Latest news with #JohnNielsen-Gammon
NBC News
09-07-2025
- Climate
- NBC News
How a confluence of extreme weather, geography and timing created Texas' flood disaster
While existing weather models can forecast flash flooding in advance, even the best models struggle to represent internal storm structure and to predict where, within a few miles, the hardest rainfall will strike. In this case, the off-the-charts colors on Friday morning indicated that the south fork of the Guadalupe River was taking a direct and prolonged hit. Then, instead of moving on, the storms stalled. Texas state climatologist John Nielsen-Gammon said that the thunderstorms hovered above the Texas Hill Country river, dumping 10-12 inches of rainfall in about six hours. The series of storms 'perfectly aligned with the South Guadalupe River Basin,' he said. The area is prone to floods and was filled with campers near the river's edge. If the storm had been even five miles in another direction it would not have produced as much destruction, he said. It's difficult to know exactly how much rain fell. The basin that flooded does not have a rain gauge despite being in an area covered by the TexMesonet monitoring system, which was created after a flash flood disaster that struck Wimberley, Texas, over Memorial Day weekend in 2015. But Friday's downpour was a record-setting for that location and a storm seen once every 1,000 years, Nielsen-Gammon said. While National Weather Service forecasters had warned broadly about flash flooding, meteorologists and forecasting experts said the best weather models could not predict precisely where the most intense rainfall would fall, or that the deluge would stall out over a flood-prone basin. 'Even the most detailed weather forecasting models at this point are just barely capable of resolving individual convective storms,' Nielsen-Gammon said, adding that it would be 'next to impossible' to predict well in advance whether successive storms would train over the area, stall out and produce intense flooding in such a confined geography.
Yahoo
08-07-2025
- Climate
- Yahoo
Intense downpours like in Texas, Kentucky are more frequent, but there's no telling where they'll happen
It's not just Texas and North Carolina. Intense rain is falling more frequently in many areas of the U.S.—though where it occurs and whether it causes catastrophic flooding is largely a matter of chance, according to experts. More than 100 people died in Texas Hill Country over the weekend after 12 inches (30 centimeters) of rain fell in just hours. The deluge was driven by warm, moist air left over from Tropical Storm Barry and Hurricane Flossie that created conditions for repeated thunderstorms in the same location, said Texas Climatologist John Nielsen-Gammon. Last year, Hurricane Helene dumped more than 30 inches (76 centimeters) of rain on western North Carolina, triggering catastrophic flooding that washed away roads and homes, killing more than 100 people in that state alone. This week, flooding from the remnants of Tropical Storm Chantal prompted dozens of water rescues in other parts of North Carolina. And this spring, record rainfall in Kentucky caused severe and deadly flooding. Although it can be difficult to attribute a single weather event to climate change—and hilly or mountainous terrain worsens flooding—experts say a warming atmosphere and oceans due to the burning of fossil fuels make catastrophic storms more likely. That's because the atmosphere can hold 7% more water for every degree Celsius (1.8 degrees Fahrenheit), creating a giant sponge of sorts that sucks up moisture from bodies of water and vegetation. The moisture later falls back to earth in increasingly intense, unpredictable and destructive downpours. Read more of the latest Kentucky Derby news 'It's just loading the dice toward heavy rainfall when the situation is right,' said Kenneth Kunkel, a climate scientist at North Carolina State University. Going back through U.S. weather station records dating to 1955, Kunkel found that rain over the past 20 years has become more intense in the eastern two-thirds of the country, including the southern Great Plains, where Texas is located. Intensities have remained the same or declined in the West and Southwest. At the 700 stations that began collecting data in the late 19th and early 20th centuries, the highest proportion of two-day rainfall records have been set in just the past 10 years, Kunkel said, though that doesn't fully reflect most Western stations, which were established later. Nielsen-Gammon said the overall intensity of extreme rainfall in Texas has increased by 15% over the past 40-50 years. Still, it's almost impossible to predict where the most catastrophic rain will fall in any given year, Kunkel said. 