May 14, 2021

The 2021 National Hurricane Preparedness Week is May 9th to May 15th, a week dedicated to sharing knowledge about hurricane hazards that can be used to prepare and take action!

The 2020 Hurricane season marked the fifth consecutive year with above-normal activity in the Atlantic hurricane season. When subtropical storm Theta formed on November 10th, it became the most active season on record. Of the 30 named storms, 11 of them made landfall in the contiguous United States, breaking the record set in 1916. This historic hurricane season saw record water levels in several locations, including along the Gulf of Mexico coast where Hurricane Sally brought the highest observed water levels since Hurricane Katrina in 2005.

These record-breaking conditions bring some of the most dangerous natural hazards associated with hurricanes to coastal areas. These include storm surge, coastal erosion, and inland flooding. The hazards associated with these powerful storms can destroy homes and businesses, wipe out roads, bridges, water and sewer systems, and profoundly alter landscapes.

The USGS closely monitors hurricanes in consultation with the NOAA National Hurricane Center and other agencies. USGS deploys field crews and equipment to provide critical data before, during and after a hurricane. The USGS has the expertise to help citizens prepare for, respond to, and recover from these hazards. We develop and use computer models to forecast storm impacts and use advanced equipment to monitor actual flood and tide conditions in real time.  We also work with partners and emergency managers to provide science and build capabilities to reduce risk and improve situational awareness when a major storm makes landfall. The USGS forecasts coastal change; tracks storm surge, streamflow, and levels; captures high-resolution ground elevation and topographic data; creates detailed maps of hazards and vulnerable areas; and measures coastal and inland flooding. Before a storm’s expected landfall, coastal change experts forecast how a storm may reshape the coastline using a sophisticated coastal change hazard forecast model. Learn more about coastal change hazards and how USGS science is focused on reducing the risks associated with these powerful storms: https://www.usgs.gov/natural-hazards/coastal-marine-hazards-and-resources/science/coastal-change-hazards

Through applied, multi-disciplinary science and collaboration, USGS develops robust and accessible scientific information to help improve the lives, property, and economic prosperity of the Nation’s coastal communities, habitats, and natural resources. Investments made in USGS science after the powerful 2017 hurricane season were focused on improving hazards planning for future storms. Those scientific advancements are paying off by improving forecasting tools, improving risk awareness, and creating more resilient communities. We continue to advance our scientific capabilities to better prepare coastal communities for Hurricane Season 2021.

Each storm is unique, both in the individual storm characteristics and the areas each affects. Here are a few tools and examples of ongoing research that can help all of us be better prepared for the 2021 hurricane season  and the specific local conditions wherever you are.

• Atlantic: June 1-November 30,

• Central Pacific: June 1-November 30

• Western Pacific: May 15-November 30

At the bottom of this story, you can find links to more science educational resources.

### Tools and Relevant Research

Coastal Change Hazards Portal

The Coastal Change Hazards portal is a tool developed by USGS to forecast the probability of coastal change on sandy beaches along the U.S. Gulf and Atlantic coasts during hurricane conditions. It predicts where protective sand dunes are likely to be eroded at their bases or overtopped by storm waves and where coastal areas behind the dunes could be inundated by seawater.

The forecasts begin 48 hours before a storm is expected to make landfall and are updated based on the latest forecasts from the National Hurricane Center. The portal also allows you to see predictions for extreme water levels, shoreline change, and sea-level rise. These forecasts can be used to help emergency managers with hurricane preparation in coastal zones.

Total Water Level and Coastal Change Forecast Viewer

USGS scientists developed the Total Water Level and Coastal Change Forecast (TWL-CC) viewer to allow coastal managers and others to see how high water levels could rise along sandy coastlines. Envisioned as a national capability, USGS continues to expand the TWL-CC viewer coverage. In late 2020, this tool was expanded to more than a thousand miles of additional coverage. The tool displays operational total water level forecasts and coastal change predictions for 4,700 km (almost 3,000 miles) of open, sandy coastline on the Atlantic Ocean and Gulf of Mexico coasts using local beach characteristics. Total water level (TWL) at the shoreline is the combination of tides, surge, and wave runup. A forecast of TWL is an estimate of the elevation where the ocean will meet the coast and can provide guidance on potential coastal erosion and flooding hazards.

Coupled Ocean-Atmosphere-Waves-Sediment Transport (COAWST) Modeling System

To better understand storm impacts and their effects on our coastlines, we need to better predict storm paths and intensities. To fill this gap, the USGS has been leading the development of a Coupled Ocean-Atmosphere-Waves-Sediment Transport (COAWST) Modeling System

COAWST is an open-source tool that combines many sophisticated systems that each provide relative earth-system components necessary to investigate the dynamics of coastal storm impacts. The USGS has provided enhanced capabilities to allow these components to feed back to one another. For example, a typical hurricane modeling simulation may include great details for the atmosphere component, but with limited connectivity to the ocean. However, with the COAWST system , these simulations will allow the ocean and waves to dynamically evolve and provide a feedback to the atmosphere simulation. This will modify the storm development and provide a more realistic suite of physical storm processes.

