LSU Partnerships Improve Hurricane Storm Surge Forecasts for Louisiana, Nation
Ahead of Hurricane Ida and throughout last year’s record-breaking hurricane season, more people than ever turned to LSU’s Coastal Emergency Risk Assessment (CERA) tool, which visualizes storm surge predictions, to help protect communities and assets from flooding. The tool helps key decision-makers see where the water will go, and how high it will rise. By using CERA, they can be faster and more accurate in issuing evacuation orders and choosing where to position resources as well as when to open or close flood gates.

The Coastal Protection and Restoration Authority (CPRA) and the U.S. Army Corps of Engineers used LSU’s storm surge prediction visualization tool, CERA, to brief Louisiana Governor John Bel Edwards (at head of table on left) ahead of Hurricane Ida making landfall near Port Fourchon on August 29, 2021. Mark Wingate, U.S. Army Corps of Engineers deputy district engineer for project management in New Orleans (in purple shirt on right), addressed the Hurricane Ida war room, while CPRA Executive Director Bren Haase pulled up the CERA website on his laptop (closest to camera).
UPDATE, September 1, 2021—
During Hurricane Ida, the CERA website got more than 20,000 public page views and 9,000 page views from pro users with a login. (For more updates, scroll to the bottom of this story.)
BATON ROUGE, December 2, 2020—
“Nothing represents reality like reality,” said Windell Curole, general manager of
the South Lafourche Levee District, as he watched the fifth named storm of the already
record-breaking 2020 hurricane season make landfall in Louisiana with Hurricane Zeta
last October 28. “As an emergency manager, you look for every piece of information
at your disposal. And when you make your call—more than a day ahead of landfall—and
you’re telling people to evacuate or open or close flood gates, you’d better be right.”
He understands the risks involved with basing decisions on guesstimates or telling
people the wrong thing—they won’t evacuate when they should; whether it’s this time,
if you don’t tell them to, or next time, if you tell them to evacuate and it turns
out they didn’t need to.
“You can evacuate to naturally high ground to get away from the surge, but if you
are not out in time, you can’t leave,” Curole said. “Greater danger and loss of life
comes with storm surge, not wind.”
He and thousands of other emergency managers along the Gulf Coast and Atlantic Seaboard
have come to rely on CERA, the Coastal Emergency Risk Assessment visualization tool
developed at LSU, to help make some of their most difficult decisions in guarding
local populations against storm surge. CERA, which relies on storm surge predictions
computed by the ADCIRC surge guidance system (ASGS) developed in collaboration with
the University of North Carolina, provides a quick visual interpretation of millions
of computer data points to show flooding risks during a storm.
As Hurricane Eta zigzagged into the Gulf of Mexico about a week after Zeta and there
was uncertainty about the storm’s track after it first devastated parts of Central
America and then inundated Cuba and southern Florida, Curole sent LSU a straight-forward
yet complicated question: What if Eta, instead of heading back across Florida as predicted,
would come straight up across the Gulf of Mexico and hit Lafourche Parish? Then what?
Curole’s question reached Carola Kaiser, CERA lead developer and IT Consultant at
LSU’s Center for Computation & Technology, or CCT, which houses seven servers that
power CERA. She was fielding a record 243 new user login requests from across the
nation, including the U.S. Coast Guard, the U.S. Army Corps of Engineers, FEMA, NASA,
the U.S. Navy, the Department of Defense, the Department of Homeland Security, the
Department of Transportation, the Department of Health & Human Services, several oil
and gas companies, local and national law enforcement, media outlets such as The Washington Post and ProPublica, and around Louisiana—levee districts, the National Guard, the Coastal Protection
and Restoration Authority (CPRA), and the Governor’s Office of Homeland Security and
Emergency Preparedness (GOHSEP). She’d already established a White House Situation
Room login.

