weather communications

Recent Trends in Tropical Cyclone Fatalities in the United States

Satellite photo of Hurricane Gonzalo (a ball of swirling clouds) over the Atlantic near Puerto Rico; other larger cloud systems are seen in the upper part of the photo, eclipsed by the curvature of the Earth in the top right. Photo taken by GOES East satellite at 1445Z on October 14, 2014. Photo credit: NOAA.

New data from the past ten years reveal increased prominence of freshwater floods and indirect fatalities in hurricane deaths

Guest post by Dr. Michael Brennan, Director, National Hurricane Center; Daniel Brown, Warning Coordination Meteorologist, National Hurricane Center; and Leah Pope, Hydrologist, Northwest River Forecast Center

The National Hurricane Center’s mission to “save lives and mitigate property loss” is not just achieved by issuing effective watches, warnings, and forecasts of tropical cyclones. We also spend a large portion of the “offseason” educating the public, emergency managers, and our media partners about the risks that tropical cyclones (TCs), including hurricanes, pose to life and property in the United States. Those include natural hazards such as storm surge, wind, and rip currents, and also includes dangerous conditions in the aftermath of a landfalling tropical cyclone, which may lead to “indirect” fatalities. These are deaths which are not directly due to the forces of the storm, but which would not otherwise have occurred. NHC routinely compiles and assesses TC-related information through vehicles such as our Tropical Cyclone Reports (TCRs). Data from the most recent decade reveal that fatality trends may be changing.  

Note:  The fatality data presented here do not include any fatalities from Hurricane Maria in Puerto Rico, since there was no specific, definitive cause provided for those deaths.

Direct Fatalities

Aerial photo of a peninsula/barrier island that has been breached by a storm surge. Sand, buildings, and other structures have been washed away or damaged, including visible broken lines of sandbags, a damaged bridge, damaged trees, and obliterated buildings; only one house appears to still be standing.
Storm surge damage from Hurricane Ike, Bolivar Peninsula, Texas, 2008. Photo credit: NOAA.

Previous studies by Rappaport (2014) and Rappaport and Blanchard (2016) summarized direct and indirect fatality data from Atlantic basin tropical cyclones in the United States for the 50-year period 1963–2012. During that period, nearly 9 out of 10 tropical cyclone-related direct deaths in the United States were due to water. Storm surge was responsible for nearly half (49%) of the direct deaths, and over one-quarter (27%) were due to rainfall-induced freshwater flooding.  

In response, the National Weather Service (NWS) and NHC worked to improve outreach, education, and communication of storm surge and rainfall hazards. We introduced new real-time storm surge maps in 2014, and in 2017 introduced a storm surge watch/warning that highlights the risk of life-threatening storm surge inundation. 

New Data Suggest Changing Trends

Since 2012, the United States has experienced 21 hurricane landfalls, including 8 major hurricanes, and more than 20 tropical storm landfalls. Eighteen of these hurricane landfalls, including all of the major hurricanes, occurred during 2017–22 after a relatively quiet period. Given the significant number of tropical cyclone landfalls in recent years, and increased deployment of warnings around the storm surge hazard, NHC examined and compared fatality data from the most recent 10-year period (2013–22) to the earlier studies.

Hazard % of direct fatalities from this cause
(1963–2012)		% of direct fatalities from this cause
(2013–2022)
Storm Surge49%11%
Freshwater Flooding27%57%
Wind8%12%
Surf/Rip Currents6%15%
Offshore Marine Incidents6%3%
Tornadoes3%2%
Other1%1%
Note: Due to rounding, numbers may not add up to 100%.

During the most recent 10-year period in the United States, about 57% of direct tropical cyclone deaths were due to drowning from freshwater (rainfall) flooding. Surf and rip current fatalities have become an increasing threat, making up about 15% of direct fatalities in the past decade. These fatalities often occur one or two at a time from distant storms hundreds of miles offshore. Florida, North Carolina, and New Jersey experienced the highest number of TC-related surf and rip current fatalities. Storm surge and wind-related deaths account for 11% and 12% of the direct fatalities, respectively.  

Every hurricane is different, however. Hurricane Harvey in 2017 had the largest number of direct deaths—68, 65 of which were due to freshwater flooding in Texas—in the past decade. Hurricane Ian (2022) was the second deadliest with 66 direct fatalities, 41 of which were due to storm surge in Florida. More than 65% of those who died from direct causes were men, with about 60% of the victims over the age of 60.

Indirect Causes

Image of a boat stranded on land, leaning against a wind-destroyed structure and a power line, amid other debris, including destroyed buildings and cars. Three people stand next to the boat observing the damage.
Aftermath of Hurricane Ike in Galveston, Texas, 2008. Photo credit: NOAA.

