More than 1 million power outages in Texas, most in the Houston area, as storms bring ‘life-threatening’ flood risk to Texas and Louisiana.

CNN
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Strong storms battered parts of Texas with damaging winds and potentially dangerous flooding, while power outages left more than a million homes and businesses in the dark across the state on Thursday, storms torrential rains hitting an already soggy south.

A rare Level 4 of 4 risk of excessive precipitation was issued Thursday for parts of east Texas and west Louisiana by the Weather Prediction Center. More than 600,000 people live in the high-risk zone.

High-risk days occur on only 4% of days per year, but account for more than 80% of all flood damage and more than a third of all flood deaths in the United States, according to the WPC . Only three other days have reached this worrying level this year, the most recent of which was almost three weeks ago.

It’s a sign that the atmosphere is ready to shed extreme amounts of rain, an increasingly common phenomenon in a world warming due to human-caused climate change.

Rainfall totals of 2 to 6 inches are expected from Texas to Georgia through Saturday morning. Some areas affected by multiple torrential storms may receive 8 inches or more of rain. It’s not out of the question that one or two places could record nearly a foot of rain in about 48 hours.

Texas and Louisiana have been in the lurch since the beginning of April under seemingly incessant torrential rains. Precipitation in the waterlogged area over the past two weeks is more than 600% of normal, according to the WPC.

Double-digit rainfall totals of between 20 and 30 inches across the region in recent weeks have soaked the ground and swollen rivers, bringing the threat of flooding to extreme levels.

Soggy soils are not expected to absorb Thursday’s precipitation, the WPC warned Thursday morning. Widespread flash flooding could begin within minutes of heavy rain beginning.

Storms, some severe, erupted Thursday afternoon in parts of Texas and triggered flash flood warnings for several cities, including Waco. Powerful and severe storms will push south and east and reach Louisiana and Mississippi late in the day.

Nearly 10 million people are under tornado watch until 10 p.m. PT Thursday in parts of southeast Texas and southwest Louisiana, including Houston and Lake Charles, Louisiana.

A large cluster of thunderstorms moving through the area Thursday afternoon brought a threat of flash flooding from heavy downpours, in addition to the risk of severe storms in the strongest cells. A few tornadoes could occur, scattered and damaging wind gusts could reach 70 mph, and there could be isolated hail up to 2 inches in diameter.

More than 1 million customers across Texas were without power Thursday evening, including more than 800,000 outages reported in Harris County, where Houston is located, according to PowerOutage.us. Harris County is the third most populous county in the United States.

A tornado warning was issued earlier Thursday evening in Harris County, Texas, including downtown Houston, according to the National Weather Service. The weather service also issued a severe thunderstorm warning for Houston with the highest level of “destructive.”

Around 6:30 p.m., the Houston Weather Service noted that a “destructive storm” with wind gusts of up to 80 mph hit the metro area and urged residents to take shelter immediately. in a post on.

Winds in the city reached 71 mph, according to the weather service. On the east side of the city, winds of up to 78 mph were reported.

Winds exceeding 74 mph are equivalent to the strength of a Category 1 hurricane.

Videos shared with CNN on Thursday showed heavy rain and electrical lightning affecting downtown Houston, while howling winds could be heard in the Heights neighborhood.

Houston Mayor John Whitmire advised residents to stay off the roads.

“The Mayor and first responders are asking Houstonians to stay off the roads and avoid unnecessary travel. Many roads are impassable due to downed power lines, debris and fallen trees,” the mayor’s office said in a statement Thursday evening. “There are major power outages and damage has been reported across the city. We are working with Centerpoint, METRO and other regional partners to keep everyone safe.

Rain rates of up to 3 inches per hour are possible during the strongest storms, which could lead to life-threatening flash flooding, according to the WPC. Damaging winds, hail and a few tornadoes are also possible.

The greatest risk of flooding will occur as storms develop later Thursday. Training storms pass through and flood the same areas over and over again, like a train pulling its cars along the same section of track.

Severe flash flooding is likely in all areas affected by multiple storms dumping 2 to 3 inches of rain per hour. Roads can quickly turn into rivers and small streams could easily overflow their banks.

View this interactive content on CNN.com

More than 35 million people in the South are under a Level 2 of 4 or Level 3 of 4 risk of excessive precipitation on Thursday. Many areas may only experience one torrential storm, but even brief downpours will be enough to cause flooding concerns given the South’s recent humidity.

The damaging storms will move eastward Friday and target more of the Gulf Coast.

Significant portions of Mississippi and Alabama are at a Level 3 of 4 Excessive Precipitation Risk on Friday. A larger area from the Texas/Louisiana border to Georgia and the Florida Panhandle is at Level 2 of 4 risk.

Severe storms Thursday evening will likely last into Friday morning for parts of the Gulf Coast. A first wave of flash flooding is likely in the first half of Friday before the rain begins to ease in the afternoon.

Another heavy rain will develop Friday evening and continue into the early hours of Saturday morning, working over the same areas affected earlier in the day. These storms could produce precipitation of 2 to 3 inches per hour and quickly restart or worsen ongoing flooding.

The rain will only add to the already extreme precipitation totals in what has been one of the wettest years on record on the Gulf Coast.

Some cities in the Southeast recorded more than half a foot of rain above normal for the first few months of the year.

Several dozen cities from Texas to west Georgia rank among the five wettest years yet and at least two East Texas cities are experiencing their wettest year, according to the Regional Climate Center from the southeast. Dallas is experiencing its third wettest year to date, while Shreveport, Louisiana, is in the midst of its second wettest year.

Excessive precipitation has largely eliminated drought conditions along the Gulf Coast, but it has not been without cost.

Earlier this month, nearly 2 feet of rain fell in just five days and plunged parts of East Texas underwater. Hundreds of people and animals were rescued from flooding as rivers in some areas reached levels not seen since Hurricane Harvey in 2017.