Much of the United States will experience some form of climate-fueled extreme weather this week, from dangerous heat across the Central and Eastern U.S. to heavy rain and flooding threats in Texas, the Grand Canyon, and Southern California. Unusually warm ocean waters are also amplifying tropical systems and the risk of extreme rainfall, underscoring the widespread influence of human-caused climate change.
Climate-Driven Heat in the U.S. South, Southeast, Ohio Valley, Upper Midwest, and Northeast
High temperatures are forecast to reach the triple digits across the Central and Southern Plains, and temperatures are expected to be in the mid-to-upper 90s across the Eastern United States through at least Friday, September 4. Near-to-all-time record high temperatures are expected in Arkansas, Delaware, Georgia, Kansas, Kentucky, Mississippi, North Carolina, South Carolina, Texas, Virginia, and West Virginia.
Daily maximum temperatures are forecast to reach a CSI level 3 in cities across multiple regions across the Central and Eastern United States, including San Antonio, Miami, and Washington, D.C. A CSI 3 indicates that human-caused climate change is making this event at least 3 times more likely, signaling a significant climate change event.
From August 31 through September 4, more than 192 million people across the central and eastern United States will experience at least one day with average temperatures reaching a CSI 3 or higher, indicating a significant influence from climate change.
Tropical Storm in Gulf to bring rain and floods to Texas
Tropical Depression Five officially formed over the northern Gulf of Mexico around 1 p.m. CDT Monday, with further intensification into Tropical Storm Edouard possible before landfall on Tuesday, September 1. The National Weather Service is forecasting 3 to 5 inches of rain, with isolated amounts of 6 to 9 inches possible over parts of Southeast and East Texas. Rainfall rates exceeding 3 to 4 inches per hour at times could lead to flash flooding in urban and other vulnerable areas.
While a tropical storm is not unusual at this time of year, the ocean temperatures it is encountering are. Sea surface temperatures are 2°F to 2.5°F above average for late August. According to the Climate Shift Index: Ocean, this unusual warmth is made at least 200 times more likely by human-caused climate change.
Flooding in Grand Canyon
Officials announced a second death, with more than a dozen people still unaccounted for following flash flooding Saturday, August 29, along Bright Angel Creek near the North Rim of the Grand Canyon. 0.5 to 1.24 inches of rain fell within just 20 to 30 minutes.
Climate change is supercharging the water cycle — hourly rainfall rates have increased in Northern Arizona since 1970. Coconino County, Arizona already faces annual average flood losses of $20 million or more. The upper-level moisture being pulled into this rain-maker was pulled from the Gulf of Mexico, which is experiencing ocean temperatures 1°F to 3°F above average for late August, made 200 to 800 times more likely by human-caused climate change.
Labor Day weekend storm in Southern California
A tropical depression or tropical storm could form by September 1, several hundred miles south-southwest of southwestern Mexico, potentially strengthening to a strong tropical storm or hurricane as it moves north toward Southern California through the week. Regardless of whether it makes landfall as a defined tropical system, the storm will likely bring heavy rain and extreme humidity to Southern California that would last into the following week, potentially causing flooding.
This tropical system will track over unusually warm ocean waters 3°F to 5°F above average for late August and early September. Along the projected path, this warmth is being made 10 to 50 times more likely by human-caused climate change.
See these events on the Climate Shift Index map or Climate Shift Index: Oceans Map