The recent study revealed that over the past 10 years there has been nearly an equal number of indirect deaths as direct fatalities. Indirect fatalities are due to a wide range of causes, including traffic accidents (16%), preparation/cleanup accidents (15%), carbon monoxide poisoning (12%), lack of medical care (11%), power problem/electrocution (11%), post-storm heat deaths (9%), unknown causes (9%), cardiac-related deaths (7%), and evacuation-related deaths (5%). 

The largest number of indirect deaths in the past decade occurred in association with Hurricanes Ian (90), Irma (82), Michael (43), Harvey (35), and Laura (34). Most (75%) of the indirect deaths are associated with major hurricane landfalls, which leave communities very vulnerable and often with long-duration, widespread power outages. More than half (57%) of the victims were over the age of 60. Younger victims tended to die in vehicle accidents; for older victims, medical-related issues, heat, evacuation, and other accidents were more likely causes of death.

Improving Warnings and Public Understanding

The results of these most recent studies have led the NWS and NHC to increase messaging on the hazards and causes of both direct and indirect fatalities. We continue to highlight rainfall flooding and storm surge risk through the Weather Prediction Center’s Excessive Rainfall Outlook, Flood Warnings from local NWS offices, and increased emphasis on the Storm Surge Warning. These warnings are the loudest “bells” that the NWS can ring during life-threatening flooding. We encourage our media and emergency management partners to work with us to encourage timely public response and personal preparedness ahead of these threats. 

Additionally, with the increased percentage of rip current fatalities associated with high surf and swells from distant hurricanes, the NWS has created new infographics to explain this deadly beach hazard, and is working on graphics to better highlight the threat in real time.

During the highly impactful 2020 hurricane season in the United States, there were more fatalities associated with carbon monoxide poisoning from the improper use of generators than there were from storm surge. After that season, NHC and the NWS developed infographics and worked with media and emergency management partners to highlight that threat. While it is difficult to determine the effectiveness of that messaging, it is encouraging to know that there were no carbon monoxide related-fatalities in the aftermath of Hurricane Ian in 2022 in Florida, despite its devastating impacts and widespread power outages in that state.   

NHC relies on relationships with media, emergency management partners, and the entire weather enterprise to help reach the public before, during, and after tropical cyclone threats. These efforts undoubtedly increase awareness, encourage preparation, and save lives. We hope to continue to improve our messaging and understanding of the threats and causes of injuries and fatalities to better meet our collective mission.  

Visit the National Hurricane Center online.

Header photo: Hurricane Gonzalo in the Atlantic. Photo taken by GOES East satellite at 1445Z on October 14, 2014. Photo credit: NOAA.

This post was invited based on a presentation given by Dr. Brennan at the 50th Conference on Broadcast Meteorology, which took place in Phoenix, Arizona, June 21–23, 2023. The conference was organized by the American Meteorological Society Board on Broadcast Meteorology and chaired by Danielle Breezy and Vanessa Alonso.

Southeasterners Perceive Tornado Risk Dangerously Different Than They Should, Especially at Night

While a major winter storm last month was plastering the United States from Texas and New Mexico to New England with heavy snow and ice, volatile conditions in the Southeast (SE) spawned damaging and deadly tornadoes. One of these overnight Monday, February 16, tragically took the lives of 3 people and injured 10 in coastal North Carolina. Such nocturnal tornadoes are common in the Southeastern U.S.—a unique trait—and represent an extreme danger to sleeping residents.


Compounding this problem, new research in the AMS journal Weather, Climate, and Society suggests there may be a deadly disconnect between tornado perception and reality in the region right when residents instead need an acute assessment of their tornado potential.
The article “Do We Know Our Own Tornado Season? A Psychological Investigation of Perceived Tornado Likelihood in the Southeast United States,” by Stephen Broomell of Carnegie Mellon University, with  colleagues from Stanford and NCAR, notes the tragic results of the regional misperception:

The recurring risks posed by tornadoes in the SE United States are exemplified by the significant loss of life associated with recent tornado outbreaks in the SE, including the 2008 Super Tuesday outbreak that killed over 50 people and the devastating 27 April 2011 outbreak that killed over 300 people in a single day.

Their survey of residents in seven states, from Louisiana and Arkansas to Georgia and Kentucky, representing the Southeastern region, finds that the residents perceive their tornado likelihood differently than meteorologists and experts familiar with Southeastern tornado risk. This puts them at great risk because residents’ experiences don’t match what actually happens where they live.