The need for better storm surge forecasting was made obvious after Hurricane Katrina, which flooded large parts of New Orleans. The LSU research effort grew from that and by public demand—emergency managers and planning commissions wanted not just federal levees on the map, but all structures that also happen to be in a constant state of change, requiring continuously updated measurements and local knowledge. To this end, LSU collaborates closely with the Louisiana Coastal Protection and Restoration Authority (CPRA), which not only gathers on-the-ground data for the university-driven forecasting effort, but uses its output to advise tide and flood gate operators across the state. Above, New Orleans as seen through the three-dimentional mesh LSU is building along with its partners to help predict where the water will go.
What-if scenarios are an integral part of CERA for decision makers who can access
layered maps in such high resolution they potentially show differences between neighboring
houses. That information is not available to the general public at cera.coastalrisk.live, as that amount of detail easily could convey a false sense of certainty about what’s
going to happen and what individual residents should do, which might contradict general
area evacuation orders. Plus, predictions change. Every six hours, as the National
Hurricane Center (NHC) issues its forecast advisories, ASGS recomputes all available
flood level data, allowing CERA to update its maps within an hour or two, in time
for critical briefings at every level.
A key recipient of this information in Louisiana is the Coastal Protection and Restoration
Authority (CPRA). Since 2018, the CPRA has provided annual funding to LSU to support
the overall forecasting efforts of CERA and ASGS. Their primary concern is the management
of the intricate system of tide and flood gates throughout the state, as well as overseeing
the complicated system of levees.
“The CERA tool is very important to CPRA—not only for operation of hurricane risk-reduction
systems, but also for the prepositioning of flood-fighting assets,” said CPRA Operations
Chief Ignacio Harrouch. “Keeping the model as up-to-date as possible is key, and this
is why CPRA continuously collects and shares bathymetric and topographic data with
LSU to facilitate continued improvement of the model.”
While Kaiser used to spend most of her time developing CERA, fixing bugs and adding
new features, the balance between development and operations has shifted.
“Ten years ago, we had about eight months for development and four months when we
responded to storms—mostly in July, August, September, and October,” Kaiser said.
“This year, we started responding to named storms headed for the United States coastline
on May 15, and we’re still responding. I don’t expect us to get more than four months
for development before we’ll need to go back into operations again.”
Louisiana has so far this year spent a total of three weeks “in the cone.” If you
plot all of the five-day cones issued by the National Hurricane Center in 2020 on
a map, Louisiana lights up like the center of a flame. While the official Atlantic
hurricane season spans June 1 to November 30, tropical storms no longer come as a
surprise when they form outside this window.
“This year, I’ve actually compared what we do with the firefighters in California
who usually spend part of their time doing land management and part of their time
fighting fires but now have no time to do land management because they’re fighting
fires all the time,” said Jason Fleming, a consultant who collaborates with Kaiser
on the software automation system, ASGS, which produces results for CERA.
If CERA is like the dashboard and GPS navigation system of a car, ASGS is the steering
wheel and the pedals while ADCIRC is the motor under the hood—a command-line Fortran
program that outputs raw data.

When the amount of time spent “in the cone” in 2020 is plotted on a map, Louisiana lights up like the center of a flame. Graphic courtesy of Sam Lillo @splillo.
“ADCIRC can’t do the job by itself—ASGS enables large-scale production of tailor-made
scenarios on supercomputers while CERA transforms the raw model results and maps them.
And meanwhile, we’ve had one storm after another, then another, back-to-back. This
leaves little time for code modifications or technical improvements while we’re always
discovering new needs expressed by decision makers in the field,” Fleming added.
And yet, CERA added a new feature this year—logged-in users can now download some
of the raw model data in a Geographic Information System (GIS) raster data format
for rapid damage assessment or to feed their own models or studies. Usually, the analysis
that follows each storm is more valuable in helping communities prepare for future
storms than the forecasts.
Last August, Hurricanes Laura and Marco broke another record—two hurricanes in the
Gulf of Mexico at the same time. While Laura rapidly intensified and made landfall
in Creole, Louisiana as the strongest storm in history to hit the southwestern part
of the state near the Texas border, Marco weakened. This didn’t relieve the CERA team,
however, which was coordinating with the governors of both Louisiana and Texas at
the same time, issuing flood maps well ahead of landfall and breaking its seasonal
record as far as unique users of the CERA website—10,223 in eight days.