'This month it was the Texas Hill Country's turn to get hit. Last fall … in western North Carolina, it was our turn,' Kunkel said, adding that just because an area was spared over the past 20 or 30 years, it 'doesn't mean that they aren't vulnerable. … They got lucky.' The worst flooding and greatest loss of life in Texas occurred in Kerr County, in an area known as 'flash flood alley' because of its steep terrain that funnels water to the Guadalupe River, a popular recreational area. Though the county did not get the most rain from the storms, the 'distribution of rainfall was one of the worst possible patterns' because the most intense downpours were over the headwaters of the south fork of the Guadalupe River, causing water to rush into areas where hundreds of people, including children, were camping, said Nielsen-Gammon. Crystal Rogers case: Brooks Houck, Joseph Lawson found guilty Intense downpours like in Texas, Kentucky are more frequent, but there's no telling where they'll happen Lexington swim school staff emphasizes summer water safety If the epicenter had been 10 miles (16 kilometers) north or south, the rain would have been divided among different river basins, he said. If it had been farther downstream, larger floodplains would have absorbed and slowed much of the water. Years of drought also likely exacerbated the flooding. Kerr County, for example, had been in extreme or exceptional drought for more than three years, aside from one four-week period last fall. That likely left the soil compacted, which caused water to run off instead of soaking into the ground, said Brad Rippey, a U.S. Department of Agriculture meteorologist. Then, air from the warmer-than-normal Gulf of Mexico—a reflection of global warming—blew into the state with a higher water content than it would have had decades ago. It all added up to 'just a perfect storm of events' that caused a catastrophe, said Rippey. 'There are things that had to come together to make this happen.' Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
Toronto Star
08-07-2025
- Climate
- Toronto Star
Intense downpours like those in Texas are more frequent, but there's no telling where they'll happen
It's not just Texas and North Carolina. Intense rain is falling more frequently in many areas of the U.S. — though where it occurs and whether it causes catastrophic flooding is largely a matter of chance, according to experts. More than 100 people died in Texas Hill Country over the weekend after 12 inches (30 centimeters) of rain fell in just hours. The deluge was driven by warm, moist air left over from Tropical Storm Barry and Hurricane Flossie that created conditions for repeated thunderstorms in the same location, said Texas Climatologist John Nielsen-Gammon.
Winnipeg Free Press
08-07-2025
- Climate
- Winnipeg Free Press
Intense downpours like those in Texas are more frequent, but there's no telling where they'll happen
It's not just Texas and North Carolina. Intense rain is falling more frequently in many areas of the U.S. — though where it occurs and whether it causes catastrophic flooding is largely a matter of chance, according to experts. More than 100 people died in Texas Hill Country over the weekend after 12 inches (30 centimeters) of rain fell in just hours. The deluge was driven by warm, moist air left over from Tropical Storm Barry and Hurricane Flossie that created conditions for repeated thunderstorms in the same location, said Texas Climatologist John Nielsen-Gammon. Last year, Hurricane Helene dumped more than 30 inches (76 centimeters) of rain on western North Carolina, triggering catastrophic flooding that washed away roads and homes, killing more than 100 people in that state alone. This week, flooding from the remnants of Tropical Storm Chantal prompted dozens of water rescues in other parts of North Carolina. And this spring, record rainfall in Kentucky caused severe and deadly flooding. Although it can be difficult to attribute a single weather event to climate change — and hilly or mountainous terrain worsen flooding — experts say a warming atmosphere and oceans due to the burning of fossil fuels make catastrophic storms more likely. That's because the atmosphere can hold 7% more water for every degree Celsius (1.8 degrees Fahrenheit), creating a giant sponge of sorts that sucks up moisture from bodies of water and vegetation. The moisture later falls back to earth in increasingly intense, unpredictable and destructive downpours. 'It's just loading the dice toward heavy rainfall when the situation is right,' said Kenneth Kunkel, a climate scientist at North Carolina State University. Intensifying rain storms Going back through U.S. weather station records dating to 1955, Kunkel found that rain over the past 20 years has become more intense in the eastern two-thirds of the country, including the southern Great Plains, where Texas is located. Intensities have remained the same or declined in the West and southwest. At the 700 stations that began collecting data in the late 19th and early 20th centuries, the highest proportion of two-day rainfall records have been set in just the past 10 years, Kunkel said, though that doesn't fully reflect most Western stations, which were established later. Nielsen-Gammon said the overall intensity of extreme rainfall in Texas has increased by 15% over the past 40-50 years. Still, it's almost impossible to predict where the most catastrophic rain will fall in any given year, Kunkel said. 'This month was the Texas Hill Country's turn to get hit. Last fall … in western North Carolina, it was our turn,' Kunkel said, adding that just because an area was spared over the past 20 or 30 years, it 'doesn't mean that they aren't vulnerable. … They got lucky.' A 'perfect storm' in Texas The worst flooding and greatest loss of life in Texas occurred in Kerr County, in an area known as 'flash flood alley' because of its steep terrain that funnels water to the Guadalupe River, a popular recreational area. Though the county did not get the most rain from the storms, the 'distribution of rainfall was one of the worst possible patterns' because the most intense downpours were over the headwaters of the south fork of the Guadalupe River, causing water to rush into areas where hundreds of people, including children, were camping, said Nielsen-Gammon. If the