August 30, 2019

Hurricane Dorian Poised To Threaten Florida As A Major Hurricane Early Next Week



Hurricane Dorian grew stronger in the southwestern Atlantic Ocean on Thursday, steadily moving toward the northwest as it pulls away from the Greater Antilles. Great uncertainty remains in the storm's eventual track and where—even if—the storm will make landfall in Florida or the southeastern United States early next week.

The National Hurricane Center's official forecast at 11:00 PM EDT on Thursday looks similar to forecasts from the last couple of days, with a couple of notable changes. The forecast makes the hurricane stronger, slows it down as it approaches land, and pushes the track farther south. Landfall next week is now expected to occur on Monday night or Tuesday, but that can (and likely will) change as we get closer to the weekend.

Dorian Is Strengthening

Aircraft reconnaissance found Hurricane Dorian strengthening rapidly on Thursday night, with its minimum pressure dropping from 986 mb to 977 mb between the 5:00 PM and 11:00 PM advisories. The storm now has maximum sustained winds of 105 MPH, which makes it a category two on the Saffir-Simpson Hurricane Wind Scale.

As you'd expect given its intensification, the hurricane looks better on satellite tonight than it did last night. Dorian lost the "blob" of convection on its east side and it looks more tightly wound than it did yesterday (don't we all). The hurricane is also more symmetric than it was this morning, with hurricane force winds now completely surrounding the storm's eyewall rather than occurring all on one side of a storm.

Hurricane Dorian spent Thursday getting itself better organized, and given the favorable environment it'll encounter north of The Bahamas, all indications point toward continued strengthening through the weekend. Strong hurricanes tend to fluctuate in intensity, so don't be surprised if its wind speeds go up and down as the storm grows in size and it undergoes eyewall replacement cycles.

The Cone Is All That Matters Right Now

It's important not to focus on specific landfall locations. Anyone in and around the cone of uncertainty is at risk for effects from this storm. The NHC's average margin of error five days out is 228 miles, and it's even greater than that about a third of the time. The cone of uncertainty doesn't account for all of the uncertainty in the forecast, and there are a wide range of scenarios that depend on small changes in the environment around Hurricane Dorian.

Four Scenarios Are Possible

Hurricane Dorian is still far enough away that every little jut and jog and gyration in the storm's structure and path will have an effect on where it goes in a couple of days. A move to the north or south, or the storm moving slower or faster than anticipated, can have big implications on its ultimate track.

Much of the nervousness right now is centered around the strength of ridges of high pressure over the United States and central Atlantic Ocean. Each weather model is resolving these features a little different, leading to disagreement between the models on exactly when the hurricane will begin its curve toward the north.

A ridge of high pressure to the north of a hurricane acts like a buffer that prevents the storm from moving north, guiding the storm around the edges of the ridge until the storm finds opening or the ridge itself weakens.

Most Likely Scenario: Landfall In Florida, Southeast Soaking

This is the scenario covered by the National Hurricane Center's current forecast. The most likely outcome right now, according to experts analyzing current data, is that Hurricane Dorian will slow down as it approaches Florida next week, making landfall somewhere along the state's east coast during the day on Monday.

After landfall, the storm is likely to begin a very slow turn toward the north in the following days. This turn, and any movement after that, is too far out to show up in the National Hurricane Center's forecasts.

The slow forward motion of the storm would lead to an extended period of heavy rain and strong winds over Florida, as well as any other state that ends up in the storm's path next week.

Other Possible Scenarios

The cone of uncertainty exists to remind us that hurricane track forecasting is still an inexact science. It's a heck of a lot better than it was a decade or two ago, but meteorologists today still don't know all the answers. That's especially true with a storm like Hurricane Dorian, where small changes in the surrounding environment can have huge ramifications a few days down the line.

I like this "extended" cone of uncertainty graphic by Tim Buckley, chief meteorologists of WFMY-TV here in Greensboro, NC. It shows the range of possibilities for the storm beyond the NHC's five-day cone.

Here are some more scenarios that could play out over the next couple of days. Again, these aren't reflected in the current NHC forecast, but each scenario isn't out of the realm of possibilities given the environmental setup and uncertainty.

Slightly Weaker Ridge: Scrapes Florida, Hits Georgia Or The Carolinas

This outcome, which is reminiscent of Hurricane Matthew in 2016, isn't too terribly far-fetched. A slightly weaker ridge would allow the storm to make its northward turn earlier than currently predicted, allowing the hurricane to scrape the Florida coast and make its way toward Georgia or one of the Carolinas. This would subject a long swath of coastline to intense winds and storm surge flooding, not to mention the threat of heavy rain from a slow-moving system.

Much Weaker Ridge: Turns Shy Of The Coast

One possibility is that the ridge to Dorian's north breaks earlier than anticipated, allowing the storm to turn shy of the coast and recurve rather than hitting Florida. It was a hot topic of discussion for much of the day on Thursday after a run of the European model hit social media. It could happen

Slightly Stronger Ridge: Landfall In Florida, Enters The Gulf

If the ridge stays stronger than predicted, there's a chance the storm could traverse the Florida Peninsula and emerge in the Gulf of Mexico by the middle of next week. If this scenario were to play out, it would put the northern Gulf Coast in contention for impacts from this storm. That said, the odds of this outcome seem to have waned a bit over the last day or so, but it's a possibility nonetheless.

Hard As It Is, We've Got To Wait On Specifics

It's maddening not to get specific information when so much is at stake. I know it. We're too far away from any potential landfall to tell you wind speeds, rainfall amounts, storm surge heights, or tornado potential for any one point on land. That's information we'll get in a couple of days when models and forecasters have a better handle on the track the storm will take.

The best thing to do right now is pay attention to each advisory from the National Hurricane Center and make sure you're prepared for extended power outages and, if you live in a flood zone, plans for what to do if you're ordered to evacuate.

This is going to be a slow-moving and prolonged storm. We've got a ways to go before it reaches land. Watch and wait, but don't hyperventilate. (And I promise I didn't mean for that to rhyme.)



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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I ran Gawker's The Vane for two years and I've contributed to Mental Floss, Forbes, Popular Science, and the Washington Post's Capital Weather Gang. I also teamed up with Outdoor Life to write a book called The Extreme Weather Survival Manual, which came out in October 2015.

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