CCT and Louisiana Sea Grant, which supports Kaiser’s and Fleming’s work, have been
driving forces behind the development and operation of CERA since the beginning.
“For Hurricane Laura, ADCIRC and CERA were actually running +20% scenarios for possible
increases in wind intensity while the event was happening,” said Louisiana Sea Grant
Director Robert Twilley. “Also, alternate scenarios for the storm moving either to
the east or to the west. ‘If the storm shifts, this is what you’re going to see.’
Nothing can touch that.”
Advisories issued by the National Hurricane Center, meanwhile, don’t include alternate
tracks—only the most likely outcome. While the government entities in charge of public
safety initially had concerns about CERA competing with their own guidance, those
worries appear to have ebbed. A recent broadcast email from the National Oceanic and
Atmospheric Administration (NOAA) ahead of Hurricane Delta last month read, “If you
live in a coastal zone, the NHC, NWS, NOAA, and CERA have tools to predict storm surge
and help you prepare.” The acronym NWS stands for the National Weather Service, and
both NHC and NWS fall under NOAA.

The ADCIRC mesh contains millions of vertices to describe the land form, both below and above the water surface. This picture shows the area near Creole, Louisiana where Hurricane Laura made landfall as the strongest storm in history to hit the southwestern part of the state.
“The uniqueness of our coast demands higher research capacity building—our challenges are greater and therefore our research capacity has to be greater,” said Louisiana Sea Grant Director Robert Twilley, a long-time supporter of the ADCIRC and CERA storm surge forecasting systems.
Twilley was the associate vice chancellor of research at LSU after Hurricane Katrina
in 2005 and in the room when then-director of the National Weather Service office
in Slidell (now director of the National Hurricane Center) Ken Graham came to campus
as the university was organizing a series of Grand Challenges to leverage its research
capacity to help the people of Louisiana—which is what CERA grew out of. Hurricane
Katrina had brought the risks of storm surge into the public consciousness. Forecasting
storm surge, however, was a knotty problem—especially in Louisiana, which has the
most complicated coast in the contiguous United States, with constant land loss due
to storms and sea level rise (a horizontal motion) as well as subsidence, which is
a general sinking of the land (a vertical motion), in combination with a complex system
of hundreds of flood gates, pumps, and levees—some federal, some not. The multifaceted
nature of that challenge alone required something like a major research university
to help find solutions—especially in connecting federal agencies with thousands of
local decision makers.
Someone else in the room that day was Curole.
“I looked at their federal storm surge map after Hurricane Katrina and it showed flooding
in Lafourche Parish,” Curole recalled. “But we never flooded; our levee was successful.
But since they don’t put any non-certified levee on a federal storm surge map, their
map showed us flooded. If we’d called it a road, they’d put it on the map, but a levee,
they did not. Meanwhile, everybody else flooded. Not us. It’s important to include
all structures in surge modeling.”
“You have to understand—all flooding is local,” he continued. “And you have to mix
the best technological information with real, on-the-ground information. You’ve got
to bring in reality. Only that way can you turn knowledge into wisdom.”
Twilley remembers looking around the room at everyone’s faces when it became clear
the Lafourche Parish levee “didn’t exist.”
“The silence of the people of Louisiana was astounding,” he said. “You can imagine
what that did to the trust people had in the federal storm surge map. It became obvious
at that point that we had to take care of ourselves and protect our own resources
and people. The National Hurricane Center simply could not reach down to all of those
people in Louisiana, like Windell Curole. Plus, it’s not NOAA’s job to protect Louisiana.
It’s their job to protect the United States.”

The LSU Coastal Emergency Risk Assessment (CERA) website broke its seasonal record in visits for Hurricanes Laura and Marco, with 10,223 unique users. CERA offers different sets of information—general guidance to the public as well as high-resolution, fine-grained information to help local, state, and federal decision makers protect people and assets. “For the general public, we need to make the information as easy-to-understand and clear as possible, so we don’t give out any misguidance,” said lead CERA developer Carola Kaiser.