epicenter had been 10 miles (16 kilometers) north or south, the rain would have been divided among different river basins, he said. If it had been farther downstream, larger floodplains would have absorbed and slowed much of the water. Years of drought also likely exacerbated the flooding. Kerr County, for example, had been in extreme or exceptional drought for more than three years, aside from one four-week period last fall. That likely left the soil compacted, which caused water to run off instead of soaking into the ground, said Brad Rippey, a U.S. Department of Agriculture meteorologist. Then, air from the warmer-than-normal Gulf of Mexico — a reflection of global warming — blew into the state with a higher water content than it would have had decades ago. It all added up to 'just a perfect storm of events' that caused a catastrophe, said Rippey. 'There are things that had to come together to make this happen.' ____ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at
Hamilton Spectator
08-07-2025
- Climate
- Hamilton Spectator
Intense downpours like those in Texas are more frequent, but there's no telling where they'll happen
It's not just Texas and North Carolina. Intense rain is falling more frequently in many areas of the U.S. — though where it occurs and whether it causes catastrophic flooding is largely a matter of chance, according to experts. More than 100 people died in Texas Hill Country over the weekend after 12 inches (30 centimeters) of rain fell in just hours. The deluge was driven by warm, moist air left over from Tropical Storm Barry and Hurricane Flossie that created conditions for repeated thunderstorms in the same location, said Texas Climatologist John Nielsen-Gammon. Last year, Hurricane Helene dumped more than 30 inches (76 centimeters) of rain on western North Carolina, triggering catastrophic flooding that washed away roads and homes, killing more than 100 people in that state alone. This week, flooding from the remnants of Tropical Storm Chantal prompted dozens of water rescues in other parts of North Carolina. And this spring, record rainfall in Kentucky caused severe and deadly flooding. Although it can be difficult to attribute a single weather event to climate change — and hilly or mountainous terrain worsen flooding — experts say a warming atmosphere and oceans due to the burning of fossil fuels make catastrophic storms more likely. That's because the atmosphere can hold 7% more water for every degree Celsius (1.8 degrees Fahrenheit), creating a giant sponge of sorts that sucks up moisture from bodies of water and vegetation. The moisture later falls back to earth in increasingly intense, unpredictable and destructive downpours. 'It's just loading the dice toward heavy rainfall when the situation is right,' said Kenneth Kunkel, a climate scientist at North Carolina State University. Intensifying rain storms Going back through U.S. weather station records dating to 1955, Kunkel found that rain over the past 20 years has become more intense in the eastern two-thirds of the country, including the southern Great Plains, where Texas is located. Intensities have remained the same or declined in the West and southwest. At the 700 stations that began collecting data in the late 19th and early 20th centuries, the highest proportion of two-day rainfall records have been set in just the past 10 years, Kunkel said, though that doesn't fully reflect most Western stations, which were established later. Nielsen-Gammon said the overall intensity of extreme rainfall in Texas has increased by 15% over the past 40-50 years. Still, it's almost impossible to predict where the most catastrophic rain will fall in any given year, Kunkel said. 'This month was the Texas Hill Country's turn to get hit. Last fall ... in western North Carolina, it was our turn,' Kunkel said, adding that just because an area was spared over the past 20 or 30 years, it 'doesn't mean that they aren't vulnerable. ... They got lucky.' A 'perfect storm' in Texas The worst flooding and greatest loss of life in Texas occurred in Kerr County, in an area known as 'flash flood alley' because of its steep terrain that funnels water to the Guadalupe River, a popular recreational area. Though the county did not get the most rain from the storms, the 'distribution of rainfall was one of the worst possible patterns' because the most intense downpours were over the headwaters of the south fork of the Guadalupe River, causing water to rush into areas where hundreds of people, including children, were camping , said Nielsen-Gammon. If the epicenter had been 10 miles (16 kilometers) north or south, the rain would have been divided among different river basins, he said. If it had been farther downstream, larger floodplains would have absorbed and slowed much of the water. Years of drought also likely exacerbated the flooding. Kerr County, for example, had been in extreme or exceptional drought for more than three years, aside from one four-week period last fall. That likely left the soil compacted, which caused water to run off instead of soaking into the ground, said Brad Rippey, a U.S. Department of Agriculture meteorologist. Then, air from the warmer-than-normal Gulf of Mexico — a reflection of global warming — blew into the state with a higher water content than it would have had decades ago. It all added up to 'just a perfect storm of events' that caused a catastrophe, said Rippey. 'There are things that had to come together to make this happen.' ____ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at .