Broomell and his fellow researchers contend that Southeast residents may be misusing knowledge of Great Plains tornado events, ubiquitous in tornado chasing reality shows and social media videos, when determining their own risk. A fatal flaw since tornado behavior is different between the two regions.
WCAS SE tornado season survey2For starters, unlike in infamous “Tornado Alley” states of Texas and Oklahoma north through Nebraska and Iowa into South Dakota, the Southeast lacks a single, “traditional” tornado season, with tornadoes “spread out across different seasons,” Broomell along with his coauthors report, including wintertime. The Southeast also endures more tornadoes overnight, as happened last week in North Carolina. And they spawn from multiple types of storm systems in the Southeast, more so than in the Great Plains. This makes knowledge about residents’ regional tornado likelihood especially critical in Southeastern states.

Another recent study published in the Bulletin of the American Meteorological Society, “In the Dark: Public Perceptions of and National Weather Service Forecaster Considerations for Nocturnal Tornadoes in Tennessee,” by Kelsey Ellis (University of Tennessee, Knoxville), et al., surveyed residents of Tennessee and came away with similar findings about tornado timing: about half of Tennessee’s tornadoes occur at night, and yet less than half of those surveyed thought they would be able to receive nighttime tornado warnings.

Local forecasters and broadcast meteorologists as well as emergency managers are tuned into the mismatch. In the BAMS study, NWS forecasters said they fear for the public’s safety, particularly with nighttime tornadoes, because they “know how dangerous nocturnal events are”—fatalities “are a given,” some said.

Ellis and her colleagues recommended developing a single, consistent communication they term “One Message” to focus on getting out word about the most deadly aspect of the tornado threat. Forecasters, broadcasters, and emergency managers through regular and social media would then be consistent in their messaging to residents, the researchers state, decreasing confusion. For example:

Nighttime tornadoes expected. Sleep with your phone ON tonight!

With severe weather season ready to pop as spring-like warmth quickly overwhelms winter’s icy grip in the next couple of weeks, the nation’s tornado risk will blossom across the South and Southeast. And nocturnal tornado threats will only increase, particularly in the Southeast, as February turns into March, and then April—a historically deadly month.
For residents in places more prone to nighttime tornadoes, Ellis et al. say the ways to stay safe are clear:

Have multiple ways to get tornado warnings, do not rely on outdoor sirens, sleep with your phone on and charged during severe weather, and do not stay in particularly vulnerable locations such as mobile homes or vehicles.

"Sleep with your phone on!": Messaging for Nighttime Tornadoes

With Hurricane Delta poised to strike Louisiana today, the risk of embedded tornadoes will increase as rainbands spiral ashore, along with the primary threats of storm surge and damaging winds. Delta is forecast to plow well inland Friday night into the weekend, continuing a low risk for tornadoes, some of which could occur at night in Alabama, Mississippi and into southern Tennessee. The threat is more than a bit worrisome as new research in BAMS finds through phone surveys and followup interviews in Tennessee that people are woefully unprepared for nocturnal tornadoes.
In their article,” Kelsey Ellis and colleagues found a host of poor practices by residents when it comes to tornadoes at night. The authors recommend forecasters narrow their messaging about nocturnal tornadoes in the Southeast to a single important message to limit confusion.
Almost half of Tennessee’s tornadoes occur at night, as in other Southeast states with large numbers of nocturnal tornadoes, and are two-and-a-half times as deadly as daytime tornadoes. This creates detection, warning, and public response challenges. Yet, respondents in the western part of the state overestimated tornado occurrence at night while those in the east substantially underestimated the number.
Additionally, nearly half of participants in the survey say they rely on sirens to receive tornado warnings. This is despite the fact that sirens are not designed to warn people inside nor be loud enough to wake anyone up. Instead, Wireless Emergency Alerts (WEAs) “should be a constant,” the authors say. Also, people mentioned they rely on TV and social media for receiving warnings even though generally neither will wake you up.
The authors felt it was “dangerous” that even the more tech savvy and tornado aware respondents answered they were compelled to look outside for evidence of a tornado—even in the dark. Interviewees explained they were “checking for sounds instead of visual cues.”
NWS forecasters were also surveyed about nocturnal tornadoes. The forecasters mentioned the lack of ground truth and fear for public safety among challenges to the nighttime warning service. They noted few spotter or social media reports inform them if “the storm is actually showing the signs on the grounds that radar is indicating aloft.” Forecasters said they felt “fearful, worried, or nervous for the public during nocturnal tornadoes because fatalities ‘are a given.’”
The survey responses moved Ellis et al. to recommend a single-emphasis message be presented to residents to combat the nighttime tornado problem:

One strategy that may improve public safety during a nocturnal tornado event, and which addresses the forecaster challenge of communication prior to and during an event, is to develop “One Message”—a consistent message that EMs and the media use throughout broadcasts, briefings, and social media. Examples of messages could be: “Nighttime tornadoes expected. Sleep with your phone ON tonight!” or “Tornadoes will form quickly! Make plans now where you will take shelter!” or “If you live in a manufactured home, you may not have much time to seek shelter tonight!” One Message may decrease confusion for receivers, making them more likely to make safe decisions. Messages could similarly be used to dispel misconceptions about local geography in ways relevant to the specific listening area, for example: “You are not protected by nearby hills. Seek shelter immediately!”