It took several years for emergency managers in Louisiana to start putting their trust
in CERA, too. Hurricane Isaac in 2012 was a turning point. About 7,000 (roughly half)
of all homes in LaPlace, Louisiana flooded as a result of storm surge from the hurricane,
which was predicted by the ADCIRC model and mapped on CERA. Yet, few people evacuated
in time because no one else saw this coming. Flooding in LaPlace is especially problematic
because that’s where the elevated I-10 interstate highway, one of the main evacuation
routes out of New Orleans, dips down to ground level.
“LaPlace was on nobody’s radar screen, but it was on ours,” Twilley said. “The credibility
that came with that storm really put CERA on the map. People realized that this is
a tool that can give you insight into the unexpected. And how often do you not hear
in Louisiana, ‘Well, I’ve never flooded…’ Well, guess what? The angle of each storm
makes every storm unique, and we can’t rely on some probabilistic analysis of all
storms in the past to estimate future risk. Instead, let’s talk about risk based on
the storm that’s coming in right now—the unique aspects of the storm as its forming.”
Sometimes Kaiser and her colleagues cannot believe what they see on CERA’s maps either—unexpected
patterns are their cue to delve into the details and make sure the outcome isn’t due
to a glitch of some kind. As the monster storm Laura was about to make landfall near
Lake Charles, Louisiana and the map turned dark red from predicted flooding, there
was a clear spot right on the coast.
“‘This looks unusual,’ we said, but it turned out to be correct because the highways
there acted like a barrier and spared an area,” Kaiser said.
The calculations for ADCIRC and CERA rely on several supercomputers and servers at
geographically distributed supercomputing centers. The main burden is carried by LSU
(SuperMIC) with CCT (CERA servers) and the Louisiana Optical Network Initiative, or
LONI (Queenbee2, Queenbee3), where the supercomputers are managed by Sam White. An
integral partner is University of Texas at Austin’s Texas Advanced Computing Center,
or TACC (Frontera, Stampede2), and the project also relies on critical resources at
the Renaissance Computing Institute, or RENCI, at University of North Carolina (UNC)
at Chapel Hill. Co-developers of the ADCIRC model framework are Rick Luettich, director
of the Department of Homeland Security Coastal Resilience Center at UNC Chapel Hill,
Joannes Westerink of Notre Dame, and Clint Dawson at University of Texas at Austin.
Often, the same calculations are run on different supercomputers in separate states,
in case one fails.
“If they’re holding a briefing at 6 a.m. to make a decision about emergency operations
and the advisory with the updated storm track comes out at 4 a.m., we have to turn
that around really quickly,” Fleming said. “Reliability is everything. If we give
them an answer that’s dead-on accurate but two hours late, it’s useless. We might
just as well have done nothing.”

CERA’s storm surge predictions for Hurricane Zeta were confirmed by hundreds of users on the ground. Here, a backyard deck in Ocean Springs, Mississippi turns into a dock.
The computations are so demanding it would take about a week to run a single scenario
on a home computer. Better storm surge forecasting and high-performance computing
have therefore grown hand in hand at LSU, one entirely reliant on the other. But it’s
about much more than computer science, Twilley is quick to point out.
“You can run code on a computer, but if you don’t know what the results mean because
you don’t understand the connections between the physics, oceanography, and the data,
well, it’s almost dangerous, if I’m honest,” Twilley said. “This is why we dedicated
the Louisiana Sea Grant Laborde Chair to hurricane storm surge forecasting research,
which allowed LSU to hire Scott Hagen in 2015.”
The arrival of Hagen as director of the LSU Center for Coastal Resiliency and his
then-Ph.D. student, Matthew Bilskie, led to annual enhancements of the existing ADCIRC
mesh for the coastal land-margin of Louisiana, and the development of ADCIRC real-time
forecasting models for Mississippi, Alabama, and the entire west coast of Florida.
