Wednesday, May 29, 2019

Seven Lessons Learned from the 2018 Hurricane Season

With the start of the 2019 Hurricane Season right around the corner, I thought I would go back and share seven lessons I learned from the 2018 Hurricane Season.

Last year I personally did my most in-depth hurricane field work to date, spending a few weeks on the ground in the areas impacted by Hurricane Florence and Hurricane Michael. I was in both areas before, during and after the storm struck. Here’s what I learned:

1) Construction Type Matters

I spent time in Panama City in the days after Hurricane Michael's landfall. The area looked like a nuclear bomb exploded.

You didn't have to be a construction scientist to see the difference in roof performance in areas like 17th Street. While most of the metal roofs in this region remained intact, wooden roofs were substantially damaged or gone.

Metal roofs generally fared better than wooden roofs around 17th Street in Panama City during Hurricane Michael. Photo: Hal Needham

Metal roofs generally fared better than wooden roofs around 17th Street in Panama City during Hurricane Michael. Photo: Hal Needham

A family in the disaster zone took me up on their metal roof and explained how well it fared. A tree branch did pierce it, creating a hole, but they were able to quickly patch it and lived in the house.

This story gave me new insight. I learned that if your house did not flood and you had a roof intact, you could live at home, even if your property sustained substantial damage.

A family invited me to see their roof following Hurricane Michael. I'm standing on the left. Photo: Hal Needham

A close-up pic of a roof that successfully weathered Hurricane Michael. Overlapping metal sheets did not allow Michael's winds to get under the roof. Photo: Hal Needham

This family told me they just put on a new roof the year before. They chose to spend a little more money on a better roof and that decision helped them immensely when Hurricane Michael struck.

Of course, there are no guarantees in hurricanes. Metal roofs sometimes fail and some wooden roofs fare better than others. This is just an observation I made from spending time in a few neighborhoods that sustained category-4 winds of around 140 – 145 mph.

2) Evacuation Direction Matters

I spoke to several people who evacuated from Hurricane Michael by moving inland and slightly to the east. While this decision removed them from proximity to saltwater storm surge, in some cases it placed them in more dangerous winds.

One woman left a neighborhood in Panama City Beach that observed category-3 winds and evacuated to Parker, a community to the east that observed upper category-4 winds and experienced catastrophic damage. In retrospect, she thought that decision could have cost her life.

By contrast, families who evacuated west, or who went farther inland, fared better. Hurricane forecast models consistently predicted Hurricane Michael would curve to the northeast before landfall.

For example, people who evacuated one hour west to Destin, Florida, were happy with their decision, found little traffic and were able to make it back home quite quickly.

Satellite image of Hurricane Michael, with an arrow showing the path of people I talked to who evacuated to the west. These people fared better than those who did not evacuate or who evacuated east. Of course, evacuating inland is usually the safest decision.

We must keep in mind, however, that uncertainty still exists in hurricane forecast modeling, and coastal residents should not make decisions on a "pinpoint" forecast, but rather consider the entire cone of uncertainty when forecasts are issued. Of course, evacuating inland is the safest bet when leaving a hurricane hazard zone.

3) Keep A Battery-Powered Radio Handy

I spoke with a pastor in Panama City who was using his church as a base for receiving and sending hurricane relief supplies. I asked him to share the biggest lesson he learned from Hurricane Michael. He said, "I wish I had a battery powered radio. I can't believe I didn't think of that because I'm usually prepared. But in the days after Michael cell phones did not work and it was hard to get information."

A radio station in the disaster zone was sharing crucial information in the days following the storm, such as where to receive food and water, where and when curfew existed, how to apply for disaster assistance, etc. A battery-powered radio can be a lifeline to the world following a disaster!

4) Prolonged Wind and Rain Leads to More Downed Trees...Even in Tropical Storms

Hurricane Florence made landfall near Wrightsville Beach, North Carolina. In the following days, Florence was downgraded to a tropical storm and slowly drifted to the southwest, not far from the South Carolina border.

The storm generated tropical storm force winds and dumped copious amounts of rain on eastern North Carolina in the days following landfall.

