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Tropical Storm Beta brings heavy rains to coastal Texas, Louisiana as it crawls closer to shore

The Washington Post logo The Washington Post 9/20/2020 Matthew Cappucci, Andrew Freedman
a close up of a map: NOAA's rainfall forecast for Tropical Storm Beta. (NOAA/NHC) NOAA's rainfall forecast for Tropical Storm Beta. (NOAA/NHC)

Tropical Storm Beta is bringing torrential rainfall to stretches of the Gulf Coast in Texas and Louisiana, with flooding possible to kick off the week.

A half-foot or more of rain is likely for millions in the Lone Star State, with isolated double-digit totals possible near Houston and Galveston. Flash flood watches blanket the area as the slow-moving tropical storm nears, and rain bands from the storm were pushing inland Sunday afternoon.

“Flash, urban, and river flooding is likely,” the National Hurricane Center warned Sunday afternoon. “The slow motion of Beta will produce a long duration rainfall event from the middle Texas coast to southern Louisiana.” As the week goes on, heavy rains are forecast to spread into the Lower Mississippi Valley, prompting flood concerns there as well.

Having run out of hurricane names, we've switched to the Greek alphabet. That could present a problem.

Wind and storm surge hazards are accompanying the system while Beta spins slowly toward landfall late Monday into Tuesday near Matagorda Bay, Tex., between Houston and Corpus Christi.

Tropical storm warnings are in effect from Port Aransas, Tex., to Morgan City, La., as a 300-mile stretch of real estate is set to be hit by Beta’s waterlogged rain bands and expansive field of strong winds.

Storm surge warnings are also in effect from Port Aransas to Rockefeller Wildlife Refuge, La., as the storm’s large wind field pushes water onshore. Tropical-storm-force winds extend out to 195 miles from the center of Beta.

Heavy rain was falling in southwest Louisiana early Sunday, drenching some of the same areas still recovering from Category 4 Hurricane Laura in late August. Tropical-storm-force winds of greater than 39 mph were occurring along the Louisiana coast Sunday morning and are expected to spread southwest along the Texas coast with time.

a close up of a colorful wall: Infrared satellite imagery of Beta on Sunday morning. (WeatherNerds.org) Infrared satellite imagery of Beta on Sunday morning. (WeatherNerds.org)

As of 5 p.m. Sunday, Beta had maximum sustained winds of 60 mph and was located about 120 miles southeast of Galveston, Tex. The storm was moving west-northwest at 6 mph, which is twice as fast as it was Sunday morning.

Beta is the second tropical or subtropical cyclone in 15 years to be named after a Greek letter, following behind Alpha, a rare subtropical storm that brought damaging winds to Portugal on Friday. This hurricane season has been spawning storms at a record pace, well ahead of the most active season on record, which occurred in 2005.

Beta is located in an area of weak upper-level winds, causing it to be slow-moving, which will exacerbate the flood threat. However, its poor organization and nearby dry air will help limit the flood potential.

a close up of a map: The National Weather Service's rainfall estimates through Wednesday morning. (WeatherBell) The National Weather Service's rainfall estimates through Wednesday morning. (WeatherBell)

The Hurricane Center indicates that while a few areas may see rainfall totals of up to 15 inches, primarily close to the coast in the vicinity of Galveston Bay, a more widespread swath from the middle Texas coast to southern Louisiana is likely to receive between 6 and 12 inches of rain.

However, it remains difficult to determine where the heaviest rain will fall. It appears that southwest Louisiana may see totals of one foot or greater, which is likely to cause flooding in already waterlogged areas hit hard last month by Hurricane Laura.

More than 30,000 are still without power in parts of coastal Louisiana from that storm, and many still lack access to fresh water.

In the Houston-Galveston corridor, bands of rainfall will probably pivot into the area by early Sunday afternoon, becoming moderate to heavy at times. Rainfall rates of an inch per hour or more are possible Sunday evening, with even heavier rainfall arriving overnight into Monday.

The Houston metro area is familiar with the risks of slow-moving tropical storms and hurricanes, having gone through Tropical Storm Allison in 2001, which caused at least $5 billion in damage, and Hurricane Harvey in 2017, which delivered the heaviest rainfall associated with a tropical storm or hurricane on record in the United States, at 60.58 inches.

While Beta exhibits some similarities to those storms, such as its sluggish movement, the rainfall forecast does not look to be nearly as significant as those historic events.

There is also a chance of heavy rainfall early this week in northwest Louisiana, southwest Arkansas or southern Oklahoma, which would be associated with the interaction between moisture streaming northward from the storm and a stalled frontal boundary. However, that scenario looks less likely than it did earlier in the weekend.

a close up of a map: The National Hurricane Center's storm surge projections for Tropical Storm Beta. (NOAA) The National Hurricane Center's storm surge projections for Tropical Storm Beta. (NOAA)

In addition to heavy rainfall, a broad area of storm surge flooding is also likely along the immediate shoreline from coastal Louisiana to Texas. Storm surge refers to the storm-driven rise in water above normally dry land at the coast.

  • The highest surge amounts, of between 3 to 5 feet, are expected between San Luis Pass to Sabine Pass, Tex., including Galveston Bay.
  • Elsewhere, 2 to 4 feet of storm surge is forecast to occur between Port Aransas to San Luis Pass, including Copano Bay, Aransas Bay, San Antonio Bay, and Matagorda Bay.
  • Two to 4 feet of surge is also forecast for the region from Sabine Pass, Tex. to the Rockefeller Wildlife Refuge in La., including Sabine Lake and Calcasieu Lake.
  • Elsewhere, a general 1- to 3-foot increase in water levels is likely along much of the Texas and western Louisiana coastline,

Coastal flooding has already being reported in Galveston, among other locations.

Strong wind gusts, probably topping 60 mph in some areas, will also move ashore — particularly near Beta’s center — when it makes landfall overnight Monday into Tuesday.

Meanwhile in the Atlantic

Beta isn’t the only tropical storm in the Atlantic right now. Hurricane Teddy will sideswipe Bermuda on Monday as a Category 1 hurricane, barely a week after Hurricane Paulette made landfall as a strong Category 1. Teddy will continue churning northward, eventually transitioning into an extratropical cyclone and bringing strong winds to the Canadian Maritimes.

The remnants of Paulette, meanwhile, could attempt to redevelop in the coming days southeast of the Azores. (If it were to do so, it would not receive a new name for technical reasons.)

There is also Tropical Storm Wilfred, a struggling low-end storm over the open Atlantic that will probably weaken into a tropical storm depression by late Sunday.

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