With Hurricane Delta’s nighttime tornado threat ramping up, the authors suggest people use multiple ways to receive warnings, keeps phones on and charged, don’t rely on tornado sirens, and if possible relocate ahead of the weather from “particularly vulnerable” situations, such as mobile homes and vehicles.

“Sleep with your phone on!”: Messaging for Nighttime Tornadoes

With Hurricane Delta poised to strike Louisiana today, the risk of embedded tornadoes will increase as rainbands spiral ashore, along with the primary threats of storm surge and damaging winds. Delta is forecast to plow well inland Friday night into the weekend, continuing a low risk for tornadoes, some of which could occur at night in Alabama, Mississippi and into southern Tennessee. The threat is more than a bit worrisome as new research in BAMS finds through phone surveys and followup interviews in Tennessee that people are woefully unprepared for nocturnal tornadoes.

In their article,” Kelsey Ellis and colleagues found a host of poor practices by residents when it comes to tornadoes at night. The authors recommend forecasters narrow their messaging about nocturnal tornadoes in the Southeast to a single important message to limit confusion.

Almost half of Tennessee’s tornadoes occur at night, as in other Southeast states with large numbers of nocturnal tornadoes, and are two-and-a-half times as deadly as daytime tornadoes. This creates detection, warning, and public response challenges. Yet, respondents in the western part of the state overestimated tornado occurrence at night while those in the east substantially underestimated the number.

Additionally, nearly half of participants in the survey say they rely on sirens to receive tornado warnings. This is despite the fact that sirens are not designed to warn people inside nor be loud enough to wake anyone up. Instead, Wireless Emergency Alerts (WEAs) “should be a constant,” the authors say. Also, people mentioned they rely on TV and social media for receiving warnings even though generally neither will wake you up.

The authors felt it was “dangerous” that even the more tech savvy and tornado aware respondents answered they were compelled to look outside for evidence of a tornado—even in the dark. Interviewees explained they were “checking for sounds instead of visual cues.”

NWS forecasters were also surveyed about nocturnal tornadoes. The forecasters mentioned the lack of ground truth and fear for public safety among challenges to the nighttime warning service. They noted few spotter or social media reports inform them if “the storm is actually showing the signs on the grounds that radar is indicating aloft.” Forecasters said they felt “fearful, worried, or nervous for the public during nocturnal tornadoes because fatalities ‘are a given.’”

The survey responses moved Ellis et al. to recommend a single-emphasis message be presented to residents to combat the nighttime tornado problem:

One strategy that may improve public safety during a nocturnal tornado event, and which addresses the forecaster challenge of communication prior to and during an event, is to develop “One Message”—a consistent message that EMs and the media use throughout broadcasts, briefings, and social media. Examples of messages could be: “Nighttime tornadoes expected. Sleep with your phone ON tonight!” or “Tornadoes will form quickly! Make plans now where you will take shelter!” or “If you live in a manufactured home, you may not have much time to seek shelter tonight!” One Message may decrease confusion for receivers, making them more likely to make safe decisions. Messages could similarly be used to dispel misconceptions about local geography in ways relevant to the specific listening area, for example: “You are not protected by nearby hills. Seek shelter immediately!”

With Hurricane Delta’s nighttime tornado threat ramping up, the authors suggest people use multiple ways to receive warnings, keeps phones on and charged, don’t rely on tornado sirens, and if possible relocate ahead of the weather from “particularly vulnerable” situations, such as mobile homes and vehicles.

Eulerian Weather, Lagrangian Lives

by Alan E. Stewart, University of Georgia

It is clear that Covid-19 will be with us for a while. So will the weather, however. We’ve been through flooding in Michigan in mid-May; an outbreak of 140 tornadoes from Texas to Maryland in April; a deadly and destructive derecho in Iowa; hurricane landfalls in Louisiana, Alabama, and Florida; and massive wildfires in the West. In other words, the weather, as always, just is—it exists and occurs as a series of events that intertwine with the activities and challenges of our daily lives. Here, I would like to borrow from dynamic meteorology and apply the concepts of the Eulerian and Lagrangian perspectives to discuss our experiential journeys through the weather and Covid-19. I also will query what this means for how we cope when severe weather threatens us during this pandemic.

