Here is what happened. Dorian is now moving west as predicted because there is a large high pressure north generally centered around Bermuda and whose nose is being extended westward into the US. So the storm is being forced west. The forecast models of 3 days ago showed the high pressure not moving and forcing Dorian into Florida and then moving north once inland.
However, there was always the question as to when the nose of the high pressure retreating to the east would occur and the NHC was quite clear in its discussion section they were not quite certain when this would occur but the path at the moment is the most likely. The NHC was moving the path a bit east every 3 hours and then yesterday morning moved it offshore since it became clear when the models started to agree the high pressure would retreat east sooner then previous runs of the models suggested. The high pressure retreating east allows the storm to move north instead of west.
I just checked the Sunday 5 am update and the path has actually moved a bit west again, a bit closer to the coast based on the movement of the high.
The storm is forecast to really slow down, too (which was forecast several days+ ago. It is moving at only 8 mph and is scheduled to almost stop. So this will do two things. The upwelling of the water will cause it to lose some strength because there will be cooler water on the surface and the second one is that it will hang out in more shallow water and can't get as much energy from shallow water so it is forecast to lose some strength today.
The important thing to keep in mind is that the NHC is really good with their 3 day forecast and not as good for day 4 or day 5. Notice their forecast does not extend beyond 5 days. Their 4 day forecast is off by an average of 155 miles and the 5 day forecast is off by 205 miles. So I have been watching this closely. Their 3 days are spot on, but when looking at the 4th or 5th day, just be aware that it will change.
These storms are so huge, that a slight shift makes a big difference. The hurricane force winds extend 30 miles out, so a slight shift at landfall can make a big difference as to whether your house is obliterated or stands.
Excellent post.
That’s the only thing I’ve read that helps with my understanding of the prediction process. Thank you!
Living in St. Petersburg, I’ve been tracking it very closely and concur that the path has been gradually shifting eastward over the last several days. With every shift, I relaxed a little more. With Irma, it was the opposite - I thought we were clear based on the models having it hit around Ft. Lauderdale, but it came up through Ft. Myers instead. Daily conditions can alter the path and we need to be aware of that.
But I still have 20 sandbags filled just in case the next one comes this way.