely left out.
I’m still bugged by the question of if we were that certain about it before it sat on Grand Bahama, why was anyone left there?