August 25

NOAA Weather Radio: Cheapest Life Insurance Around – Anatomy of a Deadly Flash Flood in Tennessee

Cheap Life Insurance: NOAA Weather Radio
Paul Douglas

My NOAA Weather Radio Alarmed Me

During the wee hours of Tuesday morning I was momentarily convinced we were under attack. Alarms blaring, a strobe light flashing in our bedroom. After unplugging the alarm clock it dawned on me that my NOAA Weather Radio was going off – for the first time in months. I’ve never been happier to see continuous lightning and hear rolling thunder, which sounded like artillery shells going off.

1-2 inches of rain soaked much of central and southern Minnesota and Wisconsin from a “meso-convective system”; a 200- mile-wide swarm of strong to severe storms.

A fresh Canadian breeze arrives today, but more thunderstorms ripple east along a frontal boundary separating sweaty and comfortable. Another 1-3 inches of rain may fall from tomorrow into Saturday night. If that verifies some of us may wind up with 3-5” of rain for the week, almost half the moisture needed to recover from the worst drought since 1988.

Expect cool 70s for Day 1 of the Minnesota Fair but I see a run of 80s and a few 90s in September.


Drought-Denting Rains Part II
Twin Cities National Weather Service

From Drought to Flood? It’s 2021 – anything can happen, and at this point nothing would surprise me. Training thunderstorms may create flash flooding in some communities by Friday. Drought to flood in the meteorological blink of an eye? Wait for it.


Tuesday morning rainfall amounts
Twin Cities National Weather Service

Tuesday’s Meso-Convective System (MCS)
CSPP GeoSphere
GR2Analyst

A Convective Swarm. Here is what satellite imagery and Doppler radar looked like around 8:30 am this morning – with heavy rain and lightning 100-200 miles behind the initial surge of thunderstorms. Multiple waves of heavy thunderstorms left behind 1-2” of rain for much of central and southern Minnesota and Wisconsin.



Heating Up Again in September. After a few cooler blips tomorrow, again next week, long range model guidance continues to build a big, fat high pressure ridge over the central US, suggesting another run of 80s and a few 90s by the second week of September. For the record we’ve already enjoyed 26 separate 90-degree days at MSP (average for an entire summer is 12 days).


More Encouraging Trends. NOAA CPC is predicting a wet bias for the Dakotas and Minnesota into mid-September with temperatures (slightly) above average. There is a basis for cautious optimism in the short term.



Vehicles in a stream on Aug. 22 in Waverly, Tenn.
Mark Humphrey/AP

On Saturday a Catastrophic Flash Flood Unfolded in Tennessee. Here’s How it Happened. Capital Weather Gang has a very good overview – here’s an excerpt: “…Radars estimated that 21 inches of rain fell over the community in a single day; nine inches fell in just three hours. A rain gauge measured 17 inches of rain in 24 hours, which will set a new daily record for the state if confirmed. “[T]he chance of getting over 17 inches of rain in 24 hours in any year at Waverly, TN is much more rare than 1 in 1,000,” wrote Geoffrey Bonnin, a hydrologist retired from the National Oceanic and Atmospheric Administration (NOAA), in a Facebook message to the Capital Weather Gang. He said that amount of rain is so rare that NOAA doesn’t have sufficient historical data to quantify it any further...”


“Henri” Drenches Northeast; Death Toll at 21 in Catastrophic Tennessee Flash Flood Yale Climate Connections has a good overview of a deadly storm: “...As recently as the 1970s, flash floods in the United States sometimes resulted in 100 or more deaths. More recently, with heightened awareness of flash flood risks and improved communication of flash flood warnings, death tolls have tended to be much smaller. It appears the Tennessee disaster is the nation’s deadliest localized flash flood in decades. A flash flood on October 18, 1998, killed 31 people in San Marcos, Texas. Flash floods are typically driven by rapid water rises in small channels as a result of persistent thunderstorm rains. They are distinct from broader-scale river flooding and from coastal storm-surge flooding during hurricanes. Some larger-scale flooding events, such as the one that killed 27 people across Tennessee on May 1-3, 2010, include both flash and river flooding, as did the deadly inland floods associated with such tropical cyclones as Floyd (1999), Allison (2001), and Harvey (2017)....”



