Houston’s bad weather year could get worse as torrential rains threaten

Rainfall could reach up to 2 to 4 inches per hour during the most severe storms, according to the National Weather Service. Showers are expected to increase through early Thursday before tapering off and becoming more sporadic.

SpaceCityWeather, a Houston weather blog, has placed the city under a “Level 1 Flood Warning,” meaning the city should expect mostly “minor impacts” and “nuisance street flooding.” The flood scale goes up to Level 5, which is unlikely to rival some of the most extreme events in recent history, such as Hurricane Harvey in 2017. But it’s the latest in a string of untoward weather events that have left widespread flooding, downed trees and wires, and hundreds of thousands of customers without power.

Rainfall amounts of 4 to 6 inches are expected along the Texas coast from Brownsville to the Louisiana border, with heavier rain in places. It won’t all fall at once, with intermittent rain through Thursday night. Amounts will taper off quickly inland, but much of the Interstate 10 corridor from Houston eastward is expected to see torrential rain.

Some weather models suggest the most moisture could remain just offshore; others suggest a risk of accumulations of up to 10 inches along the coast.

A stagnant area of ​​high-level low pressure has been present over the central United States for several days, helping to produce showers along its periphery.

Around Houston, atmospheric humidity levels are expected to be exceptional and continually replenished by moist air from the Gulf of Mexico.

A stalled front will also help concentrate showers and thunderstorms Wednesday and Thursday. Some of these could also move slowly. If they persist over the same areas, a quick 3-4 inch rain could fall in just a few hours.

Saturated ground from previous torrential rains will increase the risk of flooding. More than 15 inches of rain have fallen in Houston since June 1, nearly double the normal. Beryl, meanwhile, has dumped between 6 and 12 inches.

Just two weeks ago, Beryl hit Houston as a Category 1 hurricane with wind gusts of 80 to 90 mph. Extended power outages and heat following the storm contributed to many deaths.

And it’s only been two months since a derecho, a fast-moving, violent windstorm, hit Houston, packing winds of 90 to 100 mph (145 to 160 km/h) and an EF1 tornado near Cypress. Then more severe storms hit on May 28, knocking out power to 1.4 million people in Texas.

This year is far from being an anomaly.

Houston is one of the most extreme weather-prone cities in the country. At least 10 tornadoes have hit Harris County in the past five years, including an EF3 tornado on January 24, 2023, that traveled 23.3 miles from Pearland to Baytown near Interstate 10. A deadly winter storm covered the city in ice in mid-February 2021, with temperatures dropping to 13 degrees. Last summer, Houston had 45 days with temperatures at or above 100 degrees. Fifteen hurricanes have directly impacted Houston in the past century, as well as countless tropical storms.

Houston has been the scene of some of the most severe flooding in North America. Houston was almost completely submerged after the remnants of Harvey passed over the region in 2017; a U.S. record of 60.5 inches of rain fell in Nederland, Texas. Harvey was the third five-year (or more) flood in Houston in three years.

As the climate continues to warm, the moisture-holding capacity of the atmosphere will increase significantly. (For every degree of warming in air temperature, the air can hold 4 percent more water.) For places where moisture is readily available, like Houston, just 40 miles inland from the Gulf of Mexico, this translates into heavier rains.

Global warming is also fueling rising ocean temperatures, which can promote last-minute strengthening before a tropical storm or hurricane makes landfall. That was the case with Beryl, which intensified just before landfall. Peer-reviewed papers suggest a link between rising ocean temperatures and stronger storms that are more likely to intensify quickly before making landfall.

Jason Samenow contributed to this report.