UPDATE for Friday 20 Aug AM:
The information below is still pretty accurate for Dorian, except a few important details.
1) The storm is now expected to move more slowly as it gets closer to the Florida coast. This means that the timing is shifted later, possibly by a half a day or more. But, this is not certain, so if you were planning on buying umbrellas don’t put that off. Or, evacuation. Don’t put that off either.
2) For the same reason, the slowdown, Dorian may spend more time in a position to remain strong off the coast but still hitting the coast with severe winds and storm surges, for a longer period of time.
With hurricanes, fast is better, once you know they are coming.
Chances are about even that Dorian will affect the Florida coast as a Category 3 or a Category 4 hurricane. The centerline prediction from the National Hurricane Center has Dorian as just barely a Category 4 as it makes landfall, but as a mid-range Category 4 (i.e., more severe) prior to getting near the coast. This will, of course, cause confusion as reporters spew poorly formed sentences like “Dorian has weakened” instead of “Dorian has made the expected adjustment from a very very very dangerous storm to a very very very dangerous storm because it lost some of its energy scraping your homes and beaches into the sea” or words to that effect.
Best guess right now: Dorian will be a Category 3/4 hurricane as it moves onto land over a several hour long slog centered on about 2:00 AM on Tuesday morning. It will remain a hurricane, but weakening to a Category 1 storm over the next 24 hours as it moves well inland, veering north. Tropical storm force winds will be arriving on the Florida coast early Sunday morning.
The center point for landfall of the eye, with lots of areas to the north and south affected, is West Palm Beach or a bit north of there. 24 hours later, still as a hurricane, the storm may be just south of Orlando.
The norther Bahamas are going to have something very close to a direct hit.
The Hurricane Center has not yet put out information about storm surges, because the possible range of actual landfall is still too uncertain. Indeed, it is still possible that the storm will turn north and hardly hit anything.
It was looking for a while there that Dorian, after moving well inland in Florida, would then stay inland a couple/few hundred miles and find a track across all the states to Maine. Now, it is looking more like it will pop back across the coast and go up the Atlantic, either near the coast nor farther at sea. That would make Dorian’s future very unpredictable, and I suppose it would open up the possibility of reforming as a hurricane.
Most of the models show Hurricane Dorian striking the Atlantic Coast of Florida, though the exact location is not something that can be predicted yet. Somewhere between Palm Coast and Miami, most likely near Melbour, Palm Bay or Port St Lucie. That’s a pretty large area.
This depends, however, on a weather system that is only now forming up north of Dorian, which would cause the storm to not to the usual pull-out where the storms go north and head in the general direction of Bogna Riva.
And, if that weather system forms, some models say its western end will weaken, and that would be an escape door Dorian might use for that northward turn.
So, there is maybe a one in ten chance Dorian will bug out before hitting Florida. There is a small possibility it will come right up to Florida and then bug out, meaning, it would scrape the coast of Florida and Georgia, or just inland, at first as a hurricane then as a tropical storm.
But most likely, Dorian is going to slam into the Atlantic coast of Florida, then move inland. After moving inland, it is very likely to then stay inland, as a major storm of some sort, dumping rain and blowing winds in inland Florida, Georgia, maybe all the way up to Maine. That should be interesting. Wet, and interesting.
How strong will Dorian be? Don’t believe the hype Major news outlets are suddenly saying that Dorian may be a Category 4 storm. Maybe. But almost every model puts Dorian squarely in the extremely dangerous major-storm Category 3 range, with just a couple of models showing it forming into a Category 4 storm. One model actually shows it becoming a Category 5 storm.
But these categories are felatas. You evacuate and/or batten down the hatches for a Category 3 storm because that is a killer storm. You can save the discussion of whether your house was flattened, flooded, or flew away by a Cat 3 vs a Cat 4 storm felata.
When will Dorian strike?
As you know, “ladnfall” is not when a hurricane strikes. It strikes when the storm’s outer bands come ashore and start making for a lot of rain, some wind. It strikes when a storm surge comes through, and the timing of that can vary a lot. It strikes when the hurricane force bands arrive, which can be hours before, and continue hours after, the eye comes ashore.
The Center of the storm is currently predicted to be in “striking” distance at about sunup on Monday morning. SO, overnight Sunday to Monday is a safe estimate of when Dorian might be “strking.”
By sunup the next day, the storm should be well inland, probably turning north, and very large, wet, dangerous, but probably not really a hurricane any more.
The National Weather Service suggests that tropical storm force winds will arrive on the coast of Florida between nightfall Saturday and maybe midnight.
One more small detail: It is possible that Dorian, if it strikes Florida, will pass into the Gulf. If it does, then that will be interesting.