Tropical Storm Dorian has changed significantly over the past 24 hours, and continues to quickly strengthen and organize. As of 11am EST this morning, Dorian had 70mph sustained winds and was moving northwest at 13mph. The storm continues to develop stronger low-level circulation as well. These changes in the storm have significantly increased the forecast strength of the storm, and it is now expected to make landfall somewhere in Florida late Sunday or early Monday as a Major Hurricane. Continue reading below for a breakdown of the environment, forecast, and impacts.
2pm EST Update: Dorian has strengthened into a Category 1 hurricane with 75mph winds and continues moving northwest at 13mph. The minimum central pressure has dropped to 997mb.
In the immediate future, Hurricane Dorian will continue to impact the eastern half of Puerto Rico. Widespread flooding rains of 4-6" with isolated higher amounts to 10" are expected in the next 12-24 hours, and may be life-threatening. Tropical storm force and hurricane force winds will also impact the island this afternoon into tonight. See the image below for current tropical watches and warnings in the area. Flash Flood and Coastal Flood Warnings are also in effect for all of Puerto Rico.
While those impacts will be devastating and life-threatening, the storm will continue to organize and strengthen further over the Caribbean in the next 3-4 days, with very favorable conditions for tropical development in place. First, sea surface temperatures north of Puerto Rico are roughly 29 degrees Celsius- plenty warm to support tropical systems. Generally, we look for 25-26 degrees Celsius as a minimum to support this activity.
Second, while quickly passing through a brief field of unfavorable wind shear (red) north of Hispaniola, Dorian may weaken slightly and become a bit less organized. However, the storm will not be in that area long at all and will immediately move into an area of favorable shear (green) near the Caribbean and east of the Florida peninsula. This will allow the storm to reorganize and continue thriving off of the warm waters.
MAJOR HURRICANE LIKELY
Dorian has just strengthened into a Category 1 hurricane, and will remain at hurricane strength (Category 1-2) through Saturday morning. Once in the area of more favorable shear east of the Florida Peninsula this weekend, Dorian will further strengthen into a MAJOR HURRICANE (Category 3+) with at least 111mph sustained winds. The National Hurricane Center (NHC) is currently forecasting landfall of a major hurricane with 115mph sustained winds and gusts to 140mph near Titusville, Florida.
Keep in mind that the NHC issues forecasts with a "cone of uncertainty" for a reason. High uncertainty remains at this time exactly where the storm will make landfall along the eastern Florida coast, and possibly along the Georgia coast. Several weather model forecast tracks for the storm are below to show this spread. The forecast track of the storm WILL SHIFT in the coming days. The forecast intensity is also likely to change.
EXPECTED IMPACTS FOR FLORIDA
Regardless of where Dorian makes landfall in Florida (or possibly Georgia), significant impacts are expected for much of the state. First, damaging winds of 111mph+ with gusts to 140mph will do catastrophic damage to buildings, trees, utilities, etc and may be life-threatening if you are not properly sheltered. The NHC provides a tool to show the earliest reasonable time of arrival for tropical storm force winds, which I have included below. Note that this forecast shows tropical storm strength winds (generally 40-70mph) reaching impacting the Florida peninsula SATURDAY- two days before landfall is expected.
Many people don't know this, but the storm surge from tropical systems is the most deadly part of the storm. In this case, we don't have storm surge inundation forecasts this far out, but they are expected to be life-threatening. Looking at projected significant wave heights from the Wave Watch model, waves moving toward the eastern coast of Florida could reach 20-30 feet, which would have devastating impacts.
Lastly, flooding rains INLAND will be a huge concern. Florida has seen well above normal precipitation this summer, and ponds are at capacity. With most areas being very low-lying, flooding and flash flooding are expected with widespread rainfall amounts of 6-10" and localized higher amounts to 15" possible. The entire Florida peninsula is expected to receive at least 2-4" of rain from this storm.
PREPARING AND MORE INFORMATION
For more information and to continue monitoring the forecast for future Major Hurricane Dorian, frequently visit the National Hurricane Center (updates are posted every 3 hours). For hurricane preparedness information visit Be Ready. As the storm gets closer to making landfall or impacting Florida and/or Georgia, check with your local National Weather Service office, as they will be issuing more detailed information for your location.
As always, we will have continued updates on our social media accounts @tdswx on Twitter, Facebook, and Instagram over the next several days as well. The most frequent updates will be on Twitter.