Many neighborhoods in Wilmington experienced dozens of tree falls. This surprised many people because Florence never generated hurricane-force winds in Wilmington. In fact, the highest sustained (2-min) wind speed observed in Wilmington was 57 mph, with a gust to 91 mph, keeping Wilmington well within the zone of tropical storm force sustained winds, which range from 39 to 73 mph.

Photo of a massive tree that fell from Tropical Storm Florence in Wilmington, North Carolina. Photo: Hal Needham

However, Florence taught us a valuable lesson. A tropical storm generating winds of 50-60 mph is still able to down many trees when strong winds are blowing for multiple days and the trees are rooted in saturated soil. 

5) Strong Communities Come Together and Open Accessibility Faster

The fifth lesson I learned last year is that strong communities come together and open accessibility faster. I came across a street in Panama City that was surprisingly open two days after Hurricane Michael struck. While other neighborhoods were choked with fallen trees, the streets in this community were already open.

As I made my way down this street I discovered why. Locals had come together and shared resources, like gas containers, jeeps and chain saws. Young and old worked together to clear their street, instead of waiting for the government to come and remove the debris.

 A community in Panama City came together in the days after Hurricane Michael to share resources and open up their road. Photo: Hal Needham

 Picture of progress! This community in Panama City came together to open their road soon after Hurricane Michael struck. They cleared more than 1/4 mile of roadway within two days of Michael's landfall, giving them accessibility for disaster supplies to reach the residents. Photo: Hal Needham

I saw this same spirit of community engagement in Texas during Hurricane Harvey (2017) and in the several years I lived in Alaska. If an ice storm hits Interior Alaska and trees are across the roads, locals are going to work together to clear it right away instead of waiting for outside assistance.

These neighborhoods open up quicker and also experience the benefit of bonding from working together as a community.

6) Many People are Only Familiar With Their Own Hurricane History

I was surprised that more people were not evacuating the day before Hurricane Florence struck the Carolinas. I arrived in North Myrtle Beach, South Carolina, miles from the North Carolina border, to find that many people decided to ride the storm out because the category number dropped.

At the time, Florence was forecast to slowly drift near the coast of the Carolinas and dump tremendous rainfall. The biggest danger was from the water not the wind. The Saffir-Simpson Hurricane Wind Scale does not indicate danger from flood, it is based entirely on maximum sustained wind velocity, so a lower-category storm does not mean flood risk has reduced.

Other locals said they were not going to leave because they fared well in Hurricane Hugo (1989). Hugo was a vicious category-4 hurricane that made landfall right in the heart of South Carolina, but Florence was no Hugo. While Florence made landfall as a category-1 hurricane, the real threat from this storm was flooding from days of torrential rain as the storm drifted.

Flooded streets in Fair Bluff, North Carolina, following days of torrential rain from Tropical Storm Florence. Parts of North Carolina observed more than 30 inches of rain. Photo: Hal Needham

I told locals that this storm is not like Hugo, but more like Harvey (2017). They just looked at me with a blank stare, as if to ask, "What's Harvey?"

Hurricane Harvey stalled along the Texas Coast in 2017 and dumped more than 50 inches of rain in parts of metro Houston and the Beaumont-Port Arthur area. The storm led to $125 billion dollars in losses. I was living in nearby Galveston when Harvey struck, but I thought Harvey made the entire country aware of the danger from a stalled-out tropical system.

It had not.

I learned a lesson while on the ground in the day before Florence. People know their own hurricane history, but may not know valuable lessons taught to other cities, no matter how devastating.

7) Hurricanes Winds Can Be Strong Enough to Blow Over a Train

The seventh lesson I learned last year has to do with the power of hurricane winds. I never had seen such catastrophic wind damage as I saw in the days following Hurricane Michael.

A portion of an apartment complex, around eight or nine stories in air, was ripped out and I found slabs of the wall more than one block away. Nearby cars looked bombed out from debris strikes.

But the most lasting vision in my mind is the train that blew over from Michael's category-4 winds in the eastern part of Panama City. Michael was able to blow many cars of this train off the track, and wheels were still suspended in the air days after the storm.