“It’s all about how the computer ‘sees’ the land,” Hagen explained before his recent
passing. “We include enough computational points to model the flow of water from the
continental shelf, into the channels and bays, over the marshes and onto the upland
regions right up to the levees, hopefully not seeing levees overtopped. It’s about
depth and surface characteristics, the parameters that describe resistance to the
flow of water and help describe how the wind interacts with the water flow as well.”
The CPRA leads the development of the Coastal Master Plan for Louisiana and collects
and continuously updates the elevation data for land and levees as well as for water
depth that ADCIRC and CERA rely on.
“The CPRA is a most valued partner,” Hagen continued. “In fact, part of our success
here at LSU has been building partnerships. This comes back to what it means to be
a research university and serve the state. Most importantly, we educate students,
but it takes a people connector such as LSU to make something like this happen.”
One of Hagen’s former students, Matthew Bilskie, now an assistant professor at the
University of Georgia, graduated from LSU in 2016 with a Distinguished Dissertation
Award. He still works closely with Hagen on updating the ADCIRC model mesh and leads
the development of the slide decks provided to key decision makers.
“The slide decks show when we can expect peak water levels to occur,” Bilskie explained.
“This is important to the state of Louisiana for tide and flood gate operation. Many
floodgates have water level ‘triggers,’ or thresholds, whereby a flood gate must be
closed. The slide decks and model forecasts can provide guidance on when and where
flood gates should close and then re-open, after a storm has passed.
During the record-breaking 2020 hurricane season, first responders, including the
Louisiana National Guard, relied on CERA to help guide teams, equipment, and supplies
into position—as close to the events as possible, but out of harm’s way.
“The storm surge map helped me pre-position the right types of equipment for a windstorm
versus a flooding event,” said Colonel St. Romain, commander of Louisiana National
Guard’s 225th Engineer Brigade, about responding to Hurricane Laura in the Lake Charles
area in a recent interview for the Esri Blog. “We have high-water vehicles, we have
boat systems, and we have engineering equipment to clear roads so emergency vehicles
and power companies can access impacted areas.”
LSU’s storm surge guidance continues to help decision makers prioritize where to deploy
critical yet limited resources, whether that’s truckloads of ice, equipment to clear
debris, or manpower to secure surface and underground chemical storage tanks, which
there are quite a few of in Louisiana—essentially, where to go first.
“There is no information center you can call that tells you the answer to that question,”
Hagen said. “What our modeling does is help decision makers look beyond what’s obvious.”
Twilley nodded in agreement:
“And you might not hear about any of this in the news, because when the right decision
is made and disaster is avoided, it becomes non-news. But it’s really important stuff.”
Storm surge forecasting can also assist with long-term planning to help make communities
safe and whole. In a recent paper—written by another of Hagen’s Ph.D. students, Chris
Siverd, along with Hagen, Bilskie, Twilley, and others—the researchers discussed the
costs associated with protecting the area of Lafitte, Louisiana from flooding up until
2110 in comparison with the expected cost of securing New Orleans and other more densely
populated areas.
Much of their research stems from needs expressed by people on the ground—those who
ultimately will use and benefit from the findings, such as the residents of Lafitte.
In refining CERA and the different ways storm surge guidance is communicated to users,
the researchers conduct focus groups with people such as Curole to listen to their
needs and make sure they speak the same language.

Thirty named storms: 2020 is the only season that has seen two major hurricanes (meaning, Category 3 storms or higher) in November in Hurricanes Eta and Iota. Graphic courtesy of Sam Lillo.
To this end, the LSU team has continued to grow and now includes Denise DeLorme, professor
of environmental communication, and Paul Miller, assistant professor of coastal meteorology,
both in the LSU College of the Coast & Environment.
“The transdisciplinary aspect of our work goes beyond what you’d think of interdisciplinary
research, bringing in experts from diverse fields,” Hagen said. “We take it a step
further and involve the stakeholders, such as the CPRA and their flood gate operators.”
