Weather forecasters’ worst fears regarding Hurricane Harvey are being realized in Houston, the nation’s 4th-largest city, as a historic deluge pounded the city overnight and into Sunday morning, with no signs of relenting. Widespread, “catastrophic” flooding is occurring, with emergency responders struggling to rescue people from rapidly flooding homes.
Officials report at least 1,000 people were rescued overnight from rising waters, and the National Weather Service (NWS) has been issuing some of the most dire flood warnings in its history.
After 1 to 2 feet of rain fell on Saturday into Sunday morning, much of it in a deluge overnight, a flash flood emergency — the highest category of flood warning — was issued for all or parts of 11 counties.
And the rain is not over yet — not by a longshot. Heavy rain is forecast to continue in the Houston area on Sunday, Monday, and possibly beyond that. In fact, some meteorologists are suggesting this flood event could go down in history books as one of the — if not the worst flood in U.S. history.
The rainfall amounts as well as the geographic scope of the flooding is likely to exceed a benchmark flood for the area, which was also related to a slow-moving tropical storm. Tropical Storm Allison killed 41 and did $9 billion in damage when it hit in 2001. This storm will likely cause far more damage, in part because the region is even more urbanized now, as well as because of the broad footprint of heavy rain totals from this storm.
Houston is particularly prone to flooding from heavy rainfall. A network of bayous crisscrosses the city, and they are both a blessing and a curse, since they help to drain rainwater from the city but can be a cause of major flooding when they overflow. As of Sunday morning, most bayous, flood channels, and rivers in the Houston area were well above their banks, and many have already hit record levels and rising.
Images on social media have shown the severity of the flooding.
Forecasts call for waves of heavy rain to continue to affect Houston during the next 12 to 18 hours, and possibly as long as the next 2 days, as Harvey keeps a firehose of moisture from the Gulf of Mexico pointed at the Texas coast.
This will likely be a benchmark US flooding disaster centered on the US’ 4th biggest city – as bad as it gets. Their fight is just beginning
— Taylor Trogdon (@TTrogdon) August 27, 2017
“It’s bad and it’s going to likely stay bad through the day,” said the Houston weather blog Space City Weather.
The rains are directly tied to the nearly stationary Tropical Storm Harvey, which is pinwheeling across southeastern Texas, cut off from atmospheric steering currents that could push it out of the area. Some computer models even take Harvey back out into the Gulf of Mexico, where it could re-intensify somewhat, and then back over land in northeast Texas.
Across much of the U.S. and around the world, extreme rainfall events are becoming more common as the world warms. In addition, scientists expect that as human-caused global warming continues and the atmosphere holds more moisture, tropical storms and hurricanes will produce heavier rains.