 Hurricane Michael's category-4 winds (in this location) blew this train off the tracks in the eastern part of Panama City, Florida. Photo: Hal Needham

 Hurricane Michael's category-4 winds (in this location) blew this train off the tracks in the eastern part of Panama City, Florida. Photo: Hal Needham

Nearby, I came across several cars that look flattened. Their damage was not consistent with other cars in this part of the city. Then I saw a damaged shipping container angled into the highway and a SUV perched off the edge of a retaining wall.

Putting the pieces together, it appears that Michael flipped or rolled this shipping container through a parking lot, flattening or pushing many vehicles. In this area of the city, maximum sustained winds were estimated at category-4...probably sustained in the 140 mph range.

2019 Hurricane Season Fast Approaching

The 2019 Hurricane Season is fast approaching, as it officially begins this Saturday, June 1. In the upcoming weeks, I will be doing a series of blogs related to coastal flood and wind risk, and looking at the upcoming hurricane season.

Wednesday, May 1, 2019

Cyclone Fani Threatens to Generate Extensive Storm Surge in India

Tropical Cyclone Fani has increased in strength on Wed May 1, as it tracked northward in the Bay of Bengal, east of India. As of Wednesday evening, local time, the cyclone packed maximum sustained winds of 105 kts (121 mph, 194 kph), according to the Joint Typhoon Warning Center (JTWC).

Water vapor satellite imagery of Cyclone Fani on Wed May 1, 2019. 

If this cyclone were in the Atlantic Ocean it would be classified as a category-3 hurricane on the Saffir-Simpson Hurricane Wind Scale.

The cyclone is forecast to remain powerful as it approaches the northeast Indian coast, although it may weaken slightly before landfall. While Fani is forecast to make landfall in Orissa, severe impacts will be felt throughout Orissa and West Bengal.

Cyclone Fani's forecast track from the Joint Typhoon Warning Center

Fani’s alongshore track will enable the cyclone to generate dangerous storm surge levels along a widespread area of coastline. This occurs when cyclones move along a coastline as the center of the storm moves towards the direction of onshore winds. Another way to visualize such cyclones is by picturing them turning to the "right" in the Northern Hemisphere and the "left" in the Southern Hemisphere.

Hurricane Flossy took an alongshore track near the U.S. Gulf Coast in 1956, generating a large storm surge well to the "right" of the landfall location. However, locations much closer to the hurricane's center, but on the "left" side of the storm observed much lower storm surge levels.

For example, Flossy's eye tracked just south of Pensacola, Florida, but the maximum storm tide there only reached 2.85 feet (0.87 m). Yet, in Cedar Key, Florida, more than 400 miles from the landfall location, storm tide levels exceeded 7 feet (2.13 m). 

Hurricane Flossy (1956) generated an extensive storm surge to the "right" of the storm track. Flossy's alongshore track as well as the shallow waters of Florida's coast, provided this setup.

Marked-up version of the same graphic.

A big exception to this rule was found over the Louisiana Delta, where onshore winds "wrapped around" Flossy and pushed storm surge levels exceeding 12 feet (3.66 m) high.

The impacts of Fani's storm surge may be substantial, as saltwater flooding and "compound flooding" from both storm surge and heavy rainfall should impact densely populated areas, like Calcutta. Models also suggest that flooding may be pronounced along the densely populated Hooghly River.

Fani may produce extensive flooding along the highly-populated Hooghly River.

Although Fani will make landfall in India, coastal flood impacts could be felt as far east as Bangladesh. The coastline of northeast India and Bangladesh are extremely susceptible to storm surge flooding, and this area of the world has observed the world's highest storm surge levels.

A tropical storm in 1981 made landfall near the India/ Bangladesh border with sustained winds of 60 mph (100 kph) and generated a storm surge of 2.2 m (7.2 ft) (Dube et al. 1997). Fani should be more intense than the 1981 cyclone and has the potential to generate more extensive flooding.


Dube, S.K., A. D. Rao, P.C. Sinha, T.S. Murty, and N. Bahulayan, 1997: Storm surge in the Bay of Bengal and Arabian Sea : The problem and its prediction. Mausam, 48, 283-304.