5AM Wednesday: Gradual Strengthening, a Jiggly Path, Heavy Rain, and Arguing Models. Pay Attention but Don’t Panic.

Tropical Overview

The National Hurricane Center’s 5AM Wednesday update indicates strengthening for Tropical Storm Dorian and a slight turn to the north, but there’s still plenty of uncertainty to go around.

The 5-day cone always wobbles about but it’s especially so with Dorian because of the remaining uncertainty about the storm’s path in the area of Hispaniola and Puerto Rico. As that becomes clear later today, we’ll have a better idea of the Attractions area impact. The latest cone, for now, shows a Category 2 hurricane (max winds around 100 MPH) passing north of Castaway Cay and the rest of the Bahamas… and then located a little east of Cape Canaveral very early Monday morning.

Strength and path by the fifth day of the cone is always iffy, but uncertainty on the long-term strength and path of this storm is unusually high. Take a look at three of the major forecast models. Each of them disagree about the location of the storm around 8PM Sunday night. The European model shows a “direct hit” across the peninsula of Florida, whereas the American model shows a storm just skirting up the coast like Michael did a few years ago.

Regardless of exact path, there’s a chance that rain could be a big factor. The Weather Prediction Center’s long-term precipitation forecast is very high for the Attractions area over the coming week.

A word about uncertainty: We still honestly don’t know for sure what this thing is going to do in Central Florida. The NHC says the “uncertainty in the intensity forecast late this week remains higher than usual due to a large spread in the model guidance” (as we showed you above), but the NHC says that the threat of tropical storm or hurricane conditions along the Florida east coast has generally increased. Additionally, they add that…

… there has been considerable run-to-run variability among the models so confidence in the long term track remains low. In addition, users are reminded not to focus on the exact forecast points as the average 5-day track error is around 200 miles.

A word about strengthening: The storm’s expected strength has increased, but the model uncertainty still plays a part…

The NHC intensity forecast is increased from the previous one, especially at the longer forecast times, to be in better agreement with the latest models. This forecast, however, is still on the lower end of the guidance envelope, so additional upward adjustments could be needed if the guidance trends persists. It is also worth noting that the global models show Dorian increasing in size by the time it nears the southeast U.S.

Our vigil on this storm will continue. Once we get the storm past the Mona Passage, we’ll know more about its Floridian future. You MAY need to be ready to start executing your hurricane plan in the next day or so. We’ll know soon.

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