From the Eulerian perspective, we depict the current weather or make a forecast for a given space (county warning area, city, state, region) for a time (6 hours, 12 hours, and so on). We concern ourselves with what will occur inside the grid boxes of a model—what is the flux of weather into and out of the area? Similarly, when we look out of the windows of our life-spaces we see and experience the weather. And what is so striking about what we see is that most of the time the weather seems within its usual seasonal limits—climatologically speaking. The weather is often pleasant. It seems not to have gotten the message about Covid-19.

How could it? The weather just is. Some people have told me that during the pandemic, the closures, and the quarantines, the weather is about the only thing that has remained normal in their lives—and this has provided some degree of comfort. But with a wildfire or a hurricane, this can change quickly. Some of the same states that are threatened by hurricane landfall already have been ravaged by Covid-19.

We can think of peoples’ paths through the meteorological and nonmeteorological events in their lives with the Lagrangian perspective—metaphorically speaking. Life is a journey, a narrative, a path or a force that moves forward in time; sometimes the trajectory changes unexpectedly. The Lagrangian perspective involves the accumulated experiences of the weather through the eyes of the perceivers— individual people. Such Lagrangian living with or “under” the weather builds a corpus of weather experiences that subtly or sometimes significantly changes peoples’ subsequent responses to the weather . All of us are, to varying extents, products of what we have experienced, including the Covid-19 pandemic. So many people—in Michigan, Iowa, California, Louisiana, and elsewhere—have experienced life with both Covid-19 and disaster and displacement.

In dynamic meteorology we learn to use both the Eulerian and Lagrangian perspectives; we segue between the two to build a fuller understanding of the atmosphere. What might we learn and what questions arise when we juxtapose my uses of these perspectives? These are timely questions to consider as we deal with hurricanes, winter storms, and other weather threats during the Covid-19 pandemic.

Trust of Message Sources: During the Covid-19 pandemic, different state and federal agencies often have issued confusing, sometimes contradictory reports and recommendations about the virus. How have peoples’ experiences of this messaging affected the ways that they may receive and act upon forecasts, watches, and warnings for severe/extreme weather? How might weather-related messages from local emergency managers or health departments be received? To what extent has the trust in the weather enterprise been affected by pandemic-related messaging?

Risk Perception and Tolerance: People have dealt with multiple risks thus far during the pandemic: health, economic/financial, social, and psychological, among others. Have the experiences of these risks affected how people perceive additional risks from thunderstorms, tornadoes, floods, and hurricanes? Because people may have successfully survived an infection with Covid-19, does this affect how they perceive their risks to natural hazards? Do some people feel lucky? Because people may be more desperate for work or to keep a job, might they take additional risks to do their jobs during bad weather? Might some businesses take extra risks in bad weather to build a competitive advantage—to make up for past losses?

Preparation: As word of the pandemic spread, people in many places stocked up on consumables for daily living, leading to shortages of some items. Given how the pandemic has unfolded in different parts of the country, are people still prepared? Have they exhausted those supplies and are people fatigued from stocking up? Are suppliers ready for further waves of Covid-19 and/or a major hurricane landfall? Has stocking up and preparing made people more ready for severe weather? Is there a new appreciation for being prepared for the unexpected?

Sheltering in Place: Some severe weather events involve sheltering in place. Given the extensive sheltering in many places in the spring because of Covid-19, would some prefer to shelter in place rather than risk Covid-19 exposure elsewhere? Alternatively, would some be less likely to shelter in place because they are fatigued from it?

Evacuation Planning: Important questions involve what happens when evacuations are necessary: For example, how can the spread of Covid-19 infection be limited? Are separate shelters needed for those who are infected? How does social distancing work in the close quarters of a shelter? Are more shelters needed? Do the existing shelters have a supply of face masks and other personal protective equipment?

Interdisciplinary social and atmospheric science points to an ever-motivating realization: Often it is not simply a matter of providing a timely and accurate forecast, but it is what people do with the information they have that affects the outcomes. This is unsettling because it is often out of the direct control of the weather enterprise—much as epidemiologists and physicians cannot control how people deal with the risks of Covid-19. Efforts to communicate effectively, educate, and persuade stakeholders about the weather take on great importance. Forecasts and warnings are absorbed by people who have experienced the varying and cumulative effects of Covid-19. Being mindful of this reality may help us to better prepare people and communities.

