The tropical storm that's churning toward Florida and could move up the East Coast 'has a mind of its own'

Tropical Storm Hermine takes shape

As tropical storm Hermine — upgraded from a tropical depression Wednesday afternoon — takes aim at Florida's western Big Bend this week, a number of questions remain open.

Here's what we do know:

  • Hermine seems very likely to make landfall late Thursday night.
  • Floridians, who haven't seen a hurricane make landfall since 2005, should prepare for a significant storm surge.
  • A NOAA hurricane watch is in effect for parts of Florida and Georgia, and a warning is in effect throughout the Big Bend. There's a real risk of the storm gaining strength in the next 36 hours, possibly to hurricane levels.
  • After moving through Florida, Hermine is expected to cause some trouble in the Carolinas and across the East Coast – but the details remain uncertain.

The cone in this map offers some idea of where Hermine might travel over the course of the next several days. But it doesn't offer a full picture of how uncertain things are right now.


Just look at how far west it's moved since the last map released just a few hours earlier:

tropical storm hermineNOAA

Part of what's going on here is that the major hurricane-tracking weather models are in sharp disagreement with one another right now.

First, here's what the storm looks like as this article's being written Wednesday:

One model, run before Hermine grew into a tropical storm, predicts that the storm will sit off the East Coast for a long while, inscribe a little loop-de-loop in the Atlantic Ocean, then return to dump even more water on the East Coast.

Another suggests the storm will move up the coast of the Carolinas then crash into New York.

And more recent predictions shift the whole system over land, something that could lead to severe weather up and down most of the East Coast, but would likely spare waterfront areas a major storm surge:

Here's what's going on here.

Hurricanes and tropical storms are notoriously difficult to predict. Unlike broad patterns of warmth and cooling in the atmosphere, tropical storms can shift, shrink, or grow because of tiny events that models aren't very good at understanding.

NOAA Hurricane Specialist James Franklin told Business Insider that beyond three days out, hurricane models live in a kind of "fantasy land."

It's normal for models to look a bit chaotic that far in the future.

Thomas Downs, a meteorologist with Weatherbell Analytics, told Business Insider that some particular weather events in the middle latitudes are making Hermine especially difficult to precisely predict.

"What I see as a meteorologist is that the computer model's very confused right now," he said. "When there are shifts [from one run of a model to another] like this we know something funky is going to happen, because of the different strange tracks."

Right now, there's an atmospheric "trough" over the Carolinas. Hermine could smack into it, intermingle, and move over land as a weaker storm that moves quickly and dissipates — more like a typical winter storm than a cyclone.

Or it could shunt out to sea, where warm water would be likely to help the storm maintain its power.

"Does that mean it's going to hit Washington DC or New York or Boston?" Downs said. "This storm especially is one that has a mind of its own. The science of meteorology hasn't really caught up to quite the way hurricanes intensify and interact. And that's quite frankly why we're seeing this right now."

If Hermine does go out to sea and hold onto its power, the current atmospheric patterns might make it hover off the coast, which would be bad news for the areas impacted. (The Jersey Shore looks like a possible candidate.) But at its exact path is much harder to predict.

Here's what we don't know at all right now:

  • How weak or powerful Hermine will get.
  • How wide it will grow. Downs said it could be small enough to damage the Jersey Shore but leave New York untouched, or as big as the 943-mile Hurricane Sandy that struck the US in 2012.

Follow along with Business Insider for updates on Hermine.

RELATED: Top 5 cities vulnerable to hurricanes:

Top 5 cities vulnerable to hurricanes
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Top 5 cities vulnerable to hurricanes

Miami, Florida

Miami takes the number one spot on this list with a 16 percent chance of experiencing the impacts of a hurricane in any given year. Based on historical data, on average a hurricane will pass within 50 miles of the Miami metropolitan area every six to eight years. With the Atlantic Ocean to the east and a maximum elevation of 42 feet above sea level Miami's geography makes it highly vulnerable to hurricanes.

In addition to this, a majority of the population resides within 20 miles of the coastline increasing the risk of high property damage.

"Miami has a large population density, and as a result, the effects of a major hurricane would be catastrophic to the city," AccuWeather Meteorologist David Samuhel said. "Also, because of its southern location, Miami is probably the largest city on this list to see a Category 4 or 5 hurricane in the future."