The Southwest’s Most Important River is Drying Up. CNN.com has details on an increasingly dire water scenario shaping up for the southwestern US; here’s an excerpt: “…Today, this river system supplies 40 million people in seven western states and Mexico, and irrigates more than 5 million acres of farmland on its way into Mexico and the Gulf of California. Las Vegas relies on the river for 90% of its water supply, Tucson for 82% and San Diego for around 66%. Large portions of the water used in Los Angeles, Phoenix and Denver also come from the river, and experts say these booming metropolises would not have been possible without its supply. But a crisis is unfolding, and farmers, scientists, water managers and policy makers across the Southwest are increasingly alarmed. Water managers have long recognized that the river is plagued by overuse. But over the last two decades, demand for the river’s water has often outstripped its supply. Since 2000, the river’s flows have shrunk by roughly 20% compared to the 20th century average, due in large part to the human-caused climate crisis…”


Climate Stories…

Germany’s Deadly Floods Were Up to 9 Times More Likely Because of Climate Change, Study Estimates. CNN.com has details: “…The study, conducted by 39 scientists and researchers with the World Weather Attribution (WWA) project, also found that the most extreme rain was a once-in-400-year event, and that climate change increased the intensity of daily extreme rainfall by 3% to 19%. “These floods have shown us that even developed countries are not safe from severe impacts of extreme weather that we have seen and known to get worse with climate change,” Friederike Otto, the associate director of the Environmental Change Institute at the University of Oxford, said in a statement. “This is an urgent global challenge and we need to step up to it. The science is clear and has been for years…”


Greenland: Rain Fell at Summit For First Time on Record. CNN.com reports; here’s a clip: “…For the first time on record, precipitation on Saturday at the summit of Greenland — roughly two miles above sea level — fell as rain and not snow. Temperatures at the Greenland summit over the weekend rose above freezing for the third time in less than a decade. The warm air fueled an extreme rain event that dumped 7 billion tons of water on the ice sheet, enough to fill the Reflecting Pool at the National Mall in Washington, DC, nearly 250,000 times. It was the heaviest rainfall on the ice sheet since record keeping began in 1950, according to the National Snow and Ice Data Center, and the amount of ice mass lost on Sunday was seven times higher than the daily average for this time of year…”


Good News: The Media is Getting the Facts Right on Climate Change. Grist has the post; here’s an excerpt: “…It might be kind of a chicken-and-egg situation: The media reflect their audience and help shape its views. Some 64 percent of Americans now say that reducing the effects of climate change is “a top priority,” according to Pew Research polling. Less than 40 percent gave that response five years ago. The previous study encompassing press coverage of climate science from 1988 to 2002 found that only 35 percent of it accurately reflected the scientific discourse. At the time, the U.S. media was consistently biasing reporting of the subject by presenting “both sides” of the “debate” as equally valid, according to the analysis. That initial study made a splash, getting cited by Al Gore in An Inconvenient Truth and causing “introspection” among some journalists, Boykoff said. Despite being outdated, his article continued to be referenced nearly two decades later — which was why he figured it was time for an update…”


Bee Flight Suffers Under Temperature Extremes. ScienceDaily explains: “Rising temperatures could help some northern-latitude bees fly better, but more frequent extreme weather events could push them past their limits. Bees’ flight performance affects their ability to pollinate plants — a crucial service for many of our crops. Now, researchers from Imperial College London have measured the relationship between bumblebee flight performance and surrounding temperature. Measuring the motivation of bumblebees to fly and their flight endurance, the team found performance rose rapidly from the lower tested limit of 12oC and peaked between 25-27°C. Beyond this, however, they found performance started to decline. Their results indicate that whilst bumblebees found in more northern latitudes may see benefits to flight performance under future climate warming, populations in southern latitudes, where temperatures above 27oC are more readily exceeded, may be adversely affected. The results are published today in Functional Ecology…”