 

 

 

Hurricane Sally's Extreme Flood Potential

Hurricane Sally is inching ashore in southeast Alabama Wednesday morning and has started to flood parts of the central Gulf Coast with an expected 1-2 feet of rain, maybe more. With that much rain forecast, it seems likely to join other recent catastrophic flood disasters Harvey (2017) and Florence (2018) in ushering in a new era of rainier storms at landfall that bring with them an extreme rain and flooding threat.
Sally_rainfall-3
Recent research by NOAA’s Tom Knutson and a team of tropical weather and climate experts in the March Bulletin of the American Meteorological Society and blogged about here determined with medium-to-high confidence that more and more hurricanes in our future warming world will be wetter at landfall.
And with more wetter storms on the way, better communication about these potentially deadly impacts from copious rainfall is needed. Another BAMS article we blogged about addressed this by creating an Intuitive Metric for Deadly Tropical Cyclone Rains. Its authors designed the new tool—the extreme rainfall multiplier (ERM)—to easily understand the magnitude of life-threatening extreme rain events.
Co-author James Kossin explained to BAMS:

Water presents a much greater hazard in a hurricane than wind does, but the Saffir-Simpson categories are based on wind-speed alone. Salt-water hazards along and near the coast are caused by storm surge. Coastal residents are warned about these hazards and are provided with evacuation plans. Fresh-water flooding from extreme hurricane rainfall, however, can happen inland away from evacuation zones, and pose the greatest threat to life and property in these areas where people tend to shelter-in-place. Compound hazards such as dam failures and land-slides in mountainous regions pose additional significant threats. In this case, effective warnings and communication of the threats to inland populations is paramount to reduce mortality. This work strives to present a tool for providing warnings based on people’s past experience, which gives them a familiar reference point from which to assess their risk and make informed decisions.

Lead author Christopher Bosma:

We started out this project focused on analyzing the catastrophic and record-breaking rainfall associated with Hurricane Harvey. But, as we started to finish our analysis of that system, just a year later, Hurricane Florence brought devastating and torrential rainfall to the Carolinas, which forced us to go back and revisit some of our initial analysis. The fact that multiple major storms happened in quick succession grabbed a lot of headlines, but, from a research and scientific perspective, it also provided a chance to note how the messaging used to describe these systems had changed (or not) and think of other ways to use the metric we had developed.

ERM is not yet operational, but that is the researchers’ goal, to “convey effective warnings to people about fresh-water flooding threats,” Kossin says.
Hurricane Sally is one such extreme rainfall flood threat, with “significant to historic flooding” likely, the National Weather Service says.

Hurricane Sally’s Extreme Flood Potential

Hurricane Sally is inching ashore in southeast Alabama Wednesday morning and has started to flood parts of the central Gulf Coast with an expected 1-2 feet of rain, maybe more. With that much rain forecast, it seems likely to join other recent catastrophic flood disasters Harvey (2017) and Florence (2018) in ushering in a new era of rainier storms at landfall that bring with them an extreme rain and flooding threat.

Sally_rainfall-3

Recent research by NOAA’s Tom Knutson and a team of tropical weather and climate experts in the March Bulletin of the American Meteorological Society and blogged about here determined with medium-to-high confidence that more and more hurricanes in our future warming world will be wetter at landfall.

And with more wetter storms on the way, better communication about these potentially deadly impacts from copious rainfall is needed. Another BAMS article we blogged about addressed this by creating an Intuitive Metric for Deadly Tropical Cyclone Rains. Its authors designed the new tool—the extreme rainfall multiplier (ERM)—to easily understand the magnitude of life-threatening extreme rain events.

Co-author James Kossin explained to BAMS:

Water presents a much greater hazard in a hurricane than wind does, but the Saffir-Simpson categories are based on wind-speed alone. Salt-water hazards along and near the coast are caused by storm surge. Coastal residents are warned about these hazards and are provided with evacuation plans. Fresh-water flooding from extreme hurricane rainfall, however, can happen inland away from evacuation zones, and pose the greatest threat to life and property in these areas where people tend to shelter-in-place. Compound hazards such as dam failures and land-slides in mountainous regions pose additional significant threats. In this case, effective warnings and communication of the threats to inland populations is paramount to reduce mortality. This work strives to present a tool for providing warnings based on people’s past experience, which gives them a familiar reference point from which to assess their risk and make informed decisions.

Lead author Christopher Bosma:

We started out this project focused on analyzing the catastrophic and record-breaking rainfall associated with Hurricane Harvey. But, as we started to finish our analysis of that system, just a year later, Hurricane Florence brought devastating and torrential rainfall to the Carolinas, which forced us to go back and revisit some of our initial analysis. The fact that multiple major storms happened in quick succession grabbed a lot of headlines, but, from a research and scientific perspective, it also provided a chance to note how the messaging used to describe these systems had changed (or not) and think of other ways to use the metric we had developed.

ERM is not yet operational, but that is the researchers’ goal, to “convey effective warnings to people about fresh-water flooding threats,” Kossin says.