Although a major hurricane is long overdue in Miami, the city has dealt with its share of intense hurricanes in the past. The last major hurricane to affect the city was Hurricane Andrew in 1992, which packed winds of 165 mph and currently holds the record as the third strongest U.S. landfalling hurricane. Andrew's total damage cost was $26.5 billion as communities in the surrounding areas were severely affected due to its intense winds and high storm surge.

Key West, Florida

Key West, like Miami, has a 16 percent chance of being impacted by a hurricane during any Atlantic hurricane season. Known as the Southernmost City in the Continental United States, Key West is directly impacted by a hurricane every 5.96 years, according to Hurricane City.

The Florida Keys are an archipelago of about 1,700 islands spanning 113 miles with Key West located at the southern tip. With the Atlantic Ocean to the south and east and the Gulf of Mexico to the north and west, the coastal town is exposed to all sides to passing hurricanes.

Key West with maximum elevation of 18 feet above sea level makes it susceptible to heavy flooding and storm surge during a hurricane event. Hurricane Wilma in 2004, regarded as the worst storm to hit the area, passed just west of Key West and produced a storm surge of 8 feet leaving 60-70 percent of the island under water.

"Key West has faced several situations in the past where it has been brushed or directly affected by some of the strongest hurricanes to hit the United States. This includes the 1935 Labor Day Hurricane which was remembered as one of the most intense U.S. hurricanes based on pressure and maximum wind speeds," Samuhel said. "Because Key West is so far from the mainland, evacuating people can be a difficult challenge during a hurricane event."

Cape Hatteras, North Carolina

Located on the Outer Banks of North Carolina, Cape Hatteras has a 15 percent chance of feeling the impacts of a hurricane in any given year. Cape Hatteras is positioned 280 miles farther east than Palm Beach, Florida, (easternmost location of the Florida coast). As a result, Cape Hatteras has been exposed in the past to hurricanes that move up the Eastern Seaboard.

"Cape Hatteras is very close to the Gulf Stream, which enables hurricanes to strengthen due to warmer ocean temperatures during the summer," Samuhel explained. "Typically, when tropical systems get caught in the jet stream off the East Coast of the U.S., they tend to curve out to sea, but because of the location of Hatteras, hurricanes tend to clip that region before affecting anywhere else on the East Coast."

When Hurricane Isabel struck the region in 2003, the Army Corp of Engineers was forced to fill up an inlet that was created when the storm split Hatteras Island between Frisco and Hatteras, North Carolina.

Tampa, Florida

The western coast of Florida has endured its share of hurricanes, and the city of Tampa is no exception. The Tampa-St. Petersburg area has an 11 percent chance of feeling the impacts of a hurricane in any given year. Tampa, situated on a peninsula lying along Tampa Bay and the Gulf of Mexico, is exposed to hurricanes entering the Gulf and systems forming in the Atlantic. Many of the 347,645 people living in the area have homes along the coast, making residents susceptible to storm surge.

"Like Miami, Tampa is a large metropolitan area and the effects of a hurricane would be widespread throughout the city," Samuhel explained. "Because it is located by the shallow Tampa Bay, water piles up into the city, causing very significant storm surge along the coastline."

The city hasn't suffered a direct hit by a strong hurricane since the 1921 Tampa Bay Hurricane, the first major hurricane to hit the city, but 68 tropical storms and hurricanes have passed within 60 miles of the city according to Hurricane City. Most recently in 2004, Hurricane Charley caused $16 billion in damages when the Category 4 storm made landfall just south of Tampa.

New Orleans, Louisiana

Hurricane Katrina in 2005 shined the light on how devastating a tropical system can be for the city of New Orleans. Like Tampa, The Big Easy has an 11 percent chance of experiencing the impact of a hurricane in an average year. According to NOAA, a hurricane makes landfall within 50 miles of New Orleans about once every seven to 11 years.

The city has since made drastic improvements to its levee system since Katrina left most of the city under several feet of water. Nevertheless, with more than 50 percent of the city living below sea level and the rapid sinking of marshy coastal land in southeastern Louisiana, New Orleans still remains highly vulnerable to storm surge during a major hurricane.

"The Mississippi River is almost 30 feet above the city level just to put in perspective of how low New Orleans is in terms of elevation," Samuhel said. "The land around New Orleans is sinking, which puts the city in more danger if another major hurricane strike."


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