In 2020, scientists advanced the COAWST modeling system to include coupling between a hydrologic model that simulates routing of rainfall through the rivers, with an ocean model that predicts wave and sea surge from storms. This model coupling now includes more physics interacting during the storms and will lead to improved flood forecasts. Also, improvements for sediment transport from different types of waves and inclusion of land characteristics are now represented within COAWST. These new formulations will allow for exploration of critical conditions controlling local scale changes during extreme events. Methods are being applied to forecast coastal change in advance of storms at selected locations, partnering with the National Park Service and other local agencies.

Coastal Storm Modeling System (CoSMoS)

The Coastal Storm Modeling System (CoSMoS) is a dynamic modeling approach that has been developed by the United States Geological Survey in order to allow more detailed predictions of coastal flooding due to both future sea-level rise and storms integrated with long-term coastal evolution (i.e., beach changes and cliff/bluff retreat) over large geographic areas (100s of kilometers).

### Research

The USGS closely monitors hurricanes in consultation with the National Hurricane Center and other agencies. USGS deploys field crews and equipment to provide critical data before, during and after a hurricane.

 2020 Hurricanes DeltaSallyLauraMarcoIsaias 2019 Hurricanes Dorian Tropical Storm Barry 2018 Hurricanes Michael  Florence 2017 Hurricanes Nate Maria Jose Irma Harvey 2016 Hurricane Matthew 2015 Hurricane Joaquin 2012 Hurricanes SandyIsaac 2005 Hurricane Katrina

The Value of U.S. Coral Reefs for Risk Reduction

The degradation of coral reefs raises flood risks by increasing the exposure of coastal communities to storms. Annually U.S. coral reefs provide flood protection benefits to more than 18,100 people and $1.8 billion in averted damages to property and economic activity. Remote Sensing USGS uses remote-sensing technologies – such as aerial photography, satellite imagery, and lidar (laser-based surveying) – to measure coastal change along U.S. coastlines. Quantifying coastal change is essential for calculating trends in erosion, evaluating processes that shape coastal landscapes, and predicting how the coast will respond to future storms, including hurricanes, and sea-level rise. USGS has been developing rapid-response mapping techniques for evaluating the impacts of Hurricanes on U.S. coasts. Scientists have written a ‘best practices’ workflow on these techniques and have implemented them using the USGS high performance computing (HPC) systems available through Advanced Research Computing. USGS also developed novel ways to process the NOAA Emergency Response Imagery to develop similar topographic maps of the coast. The USGS can process this imagery on HPC to develop 3D maps of topography and coastal change. These capabilities allow USGS to deliver products much more rapidly after Hurricanes hit. For example, in 2020 USGS demonstrated the ability to collect imagery, process it, generate products, and distribute them to stakeholders within two days of Hurricane Isaias. The results provided the NPS with critical information before field-based assessment teams were deployed on the ground, helping them decide how and where to access the island so they could focus on impacted areas of the coastline. Learning about ocean dynamics during Hurricane Maria In 2017, Puerto Rico experienced several extreme hurricanes. One of these storms, Hurricane María, caused thousands of deaths, more than$90 billion in damage and the largest electrical blackout in U.S. history. Unique observations collected by U.S. Geological Survey scientists during the storm revealed how the interaction between ocean islands and extreme storms can generate underwater currents that make the storms more powerful. The results are applicable to the thousands of islands in the world's tropical oceans subject to these types of weather systems. Understanding how the underlying ocean temperature changes in response to hurricane forces is critical to accurately forecasting the tracks and intensities of extreme storms.

### Resources

Aerial Photography Viewer

Researchers can use this imagery to quickly verify coastal change model predictions, as well as inform coastal planners and managers decisions on their response to future storms. With the Aerial Photography Viewer, you can view specific baseline or storm mission activities and their related pre-mission imagery.

USGS Youth Education in Science: Learn From Home

The focus of week 8 of the YES Learn From Home Program is Floods & Hurricanes. Utilize these resources to teach the family about the impacts of hurricanes, or conduct fun erosion activities in the classroom!

Hurricane Preparedness Video

Before a hurricane, USGS Scientists undertake a data collection effort of a grand scale. They install a temporary mobile network of sensors along the coasts to collect additional data on the intensity of storm surge, one of the most dangerous elements of a hurricane. This effort provides critical information that allows various USGS partners and emergency responders to make better informed decisions during and after these extreme weather events.