Hurricane Sally is one such extreme rainfall flood threat, with “significant to historic flooding” likely, the National Weather Service says.

Keeping Score When Temperature Records Are the Expectation

Through July, 2020 has been on almost the same track as 2016: the two years had the hottest first seven months in NOAA’s 141 year dataset of global surface temperatures (land and ocean combined). Since 2016 turned out to be the hottest year on record, it might seem as if this fast start puts 2020 on track to set a new record, too, or to be a near miss. NOAA says it’s already “very likely” 2020 will be among the five hottest years on record.

But in the strange reality of ever rising global temperatures, it’s not so much the first half of the year that puts 2020 on the verge of a record. It’s the underlying trend of warming: 2020 was already on the verge on New Year’s Day.

As the new State of the Climate in 2019 released last week points out, the six hottest years in the last century and a half were…exactly the last six years, 2014-2019. Due to global warming, practically every year’s surface temperature is going to be a hot one. Just by showing up at the starting line, every year is a serious threat to set a new standard.

A paper recently published in the Bulletin of the American Meteorological Society puts this relentless streak of rising temperature expectations in terms of probabilities. There’s a greater than a 99% chance that most of the next 10 years through 2028 will be ranked among the top 10 warmest.

The study, by Anthony Arguez (NOAA/NCEI) et al. also finds an 82% chance that all years in the next decade will rank in the top 15 warmest years as global warming continues. Its authors suggest that record warm years are already “baked into the cake” of Earth’s global climate and that it would take “an abrupt climate shift for even a few years within the next decade to register outside the top 10 warmest years.”

To determine these odds, the researchers analyzed the monthly version of NOAA’s Merged Land Ocean Global Surface Temperature Analysis Dataset (NOAAGlobalTemp) to project annual global temperature rankings in the future. The ever-shifting expectations for global temperatures render the usual way of keeping tabs on the data—by comparing to 30-year normals—inadequate. So Arguez et al. formulated a new way to compare each year to surrounding years:

We introduce a “temperature score”  to help NOAA communicate the coolness or warmth of a given year relative to the long-term trend. We believe this is the first such projected ranking and temperature score currently produced operationally. Our objective is to use this tool to improve the communication of climate change impacts to the general public.

Top 10The temperature score from 1 (a very cold year) to 10 (very warm) is useful to distinguish between warmer and colder years relative to the long-term trend. As examples, the authors note that 2008 and 2011 were considerably cooler than surrounding years and below the overall trend, whereas 1998 and 2016 were not only the warmest years on record but were also notably warmer than surrounding years.

The study only includes average annual global temperatures through 2018. But as reported in the annual State of the Climate, 2019 ranks as the second or third warmest year on record (depending on your favored dataset), adding another year to the recent string of those warmer than any years back to the mid 1800s. The report notes that each successive decade since 1980 has been warmer than the previous. Arguez’ research suggests that not only will this continue but it will worsen dramatically.

This is a testament to the exceptional warmth experienced over the last few decades, punctuated by the last [5] years [2015–19], which have separated themselves from “the pack.”

We asked Arguez a few questions (more found in the latest print/digital issue of BAMS) about this work as well as about his background and what sparked his interest in meteorology.

Anthony_ArguezBAMS: What would you like readers to learn from your study of record global temperatures?

Anthony Arguez: I would like the general public to know that there is not a great deal of suspense that most years—if not all—over the next decade will likely register as top 10 years. In fact, the data suggest we should expect this, as it would likely take a pretty abrupt change to get us off this trajectory.

BAMS: How did you become interested in finding new ways to analyze the global temperatures and their trend?

AA: I feel like I’ve been staring at the annual global temperature time series continually over the past 15 years or so because it is just so interesting in many ways. I find it challenging and rewarding to develop methods to translate volumes of data into answers to specific questions posed by the general public. I’ve drawn inspiration from Nate Silver, whose penchant for expounding on and communicating the “signal” hidden in the “noise” informs the way I would like to see myself and fellow climate scientists communicate to the general public more effectively.

BAMS: What surprised you most in doing this work?

AA: I was very surprised that the ranking errors we found were so small! Before calculating the results, I had a gut feeling that these errors would be modest, but the mean absolute ranking error of ~2 spots a full 10 years out was well below anything I could have imagined. I clearly under-appreciated the predictability inherent in the observed upward trend when it comes to annual global temperature rankings.

BAMS: What was the biggest challenge?

AA: I think the biggest challenge we faced was that we were not aware of any similar operational products in existence (neither for projected rankings or global annual temperature scores), or of any papers that had characterized ranking errors in a similar fashion, so we were in uncharted territory to some extent.

