Beta's flooding rainfall could cut off some communities for days

After making landfall in Texas on Monday, Beta hasn't budged much. Its glacial pace has been adding to excessive rainfall that topped a foot in some locations by Tuesday morning, leaving roadways inundated in southwestern Houston and trapping motorists in high waters.

Beta weakened to a tropical depression at 11 a.m. EDT Tuesday, about 15 miles east-northeast of Victoria, Texas, with winds of 35 mph, according to the National Hurricane Center (NHC). The system had nearly ground to a halt and was only moving northeastward at 2 mph.

Forecasters say Beta will gradually pick up forward speed across the southern United States this week, but not before unleashing more flooding rainfall in the Houston area and triggering pockets of flooding from eastern Texas and Louisiana to Georgia in the coming days.

This image taken on Tuesday morning, Sept. 22, 2020, shows clouds associated with Beta over eastern Texas, and a pronounced swirl of clouds associated with Teddy over the North Atlantic. A band of clouds, associated with a front nearly connects both systems. (CIRA at Colorado State/GOES-East)

The initial slow movement of Beta, which weakened to a tropical rainstorm at 11 p.m. EDT Tuesday, will heighten the flooding dangers, especially across southeastern Texas and the Houston area.

"Rainfall totals of 4-8 inches will be widespread from coastal Texas to southern Louisiana with areas where rainfall can be double or triple that amount and lead to major flooding," AccuWeather Senior Meteorologist Rob Miller said.

The Brays Bayou breached its banks on Tuesday as Beta continued to soak Houston. (Twitter/@SergioChapa)

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Heavy rain got a jump start ahead of Beta's landfall along the central Texas coast early this week. The tropical storm made landfall along the Matagorda Peninsula of Texas during Monday evening. Bands of heavy rain streamed in from the Gulf of Mexico and will continue to do so into Tuesday night in the Houston area.

Radar-estimated storm-total rainfall from Tuesday morning, Sept. 22, 20202, centered on the Houston area shows areas that picked up more than 7 inches of rain (white to gray). (AccuWeather)

As of Tuesday morning, the heaviest rainfall has occurred in the Houston area with Hobby Airport receiving close to 9 inches and Clover Field Airport picking up more than 8.5 inches since Sunday morning. Locally heavier rainfall has occurred.

Additional downpours through Tuesday night can cause rainfall totals to climb from near Matagorda Bay through Houston and close to the Port Arthur, Texas, to a general 8-16 inches with an AccuWeather Local StormMax™ rainfall of 24 inches.

The Houston metro area is prone to flooding due to paved and concrete surfaces on top of a slow-drainage system that can be easily overwhelmed by prolonged torrential rainfall events like the one that Beta is triggering.

People who have lived in the Houston area during late August and early September of 2017 recall that Hurricane Harvey unloaded several feet of rain with up to 61 inches over a several-day period. Harvey resulted in widespread catastrophic flooding.

Even though major flooding from Beta is anticipated around Houston and other communities in the region, the level and coverage of flooding in areas hit the hardest from Harvey is not expected to be matched. Much less rain will fall over interior central Texas with Beta, when compared to that of Harvey, and that should lessen the amount of water coming into the metro area from slightly higher elevations to the northwest.

Still, flooding from Beta will be extensive and serious, if not life-threatening in some neighborhoods, with the worst conditions predicted from southeastern Texas to parts of southern and western Louisiana. Social media footage emerged Tuesday morning showing several creeks and bayous already bursting their banks in southeastern Texas.

"Prolonged road closures may result. Some communities could be cut off from emergency or medical services for hours or even perhaps multiple days," AccuWeather's top hurricane expert Dan Kottlowski warned. "Floodwaters in some locations along the Gulf Coast may take a week or more to recede."

Forecasters and officials urged motorists to avoid driving through flooded areas and to promptly heed evacuation orders as they are given.

Torrential rainfall will end slowly from southwest to northeast along the middle and upper Texas coast through Wednesday night, but it may not clear all of the Houston area until Wednesday afternoon. Runoff and areas of flooding may continue in some neighborhoods into the end of the week.

Farther to the north, a secondary batch of heavy rain has developed along a stalled frontal zone that has come in contact with Beta's moisture along the Arkansa/Louisiana border, westward to the tri-state area of Arkansas, Texas and Oklahoma. Localized flooding of urban areas and streams can occur in this zone with total rainfall of 4-8 inches anticipated into Thursday. Lesser rainfall amounts will affect portions of central Oklahoma to northern Arkansas and the southern tier of Missouri into Thursday as well.

Farther to the east, locally excessive rainfall is still anticipated in portions of southern Louisiana, overlapping areas that were hit hard by Hurricane Laura a few weeks ago. Rainfall will likely delay cleanup and repair in communities across southern Louisiana.

In areas from Mississippi to much of western and central Alabama to northern Georgia, a general 2-4 inches of rain is forecast, which can cause a few problems. There can be pockets of heavier rainfall in this swath, which can lead to localized urban and small stream flooding, mainly from Wednesday to Friday.

Fortunately, dry weather in recent days has helped streams and rivers to recede that were hit with heavy rainfall from Sally.

The circulation center from Beta may end up over the Tennessee Valley, but the core of the soaking rain may shift farther to the east across the interior Southern states.

As rain from Beta continues to move eastward, some downpours are forecast to reach southern and middle Tennessee, central Georgia and the Carolinas prior to the end of this week. The remnants of the same batch of dry, autumnlike air that graced the region this past weekend will still exert enough influence to suppress the rainfall somewhat. This should generally prevent flooding problems from occurring, but precipitation could still lead to disruptions in travel and outdoor activities.

Farther southeast, it is possible that moisture from yet another possible tropical system may cause showers and thunderstorms to fill in over portions of Florida and southern Georgia to the coastal areas of the Carolinas this weekend.

Beta was the ninth named storm to make landfall in the U.S. this year, tying a record set in 1916 for the most storms to strike the continental U.S. in an Atlantic hurricane season, according to Philip Klotzbach, a Colorado State University meteorologist. Sally, Laura, Marco, Isaias, Hanna, Fay and Cristobal are the other storms that crashed ashore in the U.S. in 2020.

Thousands of customers in Louisiana were still without power after Hurricane Laura's devastating blow in late August as Beta began impacting the Gulf Coast.

AccuWeather meteorologists warned that hurricane season is far from over. The official end of the season is Nov. 30, but forecasters said systems could brew into December amid this hyperactive season. In a recent seasonal forecast update, the total number of tropical storms predicted were increased to 28, which would tie the record previously set in 2005.

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