In this way, Hagen argued, large research universities are uniquely well situated
to tackle the complex challenges brought on by a constantly changing environment.
Through its extension services and physical presence in every parish in Louisiana,
LSU can work with public and private stakeholders as well as federal agencies.
“What I will never forget,” said Twilley, thinking back to that day after Hurricane
Katrina when decision makers from several agencies gathered to identify critical research
needs for the state of Louisiana, “is that the first person that spoke was Pat Santos,
who was the head of the Governor’s Office of Homeland Security and Emergency Protection
at the time. He got up and blew that place away. He showed us the timeline of every
decision he makes, and said, ‘I don’t care what your modeling does—if it doesn’t help
me with my timeline, it’s not worth a pfft.’ From that point on, our challenge was to build the operations piece to have detailed
and accurate forecasting models available in time for local decisionmakers to be able
to protect assets, infrastructure, and people. We had to make sure that what we put
out served Pat Santos, and others like him.”
Last summer, 30 emergency managers from Texas followed by 50 emergency managers from
across the nation participated in LSU workshops to get trained on how to use the more
detailed aspects of CERA. Outreach will remain a central component of the LSU effort,
said Kaiser:
“Without visualization or communication, if no one sees or uses your results, you
just have huge piles of numbers.”

Storms Laura and Marco brought two hurricanes in the Gulf of Mexico at the same time. They had emergency response teams in both Texas and Louisiana on high alert, and the LSU storm surge forecasting team coordinated with both governors to help protect people and assets.
September 1, 2021 UPDATE, cont.—New for this year, CERA is adding and integrating a new model called the Compound
Flood Inundation Guidance System (CFIGS), developed by hydrologist Katelyn Costanza
of CE Hydro, a small, woman-owned, Louisiana company. From now on, CERA pro users
will be able to see not just the water being pushed inland from the coast by storms
(wind-driven surge), but also inland-to-coast flooding caused by rainfall from not
just hurricanes, but any large storm. It will include impacts on structures, to help
disaster managers further safeguard critical infrastructure and allow for more detailed
planning.
“Before starting my own company, I worked for the National Weather Service and the
Army Corps of Engineers for 15 years with a focus on floodplain management and flood
inundation mapping,” Costanza said. “Areas that received the combined impacts from
storm surge and rainfall were the most challenging, so after starting my company,
I wanted to focus on providing flood guidance in these areas. We used CERA guidance
while at the National Weather Service, in addition to official storm surge forecasts
provided by the National Hurricane Center. We got familiar with and trusted CERA,
and that’s why it was important to me that we now collaborate.”
So far, CFIGS is primarily developed for the Lake Pontchartrain Drainage Basin, where
rivers starting in Mississippi drain into Lake Maurepas and Lake Pontchartrain. But
through ongoing collaboration between Costanza, CERA, and the Coastal Protection and
Restoration Authority (CPRA), the service area should soon expand.
Another new capability for the 2021 hurricane season is that pro users now can download data in a widely used format known as GeoTIFF, making it easier for them to take the CERA data and run their own calculations on their own platforms. Users can click on any CERA map point and pull up graphs to show surge forecasts for that particular place. In addition, CERA is “going global” this year by integrating a new National Oceanic and Atmospheric Administration (NOAA) model for storm surge that covers the entire world, the Extratropical Surge and Tide Operational Forecast System (ESTOFS).
Note: The LSU Center for GeoInformatics (C4G) supplies data to all partners in this project, including the CPRA, USACE, DOTD, and the South Lafourche Levee District.
In Back-to-Back Hurricanes, Louisiana National Guard Calls on Predictive Model (Esri
Blog)
ERDC researchers use numerical modeling to assist with hurricane preparations
CPRA Awards Storm Modeling Contract to LSU Center for Coastal Resiliency
LSU Professor Explores Possible Impact of Flooding With Storm Surge
Stakeholder Focus Groups Improve Communication of Coastal Sea Level Rise Risks
Elsa Hahne
LSU Office of Research & Economic Development
ehahne@lsu.edu