Note: Local factors such as tides and coastal profile will influence the extent of the floodplain.
Union of Concerned Scientists

Climate Change is Making Hurricanes More Dangerous. Wind speeds often receive the most airtime, but the greatest risk from hurricanes is storm surge flooding and inland flooding as these massive storms come ashore. Here’s an excerpt from a good explainer and infographic from CNN: “…If humans continue to emit heat-trapping gases into the atmosphere, scientists expect that sea levels will climb even higher, putting major cities at an even greater risk. Sea levels are now likely to rise more than 3 feet by 2100, according to the findings of a landmark report published last year by the UN’s Intergovernmental Panel on Climate Change. Generally speaking, a rise in sea levels of 2 to 3 feet would mean that a Category 1 hurricane could be capable of inflicting the kind of storm surge damage we would expect today from a Category 2 storm. In the Southeastern US alone, the annual cost of storm surge damage is projected to grow to $56 billion by 2050, according to the US government’s 2018 National Climate Assessment. And that’s even if global emissions of heat-trapping gases are moderately curbed in the next two decades…”


Tennessee Floods Show a Pressing Climate Danger Across America: Walls of Water. As in flash flooding like we haven’t witnessed before, according to research highlighted at The Washington Post (paywall): “…Tennessee’s flash floods underscore the peril climate change poses even in inland areas, where people once thought themselves immune. A warmer atmosphere that holds more water, combined with rapid development and crumbling infrastructure, is turning once-rare disasters into common occurrences. Yet Americans, who often associate global warming with melting glaciers and intense heat, are not prepared for the coming deluge. Inland flooding is the leading cause of death associated with tropical cyclones in the past 50 years, according to the Federal Emergency Management Agency. On average, damage from inland floods costs more than any other severe weather event. It’s a problem from the mountains of western North Carolina, where Tropical Storm Fred killed five people last week, to the streets of Dearborn, Mich., where heavy rains have repeatedly overwhelmed the sewer systems and destroyed homes…?


Can This Sun-Reflecting Fabric Help Fight Climate Change. WIRED.com (paywall) has details: “In 2020, a graduate student from Zhejiang University in China donned a seemingly plain white vest and sat in the direct sunlight for one hour. A few feet away, researchers monitored his body temperature with infrared cameras and sensors on his skin. Half of the vest was made from ordinary cotton; the other of metafabric, a new, experimental textile made of synthetic fibers and nanoparticles that reflect light and heat. After an hour in the sun, the half of the student covered in the metafabric was nearly 5 degrees Celsius cooler than the side covered by the cotton vest, researchers reported earlier this month in Science. Metafabric is the latest development in a broader emerging field of textiles for personal heat management, clothing that can heat or cool the wearer. Researchers hope that these textiles will not only enhance personal comfort, but reduce injury and death from extreme heat.


Paul Douglas

Study Finds “Very Concerning” 74% Increase in Deaths Associated with Extreme Heat Brought On By Climate Crisis. CNN.com has results of new research: “A pair of new studies out Thursday find a “very concerning” rise in the number of climate-related deaths and paint a picture of world where people struggle with regular temperature extremes. One of the studies finds the number of deaths caused by high temperatures increased by 74% globally between 1980 and 2016. Deaths related to extreme cold increased 31% since 1990, a new report, the first of its kind, finds. Human-caused climate changegenerated by carbon, methane and other greenhouse gas emissions from industry, transportation, and agriculture — has led to a “new normal” with more days of extreme temperatures than in recorded history. The studies published Thursday provide more evidence that both hot and cold extremes can be deadly…”

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