BAMS: This isn’t the biggest climate challenge, or surprise, you’ve ever faced…

AA: I became interested in meteorology as a teenager in 1992 when Hurricane Andrew totaled my parents’ home in Miami, Florida.

 

When Hurricanes Become Machines…or Monsters

Officially, the Atlantic season is almost upon us. The season of tropical storms and hurricanes, yes, but more to the point, the season of heat-seeking machines and relentless monsters.

At least, that’s the metaphorical language of broadcast meteorologists when confronted with catastrophic threats like Hurricane Harvey in Houston in 2017. A new analysis in BAMS of the figures of speech used by KHOU-TV meteorologists to convey the dangers of this record storm shows how these risk communicators exercised great verbal skill to not only connect with viewers’ emotions, but also convey essential understanding in a time of urgent need.

For their recently released paper, Robert Prestley (Univ. of Kentucky) and co-authors selected from the CBS-affiliate’s live broadcasts during Harvey’s onslaught the more than six hours of on-air time for the station’s four meteorologists. The words the meteorologists used were coded and systematically analyzed and categorized in a partly automated, partly by-hand process. No mere “intermediaries” between weather service warnings and the public, the meteorologists—David Paul, Chita Craft, Brooks Garner, and Blake Matthews—relied on “figurative and intense language” on-air to “express their concern and disbelief” as well as explain risks.

As monster, the hurricane frequently displayed gargantuan appetite—for example, “just sitting and spinning and grabbing moisture from off the Gulf of Mexico and pulling it up,” in Paul’s words. The storm was reaching for its “food,” or moisture. The authors write, “The use of the term ‘feeder bands’…fed into this analogy.” Eventually Matthews straight out said, “We’re dealing with a monster” and Craft called the disaster a “beast.”

When the metaphor shifted to machines, Harvey was like a battery “recharging” with Gulf moisture and heat or a combustion engine tending to “blow” up or “explode.” Paul noted the lingering storm was “put in park with the engine revving.”

Other figurative language was prominent. Garner explained how atmospheric factors could “wring out that wet washcloth” and that the saturated ground was like “pudding putty, Jello.” The storm was often compared to a tall layered cake, which at one point Garner noted was tipped over like the Leaning Tower of Pisa.

In conveying impact risks, the KHOU team resorted frequently to words like “incredible” and “tremendous.” To create a frame of reference, they initially referred to local experience, like “Allison 2.0”—referring to the flood disaster caused by a “mere” tropical storm in 2001 that deluged the Houston area with three feet of rain—until Harvey was clearly beyond such a frame of reference. Then they clarified the unprecedented nature of threats, that it would be a storm “you can tell your kids about.”

The authors note, “By using figurative language to help viewers make sense of the storm, the meteorologists fulfilled the “storyteller” role that broadcast meteorologists often play during hurricanes. They were able to weave these explanations together with contextual information from their community in an unscripted, ‘off-the-cuff’ live broadcast environment.” They conclude that the KHOU team’s word choices could “be added to a lexicon of rhetorical language in broadcast meteorology” and serve as a “a toolkit of language strategies” for broadcast meteorologists to use in times of extreme weather.

Of course all of this colorful language was, perhaps, not just good science communication but also personal reality. Prestley et al. note: “The KHOU meteorologists also faced personal challenges, such as sleep deprivation, anxiety about the safety of their families, and the flooding of their studio. The flood eventually forced the meteorologists to broadcast out of a makeshift studio in a second-floor conference room before evacuating their building and going off air.”

As water entered the building, Matthews told viewers, “There are certain things in life you think you’ll never see. And then here it is. It’s happening right now.”

The new BAMS article is open access, now in early online release.

 

Is It Just Us…or Was That the BBQ Talking?

So many conversations at the 2018 AMS Annual Meeting started–and ended–on the same note, and Dakota Smith captures it just right in his “Weather Nerds Assemble” vlog:

Communication is a huge aspect in this field….If a forecast is a hundred percent accurate, but no one understands it, it’s not a useful forecast. That in a nutshell was what this meeting was about.

According to Smith, all that geeked out conversation amongst 4,200 weather, water, and climate nerds added up to at least these four lessons:

  1. The future is bright: “I talked with so many intelligent, bright, passionate students who are bound to make an impact on our community. Keep up the grind!”
  2. Meteorologists are incredibly strong: The communications workshop reflecting on the experience of Harvey, Irma, and Maria showed that  “meteorologists across the country used…love and passion to fuel them through this relentless hurricane season.”
  3. Austin has incredible BBQ.
  4. Meteorologists are awesome. “I already knew this before…we love weather, and we love science!”

The last two are obvious, right? The first two make our day. Share your own take-away points; meanwhile, you owe yourself the injection of enthusiasm–just in case you got lost in the trees since returning home: