Drought and floods across the U.S.

Summer flooding has been making headlines as scientists are claiming those disasters have been historical rainfall events. The tragic flood in Central Texas in early July is one of the worst flooding disasters in modern history. As much as 15 inches of rain fell in a short period of time. As a result, the Guadalupe River in the region surged more than 20 feet in about 90 minutes, resulting in widespread flash flooding.

According to Texas Flood Insurance, flash flooding is the No. 1 disaster threat in Central Texas. The state has six of the highest 12 rainfall events and amounts ever recorded throughout the world. From 1986 to 2000, the state reported over 4,700 flash floods.

In addition to the horrible events in Texas, flash floods were reported last week in a remote mountain village nearly 200 miles south of Albuquerque, N.M. Parts of North Carolina were hit with up to a foot of rain in 24 hours due to Tropical Storm Chantal. Localized deluges in the Chicago region led to flash flooding of roads.

Flash floods are sudden, intense floods that occur within minutes to a few hours after heavy rainfall or other rapid water release events. Unlike slow-rising river floods, flash floods strike quickly and with little warning, making them among the most dangerous natural hazards, especially in mountainous, urban and arid regions.

The primary cause of flash flooding is extreme rainfall over a short period, usually occurring in hours. This can result from localized thunderstorms, tropical storms or weather systems that have stalled or are very slow-moving. The risk of flash flooding is particularly high when the ground is already saturated or very dry and compacted, preventing water from being absorbed. In addition to rainfall, flash floods can also be triggered by dam failures, ice jams or sudden snowmelt. Urban areas are especially vulnerable due to concrete or asphalt surfaces like roads and sidewalks that increase runoff.

Topography will also play a crucial role in flash flood development. In steep terrain, water flows rapidly downhill, funneling into narrow valleys and streams. This can turn small creeks into raging torrents in minutes. In cities, overwhelmed drainage systems can quickly lead to dangerous street flooding. I’ve seen many videos of cars, homes and buildings being swept away by massive floodwaters in a matter of seconds.

On July 8, 1999, Las Vegas endured one of the most destructive flash flood events in history. Several storms merged over the city and dumped an estimated 28 billion gallons of water. Many locations received nearly a year’s worth of rainfall in less than 24 hours.

The deadliest flash flood in U.S. history was the 1889 Johnstown Flood in Pennsylvania. The event killed over 2,200 people after a dam collapsed. Some of the most tragic flash floods in U.S. history included the Big Thompson Canyon Flood in 1976 and the Rapid City Flood in 1972. They occurred in mountainous areas where rainfall rapidly accumulated and surged through narrow channels.

In Idaho, the worst flash flooding event was the collapse of the Teton Dam on June 5, 1976. The dam’s failure sent a massive wall of water down the Snake River Plain, resulting in 11 fatalities and widespread damage.

The Coeur d'Alene Flood of 1996 was part of a widespread flood disaster that affected much of the Pacific Northwest during late winter and early spring of that year. A combination of heavy rain, rapid snowmelt and warm temperatures led to widespread flooding across North Idaho, especially in the Silver Valley and downstream along the Coeur d'Alene River. It was one of the worst floods in the history of the Coeur d'Alene River Basin and caused significant environmental and economic damage.

With rain and flooding east of the Rockies, most of the western portion of the country is experiencing severe dryness to drought conditions. According to the latest U.S. Drought Monitor, severe to extreme drought conditions are being reported across the Spokane and Coeur d’Alene region.

Since May 21, only 0.08 inches of rain has been reported at Cliff’s station in Coeur d’Alene as of the weekend. According to his records, there hasn’t been another time when conditions were this dry since 1895. Some of the outlying areas have received a little more, but overall conditions in the region have been exceptionally dry. 

The long-range computer models are not showing any indications of a major pattern change through at least the end of the month. There is the possibility we’ll see some isolated showers or a thunderstorm, which is typical at this time of year, but mainly over the mountains.

As I said last week, with an expected dry and hotter first part of the summer season, it’s possible that the second portion of summer may not be as hot or as dry. Eventually, weather patterns in this part of the country will flip to the other side. It’s difficult to say at this time how much moisture we’ll receive in the late summer and fall.

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Contact Randy Mann at [email protected].